SPIDERS, SCORPIONS, CENTIPEDES AND MITES

FRONTISPIECE: H e a d o f S o l i f u g i d ( P h o t o : R i c h a r d L . C a s s e l l )

Spiders, Scorpions,

Centipedes and Mites THE ECOLOGY AND NATURAL HISTORY OF WOODLICE,

'MYRIAPODS' AND ARACHNIDS

By J. L. CLOUDSLEY-THOMPSON M.A., PH.D. (CANTAB.), F.R.E.S., F.L.S.

Lecturer in Zoology,

University of London King's College

P E R G A M O N PRESS N E W Y O R K • L O N D O N

P A R I S • L O S A N G E L E S

1958

P E R G A M O N P R E S S I N C .

122 East 55th Street, New York 22, N.Y.

1 0 6 3 8 South Wilton Place, Los Angeles 47, California

P E R G A M O N P R E S S L T D .

4 & 5 Fi tzroy Square, London W.l

P E R G A M O N P R E S S S . A . R . L .

24 Rue des Ecoles, Paris Ve

C o p y r i g h t

L . C l o u d s l e y - T h o m p s o n

Library of Congress Card Number 5 7 - 1 4 4 9 9

P R I N T E D I N G R E A T B R I T A I N B Y R O B e R T M A C L E H O S E A N D C O L T D .

T H E U N I V E R S I T Y P R E S S , G L A S G O W

C O N T E N T S PAGE

PREFACE VII

I N T R O D U C T I O N I X

Chapter I. WOODLICE 1

Chapter II. MILLIPEDES 15

Chapter III. CENTIPEDES 40

Chapter IV. OTHER 'MYRIAPODS' 61

Chapter V. SCORPIONS 70

Chapter VI. SOLIFUGAE 87

Chapter VII. FALSE-SCORPIONS 99

Chapter VIII. W H I P - S C O R P I O N S A N D OTHERS 114

Chapter IX. HARVEST-SPIDERS 132

Chapter X. SPIDERS 148

Chapter XI. MITES A N D TICKS 182

EPILOGUE 204

GENERAL BIBLIOGRAPHY 207

CLASSIFICATORY INDEX 209

GLOSSARY A N D INDEX OF SCIENTIFIC TERMS 220

INDEX OF GENERAL TOPICS 227

V

P R E F A C E

' If anybody shall reprove me and shall make it apparent un to me that I do err, I will most gladly retract. For it is the t ru th that I seeke after, by which I am sure that never man was hur t and as sure that he is hu r t that continueth in any error or ignorance whatsoever. '

MARCUS AURELIUS

T h i s b o o k w a s c o n c e i v e d l a rge ly a t t h e s ink , w h e r e m o s t m o d e r n

h u s b a n d s h a v e t o s p e n d s o m u c h o f t h e i r l e i su re . M y d e e p e s t

t h a n k s a r e t h e r e f o r e d u e t o m y d e a r wife w h o s h o u l d e r e d far m o r e

t h a n h e r s h a r e o f t h e d o m e s t i c d r u d g e r y i n o r d e r t h a t I m i g h t s l ip

away t o j o t d o w n m y ideas . I w o u l d also l ike t o e x p r e s s m y g r a t i ­

t u d e t o m y f r i ends a n d co l l eagues a t h o m e a n d a b r o a d w h o h a v e

s o g e n e r o u s l y s e n t m e r e p r i n t s o f t h e i r p u b l i c a t i o n s . I n m a n y

cases I h a v e n o t b e e n ab le t o q u o t e t h e s e i n t h e b i b l i o g r a p h i e s for

r e a s o n s o f space , b u t m y d e b t t o t h e w o r k o f o t h e r s i n a t t e m p t i n g

to cove r a v e r y w i d e field in a s ing le v o l u m e m u s t be a b u n d a n t l y

c lear t o t h e r e a d e r .

J . L . C - T .

April 1 9 5 7

vi i

A C K N O W L E D G M E N T S

I should like to make grateful acknowledgment to the following for the use of several of the photographs and illustrations within this book: the Editors of Discovery, Naturalist, The Field and Science News; G. Fryer, R. F . Lawrence, E. A. Robins, J . H. P. Sankey, Duckwor th & Co., Shell Pho to ­graphic Unit , Zoological Society of London, and to Frank W. Lane for photographs by Richard L. Cassell, Walker van Riper and H u g h Spencer .

V l l l

I N T R O D U C T I O N

' T h e evaporating power of the air may be the pr imary factor upon which the organisation of the entire terrestrial fauna depends . '

R. HESSE, W. C. ALLEE and K. P. SCHMIDT

The A r t h r o p o d a i s t h e d o m i n a n t p h y l u m o f t h e I n v e r t e b r a t e s . I n

t h e o c e a n s , m i n u t e c r u s t a c e a n s c o m p r i s e t h e m a j o r c o m p o n e n t o f

t h e z o o p l a n k t o n u p o n w h i c h t h e food c h a i n s o f t h e w h a l e s a n d

l a rge r f ishes a re b a s e d : o n l a n d t h e m e d i c a l , e c o n o m i c a n d b i o ­

logical i m p o r t a n c e o f i n sec t s a n d m i t e s especia l ly , c a n sca rce ly be

o v e r - s t r e s s e d . T h e s e m a y b e v e r y c o g e n t r e a s o n s for t h e i r i n ­

ves t i ga t i on , b u t t h e y a re n o t t h e m o s t i m p o r t a n t . T h e l i t t l e c r e a t u r e s

a re i n t e r e s t i n g i n t h e i r o w n r i g h t , a n d r e s e a r c h i n t o t h e de ta i l s o f

t h e i r l ives p r o v i d e s m e n t a l exe rc i se t h a t i s a s o u r c e of u n e n d i n g

p l e a s u r e a n d i n t e r e s t .

Q u e s t i o n s a re s o m e t i m e s a s k e d a s t o t h e u s e o f a c a d e m i c r e ­

s e a r c h . T h e a n s w e r m a y b e t h a t i t l ies i n m a n ' s n a t u r e t o e x p l o r e

t h e s ec re t s o f t h e u n i v e r s e , for c o m p a r a t i v e l y few in t e l l ec tua l a n d

a e s t h e t i c p u r s u i t s a re m o t i v a t e d b y p u r e l y p rac t i ca l c o n s i d e r a t i o n s .

S c o t t d i d n o t g o t o t h e S o u t h P o l e i n s e a r c h o f coal , n o r d i d B e e t ­

h o v e n w r i t e h i s s t r i n g q u a r t e t s for e c o n o m i c r e a s o n s . T h e b e s t

e x c u s e for c l i m b i n g M o u n t E v e r e s t m a y h a v e b e e n t o ge t t o t h e

t o p , o r s i m p l y b e c a u s e i t w a s t h e r e . P e r h a p s t h e las t w o r d o n t h e

s u b j e c t w a s w r i t t e n by J . S . B a c h . ' T h e a i m a n d final r e a s o n o f all

m u s i c i s t h e g lo ry o f G o d a n d t h e r e c r e a t i o n o f t h e m i n d . ' A n d s o

for all t h e a r t s a n d s c i e n c e s !

M a n y exce l l en t b o o k s h a v e r e c e n t l y b e e n w r i t t e n a b o u t in sec t s

a n d o f all t h e t e r r e s t r i a l A r t h r o p o d a t h e y a re t h e m o s t ca tho l i c .

O v e r 6 0 0 , 0 0 0 spec ies a r e k n o w n t o sc ience a n d t h e to ta l n u m b e r i n

ex i s t ence p r o b a b l y e x c e e d s a m i l l i o n . T h e r e a r e m o r e spec ies o f

bee t l e s i n t h e w o r l d t h a n o f all o t h e r a n i m a l s p u t t o g e t h e r . O n e o f

t h e s e , Niptus hololeucus c an l ive on c a y e n n e p e p p e r a n d t h r i v e on

sal a m m o n i a c . T h i s spec ies h a s b e e n k n o w n t o l ive i n t h e c o r k s o f ix

x I N T R O D U C T I O N

e n t o m o l o g i s t s ' c y a n i d e k i l l i n g - b o t t l e s a n d n o less t h a n 1,547 s p e c i ­

m e n s w e r e t a k e n f r o m a j a r o f case in t h a t h a d b e e n s t o p p e r e d for

twe lve y e a r s . T h e f ly Psilopa petrolei i n h a b i t s p u d d l e s of c r u d e

p e t r o l e u m ; a n d b o t h flies a n d bee t l e s a b o u n d i n c e r t a i n h o t s p r i n g s

i n t h e w e s t e r n U n i t e d S t a t e s w h e r e t h e t e m p e r a t u r e a p p r o a c h e s

50° C . T h e la rges t i n sec t s i n c l u d e t h e A f r i c a n G o l i a t h bee t l e ,

Goliathus regius w h i c h m e a s u r e s f o u r i n c h e s in l e n g t h a n d t w o in

b r e a d t h , a n d t h e V e n e z u e l a n Dynastes hercules, r e a c h i n g a l e n g t h

of 6 | i n c h e s , w h i l e t h e m a g n i f i c e n t bu t t e r f l y Ornithoptera victoriae

of t h e S o l o m o n I s l a n d s h a s a w i n g - s p a n e x c e e d i n g o n e foot . I n

c o n t r a s t s o m e o f t h e p a r a s i t i c H y m e n o p t e r a a r e c o n s i d e r a b l y less

t h a n o n e h u n d r e d t h o f a n i n c h i n l e n g t h , d e s p i t e t h e c o m p l e x i t y o f

t h e i r s t r u c t u r e .

T h e d ive r s i t y a n d ve r sa t i l i t y o f t h e i n sec t s i s n o w h e r e e q u a l l e d

i n t h e a n i m a l k i n g d o m , b u t i n t h i s v o l u m e I h o p e t o s h o w t h a t t h e

o t h e r t e r r e s t r i a l A r t h r o p o d a , a l t h o u g h s o m e w h a t n e g l e c t e d , wil l

well r e p a y f u r t h e r a c q u a i n t a n c e .

F o r m a n y y e a r s , t h e m a j o r i t y o f zoo log i s t s w h o h a v e w o r k e d o n

t h e A r t h r o p o d a h a v e t e n d e d t o c o n c e n t r a t e t h e i r efforts e i t h e r o n

t h e m a r i n e C r u s t a c e a o r o n t h e in sec t s . A p a r t f r o m s y s t ema t i s t s ,

c o m p a r a t i v e l y few h a v e p a i d m o r e t h a n superf ic ia l a t t e n t i o n t o t h e

r e m a i n i n g m e m b e r s o f t h e p h y l u m a n d a l t h o u g h i n c r e a s i n g n u m ­

b e r s a r e n o w d o i n g so , t h e r e i s a m p l e s c o p e for n e w r e c r u i t s a s t h e

r e a d e r wil l s o o n real ise .

I t i s n o w gene ra l l y r e c o g n i s e d t h a t t h e C o l l e m b o l a a re n o t i n ­

sec ts a n d t h e s a m e m a y b e t r u e o f o t h e r A p t e r y g o t a . N e v e r t h e l e s s ,

t h e s e a n i m a l s h a v e a lways c o m e w i t h i n t h e s c o p e o f t h e e n t o m o l o ­

gis t a n d rece ive a t t e n t i o n i n m a n y w e l l - k n o w n e n t o m o l o g i c a l t e x t ­

b o o k s . I h a v e n o t , t h e r e f o r e , i n c l u d e d t h e m in t h i s b o o k even

t h o u g h t h e P a u r o p o d a a n d S y m p h y l a h a v e b e e n n o t i c e d . I n d e e d ,

i t i s n o w b e l i e v e d t h a t t h e l a t t e r a r e closely r e l a t e d to t h e In sec t a .

C o n s e q u e n t l y t h e se lec t ion o f g r o u p s d i s c u s s e d i n t h e fo l lowing

c h a p t e r s m a y a p p e a r s o m e w h a t a r b i t r a r y f rom a s y s t e m a t i c p o i n t

o f v iew: b u t i t wi l l , I h o p e , be f o u n d to h a v e p rac t i ca l jus t i f i ca t ion .

L i fe on l a n d en ta i l s a n u m b e r o f p r o b l e m s for a n i m a l s . L a r g e r

f o r m s r e q u i r e s t r u c t u r a l s u p p o r t , r e s p i r a t o r y o r g a n s m u s t b e c o m e

mod i f i ed for air b r e a t h i n g a n d t h e r e i s n o l o n g e r t h e s u r r o u n d i n g

w a t e r i n t o w h i c h tox ic e x c r e t o r y p r o d u c t s c a n freely diffuse, wh i l e

I N T R O D U C T I O N XI

m e c h a n i s m s for t h e c o n s e r v a t i o n o f w a t e r a n d t h e m a i n t e n a n c e o f

a c o n s t a n t i n t e r n a l m e d i u m m u s t b e evo lved . T h a t t h e s e p r o b l e m s

a re b y n o m e a n s easi ly o v e r c o m e i s s h o w n b y t h e fact t h a t severa l

i n v e r t e b r a t e p h y l a a r e a l m o s t e n t i r e l y m a r i n e w h i l e o t h e r s a s y e t

pos se s s few t e r r e s t r i a l spec ies . I n d e e d , t h e A r t h r o p o d a h a v e b e e n

u n u s u a l l y success fu l i n e x p l o i t i n g t h e t e r r e s t r i a l h a b i t a t a n d b y

a d a p t i v e r a d i a t i o n h a v e s u c c e e d e d i n e s t a b l i s h i n g t h e m s e l v e s i n

n e a r l y all t h e h a b i t a b l e c o r n e r s o f t h e e a r t h . E a c h a s p e c t o f t h e i r

a d a p t a t i o n to life on l a n d affects a n d i s affected by o t h e r a s p e c t s .

F o r e x a m p l e , i t m i g h t a p p e a r a fair ly s i m p l e m a t t e r for an o r g a n i s m

t o e l i m i n a t e w a t e r - l o s s b y t h e e v o l u t i o n o f a n i n t e g u m e n t c o m ­

p le t e ly i m p e r v i o u s t o w a t e r - v a p o u r ; b u t s u c h a n i n t e g u m e n t w o u l d

also be i m p e r v i o u s t o o x y g e n a n d c a r b o n d i o x i d e . A r e s p i r a t o r y

m e c h a n i s m h a s t h e r e f o r e h a d t o b e evo lved w h i c h p e r m i t s g a s e o u s

e x c h a n g e w i t h o u t excess ive w a t e r - l o s s . I f t h e i n t e g u m e n t i s r ig id

a n d p r o v i d e s s u p p o r t , t h e n g r o w t h b e c o m e s i m p o s s i b l e e x c e p t b y

m o u l t i n g a n d t h i s l imi t s s ize . T h e p h y s i o l o g y o f n u t r i t i o n a n d e x ­

c r e t i o n t o o a r e c losely c o n c e r n e d w i t h w a t e r c o n s e r v a t i o n a n d

s u p e r i m p o s e d u p o n t h i s b a s i c phys io log i ca l r e q u i r e m e n t a r e t h e i n ­

n u m e r a b l e c o n c o m i t a n t s o f b e h a v i o u r a n d ecology .

T h e r e a r e t w o o b v i o u s w a y s i n w h i c h sma l l a n i m a l s c a n e scape

de s i cca t i on o n d r y l a n d . O n e i s t o avo id d r y p l aces a n d t o r e m a i n

m o s t , i f n o t all o f t h e t i m e , in a h u m i d e n v i r o n m e n t ; t h e o t h e r , to

evolve a n i m p e r v i o u s i n t e g u m e n t . B o t h m e t h o d s h a v e b e e n ex­

p l o i t e d b y t h e A r t h r o p o d a a n d e a c h h a s i ts d r a w b a c k s a n d a d ­

v a n t a g e s . I n d e e d , o n t h e bas i s o f t h i s c h a r a c t e r t h e t e r r e s t r i a l m e m ­

b e r s o f t h e p h y l u m c a n b e d i v i d e d r o u g h l y i n t o t w o m a i n ecologica l

g r o u p s : t h e first i n c l u d e s w o o d l i c e , c e n t i p e d e s , m i l l i p e d e s a n d t h e i r

allies w h i c h lose w a t e r r a p i d l y i n d r y air; t h e s e c o n d , t h e A r a c h n i d s

a n d i n sec t s w h i c h a re c o v e r e d w i t h a l ayer o f w a x t h a t r e n d e r s

t h e m c o m p a r a t i v e l y i n d e p e n d e n t o f m o i s t s u r r o u n d i n g s .

I n t h e fo l lowing c h a p t e r s t h e s ignif icance o f t h i s gene ra l i s a t i on

wil l b e c o m e a p p a r e n t . F o r m s l ack ing a n e p i c u t i c u l a r w a x - l a y e r

a re a l m o s t en t i r e ly n o c t u r n a l i n h a b i t , a n d c a n w a n d e r a b r o a d on ly

af ter n igh t fa l l w h e n t h e t e m p e r a t u r e d r o p s a n d t h e r e l a t ive h u m i d i t y

o f t h e a i r r i ses . I n c o n t r a s t , m o s t insec t s , s p i d e r s a n d m o s t o t h e r

A r a c h n i d a a r e p o t e n t i a l l y d i u r n a l e x c e p t p e r h a p s i n d e s e r t s a n d

o t h e r r e g i o n s w i t h r i g o r o u s c l i m a t e s w h e r e , a n y w a y , t h e m a j o r i t y

X l l I N T R O D U C T I O N

o f t h e i n h a b i t a n t s avo id t h e excess ive m i d - d a y h e a t a n d d r o u g h t b y

t he i r n o c t u r n a l b e h a v i o u r . ( C o n v e r s e l y , a rc t i c a n i m a l s a r e nea r ly

a lways d i u r n a l i n h a b i t . ) T h e m o r e p r i m i t i v e g r o u p s s u c h a s scor ­

p i o n s , w h i p - s c o r p i o n s , s p i d e r s o f t h e fami l ies L i p h i s t i i d a e , T h e r a -

p h o s i d a e , D i c t y n i d a e , D y s d e r i d a e a n d s o on , h a v e p r o b a b l y b e ­

c o m e s e c o n d a r i l y a d a p t e d to n o c t u r n a l h a b i t s a s a r e su l t o f c o m ­

pe t i t i on w i t h m o r e efficient spec ies . A t t h e s a m e t i m e , h o w e v e r ,

m a n y o f t h e m a re la rge a n d s o m e w h a t v u l n e r a b l e a n d m a y n e e d t o

e scape t h e a t t e n t i o n s o f p o t e n t i a l p r e d a t o r s i n t h i s way .

FIG. 1. Rate of water-loss in dry air at different temperatures, and corresponding saturation deficiencies, from a woodlouse (Porcellio), millipede (Oxidus), spider (Lycosa) and insect (Pieris larva). In the woodlouse and millipede the rate of water-loss is proportional to the saturation deficiency of the atmosphere, but in the spider and insect it is negligible below about 30° C, the critical temperature at which their epicuticular wax-layers be­come porous. Rate of water-loss is expressed in milligrams per square centimetre of surface area per hour . (After Cloudsley-

T h o m p s o n , 1955.)

O n t h e o t h e r h a n d , l i q u i d w a t e r c a n also b e v e r y d a n g e r o u s t o

sma l l a n i m a l s t h a t m a y b e c o m e w a t e r - l o g g e d , o r t r a p p e d b y s u r ­

face t e n s i o n . T h e i r e n v i r o n m e n t m u s t b e n e i t h e r t oo w e t n o r t oo

d r y . T h i s i s espec ia l ly t r u e of spec ies l ack ing a w a t e r p r o o f i n g w a x -

layer . B e c a u s e t h e y a r e s u s c e p t i b l e t o des i cca t ion , t h e y a r e also

s u s c e p t i b l e t o w a t e r u p t a k e b y o s m o s i s : c o n s e q u e n t l y t h e y t e n d t o

I N T R O D U C T I O N Xl l l

i n h a b i t t h i ck leaf- l i t te r , o r b u r r o w d e e p i n t o t h e soil w h e r e t h e y

a r e less l iable e i t h e r t o b e c o m e w a t e r - l o g g e d o r de s i cca t ed .

R ig id , m e c h a n i s t i c b e h a v i o u r p a t t e r n s i n r e s p o n s e t o e n v i r o n ­

m e n t a l s t i m u l i h a v e b e e n evo lved b y m e a n s o f w h i c h t h e a n i m a l s

f i n d a n d m a i n t a i n t h e m s e l v e s i n s u i t a b l e h a b i t a t s . Phys io log ica l a n d

m o r p h o l o g i c a l a d a p t a t i o n s a lone w o u l d o b v i o u s l y b e insuff icient

t o s u p p o r t t h e life o f a n y f ree - l iv ing a n i m a l . O r i e n t a t i o n a n d b e ­

h a v i o u r m e c h a n i s m s m u s t also b e evo lved t o r e t a in o r g a n i s m s i n

e n v i r o n m e n t s t o w h i c h t h e y a r e s u i t e d , t o e n a b l e t h e m t o f i n d

food, m a t e , a n d i n d e e d t o c a r r y o u t t h e i n n u m e r a b l e f u n c t i o n s e s ­

sent ia l for t h e i r c o n t i n u e d ex i s t ence .

FIG. 2. Woodlice. Trichoniscus pusillus (length 4 m m ) , Porcellio scaber (length 14 m m ) and Armadillidium vulgare (length 15 mm) .

(After W e b b and Sillem, 1906.)

T h e eco logy o f a n i m a l s i s t h e r e f o r e g o v e r n e d n o t o n l y b y t h e

fac to rs o f t h e i r e n v i r o n m e n t s , p h y s i c a l a n d b io logica l , b u t a lso b y

t h e i r o w n phys io log ica l r e q u i r e m e n t s a n d b e h a v i o u r . T h e i n t e r ­

r e l a t i o n s h i p s b e t w e e n l iv ing o r g a n i s m s a n d t h e i r e n v i r o n m e n t s

i n c l u d e b o t h in te r - spec i f i c a n d in t ra - spec i f i c f ac to r s . T h e s e r e ­

l a t i o n s h i p s a r e specific for eve ry o r g a n i s m a n d c o n t i n u o u s t h r o u g h ­

o u t its life: t h e y a r e r ec ip roca l i n t h a t t h e o r g a n i s m i s n o t m e r e l y

in f luenced b y , b u t a t t h e s a m e t i m e pos i t ive ly affects i ts e n v i r o n ­

m e n t , a n d a r e i n d i s s o l u b l e b e c a u s e t h e o r g a n i s m c a n n o t exis t i n ­

d e p e n d e n t l y of i ts e n v i r o n m e n t . C o n s e q u e n t l y eco logy is a vas t

a n d c o m p l e x s u b j e c t a b o u t w h i c h c o m p a r a t i v e l y l i t t le i s ye t k n o w n .

O n e a d v a n t a g e of t h i s lies in t h e fact t h a t i t i s stil l pos s ib l e , as

XIV I N T R O D U C T I O N

C h a r l e s E l t o n p o i n t e d o u t i n 1927, for a l m o s t a n y o n e d o i n g e c o ­

logical w o r k o n t h e r i g h t l ines , t o s t r ike u p o n s o m e n e w a n d ex­

c i t ing fact or idea.

E c o l o g y h a s b e e n d e s c r i b e d a s scient if ic n a t u r a l h i s t o r y a n d a c ­

c u r a t e iden t i f i ca t ion m u s t b e m a d e o f a n y a n i m a l s s t u d i e d . O n e

o f t h e ob jec t s o f t h i s b o o k i s to i n d i c a t e s o m e of t h e i n n u m e r a b l e

p r o b l e m s a w a i t i n g e l u c i d a t i o n a n d t o p r o v i d e a g u i d e t o s o u r c e s

for t h e iden t i f i ca t ion of t h e B r i t i s h spec ies in p a r t i c u l a r , as wel l as

t o o t h e r r e l evan t l i t e r a tu re . 1 I t i s h o p e d t h a t i t wil l i n t e r e s t n a t u r a l

h i s t o r y w o r k e r s i n t h i s c o u n t r y a n d a b r o a d : i t m a y also b e o f u s e t o

u p p e r schoo l b io logy t e a c h e r s . A t t h e s a m e t i m e , h o w e v e r , I be l i eve

t h a t m a n y u n i v e r s i t y s t u d e n t s m a y f i n d i n i t i n f o r m a t i o n , a l t h o u g h

s i m p l y p o r t r a y e d , t h a t wil l b e o f v a l u e t o t h e m b o t h i n t h e j o y s o f

t h e f i e l d a n d t h e g l o o m o f t h e e x a m i n a t i o n ha l l .

1 Inevitably this is somewhat arbitrary and no doubt , reflects a bias towards the works with which I am more familiar. Both modern and old publications have been quoted, especially where the latter have useful illus­trations.

C H A P T E R I

W O O D L I C E

Classification and distribution W o o d l i c e a r e i n c l u d e d i n t h e s u b - o r d e r O n i s c o i d e a o f t h e

c r u s t a c e a n o r d e r I s o p o d a . T h e y f o r m a r e a s o n a b l y h o m o g e n e o u s

g r o u p a n d a r e o f p a r t i c u l a r i n t e r e s t b e c a u s e t h e r e a re severa l c o m ­

m o n spec ies s h o w i n g di f ferent d e g r e e s o f a d a p t a t i o n t o life on

l a n d . T h e m a j o r i t y a re b e t w e e n o n e a n d t w o c e n t i m e t r e s i n l e n g t h ,

a n d t h e sma l l s ize of ce r t a in g e n e r a s u c h as Platyarthrus, Trichonis-

cus a n d Sphaerobathytropa is a l m o s t ce r t a in ly a s e c o n d a r y f ea tu re

c o r r e l a t e d w i t h v a r i o u s r eg re s s ive c h a r a c t e r s s u c h as a s impl i f ica­

t i o n i n t h e s t r u c t u r e o f t h e eyes a n d a p p e n d i c e s , r e d u c t i o n i n t h e

n u m b e r o f b o d y s e g m e n t s a n d loss o f p i g m e n t a t i o n . A n a n a l o g o u s

p h e n o m e n o n i s f o u n d i n t h e A c a r i .

FIG. 3. Fifth thoracic segment of a female Oniscus asellus cut across to show the brood pouch with eggs. (After W e b b and

Sillem, 1906.)

T h e O n i s c o i d e a a r e s o m e w h a t oval i n f o r m a n d t h e i r b o d i e s a re

a r c h e d , t h e c u r v e v a r y i n g i n d i f ferent g e n e r a a n d spec ie s . T h e

h e a d b e a r s t w o l a rge a n t e n n a e a n d a s m a l l e r p a i r o f a n t e n n u l e s

a n t e r i o r t o t h e m . T h e t h o r a x cons i s t s o f s even s e g m e n t s w h i c h a re

of ten c o n s i d e r a b l y b r o a d e r t h a n t h e six s u c c e e d i n g o n e s t h a t f o r m

A 1 S.S.C.M.

2 W O O D L I C E

FIG. 4. Pleopods of first thoracic segment of Porcellio scaber showing pseudotracheae. Male on the left, female on the right.

(Diagrammatic.")

In a c o m p r e h e n s i v e s u r v e y o f t h e O n i s c o i d e a , V a n d e l (1943)

r ecogn i se s s o m e 18 fami l ies , o f w h i c h f ive a r e i n c l u d e d in t h e

Br i t i sh f auna . T h e s e a re t h e L i g i i d a e , T r i c h o n i s c i d a e , O n i s c i d a e ,

P o r c e l l i o n i d a e a n d A r m a d i l l i d i i d a e . T h e geologica l h i s t o r y o f t h e

C r u s t a c e a i s a l o n g o n e a n d fossils o c c u r in t h e O l d R e d S a n d s t o n e

o f t h e D e v o n i a n p e r i o d a n d i n t h e C a r b o n i f e r o u s Coa l M e a s u r e s .

Foss i l wood l i ce , h o w e v e r , h a v e n o t b e e n f o u n d b e l o w t h e U p p e r

E o c e n e w h i c h m i g h t s u g g e s t t h a t co lon i sa t i on o f t h e l a n d h a s b e e n

a c h i e v e d s o m e w h a t la te i n t h e h i s t o r y o f t h e g r o u p . W h e n t h e y d o

t h e a b d o m e n . E a c h of t h e t h o r a c i c s e g m e n t s ca r r i e s a p a i r o f

w a l k i n g legs a n d i n t h e f ema le , a t t h e t i m e w h e n t h e eggs a r e laid,

a p a i r o f p l a t e s ar ises on s e g m e n t s t w o to five. T h e s e p l a t e s t o ­

g e t h e r f o r m a b r o o d p o u c h i n w h i c h t h e eggs a re c a r r i e d u n t i l t h e y

h a t c h a n d i n w h i c h t h e y o u n g r e m a i n for s o m e t i m e a f t e r w a r d s .

T h e a p p e n d a g e s o f t h e a b d o m e n a r e also p l a t e - l i ke , w i t h t h e ex­

c e p t i o n o f t h e last p a i r o r u r o p o d s . T h e e n d o p o d i t e s o r p l e o p o d s

a re h o m o l o g o u s w i t h t h e gil ls o f a q u a t i c I s o p o d s a n d h a v e a

r e s p i r a t o r y f u n c t i o n , w h i l e t h e o u t e r e x o p o d i t e s ac t a s a p r o t e c t i v e

cover . I n t h e m a l e t h e first t w o pa i r s o f a b d o m i n a l a p p e n d a g e s a re

specia l ly mod i f i ed , t h e i r e n d o p o d i t e s b e i n g l o n g a n d p o i n t e d ,

w h i l e t h e u r o p o d s a re o f ten c o n s i d e r a b l y l a rge r t h a n i n t h e female

a n d t h e i r s h a p e i s s o m e t i m e s o f v a l u e in classif icat ion.

W O O D L I C E 3

a p p e a r , h o w e v e r , t h e y a r e gene r i ca l ly i n d i s t i n c t f r om l iv ing f o r m s ,

a n d V a n d e l be l i eves t h a t t h e a n c e s t o r s o f w o o d l i c e b e c a m e t e r ­

res t r ia l d u r i n g t h e s e c o n d hal f o f t h e P a l a e o z o i c e ra . H e b a s e s t h i s

c o n c l u s i o n o n t h e fact t h a t all t h e m a i n t y p e s o f o r g a n i s a t i o n

w i t h i n t h e O n i s c o i d e a h a v e a w o r l d - w i d e d i s t r i b u t i o n a n d c o n ­

s e q u e n t l y m u s t h a v e a v e r y a n c i e n t o r ig in .

T h e m o s t p r i m i t i v e a n d a t t h e s a m e t i m e t h e leas t we l l a d a p t e d

o f t h e w o o d l i c e t o t e r r e s t r i a l c o n d i t i o n s a r e l i t to ra l spec ies b e l o n g ­

i n g t o t h e f ami ly L i g i i d a e . T h e r e a re t w o B r i t i s h spec i e s i n t h i s

family , Ligia oceanica, t h e l a rges t of t h e Br i t i sh w o o d l i c e — u p to

3 0 m m i n l e n g t h a n d r a t h e r m o r e t h a n t w i c e a s l o n g a s b r o a d — a n d

t h e s m a l l e r Ligidium hypnorum w h i c h i s s o m e t i m e s f o u n d far i n ­

l and , n e a r l y a lways i n t h e n e i g h b o u r h o o d o f w a t e r .

Ligia oceanica h a s a w i d e d i s t r i b u t i o n a r o u n d t h e s h o r e s of

G r e a t B r i t a i n a n d i n d e e d o f p r ac t i c a l l y t h e w h o l e n o r t h coas t o f

E u r o p e . I t a lso o c c u r s i n F r a n c e , S p a i n , M o r o c c o a n d A m e r i c a .

A l t h o u g h n e v e r f o u n d far f r o m t h e sea, i t i s t r u l y t e r r e s t r i a l a n d c a n

w i t h s t a n d p r o l o n g e d s u b m e r s i o n in sea w a t e r o n l y i f t h i s i s wel l

a e r a t e d . T h e n o r m a l h a b i t a t i s i n d e e p n a r r o w c rev ices i n t h e

rocks j u s t a b o v e h i g h - t i d e level , u n d e r s t o n e s o n s a n d y b e a c h e s o r

o n t h e s ides o f q u a y s : h e n c e t h e n a m e ' q u a y - l o u s e ' o r ' q u a y -

l o w d e r ' . I n S t . K i l d a Ligia h a s b e e n f o u n d in t h e c rev ices o f

b o u l d e r s o v e r 4 5 0 ft. a b o v e sea level , b u t on t h a t e x p o s e d islet

s p r a y i s o f ten b l o w n to t h i s h e i g h t ( N i c h o l l s , 1931) . I h a v e f o u n d

s p e c i m e n s o v e r a m i l e i n l a n d on t h e I s le o f M a n .

T h e fami ly T r i c h o n i s c i d a e a lso o c c u r s i n v e r y m o i s t p l aces , b u t

t h e P o r c e l l i o n i d a e a n d A r m a d i l l i d i i d a e a re f o u n d i n p r o g r e s s i v e l y

d r i e r local i t ies . N o w t h i s s e q u e n c e i s a lso o n e o f i n c r e a s i n g m o r p h o ­

logical spec ia l i sa t ion w i t h i n t h e g r o u p , t h e s igni f icance o f w h i c h

wi l l b e c o n s i d e r e d b e l o w .

H a t c h e t t (1947) h a s f o u n d t h a t i n M i c h i g a n Armadillidium

nasatum d o e s n o t o c c u r o u t s i d e b u i l d i n g s , w h i l e A. vulgare is

chiefly f o u n d a r o u n d h u m a n h a b i t a t i o n s ; Cylisticus convexus p r e f e r s

r o c k y r e g i o n s a n d Ligidium longicaudatum o c c u r s o n l y in v e r y w e t

s i t u a t i o n s . Metoponorthus pruinosus is s o m e w h a t u r b a n in i ts d i s ­

t r i b u t i o n . Porcellio scaber l ives on b e a c h e s , r i ve r b a n k s a n d o t h e r

m o i s t s i t u a t i o n s . P. spinicornis r e q u i r e s a h a b i t a t w h e r e p l e n t y of

l ime i s ava i l ab le a n d P . rathkei i s g e n e r a l l y d i s t r i b u t e d b u t m o r e

4 W O O D L I C E

a b u n d a n t in d e c i d u o u s w o o d l a n d s t h a n e l s e w h e r e , w h i l e P . demi-

virgo def in i te ly p re f e r s m o i s t w o o d l a n d s i t u a t i o n s .

W i t h r e g a r d t o t h e B r i t i s h spec ies , H e e l e y (1941) n o t e s t h a t

Trichoniscus pusillus i s a b u n d a n t in v e r y m o i s t w o o d l a n d s , t h o u g h

t h e a n i m a l s a r e f r e q u e n t l y o v e r l o o k e d o w i n g t o t h e i r smal l s ize a n d

d a r k c o l o u r i n g . T h e y c a n easi ly be m i s t a k e n for y o u n g Philoscia.

T h e y f a v o u r t h e t h i ck s o d d e n layers o f d e c a y i n g leaves w h i c h lie

b e n e a t h t h e t r e e s t h r o u g h o u t t h e w i n t e r a n d d u r i n g t h e s u m m e r

t h e y l ive a m o n g s t t h e r e s u l t i n g leaf m o u l d b e n e a t h low b u s h e s

wel l s h a d e d f r o m t h e s u n , o r w i t h i n r o t t i n g t w i g s .

Philoscia muscorum is fair ly c o m m o n in m o i s t s h a d y s i t u a t i o n s

i n m o o r s a n d w o o d l a n d s , p a r t i c u l a r l y a m o n g s t t h e r o o t s o f g ras ses

b e n e a t h b u s h e s a n d b r a m b l e s a n d a t t h e b a s e o f t r e e t r u n k s , w h e r e

t h e soil r ece ives t h e d r i p p i n g s f r o m t h e t r e e s a n d i s s h a d e d f ro m

t h e s u n . T h i s spec ies i s s o m e w h a t local a n d r e s t r i c t e d i n i t s d i s ­

t r i b u t i o n a n d i s p r e s e n t m a i n l y in w o o d l a n d . Oniscus asellus on t h e

o t h e r h a n d i s t h e c o m m o n e s t o f all w o o d l i c e a n d i s f o u n d a l m o s t

e v e r y w h e r e t h a t d a m p c o n d i t i o n s p reva i l , p a r t i c u l a r l y b e n e a t h

half b u r i e d s t o n e s a n d b a r k . I t s e e m s t o p r e f e r r a t h e r m o r e m o i s t

s i t u a t i o n s t h a n Porcellio scaber a n d m a y of ten be f o u n d w i t h t h e

l a t t e r i n t h e s a m e t r e e , b u t u s u a l l y n e a r e r t h e g r o u n d w h e r e t h e

w o o d i s o ld a n d r o t t i n g .

Porcellio scaber i s also v e r y c o m m o n , p a r t i c u l a r l y b e n e a t h t h e

d r y loose b a r k o f ve r t i ca l t r u n k s o f l iv ing t r e e s . I t s o m e t i m e s i n ­

h a b i t s d a m p h o u s e s a n d h a s b e e n f o u n d i n h e a p s o f c l i nke r a n d

t h e n e s t s of w o o d a n t s , Formica rufa.

Fina l ly , Armadillidium vulgare is p a r t i c u l a r l y c o m m o n on cha lk

l a n d s , o n h e a t h s a n d s lopes c o v e r e d w i t h low s c r u b s u c h a s a re

f o u n d i n r a i lway c u t t i n g s a n d o n r o a d s i d e s . T h e spec ies also o c ­

c u r s i n t h e n e i g h b o u r h o o d o f h o u s e s a n d b u i l d e r s ' y a r d s w h e r e

t h e r e i s loose c e m e n t o r l i m e , b u t i s n e v e r v e r y n u m e r o u s i n w o o d ­

l a n d . I t can e v e n s u r v i v e u n d e r d r y s t o n e s w a r m e d b y t h e s u n .

N o w H e e l e y c l a ims t h a t i t i s p o s s i b l e t o p r e d i c t w h i c h spec ies o f

w o o d l o u s e wi l l be p r e s e n t in a g iven h a b i t a t by i ts w a t e r - c o n t e n t .

I n h i s e x p e r i m e n t s , h o w e v e r , he p r o v i d e d a m o i s t su r face for t h e

a n i m a l s in t h e f o r m of a c a r r o t a s food. I t h a s s ince b e e n s h o w n

t h a t w o o d l i c e o f t h e s a m e spec ies , i f de s i cca t ed a n d s u b s e q u e n t l y

k e p t i n u n s a t u r a t e d air , b u t w i t h access t o m o i s t p l a s t e r o f P a r i s

W O O D L I C E 5

sur faces , r ega in t h e i r w e i g h t b y a b s o r p t i o n o f w a t e r t h r o u g h t h e

m o u t h . T h e s e e x p e r i m e n t s e x p l a i n h o w w o o d l i c e w h i c h a re k n o w n

to lose w a t e r i n all b u t s a t u r a t e d air , can n e v e r t h e l e s s s u r v i v e in ­

def in i te ly in u n s a t u r a t e d air p r o v i d e d t h a t a m o i s t su r face i s

ava i l ab le ( E d n e y , 1954) .

General behaviour I n d i f ferent p a r t s o f t h e c o u n t r y t h e r e a re m a n y c u r i o u s s u p e r ­

s t i t ions a b o u t w o o d l i c e . F o r e x a m p l e , i n s o m e p laces t h e i r p r e s e n c e

i n d o o r s i s r e g a r d e d a s u n l u c k y a n d a n y food o n w h i c h t h e y m a y

h a p p e n t o w a n d e r i s c o n s i d e r e d p o i s o n e d . O n t h e o t h e r h a n d , i n

ce r t a in o t h e r d i s t r i c t s u n t i l v e r y r e c e n t l y a f ew live w o o d l i c e

t h r u s t d o w n t h e t h r o a t o f a c o w w e r e b e l i e v e d to h a v e beneficial

effects a n d ' t o p r o m o t e t h e r e s t o r a t i o n o f t h e c u d ' . N o d o u b t t h i s

i s w h y i n S h r o p s h i r e a n d n e i g h b o u r i n g c o u n t i e s w o o d l i c e o r

s la ters a r e s o m e t i m e s r e f e r r ed t o a s ' c u d - w o r m s ' . A t o n e t i m e too ,

w o o d l i c e w e r e p r e s c r i b e d to be s w a l l o w e d alive as a r e m e d y for

sc ro fu lous s y m p t o m s a n d for d i seases o f t h e l iver a n d d iges t ive

o r g a n s . I t i s s u r p r i s i n g t o o h o w m a n y local n a m e s h a v e b e e n

g iven to w o o d l i c e : Co l l i nge (1935) l i s ted no less t h a n 65 r a n g ­

ing f r o m 'Bubble b u g s ' (S ta f ford) , ' C h e e s e - p i g s ' ( B e r k s h i r e ) a n d

'Co f f i n - cu t t e r s ' ( I r e l a n d ) t o ' M o n k e y p e a s ' ( K e n t ) , ' P e n n y -

p igs ' ( W a l e s ) , ' S i n k - l i c e ' ( L a n c a s h i r e a n d Staf ford) a n d ' T i g g y -

h o g s ' ( N o r t h a m p t o n s h i r e ) . I n A m e r i c a t h e y are k n o w n a s ' S o w -

b u g s ' .

H u m i d i t y i s a n e n v i r o n m e n t a l fac tor o f p r i m e i m p o r t a n c e , b o t h

to w o o d l i c e a n d to m y r i a p o d s , as t h e y all lack a w a t e r p r o o f i n t e g u ­

m e n t . W o o d l i c e a re v e r y sens i t ive t o h u m i d i t y g r a d i e n t s a n d a g ­

g r e g a t e i n a reas o f h i g h h u m i d i t y . T h e m e c h a n i s m b y w h i c h t h i s

o c c u r s i s two- fo ld : firstly, t h e a n i m a l s s h o w a d e c r e a s e in ac t iv i ty

a n d s p e e d i n m o i s t a i r a n d s e c o n d l y t h e y c h a n g e d i r e c t i o n m o r e

f r e q u e n t l y in d a m p p laces so t h a t o n c e t h e y h a v e a r r i v e d in a

m o i s t s i t u a t i o n t h e y t e n d t o r e m a i n t h e r e . T h i s r e a c t i o n t o t h e

re la t ive h u m i d i t y of t h e air i s also c o m b i n e d w i t h a v o i d a n c e of

l ight a n d a r e a c t i o n t h a t c ause s t h e m to m a k e c o n t a c t w i t h a s

m u c h o f t h e i r s u r r o u n d i n g s a s pos s ib l e . T h e r e su l t o f t h i s i s t h a t

n o t o n l y d o t h e a n i m a l s e n t e r n a r r o w crev ices , b u t t h e y b u n c h

t o g e t h e r a n d c o n s e q u e n t l y p r o t e c t e ach o t h e r f rom e v a p o r a t i o n .

6 W O O D L I C E

H o w e v e r , a r eve r sa l o f t h e r e s p o n s e t o l igh t o c c u r s w h e n w o o d -

lice b e c o m e s o m e w h a t de s i cca t ed , so t h a t i f t h e i r d a y t i m e h a b i t a t

s h o u l d d r y u p t h e y a r e n o t r e s t r a i n e d t h e r e u n t i l t h e y d ie , b u t

b e c o m e a t t r a c t e d t o l igh t a n d a r e t h e n ab l e t o w a n d e r i n t h e o p e n

u n t i l t h e y f ind s o m e o t h e r d a m p d a r k h i d i n g p l a c e w h e r e t h e y

aga in b e c o m e p h o t o - n e g a t i v e ( C l o u d s l e y - T h o m p s o n , 1952) .

T h e c lea res t a d a p t a t i o n t o t e r r e s t r i a l life i s t o b e f o u n d i n t h e

p l e o p o d s . T h e s e a re v a r i o u s l y m o d i f i e d a n d i n t h e m o r e a d v a n c e d

f o r m s b e a r t u f t s o f i n v a g i n a t e d t u b u l e s f o r m i n g ' l u n g - t r e e s ' o r

' p s e u d o t r a c h e a e ' . E a c h t r e e o p e n s t o t h e e x t e r i o r b y a s l i t - l ike

a p e r t u r e n e a r t h e e d g e o f t h e p l e o p o d , a n d t h e m i n u t e r a m i f y i n g

t r a c h e a e a r e t h i n - w a l l e d t u b e s s u r r o u n d e d b y b l o o d w h i c h ca r r i es

o x y g e n t o t h e t i s sues o f t h e b o d y . W h e n t h e a i r i s d r y , t h e p l e o p o d s

a re p r o b a b l y k e p t m o i s t b y w a t e r t h a t diffuses f r o m t h e b o d y

f lu ids o f t h e a n i m a l .

L i k e m o s t o t h e r w o o d l i c e , Ligia oceanica i s n o c t u r n a l in h a b i t

a n d e m e r g e s d u r i n g t h e n i g h t a t l o w t i d e t o feed o n s e a w e e d s s u c h

a s Fucus a n d o t h e r a lgae . T h e spec ies i s s t r o n g l y p h o t o - n e g a t i v e

a n d t e n d s t o r e m a i n u n d e r c o v e r o n m o o n l i g h t n i g h t s . E d n e y

(1954) h a s r e c e n t l y p o i n t e d o u t t h a t Ligia c a n l ive on l a n d as a

r e su l t o f w i d e o s m o t i c t o l e r a n c e r a t h e r t h a n b y d e v e l o p i n g o s ­

m o t i c i n d e p e n d e n c e . S i n c e o t h e r spec ies o f w o o d l o u s e c a n lose

m u c h w a t e r b y e v a p o r a t i o n w i t h o u t d y i n g , i t s e e m s l ikely t h a t

s u c h o s m o t i c i n d e p e n d e n c e i s c h a r a c t e r i s t i c o f t h e g r o u p as a

w h o l e . T h e c o l o u r of Ligia r a n g e s f r o m a d a r k g r e y i s h - g r e e n to a

l igh t , d i r t y b r o w n , w h i l e y o u n g s p e c i m e n s h a v e t w o l i gh t -

c o l o u r e d p a t c h e s o n t h e m i d d l e o f t h e do r sa l s ide . T h e Br i t i sh

Ligia oceanica, as wel l as t h e A m e r i c a n L. baudiniana a n d L.

exotica, h a v e b e e n f o u n d t o s h o w wel l m a r k e d c o l o u r r e s p o n s e s

d u e t o t h e e x p a n s i o n a n d c o n t r a c t i o n o f c o l o u r p i g m e n t cel ls o r

c h r o m a t o p h o r e s , s o t h a t t h e y b e c o m e l i gh t w h e n p l a c e d o n a

w h i t e b a c k g r o u n d a n d t u r n d a r k o n a b l ack b a c k g r o u n d . I n a d ­

d i t i o n t h e r e i s a d i u r n a l r h y t h m o f c o l o u r c h a n g e a n d t h e y t e n d to

b e d a r k b y d a y a n d pa l e b y n i g h t .

T h e fami ly T r i c h o n i s c i d a e i n c l u d e s a n u m b e r o f smal l , e l onga ­

t e d w o o d l i c e t h a t a r e fair ly w i d e l y d i s t r i b u t e d i n d a m p p laces

u n d e r m o s s , b a r k , fal len leaves , logs a n d s o o n . T h e O n i s c i d a e a re

less d e p e n d e n t on m o i s t u r e , b u t t h e c o m m o n Philoscia muscorum

W O O D L I C E 7

w h i c h c a n be d i s t i n g u i s h e d f r o m Oniscus asellus by i ts n a r r o w

b o d y a n d p r e t t y m a r b l e d a p p e a r a n c e i s aga in u s u a l l y f o u n d i n

m o i s t s i t u a t i o n s u n d e r r u b b i s h h e a p s , d a m p m o s s a n d t h e c a r p e t

o f d e a d leaves in w o o d s .

A c u r i o u s l i t t le , w h i t e , b l i n d w o o d l o u s e is Platyarthrus hoffmann-

seggi. I t i s easi ly r e c o g n i s e d by i ts b r o a d f l a t t ened b o d y up to 3-6

m m i n l e n g t h w i t h d e n t i c u l a t e e d g e s t o i ts s e g m e n t s a n d s h o r t ,

s t o u t a n t e n n a e . T h i s spec i e s o c c u r s t h r o u g h o u t t h e B r i t i s h I s l e s

a n d t h e res t o f E u r o p e , a n d i ts r a n g e e x t e n d s i n t o N o r t h Afr ica . I t

i s u s u a l l y f o u n d i n t h e n e s t s o f a n t s a n d t h e b u r r o w s o f w o o d -

b o r i n g b e e t l e s . T h e spec ies w a s d e s c r i b e d i n 1833 b y B r a n d t f r o m

s p e c i m e n s t a k e n i n P r u s s i a a n d w a s first n o t i c e d i n B r i t a i n l iv ing

w i t h severa l spec ies o f a n t s a t L u l w o r t h C o v e , i n 1859 . A l t h o u g h i t

h a s no eyes , Platyarthrus a p p e a r s t o be v e r y ave r se t o l igh t a n d

qu ick ly h i d e s i f d i s t u r b e d .

A N e w Z e a l a n d spec ies of Trichoniscus, T. commensalis, h a s i n ­

d e p e n d e n t l y evo lved t h e s a m e h a b i t o f a s soc ia t ing w i t h a n t s . I t i s

r a t h e r l a r g e r t h a n Platyarthrus a n d i s n o t q u i t e w h i t e , b u t gene ra l ly

m a r k e d w i t h b a n d s o r p a t c h e s o f p a l e b r o w n o n a w h i t e g r o u n d .

M o r e o v e r , i t i s n o t b l i n d b u t pos se s se s fair ly pe r fec t eyes p r o v i d e d

w i t h t h e n o r m a l a m o u n t o f p i g m e n t a t i o n .

O n e o f t h e l a rges t a n d m o s t c o m m o n o f w o o d l i c e i s t h e g a r d e n

s la te r Oniscus asellus w h i c h r e a c h e s a l e n g t h of 15 mm a n d a b o u t

half t h a t w i d t h . A g a i n t h e p l e o p o d s a r e w i t h o u t p s e u d o t r a c h e a e ,

b u t Oniscus s p p . s e e m t o w a n d e r i n d r i e r p laces t h a n a n y o f t h e

spec ies m e n t i o n e d p r e v i o u s l y . A n u m b e r o f spec ies o c c u r in t h e

fami ly P o r c e l l i o n i d a e , of w h i c h Porcellio scaber i s t h e m o s t u s u a l

a n d h a s b e e n r e c o r d e d f r o m all o v e r t h e B r i t i s h I s l e s . I t r e a c h e s a

size e v e n l a rge r t h a n t h a t of Oniscus asellus a n d is v e r y va r i ab l e in

co lour , b u t i t i s u sua l l y a d a r k s la ty g r e y w i t h i r r e g u l a r l i g h t e r

m a r k i n g s . I t c a n b e r e c o g n i s e d b y t h e t r a n s v e r s e r o w s o f smal l

t u b e r c l e s t h a t cove r t h e b a c k o f t h e h e a d a n d b o d y . T h i s fami ly i s

b e t t e r a d a p t e d t o l ive i n d r i e r c o n d i t i o n s t h a n a n y o f t h e p r e c e d i n g

a n d t h e p l e o p o d s b e a r w e l l - d e v e l o p e d p s e u d o t r a c h e a e a l t h o u g h a

ce r t a in a m o u n t o f r e s p i r a t i o n a lso t akes p l ace t h r o u g h t h e i n t e g u ­

m e n t o f t h e b o d y .

T o t h e s a m e fami ly b e l o n g s t h e r e m a r k a b l e d e s e r t w o o d l o u s e

Hemilepistus reaumuri w h i c h i s n o t u n c o m m o n in N o r t h Afr ica a n d

8 W O O D L I C E

t h e M i d d l e E a s t . T h e a n i m a l s l ive t o g e t h e r i n ver t i ca l ho l e s 5 - 6

c m i n d i a m e t e r a n d m a n y c e n t i m e t r e s i n d e p t h . A d i g g i n g r e ­

ac t i on is r e l eased by a t e m p e r a t u r e of 35° C if t h e soil is d r y , a n d

45° C i f i t i s m o i s t . T h e h e a d is p l a c e d aga in s t a sma l l s t o n e or

s o m e o t h e r r ig id b o d y : t h e a n t e r i o r legs t h e n lift t h e s a n d b a c k ­

w a r d s w h i l e t h e p o s t e r i o r o n e s t h r o w i t away . S o m e t i m e s severa l

a n i m a l s c o m b i n e to d ig a s ing le ho l e a n d f r e q u e n t l y t w o w o o d l i c e

c a n b e seen d i g g i n g h e a d t o h e a d .

T h e p i l l - w o o d l i c e o r A r m a d i l l i d i i d a e a re s o ca l led b e c a u s e o f

t h e i r h a b i t of ro l l ing i n t o a ba l l l ike a l i t t le a r m a d i l l o . T h e ab i l i ty

t o d o t h i s i s b y n o m e a n s r e s t r i c t e d t o t h i s fami ly h o w e v e r , b u t h a s

evo lved i n d e p e n d e n t l y i n severa l d i v e r s e g r o u p s . I n f o r m s t h a t

c a n cu r l u p c o m p l e t e l y t h e h e a d h a s b e c o m e f l a t t ened i n a n a n t e r o ­

p o s t e r i o r d i r e c t i o n s o t h a t i ts h e i g h t i s m u c h g r e a t e r t h a n i ts

l e n g t h a n d t h e f ron t p a r t i s c o v e r e d b y t h e las t a b d o m i n a l a p p e n ­

dages o r u r o p o d s w h e n t h e a n i m a l ro l l s u p . ( I n o t h e r w o o d l i c e t h e

u r o p o d s p ro j ec t l ike a c o u p l e of sma l l ta i ls f r o m t h e h i n d e r e n d of

t h e b o d y ) . T h e m o s t c o m m o n B r i t i s h spec ies i s Armadillidium

vulgare, s o m e t i m e s ca l led t h e 'Pi l l b u g ' , w h i c h r e a c h e s a l e n g t h o f

1 8 m m a n d i s a l i t t le m o r e t h a n t w i c e a s l o n g a s b r o a d . T h e c o l o u r

var ies f r o m c o m p l e t e l y b l ack t o pa l e ye l low, b u t t h e m o r e u s u a l

s h a d e s a re l igh t g rey .

A s a l r e a d y m e n t i o n e d , w o o d l i c e h a v e l i t t le ab i l i ty t o p r e v e n t

loss o f w a t e r b y e v a p o r a t i o n a n d exc re t i on , a n d a l t h o u g h t h e y can

r ega in lost w a t e r b o t h b y ac t ive ly d r i n k i n g a n d a b s o r b i n g m o i s ­

t u r e t h r o u g h t h e i r p l e o p o d s , t h e y c a n on ly s u r v i v e o n l a n d a s

a r e s u l t o f b e h a v i o u r m e c h a n i s m s t h a t k e e p t h e m in cool , m o i s t

p laces .

D u r i n g t h e d a y t h e y n o r m a l l y col lec t a t t h e m o i s t e n d o f a

h u m i d i t y g r a d i e n t a n d avo id t h e l ight : i t i s a t n i g h t t h a t d i spe r sa l

t o n e w e n v i r o n m e n t s m o s t l y t akes p l ace . C h a n g e s i n b e h a v i o u r

b e t w e e n d a y a n d n i g h t h a v e r e c e n t l y b e e n d e m o n s t r a t e d i n Oniscus

asellus t h a t can p e r h a p s be c o r r e l a t e d w i t h t h e eco logy o f t h e

spec ies as fol lows: a fall in t h e i n t e n s i t y of t h e h u m i d i t y r e s p o n s e

af ter d a r k e n a b l e s t h e a n i m a l s for a t i m e to w a l k in d r i e r p laces

t h a n t h e i r d a y - t i m e r e t r e a t s , b u t i n c r e a s e d p h o t o - n e g a t i v e b e ­

h a v i o u r after e x p o s u r e t o d a r k e n s u r e s t h a t t h e y r e t u r n t o cove r a t

d a y b r e a k , a n d t h u s n o d o u b t avo id t h e ear ly b i r d ( C l o u d s l e y -

W O O D L I C E 9

T h o m p s o n , 1952) . T h e d e g r e e o f n o c t u r n a l ac t iv i ty i n di f ferent

spec ies i s c o r r e l a t e d w i t h t h e ab i l i ty t o w i t h s t a n d w a t e r - l o s s b y

t r a n s p i r a t i o n ( C l o u d s l e y - T h o m p s o n , 1956) .

I s o p o d s s h o w a r eg re s s ion in t h e size o f t h e i r s e n s e o r g a n s

w h i c h m a y b e c o r r e l a t e d w i t h r e d u c t i o n i n t h e r a p i d i t y o f m o v e ­

m e n t o n b e c o m i n g t e r r e s t r i a l , for t h e a q u a t i c f o r m s a r e r a p i d

s w i m m e r s . Ligia s p p . h o w e v e r , w h i c h can r u n p a r t i c u l a r l y r ap id ly ,

h a v e r e t a i n e d t h e b i g eyes o f t h e i r m a r i n e a n c e s t o r s .

In a r e c e n t r e v i e w of t h e a d a p t a t i o n s o f w o o d l i c e to t h e t e r r e s ­

t r ia l h a b i t a t , E d n e y (1954) c o n c l u d e s t h a t d i f ferent spec i e s can

w i t h s t a n d t e r r e s t r i a l c o n d i t i o n s o f d r o u g h t t o v a r y i n g d e g r e e s , b u t

p r o b a b l y all spec ies s p e n d m o s t o f t h e t i m e i n a n a t m o s p h e r e

s a t u r a t e d w i t h w a t e r v a p o u r a n d m e r e l y differ i n t h e l e n g t h o f

t i m e t h a t t h e y a re c a p a b l e o f s u r v i v i n g a w a y f r o m d a m p n e s s .

T h u s e v e n Armadillidium a n d Hemilepistus s p p . c a n v e n t u r e i n to

d r y p l aces w i t h i m m u n i t y o n l y for c o m p a r a t i v e l y s h o r t p e r i o d s .

E d n e y a lso s u g g e s t s t h a t t h e r e a s o n w h y s o l i t t le p r o g r e s s h a s b e e n

m a d e t o w a r d full e x p l o i t a t i o n o f t h e l a n d b y w o o d l i c e m a y lie i n

t h e fact t h a t t h e c o n q u e s t o f t h e l a n d b y t h e I s o p o d a t ook p lace

via t h e l i t to ra l z o n e , for Ligia a n d Halophiloscia a r e u n d o u b t e d l y

p r i m i t i v e m o r p h o l o g i c a l l y . N o w a n i m a l s c r o s s i n g t h i s z o n e m a y

wel l b e s u b j e c t e d t o e x t r e m e l y h i g h t e m p e r a t u r e s , a n d t h e ab i l i ty

t o lose h e a t b y e v a p o r a t i o n o f w a t e r m a y h a v e c o n s i d e r a b l e s u r ­

vival v a l u e in all spec ies .

Food and feeding habits W o o d l i c e a r e o m n i v o r o u s a n d n o d o u b t usefu l a s s c a v e n g e r s .

S o m e spec ies a r e o f e c o n o m i c i m p o r t a n c e b e c a u s e t h e y d o n o t

conf ine t h e i r a t t e n t i o n t o d e a d a n d d e c a y i n g m a t t e r b u t s o m e ­

t i m e s a t t ack s eed l ings , r i p e f rui t s u c h a s p l u m s , p e a c h e s o r m e l o n s ,

a n d m u s h r o o m s — i n d e e d t h e y wi l l ea t a n y t h i n g t h a t i s soft a n d

j u i c y t h o u g h t h e y d o m o r e m i s c h i e f b y d i s f igur ing t h a n b y c o n ­

s u m i n g a n y l a rge q u a n t i t i e s . T h e y a r e s o m e t i m e s difficult t o d i s ­

l o d g e f r o m h o t h o u s e s a s t h e y f ind s h e l t e r i n eve ry l i t t l e c rev ice .

N i c h o l l s (1931) h a s s h o w n t h a t a l t h o u g h Ligia oceanica f eeds

p r i n c i p a l l y on Fucus vesiculosus a n d o t h e r a lgae , n o t h i n g ed ib l e

c o m e s a m i s s , p a r t i c u l a r l y i f i t be in t h e n a t u r e o f a n i m a l offal, a n d

c a n n i b a l i s m f r e q u e n t l y t akes p l ace i n cap t iv i ty . T h e g u t c o n t e n t s

1 0 W O O D L I C E

o f o n e i n d i v i d u a l w e r e f o u n d t o i n c l u d e m o s s c a p s u l e s a n d p a r t o f

a s y n c y t i u m of Vaucheria.

T h e s m a l l , m y r m e c o p h i l o u s Platyarthrus hoffmannseggi f eeds on

fungi a n d t h e i r s p o r e s , t h e exc re t a o f a n t s a n d o t h e r v e g e t a b l e

m a t t e r . S o m e spec ies , espec ia l ly Oniscus asellus, a r e d e c i d e d l y m o r e

o m n i v o r o u s t h a n o t h e r s s u c h as Porcellio scaber w h i c h conf ines its

d i e t l a rge ly to t h e b a r k of t r e e s a n d Trichoniscus pusillus w h i c h

l ives a l m o s t en t i r e ly o n d e c a y i n g leaves . A c c o r d i n g t o B r i s t o w e

( 1 9 4 1 ) * 1 , w o o d l i c e wil l ea t s p i d e r s ' eggs i n cap t iv i ty , a n d a s t h e y

a r e of ten t o b e f o u n d i n u n t e n a n t e d cel ls b e s i d e e m p t y egg-sacs

i t c a n b e s u p p o s e d t h a t t h e y d e v o u r A r t h r o p o d eggs w h e n e v e r a n

o p p o r t u n i t y o c c u r s . Armadillidium vulgare r e q u i r e s cha lk in i ts

d ie t , a n d t h i s m a y b e c o r r e l a t e d w i t h i ts excep t iona l l y t h i ck l y ca l ­

cified i n t e g u m e n t .

Enemies W o o d l i c e a re e a t e n b y b i r d s , r ep t i l e s , a m p h i b i a , a n d m a n y o t h e r

i n s e c t i v o r o u s a n i m a l s i n c l u d i n g s p i d e r s , h a r v e s t - s p i d e r s , m i t e s a n d

c e n t i p e d e s . T h e n u m b e r o f spec ies o f s p i d e r w h i c h wil l d e s t r o y a

w o o d l o u s e is, h o w e v e r , s o m e w h a t l i m i t e d . Armadillidium vulgare

rol ls i n t o a ba l l d i r ec t ly i t i s a t t a c k e d , a n d i ts h a r d , t h i c k i n t e g u m e n t

saves i t f r o m in ju ry , e v e n f r o m la rge spec ies s u c h as Tegenaria

atrica a n d Araneus diadematus. A c c o r d i n g to B r i s t o w e (1941)*

Porcellio, Oniscus a n d Philoscia s p p . s e c u r e s o m e p r o t e c t i o n f ro m

t h e c h i t i n w i t h w h i c h t h e i r do r sa l su r face i s c o v e r e d so l o n g a s t h e y

r e m a i n dorsa l su r face u p p e r m o s t . I n a d d i t i o n t h e y a re d is tas te fu l

t o m o s t s p i d e r s , w h i c h re jec t t h e m e x c e p t i n t i m e s o f food s h o r t a g e

w h e n t h e i r n o r m a l a v e r s i o n i s o v e r c o m e b y h u n g e r . D i s t a s t e f u l n e s s

i s m o s t m a r k e d in Porcellio s p p . a n d least in Philoscia s p p . ( excep t

for Platyarthrus hoffmannseggi w h o s e m y r m e c o p h i l o u s h a b i t r e n d e r s

i t leas t l ikely t o a t t ack b y s p i d e r s ) . O n t h e o t h e r h a n d t h e cave a n d

cel lar s p i d e r Meta menardi o f ten owes i t s su rv iva l in s u b t e r r a n e a n

s i t u a t i o n s to t h e p r e s e n c e of w o o d l i c e , a n d Dysdera crocota a n d

D. erythrina h a v e j a w s spec ia l ly a d a p t e d to g r i p a n d p e n e t r a t e t h e

c r u s t a c e a n cu t ic le .

A t o n e t i m e i t w a s be l i eved t h a t c e r t a i n t e g u m e n t a l g l a n d s

1 For references marked with an asterisk see bibliography of general works at the end of the volume.

W O O D L I C E 1 1

k n o w n a s ' W e b e r ' s g l a n d s ' p l a y e d a n i m p o r t a n t p a r t i n r e s p i r a ­

t i on . F o r n e a r l y ha l f a c e n t u r y t h e c o n c e p t t h a t t h e s e g l a n d s

s ec r e t ed a f luid w h i c h m o i s t e n e d t h e gi l ls c r e p t i n to a l m o s t eve ry

t e x t - b o o k d e a l i n g w i t h t h e s u b j e c t o f r e s p i r a t i o n i n w o o d l i c e .

G r e a t , t h e r e f o r e , w a s t h e s u r p r i s e o f G o r v e t t (1950) , w h o h a s m a d e

a spec ia l s t u d y of t h e g l a n d s o f w o o d l i c e , to f ind t h a t ' W e b e r ' s

g l a n d s ' d o n o t i n fact exis t e i t h e r i n t h e a n i m a l s o r i n t h e p u b l i c a ­

t i ons o f t h e i r s u p p o s e d d i s c o v e r e r . G o r v e t t t r a c e d t h e m y t h t o a n

' i n a u g u r a l d i s s e r t a t i o n ' o n r e s p i r a t i o n i n w o o d l i c e p u b l i s h e d i n

1909, i n w h i c h g l a n d s d e s c r i b e d b y W e b e r w e r e c o n f u s e d w i t h

c e r t a i n s t r u c t u r e s i n t h e a b d o m e n t h a t h a d b e e n d e s c r i b e d , also

i nco r r ec t l y , b y N e m e c i n 1 8 9 5 - 6 . A p p a r e n t l y t h e a c c o u n t s o f

W e b e r a n d N e m e c h a d n e v e r b e e n c o m p a r e d , o r i t w o u l d a t o n c e

h a v e b e e n rea l i sed t h a t t h e t w o a u t h o r s w e r e dea l i ng w i t h en t i r e ly

dif ferent a n d to ta l ly u n r e l a t e d s t r u c t u r e s .

A t leas t five k i n d s o f t e g u m e n t a l g l a n d s d o , h o w e v e r , o c c u r i n

w o o d l i c e , o f w h i c h t h e r o s e t t e a n d l o b e d g l a n d s h a v e s o far b e e n

i n v e s t i g a t e d b y G o r v e t t . S o m e o f t h e l a t t e r d i s c h a r g e a n acid

sec re t ion s m e l l i n g o f b u t y r i c ac id , b u t o t h e r s posses s a n o d o u r l e s s ,

n e u t r a l s o l u t i o n . T h e g l a n d s v a r y i n n u m b e r a n d size i n d i f ferent

spec ies , b u t t h e i r v a r i a t i o n a p p e a r s t o b e i n d e p e n d e n t o f h a b i t a t o r

e v o l u t i o n a r y p o s i t i o n : in fact t h e i r f u n c t i o n i s p r o b a b l y to ac t as a

d e t e r r e n t t o e n e m i e s , p r i n c i p a l l y h u n t i n g - s p i d e r s , s i n c e t h e y d o

n o t s e e m t o p r e v e n t excess e v a p o r a t i o n a s h a s s o m e t i m e s b e e n

s u g g e s t e d . T h e y a re t h u s a n a l o g o u s t o t h e r e p u g n a t o r i a l g l a n d s o f

m i l l i p e d e s , h a r v e s t - s p i d e r s a n d m a n y in sec t s ( G o r v e t t , 1956) .

W o o d l i c e d o n o t s e e m t o b e a t t a c k e d t o a n y g r e a t e x t e n t b y

pa r a s i t o ida l i n sec t s . T h o m p s o n (1934) m a d e a de t a i l ed s t u d y o f

t h e i r T a c h i n i d p a r a s i t e s d u r i n g w h i c h h e d i s s e c t e d 1,737 spec i ­

m e n s of Porcellio scaber a n d Oniscus asellus co l lec ted f r o m v a r i o u s

local i t ies i n E n g l a n d a n d F r a n c e b u t on ly 9 . 1 % w e r e pa ra s i t i s ed ,

a n d t h e ave rage p a r a s i t i s m o f O . asellus w a s on ly 3 . 1 % . H e c o n ­

c l u d e d , t h e r e f o r e , t h a t D i p t e r o u s pa r a s i t e s a re n o t f ac to r s o f m a j o r

i m p o r t a n c e i n t h e c o n t r o l o f w o o d l i c e : c e r t a i n spec ies a r e scarce ly

p a r a s i t i s e d a t all a n d in t h e case o f o t h e r s , s t a r v a t i o n a n d c a n n i b a l ­

i s m c o m e i n t o p l ay a s d e n s i t y - d e p e n d e n t fac to rs 1 c o n t r o l l i n g t h e

1 See discussion of densi ty-dependent and densi ty- independent factors o n p . 1 4 1 .

1 2 W O O D L I C E

size o f p o p u l a t i o n s be fo re p a r a s i t e s can i nc r ea se suff icient ly to b e ­

c o m e o f ecological i m p o r t a n c e .

Reproduction and life cycle L i k e o t h e r C r u s t a c e a , w o o d l i c e c a r r y t h e i r eggs in a t h o r a c i c

b r o o d p o u c h o r m a r s u p i u m a n d a w h o l e f ami ly o f n e w l y h a t c h e d

y o u n g m a y b e f o u n d h u d d l e d u p o n t h e u n d e r s i d e o f t h e m o t h e r .

T h e n u m b e r o f eggs v a r i e s f r o m seven p e r b r o o d i n Trichoniscus t o

1 0 0 - 2 0 0 or m o r e in Armadillidium.

T h e n e w l y h a t c h e d l a rvae h a v e a d i s t i nc t h e a d a n d eyes , seg ­

m e n t e d b o d y a n d s h o r t , s t u m p y l i m b s . T h e y a r e i n c a p a b l e o f

m o v e m e n t for t h e first t h r e e d a y s a s t h e i r a p p e n d a g e s a re t i gh t ly

d o u b l e d aga in s t t h e b o d y . A t t h i s s t age t h e y a r e k e p t v e r y m o i s t ,

b u t a s t h e i r s ize i n c r e a s e s t h e fluid i n t h e b r o o d p o u c h dec r ea se s .

T h e y o u n g e m e r g e ove r a p e r i o d o f t w o o r t h r e e d a y s a n d t h e first

m o u l t o c c u r s w i t h i n 2 4 h o u r s o f l i b e r a t i o n . T h e p e r i o d b e t w e e n t h e

first a n d s e c o n d m o u l t i s t h e m o s t cr i t ica l i n t h e i r l ives , b e c a u s e i f t h e

soil i s d r y a t t h i s t i m e t h e y d ie , w h i l e i f i t i s t o o m o i s t t h e y a re u s u ­

ally k i l led b y fung i . L a t e r t h e y a re m o r e r e s i s t a n t a n d t h e i r life m a y

be q u i t e a l o n g o n e , for t h e y s e l d o m b r e e d u n t i l t h e y a re t w o y e a r s o ld .

T h e life cycle of Ligia oceanica las ts for t h r e e y e a r s a c c o r d i n g to

N i c h o l l s (1931) . A t leas t five b r o o d s o f y o u n g a r e p r o d u c e d , a n d

t h e ave rage n u m b e r o f y o u n g p e r b r o o d i s 80 . T h e t i m e t a k e n for

t h e d e v e l o p m e n t o f t h e y o u n g va r i e s f r o m 4 0 d a y s i n s u m m e r t o 9 0

i n w i n t e r , a n d a l t h o u g h t h e g r e a t e s t n u m b e r o f a n i m a l s w i t h b r o o d

p o u c h e s i s f o u n d i n s p r i n g , b r e e d i n g o c c u r s t h r o u g h o u t t h e yea r .

T h e g r e a t e s t i n t e rva l b e t w e e n m o u l t s o c c u r s i n f u l l - g r o w n m a l e s

i n w i n t e r , t h e s h o r t e s t i n y o u n g s p e c i m e n s d u r i n g t h e s u m m e r .

T h e g r o w t h r a t e w a s o b s e r v e d i n a y o u n g s p e c i m e n to ave rage 1 .3

m m inc rea se i n l e n g t h a n d 0 . 5 m m i n w i d t h p e r m o n t h . C o p u l a ­

t i o n o c c u r s af ter t h e a p p e a r a n c e o f t h e m a t u r e b r o o d p l a t e s i n t h e

f ema le . T h e ova a re s p a w n e d a b o u t t w o d a y s af ter t h e c o m p l e t i o n

o f t h e m o u l t a n d , i f un fe r t i l i s ed , r e m a i n v i ab l e for a t leas t t h r e e

d a y s s u b s e q u e n t t o t h e i r a p p e a r a n c e i n t h e b r o o d p o u c h . H e e l e y

(1941) f o u n d t h a t t h e r e s p e c t i v e d u r a t i o n s o f t h e success ive s tages

i n t h e b r e e d i n g p r o c e s s e s , espec ia l ly t h e e m b r y o n i c a n d la rva l

p e r i o d s , w h i l s t v a r y i n g i n di f ferent spec ies a re m o r e o r less c o n ­

s t a n t for each p a r t i c u l a r spec ies . T h e s e p e r i o d s r a n g e f rom a n

W O O D L I C E 1 3

a v e r a g e of 21 1 / 2 d a y s e m b r y o n i c a n d 3 d a y s larval p e r i o d in Philoscia

muscorum to an a v e r a g e o f 64 1 / 2 d a y s e m b r y o n i c ( in f i r s t b r o o d ) a n d

9 d a y s la rva l p e r i o d in Porcellio dilatatus. In t h e s e spec ies t h e b r e e d ­

ing p h a s e r a n g e s f r o m an a v e r a g e of 36 d a y s in Ph. muscorum to 84

d a y s i n P . dilatatus. T h e a v e r a g e ra t ios o f t h e larval p e r i o d t o t h e

e m b r y o n i c p e r i o d o f d e v e l o p m e n t i n t h e b r o o d p o u c h , i n di f ferent

spec ies , i nc r ea se s a p p r o x i m a t e l y i n p r o p o r t i o n t o t h e ave rage

n u m e r i c a l s ize o f t h e b r o o d s .

T h e g r a v i d i t y p e r i o d for Armadillidium vulgare in M i c h i g a n

ave rages 4 3 d a y s a t n o r m a l t e m p e r a t u r e s , a c c o r d i n g t o H a t c h e t t

(1947) . F o r Cylisticus convexus i t va r i e s f r o m 44 to 62 d a y s a n d

ave rages 53 days , w h i l e Porcellio scaber c a r r i e s i ts b r o o d for an

a v e r a g e of 44 d a y s . F e m a l e s of P . (Tracheoniscus) rathkei a r e g r av id

on t h e a v e r a g e for 39 d a y s . M a n y f ema les of A. vulgare, C. convexus

a n d P . scaber h a v e a t leas t t w o b r o o d s p e r yea r , w h i l e P . rathkei

u s u a l l y r e p r o d u c e s o n l y o n c e . T h e s ize o f t h e b r o o d in C . convexus

r a n g e s f r o m 1 0 t o 7 0 w i t h a n a v e r a g e o f 3 3 a n d t h e n u m b e r o f y o u n g

i n b r o o d s r a i sed i n t h e l a b o r a t o r y w a s 2 4 . U n d e r s i m i l a r c o n d i ­

t i o n s A. vulgare r a i s ed 2 8 , P. scaber 24 a n d P. rathkei 17 y o u n g .

In c o n t r a s t i n D a l l a s , T e x a s , A . vulgare h a s b e e n f o u n d to p r o ­

d u c e f r o m 2 9 t o 7 9 y o u n g , w h i l s t i n S c o t l a n d , C o l l i n g e (1915) r e ­

p o r t e d t h a t i n d i v i d u a l s r a i sed i n cap t i v i t y h a d b r o o d s o f 5 0 t o 150

w i t h a m a x i m u m i n o n e i n s t a n c e o f 2 6 7 . I n F r a n c e t h e n u m b e r

va r i e s f r o m 48 to 156.

W h e n t h e y o u n g a re r e a d y t o leave t h e b r o o d p o u c h t h e y b e ­

c o m e r a t h e r ac t ive a n d c rawl a b o u t u n t i l t h e y a r e r e l ea sed t h r o u g h

a n o p e n i n g b e t w e e n t h e p l a t e s o f w h i c h t h e p o u c h i s c o m p o s e d .

D u r i n g t h e i r d e p a r t u r e , t h e m o t h e r u s u a l l y r e m a i n s q u i e t o r m o v e s

ve ry s lowly , k e e p i n g t h e f i r s t p a i r o f legs i m m o b i l e : t h e y o u n g

e m e r g e h e a d f i r s t a n d c l i m b d o w n h e r f i r s t o r s e c o n d p a i r o f legs .

T h e m a j o r i t y o f t h e y o u n g , af ter l eav ing t h e i r p a r e n t , a r e n o t v e r y

ac t ive a n d r e m a i n t o g e t h e r i n a g r o u p . T o w a r d s t h e e n d o f t h e

e m e r g e n c e p e r i o d t h e f ema le m o v e s away , t h i s t i m e u s i n g all h e r

legs , a n d t h e i r m o t i o n forces t h e f ew r e m a i n i n g y o u n g f r o m t h e

m a r s u p i u m . I f s h e i s d i s t u r b e d w h i l e c a r r y i n g y o u n g i n h e r b r o o d

p o u c h t h e f ema le m a y , b y r h y t h m i c a l c o n t r a c t i o n o f h e r b o d y ,

force a p a r t t h e p a i r s o f p l a t e s f o r m i n g t h e m a r s u p i u m a n d re lease

all h e r b r o o d a t o n c e . A full b r o o d p o u c h m a k e s i t n e c e s s a r y for

1 4 W O O D L I C E

t h e f ema le t o m o v e a r o u n d r a t h e r s lowly a n d i n a h u m p e d pos i t i on :

af ter t h e re lease o f t h e b r o o d s h e a s s u m e s h e r n o r m a l p o s i t i o n a n d

m o v e s a b o u t m o r e qu i ck ly .

B I B L I O G R A P H Y Identification

EDNEY , E. B. (1953) T h e woodlice of Great Britain and Ireland. A concise systematic monograph. Proc. Linn. Soc. Lond., 1 6 4 , 49-98 .

(1954) Synopses of the British Fauna, No. 9. British Woodlice. London: Linn. Soc.

SARS , G. O. (1896-9) An Account of the Crustacea of Norway, 2, (Isopoda). Bergen.

V A N N A M E , W. G. (1936) T h e American land and freshwater Isopod Crustacea. Bull. Amer. Mus. Nat. Hist., 7 1 , 1 - 5 3 5 .

W E B B , W. M. and SILLEM , C. (1906) The British Woodlice. London .

Biology CLOUDSLEY-THOMPSON, J. L. (1952) Studies in diurnal rhythms, I I .

Changes in the physiological responses of the woodlouse Oniscus asellus to environmental stimuli. J. Exp. Biol., 2 9 , 295-303.

(1955) T h e biology of woodlice. Discovery, 1 6 , 248-51 . (1956) Studies in diurnal rhythms, V I I . Humid i ty responses and

nocturnal activity in woodlice (Isopoda). J. Exp. Biol., 3 3 , 576-82. COLLINGE , W. E. (1915) Some observations on the life history and habits

of Isopoda (woodlice). Scot. Nat., 2 4 , 299-307. (1935) Woodlice, their folklore and local names. North w. Nat.,

1 0 , 1 9 - 2 1 . EDNEY , E. B. (1954) Woodlice and the land habitat . Biol. Rev., 2 9 ,

185-219. (1954) Idem. New Biology, 1 7 , 41-57 .

GORVETT, H. (1950) 'Weber ' s glands ' and respiration in woodlice. Nature, Lond., 1 6 6 , 115.

(1956) Tegumenta l glands and terrestrial life in woodlice. Proc. Zool. Soc. Lond., 1 2 6 , 291-314.

HATCHETT , S. P. (1947) Biology of the Isopoda of Michigan. Ecol. Monogr., 1 7 , 47-79 .

HEELEY , W. (1941) Observations on the life-histories of some terrestrial Isopods. Proc. Zool. Soc. Lond. (B), 1 1 1 , 79-149.

HEWITT , C. G. (1907) Ligia. L.M.B.C. Memoirs, X I V , 1-37. NICHOLLS , A. G. (1931) Studies on Ligia oceanica, 1. A. Habi ta t and

effect of change of environment on respiration. B. Observation on moult ing and breeding. J. Mar. Biol. Ass. U.K., 1 7 . 655-74.

THOMPSON , W. R. (1934) T h e Tachin id parasites of woodlice. Parasito­logy, 2 6 , 378-448.

VANDEL , A. (1943) Essai sur l 'origine, Involution et la classification des Oniscoidea (Isopodes terrestres). Bull, biol., 3 0 , 1 - 1 3 6 .

C H A P T E R I I

M I L L I P E D E S

Classification and distribution T h e D i p l o p o d a , c o m m o n l y ca l led m i l l i p e d e s , w e r e f o r m e r l y a s ­

soc ia t ed w i t h t h e C h i l o p o d a , P a u r o p o d a a n d S y m p h y l a i n a class,

t h e ' M y r i a p o d a ' , w h i c h c o n t a i n e d all t h e t e r r e s t r i a l A r t h r o p o d s

t h a t w e r e n o t C r u s t a c e a , A r a c h n i d a o r I n s e c t a , b u t t h e y a r e n o w

F I G . 5. Examples of millipede families: 1 . Glomeridae, 2 . Polyzoniidae, 3 . Chordeumidae, 4 . Craspedosomidae, 5 . Polydesmidae, 6. Strongylosomidae, 7. Iulidae, 8. Blaniulidae, 9. Spirobolidae, 1 0 . Polyxenidae. (Drawings not to scale.) (After various authors.)

1 5

16 M I L L I P E D E S

t r e a t e d a s a s e p a r a t e class . T h e n a m e D i p l o p o d a , w h i c h m e a n s

' d o u b l e - f o o t e d ' , w a s g i v e n t o t h e m b e c a u s e i n t h e s e a n i m a l s m o s t

o f t h e s e g m e n t s o f t h e b o d y a re p r o v i d e d w i t h t w o p a i r s o f l i m b s ,

a c o n d i t i o n a r i s ing f r o m t h e con f luence of t w o ad jacen t t e rga l

p l a t e s . A s i n t h e P a u r o p o d a a n d S y m p h y l a , t h e r e p r o d u c t i v e

o r g a n s h a v e t h e i r a p e r t u r e s on t h e v e n t r a l s ide o f t h e fore p a r t o f

t h e b o d y n e a r t h e h e a d , w h e r e a s i n t h e C h i l o p o d a t h e s e o p e n o n

t h e last a b d o m i n a l s o m i t e a s t h e y do in i n sec t s . M i l l i p e d e s h a v e a

d i s t i n c t h e a d b e a r i n g a p a i r o f s h o r t , u n b r a n c h e d a n t e n n a e , a t least

t w o pa i r s o f j a w s a n d u s u a l l y eyes . Sp i r ac l e s l e a d i n g i n t o t u b u l a r

t r a c h e a e o p e n a b o v e t h e coxae o f t h e legs a n d t h e dorsa l p l a t e s o f

t h e s e g m e n t s a r e g rea t l y d e v e l o p e d a s c o m p a r e d w i t h t h e v e n t r a l .

T h e m a j o r i t y o f t h e D i p l o p o d a a re i n c l u d e d i n t h e s u b - c l a s s

C h i l o g n a t h a a n d t h e i r i n t e g u m e n t i s h a r d a n d h o r n y . E a c h d o u b l e

s e g m e n t i s c o m p o s e d typ ica l ly of a v a u l t e d or n e a r l y c i r cu la r t e r -

g u m , o n e o r t w o sma l l p l e u r a l p l a t e s , t w o s t e r n i t e s a n d t w o pa i r s

o f legs . T h e t e rg i t e s , p l e u r i t e s a n d s t e r n i t e s m a y all b e m o v a b l e ,

o r t h e y m a y coa lesce i n t o a so l id r i ng , t h e s igni f icance o f w h i c h

wil l b e c o n s i d e r e d la te r . T h e r e a re on ly t w o p a i r s o f m o u t h p a r t s ;

t h e first a r e b i t i n g m a n d i b l e s c o m p o s e d o f t w o o r t h r e e s e g m e n t s ;

t h e s e c o n d p a i r i s fused to f o r m a b r o a d p l a t e o r g n a t h o c h i l a r i u m .

I n t h e m a l e s o n e p a i r o f legs i s m o d i f i e d for m a t i n g p u r p o s e s a n d

i ts s t r u c t u r e i s a d i a g n o s t i c c h a r a c t e r in m a n y spec ies .

FIG. 6. T h e pill-millipede Glomeris marginata. (After Cloudsley-Thompson , 1 9 5 6 . )

T h e o r d e r O n i s c o m o r p h a c o n t a i n s m i l l i p e d e s w h o s e b o d y i s

s h o r t , b r o a d , s t r o n g l y c o n v e x a b o v e a n d flat b e l o w , a n d c a p a b l e o f

b e i n g ro l l ed i n t o a ba l l as in s o m e w o o d l i c e . T h e r e a re f r o m 11 to

M I L L I P E D E S 1 7

13 te rga l p l a t e s o f w h i c h t h e s e c o n d i s e n o r m o u s l y e x p a n d e d a t

t h e s ides w h i l e t h e last f o r m s a r o u n d e d sh ie ld w h i c h fits aga ins t

i t a n d concea l s t h e h e a d w h e n t h e a n i m a l s a re coi led u p . I n t h e

m a l e s t h e last , o r last t w o pa i r s o f legs f o r m c l a spe r s a n d t h e basa l

s e g m e n t s o f t h e last p a i r a re m o d i f i e d a s s p e r m c a r r i e r s . T h e

fami ly G l o m e r i d a e c o n t a i n s t h e c o m m o n Br i t i sh p i l l - m i l l i p e d e ,

a n d a n u m b e r o f o t h e r sma l l spec ies f o u n d i n E u r o p e , A m e r i c a a n d

Asia; w h i l e t h e S p h a e r o t h e r i i d a e h a v e a s o u t h e r n d i s t r i b u t i o n a n d

o c c u r i n S o u t h Afr ica , M a d a g a s c a r , s o u t h e r n As ia a n d A u s t r a l a s i a .

S o m e of t h e m a r e o f l a rge size, s u r p a s s i n g a golf ba l l w h e n ro l led

u p .

T h e m i l l i p e d e s o f t h e o r d e r L i m a c o m o r p h a r e s e m b l e t h e O n i s -

c o m o r p h a i n g e n e r a l s t r u c t u r e b u t a r e o f sma l l size, m e a s u r i n g

n o t m o r e t h a n a b o u t o n e q u a r t e r o f a n i n c h i n l e n g t h . T h e t w o

fami l ies G l o m e r i d e s m i d a e a n d Z e p h r o n i o d e s m i d a e i n h a b i t t r o p i c a l

A m e r i c a a n d t rop i ca l As ia r e spec t ive ly : n o t h i n g i s k n o w n o f t h e i r

b io logy .

T h e t h i r d o r d e r , C o l o b o g n a t h a , a n d t h o s e t h a t fo l low differ

f rom t h e t w o p r e c e d i n g i n t h a t t h e las t t e rga l p l a t e enc i r c l e s t h e

a n u s w h i c h i s c losed b e l o w by a s t e r n i t e a n d la tera l ly by a p a i r of

va lves . T h e las t p a i r o f legs i s u n m o d i f i e d i n t h e m a l e . T h e b o d y

i s l ong , sp i ra l ly coi led w h e n a t r e s t a n d c o n t a i n s a l a rge a n d

va r i ab l e n u m b e r o f t e rga l p l a t e s w h i c h c a r r y r e p u g n a t o r i a l g l a n d s

u sua l l y o p e n i n g o n t u b e r c l e s o r l a rge r kee l - l ike o u t g r o w t h s . T h i s

o r d e r i s f o u n d in all t h e w a r m e r c o u n t r i e s o f t h e w o r l d w h e r e i t i s

r e p r e s e n t e d b y severa l fami l ies , s u c h a s t h e P s e u d o d e s m i d a e ,

P l a t y d e s m i d a e , P o l y z o n i i d a e a n d S i p h o n o p h o r i d a e , w h i c h ex­

h i b i t a p r o g r e s s i v e r e d u c t i o n of t h e m a n d i b l e s . In Siphonophora

s p p . t h e m o u t h o p e n s a t t h e t i p o f a l ong , p o i n t e d , s u c k i n g a n d

p i e r c i n g b e a k f o r m e d b y t h e l a b r u m a n d g n a t h o c h i l a r i u m , t h e

m a n d i b l e s w i t h i n i t b e i n g g r e a t l y r e d u c e d . T h e o n l y B r i t i s h m e m ­

b e r of t h e C o l o b o g n a t h a is Polyzonium germanicum w h i c h h a s b e e n

f o u n d o n t h e cha lk d o w n s o f K e n t a n d S u r r e y . I t i s a b i z a r r e f o r m

w i t h s e m i - s u c t o r i a l m o u t h p a r t s a n d c a n b e r ead i ly iden t i f i ed i n

co l l ec t ions f r o m t h e fact t h a t w h e n p r e s e r v e d in a lcohol i t i s c o n v e x

dorsa l ly a n d flat o r c o n c a v e ven t r a l l y .

T h e m e m b e r s o f t h e o r d e r A s c o s p e r m o p h o r a h a v e 2 6 t o 3 2

s e g m e n t s . T h e t e rga l p l a t e s coa lesce w i t h t h e p l e u r a , b u t t h e

B S.S.C.M.

1 8 M I L L I P E D E S

s t e rn i t e s a re free. I n t h i s f e a t u r e t h e y c o n t r a s t w i t h all o t h e r

C h i l o g n a t h a e x c e p t t h e O n i s c o m o r p h a . T h e t e rg i t e s a re p r o v i d e d

w i t h t h r e e pa i r s o f s y m m e t r i c a l l y p l a c e d b r i s t l e s a n d a re u sua l ly

k e e l - s h a p e d o r c a r i n a t e a t t h e s ides , b u t h a v e n o s t ink g l a n d s .

T h e r e i s a p a i r o f s p i n n i n g pap i l l ae on t h e las t t e rga l p l a t e . T h e

o r d e r i s r e p r e s e n t e d b y severa l fami l ies , o f w h i c h t h e C h o r -

d e u m i d a e , B r a c h y c h a e t e u m i d a e a n d C r a s p e d o s o m i d a e a re f o u n d

typ ica l ly i n E u r o p e a n d N o r t h A m e r i c a i n t h e n o r t h e r n h e m i s p h e r e ,

w h i l e t h e H e t e r o c h o r d e u m i d a e r a n g e f r o m t r o p i c a l As ia t o N e w

Z e a l a n d i n t h e s o u t h e r n h e m i s p h e r e . T h e B r i t i s h f o r m s a re smal l ,

pa l e a n i m a l s a n d i n c l u d e spec ies of Brachychaeteutna, Micro-

chordeuma, Craspedosoma rawlinsi w h i c h is m o r e r i ch ly c o l o u r e d

a n d h a s la te ra l t e rga l e x p a n s i o n s like t h o s e o f t h e P o l y d e s m i d a e ,

a n d Polymicrodon polydesmoides, w h i c h u s u a l l y i n h a b i t s t h e leafy

floor of d e c i d u o u s w o o d l a n d s .

T h e f l a t -backed m i l l i p e d e s o f t h e o r d e r P r o t e r o s p e r m o p h o r a

h a v e 1 9 o r 2 0 t e rga l p l a t e s w e l d e d w i t h t h e p l e u r a a n d s t e r n i t e s t o

f o r m sol id r i n g s u s u a l l y p r o v i d e d w i t h la te ra l shel f - l ike ca r inae .

I n th i s , t h e y differ f r o m o t h e r f l a t -backed f o r m s ( B r a c h y c h a e -

t u m i d a e ) . T h e r e a re n o eyes , n o s p i n n i n g pap i l l a e o n t h e last t e rga l

p l a t e , a n d t h e p o r e s o f t h e r e p u g n a t o r i a l g l a n d s w h e n t h e s e a re

p r e s e n t a re b o r n e o n t h e la tera l c a r i n a e . T h e m e m b e r s o f t h i s o r d e r

b e l o n g t o severa l fami l ies s u c h a s t h e P o l y d e s m i d a e , C r y p t o -

d e s m i d a e a n d S t r o n g y l o s o m i d a e , a n d a re r e f e r r e d t o a vas t n u m b e r

o f g e n e r a a n d spec ies f o u n d in all t h e c o u n t r i e s o f t h e w o r l d . S o m e

of t h e t r op i ca l spec ies a re la rge r e a c h i n g a l e n g t h of a b o u t six

i nches , a n d m a y b e b r i g h t l y c o l o u r e d . T h e B r i t i s h f auna i n c l u d e s

a n u m b e r of spec ies of P o l y d e s m i d a e of w h i c h Polydesmus angustus

i s t h e m o s t c o m m o n , a d o u b t f u l r e c o r d of Eumastigonodesmus

bond ( family M a s t i g o n o d e s m i d a e ) a n d s o m e r e p r e s e n t a t i v e s of t h e

fami ly S t r o n g y l o s o m i d a e . T h e s e i n c l u d e Macrosternodesmus pali-

cola, t h e sma l l e s t B r i t i sh D i p l o p o d , Ophiodesmus albonanus a n d

Oxidus (Paradesmus) gracilis w h i c h is f o u n d in g r e e n h o u s e s all over

t h e c o u n t r y .

T h e L y s i o p e t a l i d a e , w h i c h a re u sua l l y r e g a r d e d a s a s e p a r a t e

s u b - o r d e r f r o m t h e p r e v i o u s famil ies w h i c h a r e g r o u p e d t o g e t h e r

i n t h e s u b - o r d e r P o l y d e s m o i d e a , a re n o t r e p r e s e n t e d i n t h e

Br i t i sh f auna l list . T h e s e a n i m a l s a re f o u n d i n E u r o p e , Asia M i n o r

M I L L I P E D E S 1 9

a n d N o r t h Afr ica a n d h a v e a g r e a t a n d va r i ab l e n u m b e r o f t e rga l

p la t e s , m o s t o f w h i c h a r e p r o v i d e d w i t h r e p u g n a t o r i a l g l a n d s . T h e

a n t e r i o r p a i r o f legs o f t h e s e v e n t h s e g m e n t i s aga in mod i f i ed , as

s p e r m ca r r i e r s h o w e v e r , a n d t h e s e m i n a l d u c t s p e r f o r a t e t h e basa l

s e g m e n t s of t h e s e c o n d pa i r . S o m e spec ies of Lysiopetalum m a y

r e a c h f o u r o r five i n c h e s in l e n g t h .

T h e las t o r d e r o f C h i l o g n a t h a i s t h e O p i s t h o s p e r m o p h o r a , t h e

m e m b e r s o f w h i c h h a v e a l a rge a n d va r i ab l e n u m b e r o f cy l indr i ca l

t e rga l p l a t e s all of w h i c h , e x c e p t for a few a t t h e a n t e r i o r e n d , a re

p r o v i d e d w i t h r e p u g n a t o r i a l g l a n d s . I n n u m b e r o f spec ies , g e n e r a

a n d fami l ies , t h e o r d e r s u r p a s s e s all o t h e r o r d e r s o f t h e C h i l o ­

g n a t h a . T h e fami l ies a re u s u a l l y g r o u p e d in to t h r e e s u b - o r d e r s ,

t h e first o f w h i c h i n c l u d e s t h e S t e m m i u l i d a e w h i c h a r e f o u n d i n

t h e t r o p i c s o f Asia , Afr ica a n d A m e r i c a . T h e s e c o n d c o n t a i n s t h e

fami l ies I u l i d a e , B l a n i u l i d a e , w h i c h a re r e p r e s e n t e d i n B r i t a i n b y

m a n y spec ies a n d g e n e r a , a n d t h e S p i r o s t r e p t i d a e w h i c h i s a b u n ­

d a n t i n t h e t r o p i c s a n d c o n t a i n s s o m e o f t h e l a rges t m i l l i p e d e s i n

t h e w o r l d . T h e t h i r d s u b - o r d e r i n c l u d e s t h e S p i r o b o l i d a e w h i c h

are also w i d e l y d i s t r i b u t e d i n t r o p i c a l r e g i o n s a n d a re r e p r e s e n t e d

b y n u m e r o u s g e n e r a a n d spec ies , s o m e o f w h i c h r ival t h e la rges t

spec ies of Spirostreptus in size.

T h e s u b - c l a s s P s e l a p h o g n a t h a c o n t a i n s a s ing le w i d e l y d i s ­

t r i b u t e d o r d e r , Pen ic i l l a t a , c o m p r i s i n g t h e fami ly P o l y x e n i d a e a n d

t w o g e n e r a Polyxenus a n d Lophoproctus. T h e s e a re m i n u t e mi l l i ­

p e d e s h a v i n g a soft i n t e g u m e n t w i t h o u t h o r n y p l a t e s b u t r i ch ly

p r o v i d e d w i t h r o w s a n d tu f t s o f p e c u l i a r l y s h a p e d b r i s t l e s . T h e

m o u t h p a r t s a re c o m p l i c a t e d a n d a p p e a r t o cons i s t o f f o u r p a i r s .

T h e b o d y i s c o m p o s e d o f e l e v e n s o m i t e s o f w h i c h t h e first f ou r

c a r r y a s ing le p a i r o f legs , t h e n e x t f o u r t w o pa i r s a n d t h e n i n t h o n e

pa i r , t h e last t w o s e g m e n t s b e i n g legless . O f t h e t h i r t e e n pa i r s o f

legs n o n e is m o d i f i e d as g o n o p o d s . O n e spec ies , Polyxenus lagurus,

o c c u r s i n G r e a t Br i t a in .

General behaviour F r o m a s t u d y o f t h e l o c o m o t o r y m e c h a n i s m s a n d assoc ia ted

s t r u c t u r e s of a ser ies of m i l l i p e d e s r e p r e s e n t i n g t h e m a j o r s u b ­

d iv i s ions o f t h e D i p l o p o d a , M a n t o n (1954) ha s s h o w n t h a t t h e

evo lu t i on of t h e class h a s b e e n r e l a t ed to t h e d e v e l o p m e n t of a

20 M I L L I P E D E S

m a r k e d abi l i ty t o p u s h b y t h e m o t i v e force o f t h e legs . B y th i s

m e a n s t h e a n i m a l s a c h i e v e e i t h e r h e a d - o n b u r r o w i n g i n t o leaf

m o u l d , o r p u s h w i t h t h e do r sa l su r face o f t h e b a c k i n t o sp l i t s i n

w o o d , space s u n d e r b a r k a n d o t h e r spec ia l i sed h a b i t a t s . T h e h a b i t

o f c u r l i n g t h e b o d y i n t o a p r o t e c t i v e sp i ra l h a s b e e n a s e c o n d

fac tor o f m a j o r e v o l u t i o n a r y i m p o r t a n c e . T h e n e c e s s a r y p o w e r for

t h i s p u s h i n g i s a c h i e v e d b y t h e u s e o f ga i t s i n w h i c h t h e b a c k s t r o k e

o f t h e l i m b s i s o f v e r y m u c h l o n g e r d u r a t i o n t h a n t h e f o r w a r d

s t r o k e . T h e s e ga i t s r e q u i r e t h e p r e s e n c e o f v e r y m a n y legs t o each

m e t a c h r o n a l w a v e a n d t h i s h a s b e e n a c h i e v e d b y t h e e v o l u t i o n o f

n u m e r o u s d i p l o - s e g m e n t s . A l t h o u g h m o d e r a t e f l e e t n e s s h a s b e e n

evo lved m a n y t i m e s , p a r t i c u l a r l y i n t h e C o l o b o g n a t h a a n d P o l y -

d e s m o i d e a , fast ga i t s u s u a l l y a p p e a r t o be o f lesser s igni f icance to

m i l l i p e d e s t h a n t h e s low, p o w e r f u l ga i t s . S o m e spec ies o f I u l i d a e

c a n o n occas ion m a k e u s e o f a n u n u s u a l e scape r e a c t i o n . I n s t e a d o f

c u r l i n g u p , t h e y w r i t h e t h e b o d y i n a se r ies o f u n d u l a t i n g f lexions,

w r i g g l i n g r a p i d l y t h r o u g h t h e g r a s s o r v e g e t a t i o n w i t h o u t u s i n g

t h e i r feet a t all ( F r y e r , 1957 e tc) .

T h i s h a b i t a p p e a r s t o b e a n i n c i d e n t a l a c c o m p l i s h m e n t , h o w e v e r ,

a n d h a s n o t b e e n o f e v o l u t i o n a r y s igni f icance . M o r e i m p o r t a n t i s

t h e ab i l i ty t o c l i m b s m o o t h rock su r faces a t a n y a n g l e f o u n d i n

Polyzonium germanicum a n d a m o n g t h e o t h e r C o l o b o g n a t h a , w h i c h

a re also a d a p t e d for p u s h i n g i n s t o n y p l aces . T h i s c l i m b i n g h a b i t

neces s i t a t e s a p o w e r f u l g r i p by t h e o p p o s i t e legs of a p a i r a n d p o s ­

s ib ly t h e u s e o f a d h e s i v e coxal sacs w h e n t h e a n i m a l i s a t r es t .

V a r i o u s spec ia l i sa t ions exis t for s t r e n g t h e n i n g t h e s k e l e t o n a n d

for r e s i s t i ng t e l e s c o p i n g a t t h e i n t e r - r i n g j o i n t s ( M a n t o n , 1954) .

T h i s m a y wel l b e t h e e x p l a n a t i o n for t h e u n u s u a l so l id i ty o f t h e

m i l l i p e d e cu t i c le w h i c h i s h a r d e n e d n o t o n l y b y p h e n o l i c t a n n i n g

a s i n i n sec t s a n d A r a c h n i d s , b u t a lso b y t h e d e p o s i t i o n o f c a l c i u m

a s i n t h e C r u s t a c e a ( C l o u d s l e y - T h o m p s o n , 1950b) .

F r o m a phys io log ica l p o i n t o f v i e w d e p e n d e n c e u p o n m o i s t a n d

h u m i d s u r r o u n d i n g s i s o n e o f t h e m o s t i m p o r t a n t fac tors i n t h e

l ives o f m i l l i p e d e s , a s o f w o o d l i c e , c e n t i p e d e s a n d o t h e r m y r i a p o d s .

F o r e x a m p l e , i t h a s b e e n s h o w n t h a t Oxidus (Paradesmus) gracilis,

a t r o p i c a l spec ies w i d e l y d i s t r i b u t e d in g l a s s h o u s e s in t e m p e r a t e

r e g i o n s , a n d t h e ' s p o t t e d s n a k e m i l l i p e d e ' Blaniulus guttulatus, a r e

s t i m u l a t e d b y d r o u g h t a n d c o m e t o res t o n l y i n m o i s t p l aces

M I L L I P E D E S 2 1

( C l o u d s l e y - T h o m p s o n , 1951c) . U n d e r t h e in f luence o f des i cca t ion

t h e a n i m a l s s h o w pos i t i ve geo tax i s a n d m o v e d e e p e r i n t o t h e soil .

A l t h o u g h t h e r e a c t i o n s o f m i l l i p e d e s t o m o i s t u r e a r e far m o r e

m a r k e d t h a n a re t h e i r r e s p o n s e s t o t h e h u m i d i t y o f t h e a t m o s p h e r e ,

S h e l f o r d (1913) h a s s h o w n t h a t Fontaria corrugata is r epe l l ed by

d r y a i r a n d m o r e r e c e n t l y P e r t t u n e n (1953) h a s f o u n d t h a t w h e r e a s

O. gracilis i s v e r y sens i t ive to d i f ferences a t t h e h i g h e r e n d of t h e

h u m i d i t y r a n g e , Schizophyllum sabulosum, w h i c h ha s a m u c h lower

r a t e o f w a t e r - l o s s , p a r t i c u l a r l y i n s u m m e r , t e n d s in i t ia l ly t o m o v e

t o w a r d s d r y a i r a n d t h e r e a c t i o n i s g r a d u a l l y r e v e r s e d to m o i s t a s

d e s i c c a t i o n p r o c e e d s . O r i e n t a t i o n i s en t i r e ly ' k i n e t i c ' o r n o n -

d i r e c t i o n a l , s p e e d i s g r e a t e r i n d r y a i r t h a n i n m o i s t , a n d i n a n ex ­

p e r i m e n t a l c h a m b e r in w h i c h a cho i ce of h u m i d i t i e s i s p r o v i d e d ,

b o t h t h e t i m e s p e n t a n d t h e d i s t a n c e c o v e r e d a re g r e a t e r o n t h e

m o i s t s ide . I n t h i s spec ies f emales t h a t a re jus t a b o u t t o s t a r t egg -

lay ing s h o w a reversa l o f t h e i r h u m i d i t y r eac t ion a n d t h e r e i s t h e n

a c lear a n d i n t e n s e r e s p o n s e to m o i s t u r e ( P e r t t u n e n , 1955). In a

s imi l a r w a y , d u r i n g t h e s u m m e r , Polyzonium germanicum wa lks on

t h e u n d e r su r face o f s m o o t h cha lk b o u l d e r s , w h e r e i t m a y r e m a i n

for h o u r s o r d a y s h a n g i n g on ' in a c h i t o n - l i k e m a n n e r w i t h n e i t h e r

h e a d , a n t e n n a e o r legs e x p o s e d ' , b u t d u r i n g t h e w i n t e r i t p e n e ­

t r a t e s i n t o d a m p a n d c o m p a c t v e g e t a b l e m a t t e r a n d leaf m o u l d ,

f r e q u e n t l y d e e p i n m o s s , w h e r e i t r e m a i n s c u r l e d u p for w e e k s

w i t h o u t m o v i n g . I t i s t h e n difficult t o f i n d d e s p i t e its b r i g h t

o r a n g e c o l o u r ( M a n t o n 1954).

T h e r e s p o n s e o f m i l l i p e d e s t o m o i s t u r e h a s s o m e e c o n o m i c i m ­

p o r t a n c e for, u n d e r c o n d i t i o n s o f d r o u g h t , t hey m a y b e forced t o

a t t ack g r o w i n g c r o p s for t h e sake o f w a t e r . Af te r s o m e y e a r s ' r e ­

s ea rch o n t h e p h y s i o l o g y a n d eco logy o f t h e s e a n i m a l s , t h e w r i t e r

c o n c l u d e d t h a t o u t b r e a k s o f t h e ' s p o t t e d s n a k e m i l l i p e d e ' t e n d t o

be s t i m u l a t e d by a d r y spel l fo l lowing a p e r i o d s u i t a b l e to t h e r e ­

p r o d u c t i o n o f t h e spec ies w h e n t h e soil i s d a m p , u n d i s t u r b e d a n d

r ich i n h u m u s . I t w a s s h o w n e x p e r i m e n t a l l y t ha t h u m u s a n d r o t ­

t i n g s u b s t a n c e s h a v e a t e x t u r e w h i c h i s p r e f e r r e d by m i l l i p e d e s to

t h a t o f l iv ing p l a n t t i s sues , a n d t ha t t h e a n i m a l s a re a t t r a c t e d to

d i lu t e c o n c e n t r a t i o n s o f s u g a r s .

N o d o u b t a m o i s t s ea son c o m b i n e d w i t h t h e u s e o f f a r m y a r d

m a n u r e o r t h e g r o w i n g o f s o m e c r o p p r o d u c i n g a c o n s i d e r a b l e

22 M I L L I P E D E S

a m o u n t o f h u m u s , wil l e n g e n d e r a g r e a t i n c r e a s e in t h e n u m b e r o f

m i l l i p e d e s in t h e soil , p a r t i c u l a r l y i f t h e g r o u n d i s n o t d i s t u r b e d by

p l o u g h i n g , e t c . T h e y m a y b e benef ic ia l a t t h i s s t age i n a i d i n g t h e

b r e a k d o w n o f t h e h u m u s , b u t i f t h e fo l lowing season i s d r y , e v e n

for a s h o r t spel l , t h e y m a y be c o m p e l l e d to a t t ack c r o p s for t h e

sake o f m o i s t u r e . O n c e an a t t ack h a s b e e n in i t i a t ed , a r e t u r n to

t h e i r n o r m a l d ie t o f h u m u s a n d d e c o m p o s i n g m a t t e r i s m o s t u n ­

l ikely, d u e t o t h e a t t r a c t i o n o f s u g a r s i n t h e p l a n t s a p . I t i s u n ­

l ikely t h a t d a m a g e b y m i l l i p e d e s t o c r o p s w i t h t o u g h ex te r io r s

s u c h a s p o t a t o e s a n d m a n g o l d s can eve r b e p r i m a r y , for n o t o n l y d o

t h e i r w e a k m o u t h p a r t s p r e v e n t t h e m f r o m g a i n i n g access , b u t i n

a d d i t i o n t h e y a re n o t a t t r a c t e d t o u n b r o k e n sk ins o f p o t a t o e s , on ly

t o c u t su r faces . O n c e a n e n t r a n c e h a s b e e n a c h i e v e d h o w e v e r ,

t h r o u g h m e c h a n i c a l d a m a g e o r t h e b i t e s o f w i r e - w o r m s a n d o t h e r

p e s t s , t h e m i l l i p e d e s wil l eat o u t t h e e n t i r e c e n t r e o f a p o t a t o a n d

t h e d a m a g e t h e y c a u s e i s o f ten fo l lowed b y funga l a t t ack ( C l o u d s l e y -

T h o m p s o n , 1950a) . F u r t h e r m o r e , t h e fact t h a t s ing le p o t a t o e s

h a v e b e e n f o u n d c o n t a i n i n g ove r a h u n d r e d Blaniulus guttulatus of

all ages w h i l e t h e r e m a i n d e r o f t h e c r o p w a s u n h a r m e d , s h o w s

t h a t t h e y m u s t h a v e b e e n a t t r a c t e d t o a d a m a g e d t u b e r a n d c o u l d

n o t h a v e b r e d t h e r e .

M i l l i p e d e s t e n d to avo id t h e l igh t , b u t w i t h t h e e x c e p t i o n o f a

d i r e c t e d r e s p o n s e o r ' t ax i s ' a w a y f r o m l igh t i n t h o s e f o r m s t h a t

posses s eyes a n d a r e s p o n s e to g r av i t y ( w h i c h o f c o u r s e c a n n o t be

o t h e r t h a n d i r e c t e d s ince t h e s t i m u l u s i s c o n s t a n t ) t h e b e h a v i o u r

r eac t i ons of m i l l i p e d e s a r e en t i r e ly n o n - d i r e c t i o n a l . Oxidus gracilis

a n d Blaniulus guttulatus a r e w i t h o u t eyes b u t t h e y posses s a d e r m a l

l ight s ense . W h e n i l l u m i n a t e d t h e y c rawl a r o u n d u n t i l b y c h a n c e

t h e y f i n d t h e m s e l v e s i n d a r k n e s s w h e r e t h e y c o m e t o res t . T h e i r

t e m p e r a t u r e r e a c t i o n s fall i n t o t h r e e ca t egor i e s . T h e r e i s a gene ra l

m e t a b o l i c effect u p o n t h e s p e e d o f l o c o m o t i o n a n d d u r a t i o n o f t h e

sp i ra l reflex a n d a k i n e t i c ' p r e f e r e n c e ' for t e m p e r a t u r e s a b o u t 15° C,

w h i l e s u d d e n d r o p s o f t e m p e r a t u r e e n g e n d e r i n t e n s e l o c o m o t o r y

ac t iv i ty . A i r b o r n e o d o u r s a re a p p a r e n t l y n o t d e t e c t e d , b u t mi l l i ­

p e d e s r e s p o n d t o s u g a r s b y m e a n s o f t a s t e s ense o r g a n s o n t h e i r

a n t e n n a e a n d m o u t h p a r t s ( C l o u d s l e y - T h o m p s o n , 1951c) . A s t h e y

walk a b o u t , m i l l i p e d e s s t ead i ly t a p t h e sur face ove r w h i c h t h e y are

m o v i n g w i t h t h e t i p s o f t h e i r a n t e n n a e a n d n o d o u b t c o n s t a n t l y

M I L L I P E D E S 23

tes t i ts n a t u r e b y m e a n s o f t h e s e n s o r y ha i r s a n d c h e m o - r e c e p t i v e

sensi l lae r e f e r r ed t o .

A l t h o u g h t o m i l l i p e d e s , a s t o w o o d l i c e a n d t o t h e o t h e r m y r i a -

p o d s , h u m i d i t y i s t h e m o s t i m p o r t a n t fac to r o f t h e e n v i r o n m e n t ,

t h e s e a n i m a l s a re n o t ab le t o f ind t h e i r w a y d i r ec t ly t o d a m p

p laces : i n s t e a d , t h e y a re m e r e l y r epe l l ed b y d r o u g h t . N e v e r t h e l e s s

FIG. 7. Sense organs of the millipede Oxidus gracilis. Left, antenna and below the seventh and eighth segments more highly enlarged to show peg and cone sensillae. Right, gnathochilarium or lower lip with one of the palps more highly magnified to show

peg-organs. (After Cloudsley-Thompson, 1951.)

t h i s s t e r e o t y p e d a n d c u r i o u s l y nega t i ve b e h a v i o u r i s s u r p r i s i n g l y

effective i n p r e v e n t i n g t h e m f r o m w a n d e r i n g a w a y f r o m t h e i r n o r ­

m a l h a b i t a t s : b u t i t d o e s ra ise t h e p r o b l e m o f h o w d i spe r sa l can

t ake p lace a n d n e w h a b i t a t s b e c o m e co lon i sed .

T h e r e a re a n u m b e r o f cases on r e c o r d o f m i l l i p e d e s , s o m e t i m e s

a c c o m p a n i e d b y c e n t i p e d e s , a n d w o o d l i c e m i g r a t i n g i n vas t a r m i e s .

24 M I L L I P E D E S

Occas iona l l y t h e y h a v e c ros sed ra i lways a n d b e e n s q u a s h e d i n

s u c h n u m b e r s t h a t l o c o m o t i v e s h a v e b e e n i m p e d e d a n d s a n d h a s

h a d t o b e s t r e w n o n t h e l ines be fo re t h e i r d r i v i n g w h e e l s w o u l d

g r i p . A t o t h e r t i m e s ca t t l e h a v e r e fused t o g r a z e o n i n v a d e d p a s ­

t u r e s , we l l s h a v e b e e n filled w i t h d r o w n e d c o r p s e s a n d w o r k m e n

c u l t i v a t i n g t h e fields h a v e b e c o m e n a u s e a t e d a n d d izzy f r o m t h e

o d o u r o f m i l l i p e d e s c r u s h e d b y t h e i r h o e s . H o w e v e r , s u c h m a s s

m i g r a t i o n s a re o f r a r e o c c u r r e n c e a n d local i n e x t e n t , so t h a t t h e i r

n e t effect on d i s t r i b u t i o n i s p r o b a b l y neg l ig ib le .

T h e s u b j e c t o f m i g r a t i o n i n m y r i a p o d s h a s b e e n r e v i e w e d b y

C l o u d s l e y - T h o m p s o n ( 1 9 4 9 b ; 1951a) a n d i t h a s b e e n s u g g e s t e d

t h a t a l t h o u g h c e r t a i n a s p e c t s o f t h e p h e n o m e n o n a r e still n o t ex ­

p l a i n e d , t h e e v i d e n c e l e n d s s u p p o r t t o t h e h y p o t h e s i s t h a t m a s s

m i g r a t i o n i s m e r e l y a n e x t r e m e case o f t h e m o r e fami l i a r s u d d e n

a t t a cks on c r o p s d u e t o e x t r e m e l y f a v o u r a b l e local c o n d i t i o n s , fol­

l o w e d b y d r o u g h t a n d p o s s i b l y a c c o m p a n i e d b y a b n o r m a l p h y s i o ­

logical c o n d i t i o n s o f r e p r o d u c t i o n .

A n e x p l a n a t i o n o f t h e p r o b l e m o f h o w d i spe r sa l c a n t ake p l ace

h a s b e e n s u g g e s t e d as a r e s u l t o f r e c e n t w o r k in w h i c h i t h a s b e e n

s h o w n t h a t m i l l i p e d e s a r e m a r k e d l y n o c t u r n a l a n d s h o w a d i u r n a l

cycle of r h y t h m i c ac t iv i ty . In O. gracilis a n d B. guttulatus t h i s is

p r i m a r i l y a r e s p o n s e to l i gh t a n d d a r k n e s s , b u t i s a lso c o r r e l a t e d

w i t h t h e s t i m u l u s o f fa l l ing t e m p e r a t u r e i n t h e e v e n i n g . A k t o g r a p h

e x p e r i m e n t s o n t w o l a rge W e s t Af r i can spec ies o f m i l l i p e d e s h a v e

d e m o n s t r a t e d a n e n d o g e n o u s d i u r n a l r h y t h m i n d e p e n d e n t o f f l u c ­

t u a t i n g l igh t a n d t e m p e r a t u r e a n d p e r s i s t i n g i n Ophistreptus s p . u p

t o n i n e t e e n days . L o c o m o t o r y ac t iv i ty i s s t i m u l a t e d b y i nc r ea se s o r

d e c r e a s e s o f t e m p e r a t u r e , a n d i t i s p r o b a b l e t h a t i n t r op i ca l f o r m s

t e m p e r a t u r e f l u c t u a t i o n s a re o f p r i m a r y i m p o r t a n c e i n t h e in i t i a ­

t i on o f d i u r n a l r h y t h m s . P e r h a p s i n t h e i r n a t u r a l g l o o m y h a b i t a t

in t r o p i c a l fo res t s , l igh t i s an ins ign i f ican t e n v i r o n m e n t a l fac tor

( C l o u d s l e y - T h o m p s o n , 1951b) . T h u s i t i s a t n i g h t t h a t m i l l i p e d e s ,

l ike o t h e r m y r i a p o d s a n d w o o d l i c e , a r e ab le t o d i s p e r s e t h e m s e l v e s

a n d o v e r c o m e t h e r e s t r i c t i o n s i n h e r e n t i n t h e p h y s i o l o g y o f t h e i r

i n t e g u m e n t s .

B l o w e r (in K e v a n , 1955)* h a s s u g g e s t e d t h a t m i l l i p e d e s a re d i s ­

t r i b u t e d a t v a r i o u s d e p t h s i n t h e soil a c c o r d i n g t o t h e i r w a t e r -

r e l a t ions a n d b o d y f o r m s . N e m a t o p h o r a a n d P o l y d e s m o i d e a w h i c h '

M I L L I P E D E S 25

a r e m o s t s u s c e p t i b l e t o de s i cca t i on a n d w e t t i n g t e n d t o i n h a b i t

t h i ck leaf - l i t te r w h i c h i s p r o o f aga ins t f l o o d a n d d r o u g h t , w h i l e

m a n y o f t h e I u l i d a e a n d B l a n i u l i d a e p e n e t r a t e d e e p l y i n t o t h e soil .

H e also m a k e s t h e i n t e r e s t i n g s u g g e s t i o n t h a t c a l c i u m ions i n t h e

soil w a t e r m a y exe r t a beneficial effect by l i m i t i n g t h e p e r m e a b i l i t y

o f t h e e p i d e r m i s .

FIG. 8. T w o types of aktograph apparatus suitable for use with millipedes, each consisting of an arena or box pivoted on a knife-edge along its median transverse axis. Any movement of an animal along the longitudinal axis tips the arena and is recorded by a lever balanced by an adjustable counterpoise and writing on a revolving smoked d rum. (After G u n n and Kennedy, 1937, and

D'Aguillar, 1952.)

S o m e o t h e r a s p e c t s o f t h e b io logy o f t h e D i p l o p o d a a re w o r t h y

o f m e n t i o n . M i l l i p e d e s n o t i n f r e q u e n t l y o c c u r a s g u e s t s i n t h e

n e s t s of a n t s a n d t e r m i t e s . In B r i t a i n t h r e e spec ies , Blaniulus gut­

tulatus, Proteroiulus fuscus a n d Polyxenus lagurus, a re f r e q u e n t l y

m y r m e c o p h i l o u s ( D o n i s t h o r p e , 1927)* a n d i n t h e t r o p i c s severa l

spec ies h a v e b e e n s een a c c o m p a n y i n g c o l u m n s o f a r m y a n t s o n t h e

m a r c h . A n u m b e r o f spec ies a r e c a v e r n i c o l o u s a n d h a v e b e c o m e

a d a p t e d in v a r y i n g d e g r e e s to a t r o g l o d y t i c ex i s t ence . T h e r e i s

ex t ens ive l i t e r a t u r e o n t h e sub jec t .

R e p o r t s o f l u m i n o u s m i l l i p e d e s a r e few. O n e o f t h e m o s t s t r i k ing

e x a m p l e s is Luminodesmus sequoiae, a l a rge a n d h a n d s o m e spec ies

m e a s u r i n g s o m e 4 0 m m i n l e n g t h , t h a t i n h a b i t s t h e S e q u o i a

N a t i o n a l F o r e s t i n Ca l i fo rn ia . L u m i n e s c e n c e f i r s t a p p e a r s o n

h a t c h i n g . I t i s c o n t i n u o u s , u n d e r n o v o l u n t a r y c o n t r o l . I t s s o u r c e

26 M I L L I P E D E S

a p p a r e n t l y l ies i n t h e d e e p e r l ayers o f t h e i n t e g u m e n t . A t t e m p t s t o

d e m o n s t r a t e t h e classical ' l uc i f e r in - luc i f e ra se ' ac t iv i ty i n t h i s

spec ies h a v e b e e n u n s u c c e s s f u l ( D a v e n p o r t , W o o t t o n a n d C u s h -

ing , 1952) .

F ina l l y t h e r e a re a n u m b e r of cases on r e c o r d of p s e u d o - p a r a s i t ­

i s m b y m i l l i p e d e s i n t h e a l i m e n t a r y t r a c t o f m a n .

Food and feeding habits M i l l i p e d e s a re v e g e t a r i a n a n d feed on a w i d e r a n g e o f p l a n t s u b ­

s t a n c e s , a l t h o u g h o n a c c o u n t o f t h e i r w e a k m o u t h p a r t s m a n y

spec ies t e n d t o p r e f e r soft o r d e c o m p o s i n g t i s sue s ( B r a d e - B i r k s ,

1930) . T h e y h a v e also b e e n r e c o r d e d a s e a t i n g d e a d w o r m s , m o l ­

luscs , i n sec t s a n d v e r t e b r a t e s . As a l r e a d y m e n t i o n e d , a n u m b e r o f

spec ies a re w e l l - k n o w n a g r i c u l t u r a l a n d g l a s s - h o u s e p e s t s . O f

t h e s e w i t h o u t d o u b t t h e w o r s t of fender i n t e m p e r a t e c l ima te s i s

t h e ' s p o t t e d s n a k e m i l l i p e d e ' , Blaniulus guttulatus, w h i c h h a s l ong

b e e n r e g a r d e d as a p e s t o f s u g a r b e e t , p o t a t o e s , m a n g o l d s , oa t s ,

w h e a t , s t r a w b e r r i e s a n d o t h e r a g r i c u l t u r a l c r o p s a n d f ru i t . I t ha s

b e e n s h o w n t h a t o u t b r e a k s o f t h i s spec ies t e n d of ten t o b e s t i m u l a ­

t e d by a d r y spel l fo l lowing a p e r i o d s u i t a b l e to t h e r e p r o d u c t i o n of

t h e spec ies , w h e n t h e soil i s d a m p , u n d i s t u r b e d a n d r i ch i n h u m u s .

T h e y u sua l l y o c c u r o n m e d i u m o r h e a v y soil a n d a re i n h i b i t e d o r

d e s t r o y e d b y e x t r e m e d r o u g h t . B r e e d i n g i s p r o b a b l y i n h i b i t e d b y

m o d e r a t e l y d r y w e a t h e r . T h e spec ies m a y b e benef ic ia l i n a i d i n g

t h e b r e a k d o w n o f h u m u s , b u t i s a p o t e n t i a l d a n g e r t o g r o w i n g

c r o p s a n d m a y e v e n a t t ack p o t a t o e s a n d m a n g o l d s i f w i r e - w o r m s

a n d o t h e r a g r i c u l t u r a l p e s t s a re p r e s e n t t o m a k e a n ini t ia l e n t r y

( C l o u d s l e y - T h o m p s o n , 1950a) . S c h u b a r t (1942) h a s g iven a c o m ­

p r e h e n s i v e b i b l i o g r a p h y o f t h e m y r i a p o d s a n d t h e i r r e l a t ion t o

a g r i c u l t u r e , a n d t h i s h a s b e e n s u p p l e m e n t e d b y R e m y (1950a) ,

w h i l e B r a d e - B i r k s (1930) h a s s t u d i e d t h e e c o n o m i c s t a t u s o f t h e

Br i t i sh D i p l o p o d a .

A l t h o u g h i t h a s l o n g b e e n a s s u m e d t h a t m y r i a p o d s posses s

p o w e r s o f t a s t e a n d v a r i o u s a n t e n n a r y a n d g n a t h o c h i l a r i a l s t r u c ­

t u r e s h a v e b e e n r e g a r d e d a s g u s t a t o r y s ense o r g a n s , t h e ab i l i ty o f

m i l l i p e d e s t o r eac t t o c o n t a c t c h e m i c a l s t i m u l i h a s on ly o n c e o r

t w i c e b e e n t e s t e d e x p e r i m e n t a l l y . I n 1943 , L y f o r d p u b l i s h e d a n

i n t e r e s t i n g a c c o u n t o f h i s e x p e r i m e n t s on t h e pa l a t ab i l i t y o f v a r i o u s

M I L L I P E D E S 27

fores t leaves to Cylindroiulus londinensis. I t w a s f o u n d t h a t t h e pa la -

t ab i l i ty o f leaves f r o m t h e s a m e t r e e a n d f r o m ad jacen t t r e e s o f t h e

s a m e spec ies s h o w e d s o m e va r i ab i l i ty b u t n o t e n o u g h t o m a s k t h e

d i f ference i n pa l a t ab i l i t y b e t w e e n spec ies . I n g e n e r a l , t h e m o s t

p a l a t a b l e leaves h a d a h i g h c a l c i u m c o n t e n t w h i l e t h e u n p a l a t a b l e

leaves h a d n o t . M o r e r e c e n t l y i t h a s b e e n f o u n d t h a t lulus a n d

Cylindroiulus s p p . ea t q u a n t i t i e s of n e w l y fal len leaves f ro m t h e

sur face of a m i x e d b e e c h fores t floor, a n d e v e n m o r e of t h e leaves

t h a t a re a y e a r o lde r . Iulus s p p . ea t m o r e oak t h a n of a n y o t h e r

t y p e o f leaf, Cylindroiulus s p p . m o r e p i n e . I t h a s also b e e n s h o w n

t h a t Oxidus gracilis a n d Blaniulus guttulatus a r e a t t r a c t e d to g lucose

a n d s u c r o s e w i t h a t h r e s h o l d a b o u t 0 . 5 g m / l i t r e : b u t t h e r e i s n o

a t t r a c t i o n t o a s p a r a g i n e o r s t a r c h . A s a l r e a d y m e n t i o n e d , t h e a n -

t e n n a l a n d g n a t h o c h i l a r i a l b a s i c o n i c sens i l lae a r e t h e s e n s o r y r e ­

c e p t o r s for t a s t e s t i m u l i : m i l l i p e d e s d o n o t r e s p o n d t o a i r b o r n e

o d o u r s ( C l o u d s l e y - T h o m p s o n , 1951c) .

Enemies M i l l i p e d e s , on occas ion , a re e a t e n by a w i d e r a n g e o f p r e d a t o r y

a n i m a l s . T h e s e i n c l u d e s p i d e r s , s o m e spec ies o f w h i c h wil l feed

r e l u c t a n t l y on t h e c o m m o n b l ack Tachypodoiudus niger, Oxidus

gracilis a n d o t h e r sma l l f o r m s ; a n t s , f ishes, a m p h i b i a n s , r ep t i l e s ,

m a m m a l s a n d b i r d s ( C l o u d s l e y - T h o m p s o n , 1949) . O f t h e s e , on ly

t o a d s a n d b i r d s feed o n m i l l i p e d e s t o a n a p p r e c i a b l e d e g r e e . M i l l i ­

p e d e s f o r m a c o n s t a n t a r t i c le of d i e t of t h e A m e r i c a n t o a d Bufo

lentiginosus, a s m a n y a s s e v e n t y - s e v e n h a v i n g b e e n f o u n d in o n e

s t o m a c h , a n d 1 0 % b y b u l k o f t h e food o f t h i s spec ies i s c o m p o s e d

of m i l l i p e d e s . T h e Br i t i sh B . vulgaris, w h i c h wil l ea t a l m o s t a n y ­

t h i n g i t c a n ca t ch , will r ead i ly d e v o u r m i l l i p e d e s , w h i c h a re also

e a t e n by frogs a n d s a l a m a n d e r s . M i l l i p e d e s c o m p r i s e a p r o p o r t i o n

o f t h e food o f m a n y spec ies o f b i r d s , b u t a s far a s i s k n o w n n o n e

e q u a l s t h e s t a r l i ng i n t h e i r d e s t r u c t i o n . I n A m e r i c a m i l l i p e d e s

ave rage u p t o 1 1 . 7 1 % o f t h i s b i r d ' s yea r ly d ie t . I n A p r i l t h e y f o r m

5 4 . 6 9 % , i n M a y 4 2 . 1 9 % a n d i n J u n e 2 3 . 6 6 % . Af t e r a fa l l ing off i n

t h e l a te r s u m m e r m o n t h s t h e y aga in r ise t o 7 . 6 4 % i n O c t o b e r . T h e

fact t h a t in A p r i l 119 o f 132 a d u l t b i r d s e x a m i n e d , in M a y 133 of

140 a n d in J u n e 146 o f 2 1 5 , h a d e a t e n m i l l i p e d e s , g ives an idea o f

t h e p e r s i s t e n c e w i t h w h i c h s t a r l i ngs m u s t s ea r ch for s u c h food.

28 M I L L I P E D E S

F i f t een o f t h e b i r d s t a k e n i n A p r i l w e r e f o u n d t o h a v e ea t en

n o t h i n g else, a n d n i n e t e n t h s o f t h e food o f f o u r t e e n o t h e r s w a s

c o m p o s e d of m i l l i p e d e s .

T o m o s t a n i m a l s , h o w e v e r , m i l l i p e d e s a re r e n d e r e d s o m e w h a t

u n p a l a t a b l e o n a c c o u n t o f t h e i r t o u g h i n t e g u m e n t a n d b y t h e i r r i ­

t a n t e x u d a t e s s e c r e t e d b y t h e r e p u g n a t o r i a l g l a n d s o f t h e C o l o b o ­

g n a t h a , P r o t e r o s p e r m o p h o r a a n d O p i s t h o s p e r m o p h o r a . T h e s t r u c ­

t u r e o f t h e s e g l a n d s i s v e r y s imi la r i n all t h r e e o r d e r s . T h e y a re

sac- l ike i n s h a p e a n d e a c h d i s c h a r g e s i n t o a l u m e n w h i c h in t u r n

l eads t o t h e f o r a m e n o r o p e n i n g . T h o u g h t h e g l a n d s t h e m s e l v e s

c a n n o t b e c o m p r e s s e d , t h e i r o p e n i n g s can b e r e g u l a t e d b y specia l

m u s c l e s , w h i l e o t h e r m u s c l e s n e a r b y exe r t c o n s i d e r a b l e p r e s s u r e

w h e n t h e a n i m a l m o v e s s u d d e n l y . I n m o s t cases t h e s ec r e t i on i s

e x u d e d fair ly s lowly f r o m t h e p o r e s o f t h e g l a n d s b u t i n s o m e o f

t h e l a rge r t r op i ca l f o r m s i t c a n be d i s c h a r g e d to a c o n s i d e r a b l e d i s ­

t a n c e in t h e f o r m of a fine j e t or s p r a y .

FIG. 9. Distr ibution of repugnatorial glands on the segments of a millipede Oxidus gracilis. Right, section of an individual gland.

(After Weber , 1882.)

T h e m a x i m u m r e c o r d e d a c h i e v e m e n t w a s a d o u b l e salvo f ro m

a Rhinocricus lethifer in H a i t i w h i c h sen t i ts d i s c h a r g e 28 i n c h e s on

o n e s ide a n d 3 3 o n t h e o t h e r , t h e d r o p l e t s fa l l ing fanwise a r o u n d

t h e b o d y . T h e r e p u g n a t o r i a l f luid o f t h e la rge t r op i ca l spec ies has

a s t r o n g caus t i c ac t ion a n d causes b l a c k e n i n g on c o n t a c t w i t h t h e

M I L L I P E D E S 29

h u m a n sk in . L a t e r t h e affected p a r t pee l s , l eav ing a w o u n d w h i c h

hea l s o n l y v e r y s lowly . I t i s d a n g e r o u s to t h e eyes a n d i s r e s p o n s i b l e

for n u m e r o u s cases o f b l i n d n e s s a m o n g c h i c k e n s i n t h e W e s t

I n d i e s a n d e l s e w h e r e ( B u r t t , 1947) .

I n i ts smel l a n d c o l o u r t h e s ec r e t i on o f m o s t O p i s t h o s p e r m o -

p h o r a r e s e m b l e s i o d i n e a n d s t a ins t h e f ingers a p u r p l i s h - b r o w n

c o l o u r i n t h e s a m e m a n n e r a s t h i s s u b s t a n c e . T h e chief c o m p o u n d s

o f phys io log ica l i n t e r e s t i n t h e s e c r e t i o n s a r e h y d r o c y a n i c ac id ,

i o d i n e a n d q u i n i n e . S m a l l a m o u n t s o f c h l o r i n e w h i c h g ive t h e

s u b s t a n c e i ts c h a r a c t e r i s t i c o d o u r h a v e b e e n d e t e r m i n e d e x p e r i ­

m e n t a l l y . I t h a s b e e n s u g g e s t e d t h a t t h e d i s in fec t ing p r o p e r t i e s o f

t h e c h l o r i n e a n d h y d r o c y a n i c ac id m a y assis t i n k e e p i n g t h e a n i m a l

free f r om b a c t e r i a a n d o t h e r m i c r o - o r g a n i s m s .

I n c o n t r a s t t h e P r o t e r o s p e r m o p h o r a ra re ly sec re t e v is ib le q u a n ­

t i t ies of o d o r i f e r o u s s u b s t a n c e , a l t h o u g h i f a n u m b e r of P o l y -

d e s m i d m i l l i p e d e s be g a t h e r e d t o g e t h e r , a d i s t i nc t a l m o n d - l i k e

smel l b e c o m e s d i s c e r n i b l e . T h e n a t i v e s o f c en t r a l M e x i c o g r i n d u p

Polydesmus ricinus w i t h v a r i o u s p l a n t s to m a k e a p o i s o n for t h e i r

a r r o w s a n d t h e l a rge Lysiopetalum foetidissimum t a k e s i ts n a m e

f rom t h e o b n o x i o u s sme l l o f t h e s ec r e t i on f rom i ts s t i nk g l a n d s .

M a n y o f t h e t r o p i c a l spec ies e x h i b i t p a t t e r n s o f s t r o n g l y c o n ­

t r a s t e d w a r n i n g c o l o u r s w h i c h a r e c lear ly a s soc ia t ed w i t h t h e i r

p o i s o n o u s n a t u r e . T h e m a j o r i t y o f t h e C o l o b o g n a t h a d o n o t a p p e a r

to s ec r e t e r e p u g n a t o r i a l f luids, b u t spec ies of Polyzonium p r o d u c e

a w h i t i s h s u b s t a n c e t h a t m a y h a v e an o d o u r o f c a m p h o r a n d i s

p r o b a b l y aga in a d e t e r r e n t to p r e d a t o r y e n e m i e s .

T h e O n i s c o m o r p h a a n d L i m a c o m o r p h a cu r l u p i n t o a ba l l w h e n

d i s t u r b e d a n d m e m b e r s o f t h e o t h e r o r d e r s f o r m a m o r e o r less

c o m p a c t s p i r a l . T h e s e de fens ive r e a c t i o n s n o t on ly r e n d e r t h e

a n i m a l s less v u l n e r a b l e t o t h e i r e n e m i e s , b u t also a re effective in

r e d u c i n g w a t e r - l o s s b y e v a p o r a t i o n w h e n t h e m i l l i p e d e s a r e i n d r y

s u r r o u n d i n g s . T h e y h a v e b e e n a fac to r o f m a j o r e v o l u t i o n a r y i m ­

p o r t a n c e ( M a n t o n , 1954) .

T h e m i n u t e P s e l a p h o g n a t h a a re c o v e r e d w i t h tu f t s o f p e c u l i a r

h a i r s l ike sma l l p i n - c u s h i o n s w h i c h r e s e m b l e t h e u r t i c a t i n g ha i r s o f

s o m e L e p i d o p t e r o u s ca t e rp i l l a r s . L i k e t h e m t h e y a re h o l l o w , v e r y

easi ly d e t a c h e d f r o m t h e b o d y a n d b e a r a n u m b e r o f r e t r o v e r t e d

b a r b s o r p roce s se s n e a r t h e i r t i p s a n d a l o n g t h e i r axes . T h e s e a n d

30 M I L L I P E D E S

t h e smal l size o f t h e a n i m a l s c o n s t i t u t e t h e i r on ly m e a n s o f de fence .

T h e c o m m o n e s t p a r a s i t e s o f m i l l i p e d e s a re G r e g a r i n i d e a . T h u s

i t h a s b e e n f o u n d t h a t of 165 lulus a n d Paraiulus s p p . e x a m i n e d ,

158 w e r e p a r a s i t i s e d by G r e g a r i n e s , 26 o u t o f 32 Polydesmus s p .

a n d 6 o u t of 16 Lysiopetalum s p . T h e p a r a s i t e s h a d no seasona l

cycle a n d all s t a g e s w e r e f o u n d t o g e t h e r . N o d o u b t t h e I u l i d a e

w e r e so p e r s i s t e n t l y p a r a s i t i s e d on a c c o u n t o f t h e i r g r e g a r i o u s

h a b i t s a n d d ie t o f r o t t i n g w o o d a n d v e g e t a b l e m a t t e r . Lysiopetalum

s p p . w h i c h l ive u n d e r s t o n e s i n d r i e r p l aces a n d a re s o m e w h a t

so l i t a ry a re far less pa r a s i t i s ed . Af te r G r e g a r i n i d e a , Cocc id i a a n d

F l age l l a t e s a re t h e m o s t n u m e r o u s pa r a s i t e s o f m y r i a p o d s . I t i s

p r o b a b l e t h a t a h i g h d e g r e e o f t o l e r a n c e h a s b e e n r e a c h e d b e t w e e n

p a r a s i t e a n d h o s t a n d u n l i k e l y t h a t t h e f o r m e r d o a n y h a r m . M o s t

o f t h e m i l l i p e d e s f rom t h e A m a z o n ba s in a re in fes ted w i t h n e m a ­

t o d e s a n d t h e s e p a r a s i t e s are b y n o m e a n s u n c o m m o n e l s ewhe re :

w h i l e severa l D i p l o p o d a a re i n t e r m e d i a t e h o s t s o f ce s todes o f t h e

r e l a t ed fami l ies D i l i p i d i d a e a n d H y m e n o l i p i d i d a e ( R e m y , 1950b) .

N o d o u b t p h y t o p h a g o u s a n i m a l s w h i c h c o n s u m e a c e r t a i n a m o u n t

o f soil w i t h t h e i r food a re espec ia l ly l iable to in fec t ion by t h e s e

a n i m a l s .

N u m e r o u s m i t e s o f t w o ecological ly s e p a r a t e a n d sys temat i ca l ly

u n r e l a t e d g r o u p s a re f o u n d o n m i l l i p e d e s . I n t h e first, w h i c h i n ­

c l u d e s M e s o s t i g m a t a a n d A c a r i d a e , t h e m y r i a p o d s a re u s e d m e r e l y

for t r a n s p o r t ( p h o r e s y ) 1 w h i l e t h e s e c o n d g r o u p , all M e s o s t i g m a t a ,

i n c l u d e s m o r e o r less i n t e r m i t t e n t c o m m e n s a l s w h i c h l ive freely,

n o t a t t a c h e d t o t h e i r h o s t a n d feed o n d e t r i t u s . E v a n s (1955) h a s

r e v i e w e d t h e L a e l a p t i d a e pa ra s i t i c o n m y r i a p o d s . S o m e t i m e s t h e

b o d y of a sick m i l l i p e d e m a y b e c o m e c o v e r e d w i t h a m u l t i t u d e of

l i t t le m i t e s b u t u s u a l l y t h e s e p a r a s i t e s a re con f ined t o t h e h e a d ,

f ron t legs a n d g o n o p o d s w h e n c e t h e y c a n n o t easi ly b e r e m o v e d .

T h e a d u l t s o f o n e spec ies o f m i t e f o u n d o n I u l i d a e i n N a t a l a n d

Z u l u l a n d , feed u p o n t h e l i q u i d s e c r e t e d b y t h e r e p u g n a t o r i a l

g l a n d s o f t h e i r h o s t .

An i n t e r e s t i n g case of aggress ive p a r a s i t i s m of a m i l l i p e d e by a

fly of t h e fami ly P h o r i d a e w h i c h b a t t l e d w i t h a h u g e b lack lulus

s p . for severa l h o u r s h a s b e e n r e c o r d e d , a n d la rvae o f a n o t h e r

spec ies of P h o r i d a e , Megaselia juli, h a v e b e e n f o u n d in a n u m b e r 1 See discussion of phoresy on p. 103.

M I L L I P E D E S 31

of spec ies of Iulus a n d Spirobolus. P l a n i d i u m larvae of pa ra s i t i c

H y m e n o p t e r a h a v e b e e n f o u n d on Gymnostreptus parasitarius in

Brazi l a n d a la rva l L a m p y r i d b e e t l e i n t r o d u c e s itself t h r o u g h t h e

a n u s i n t o t h e p o s t e r i o r i n t e s t i n e o f Pachyiulus s p p . ( R e m y , 1950b) .

I t i s p r o b a b l e t h a t p a r a s i t e s p l a y a neg l ig ib l e p a r t in c o n t r o l l i n g

t h e d e n s i t y o f m i l l i p e d e p o p u l a t i o n s . 1 O n l y t h r e e c lasses p a r a ­

si t ise t h e m t o a n a p p r e c i a b l e d e g r e e : A c a r i , w h i c h a re l i t t le m o r e

t h a n c o m m e n s a l s , S p o r o z o a a n d N e m a t o d a w h i c h p r o b a b l y cause

l i t t le i n c o n v e n i e n c e t o t h e i r hos t .

Reproduction and life cycle T h e r e is a M a l a y bel ief t h a t i f t h e v e r t e b r a of a f ish is k e p t u n d e r

a m a t t r e s s for s o m e t i m e i t b e c o m e s a c e n t i p e d e , a n d t h a t t h e

s t r a n d s w h i c h a re f o u n d b e t w e e n t h e p u l p a n d t h e r i n d o f a p l a n ­

ta in b e c o m e m i l l i p e d e s i f t h e y a r e s ecu re ly b o t t l e d u p a n d k e p t i n

a d a r k c o r n e r !

T h e p a i r e d gen i t a l o p e n i n g s o f m i l l i p e d e s a re s i t u a t e d o n t h e

t h i r d s e g m e n t j u s t b e h i n d , o r o n , t h e s e c o n d p a i r o f legs . I n t h e

female , t h e orifice i s s u r r o u n d e d by t w o sc le ro t i sed p i eces , o n e

f o r m i n g t h e b u r s a , a r r a n g e d l ike t h e t w o she l l s o f a m u s s e l w i t h

t h e h i n g e d i r e c t e d p o s t e r i o r l y a n d t h e s e c o n d , t h e o p e r c u l u m ,

c o v e r i n g t h e g a p e o f t h e t w o va lves o f t h e b u r s a . T h e w h o l e e n ­

s e m b l e i s t e r m e d t h e v u l v a a n d i s o f d i a g n o s t i c v a l u e . I n t h e m a l e

t h e gen i t a l o p e n i n g s m a y o r m a y n o t b e d e v e l o p e d i n t o p a i r e d o r

s ing l e p e n e s . T h e accesso ry gen i t a l i a cons i s t o f o n e o r b o t h a p p e n ­

dages o f t h e s e v e n t h s e g m e n t w h i c h a re m o d i f i e d t o f o r m i n t r o -

m i t t e n t o r g a n s ca l led g o n o p o d s , e x c e p t i n t h e O n i s c o m o r p h a a n d

L i m a c o m o r p h a w h e r e t h e h i n d e r m o s t legs se rve t h i s f u n c t i o n .

T h e s e o r g a n s a r e t h e on ly c r i t e r i a for a c c u r a t e d i agnos i s : i n s o m e

spec ies t h e y a re r e t r a c t e d w i t h i n t h e cav i ty o f t h e s e v e n t h s e g m e n t .

Before c o p u l a t i o n t akes p l a c e t h e m a l e , b y f l e x i n g h i s a n t e r i o r seg­

m e n t s , ' c h a r g e s ' h i s g o n o p o d s f r o m t h e o p e n i n g o n t h e t h i r d b o d y

s e g m e n t . F r o m t h e g o n o p o d s t h e s p e r m a t i c f l u i d i s t r a n s f e r r e d t o

the v u l v a e of t h e f ema le : fe r t i l i sa t ion i s i n t e r n a l .

D u r i n g c o p u l a t i o n t h e p o s i t i o n s a s s u m e d b y t h e m a l e a n d female

a re s o m e w h a t s imi l a r i n all spec ies . T h e fo l lowing d e s c r i p t i o n ap¬ 1 See discussion of densi ty-dependent and densi ty- independent factors

on p . 141.

32 M I L L I P E D E S

pl ies to Oxidus gracilis in p a r t i c u l a r . T h e v e n t r a l su r face of t h e

p o s t e r i o r 13 o r 14 b o d y s o m i t e s o f t h e m a l e i s para l le l a n d do r sa l to

t h e a n t e r i o r 10 o r 11 b o d y s o m i t e s o f t h e f ema le a n d t h e legs o f t h e

m a l e o n t h e s e s o m i t e s a r e b e n t c losely a r o u n d t h e f emale . I n t h e

r eg ion o f t h e e i g h t h , n i n t h a n d t e n t h s o m i t e s t h e b o d y o f t h e m a l e

i s t w i s t e d half a r o u n d t h e f emale so t h a t h i s g o n o p o d s a re i n c o n ­

tac t w i t h h e r v u l v a e w h i c h o p e n o n t h e t h i r d b o d y s o m i t e . T h e

h e a d a n d t h o r a x o f t h e m a l e a r e d i r e c t e d a n t e r i o r l y a n d b e n t over

t h e h e a d o f t h e female w h i c h i s h e l d by h i s s even a n t e r i o r pa i r s o f

legs . B r i g h t l igh t o r h a n d l i n g u s u a l l y c ause s a p a i r t o s e p a r a t e : b u t

i f u n d i s t u r b e d c o p u l a t i o n m a y o c c u r severa l t i m e s a n d last for

severa l h o u r s ( C a u s e y , 1943) .

FIG. 10. Millipedes of the family Polydesmidae in copulation. T h e male is below. (After Seifert, 1932.)

T h e m a l e Polydesmus angustus a p p r o a c h e s t h e female f r o m b e ­

h i n d a n d r u n s a long h e r b a c k u n t i l h e r h e a d i s r e a c h e d . S u d d e n l y

t u r n i n g r o u n d t o w a r d s h e r v e n t r a l su r face , h e seizes h e r g n a t h o -

c h i l a r i u m w i t h h i s m a n d i b l e s , r e t a i n i n g t h i s h o l d u n t i l h e r b o d y i s

for t h e m o s t p a r t o f i ts l e n g t h e m b r a c e d in h i s b r o a d e r g r a s p . I t i s

i n t e r e s t i n g t o n o t e t h a t a fer t i l i sed female , w h e n t o u c h e d on t h e

ana l s e g m e n t by a m a l e , i m m e d i a t e l y d a r t s f o r w a r d a n d re fuses to

be c a u g h t . T h e fer t i l i sed f emales i n a co l l ec t ion c a n be read i ly

r e c o g n i s e d by t o u c h i n g l igh t ly on t h e ana l s e g m e n t w i t h a c a m e l -

ha i r b r u s h ( E v a n s , 1910) . In Glomeris marginata t h e m a l e i s m u c h

s m a l l e r t h a n t h e f ema le a n d c o p u l a t i o n t akes p l a c e b y a p p o s i t i o n

o f t h e p a i r i n t h e h e a d t o tail pos i t i on . I n c o n t r a s t t o t h e P r o t e r o -

s p e r m o p h o r a , c o p u l a t i o n i n t h e O n i s c o m o r p h a i s brief, w h i c h m a y

M I L L I P E D E S 33

b e c o r r e l a t e d w i t h t h e fact t h a t e g g - l a y i n g i s a n i n t e r r u p t e d p r o c e s s

a n d t h e f ema le lays h e r eggs i n sma l l g r o u p s i n severa l p laces ,

u sua l l y b u r i e d i n loose soil a n d a lways u n d e r cove r o f m o s s o r

d e a d leaves . T h e B r i t i s h O p i s t h o s p e r m o p h o r a b e g i n t h e i r b r e e d ­

ing r a t h e r l a te r i n t h e y e a r t h a n d o t h e P o l y d e s m i d s .

I n s o m e spec ies o f m i l l i p e d e s t h e eggs a r e c o a t e d w i t h e a r t h a n d

e x c r e m e n t a n d t h e n left in c rev ices in t h e soil; in o t h e r s a n e s t i s

c o n s t r u c t e d o f soil pa r t i c l e s t h a t h a v e b e e n m o i s t e n e d w i t h sal iva.

W h e n c o m p l e t e d , t h e n e s t h a s t h e s h a p e o f a h o l l o w s p h e r e . T h e

in s ide i s l i ned w i t h d r i e d e x c r e m e n t a n d i s s m o o t h a n d even ,

w h e r e a s t h e o u t s i d e i s r o u g h a n d i r r egu l a r . S o m e t i m e s t h e female

d o e s n o t leave t h e n e s t i m m e d i a t e l y , b u t r e m a i n s for severa l days

c u r l e d r o u n d i t so t i g h t l y t h a t s h e i s difficult t o r e m o v e .

W h e n t h e f ema le Glomeris marginata i s a b o u t to lay s h e rol ls

over o n h e r b a c k a n d t h e l i t t le egg i s p a s s e d b a c k w a r d s f r o m seg­

m e n t t o s e g m e n t u n t i l i t a r r i ves a t t h e e n d o f t h e b o d y . T h e r e i t i s

h e l d i m m e d i a t e l y ove r t h e ana l r e g i o n a n d t h e r e c t u m i s e v e r t e d t o

a c o n s i d e r a b l e e x t e n t so as to f o r m a m o b i l e p a d h o l d i n g a smal l

q u a n t i t y o f v e r y f luid e x c r e m e n t w h i c h i s careful ly p l a s t e r e d ove r

t h e egg . W h e n d r y t h i s f o r m s a s p h e r i c a l c h a m b e r i n w h i c h t h e

egg lies freely. Occas iona l l y t w o o r t h r e e eggs a re e n c l o s e d in o n e

m a s s , b u t a lways in s e p a r a t e c o m p a r t m e n t s . In Polydesmus angustus

a n d o t h e r P r o t e r o s p e r m o p h o r a a n d C o l o b o g n a t h a , all t h e eggs a re

e n c l o s e d in a c o m m o n c o v e r i n g . T h e n e s t i s l ike a t h i n - w a l l e d ,

d o m e - s h a p e d t e n t s u r m o u n t e d b y a n a r r o w t u b u l a r c h i m n e y . I t i s

b u i l t on s o m e f i rm s u b s t r a t u m — a s t o n e , a leaf, t h e i n s i d e o f an

a c o r n c u p , o r t h e i n n e r su r face of a p i ece of b a r k — a n d i s c o n ­

s t r u c t e d w i t h t h e m o b i l e su r f ace o f t h e e x t r o v e r t e d r e c t u m . T h e

f ema le first g n a w s a sma l l cav i ty on t h e su r face on w h i c h s h e i n ­

t e n d s t o lay. T h e n s h e b e n d s he r se l f i n t o a c i rc le a n d w a l k s r o u n d

a n d r o u n d , l eav ing a r a p i d l y d r y i n g b l o b o f e x c r e m e n t a s s h e goes ,

u n t i l t h e c o n c a v e s p o t i s s u r r o u n d e d b y a r a m p a r t , t h e c i r c u m ­

fe rence o f w h i c h i s s l igh t ly g r e a t e r t h a n t h e l e n g t h o f h e r b o d y .

W h e n t h e n e s t h a s r e a c h e d a b o u t t w o - t h i r d s i ts full h e i g h t t h e

eggs a r e la id . T h e f ema le lies a c r o s s h e r n e s t a n d t h e eggs d r o p i n

o n e af ter t h e o t h e r , s t i ck ing t o g e t h e r a s t h e y fall. T h e n e s t i s t h e n

roofed ove r a n d t h e c h i m n e y c o m p l e t e d w i t h t h e a id o f t h e e v e r t e d

r e c t u m a n d t h e s u p r a - a n a l p r o c e s s w h i c h possesses s ix tac t i le

c S.S.C.M.

34 M I L L I P E D E S

ha i r s . W h e n t h e n e s t i s f in ished t h e female d o e s n o t leave i t i m ­

m e d i a t e l y b u t r e m a i n s co i led a r o u n d i t for a b o u t a w e e k . S h e

cove r s i t w i t h b i t s o f l eaves a n d w i s p s o f g r a s s a n d wil l r ep l ace

t h e m ove r a n d ove r aga in i f t h e y a r e r e m o v e d ( E v a n s , 1910) .

Oxidus gracilis f emales , h o w e v e r , d e p o s i t t h e i r eggs in sma l l r o u g h

cavi t ies f r o m 3 t o 15 mm b e l o w t h e su r face o f t h e soil , b u t do n o t

c o n s t r u c t b r o o d i n g c h a m b e r s n o r r e m a i n w i t h t h e m d u r i n g t h e in ­

c u b a t i o n p e r i o d .

In c o n t r a s t , m o s t o f t h e O p i s t h o s p e r m o p h o r a c o n s t r u c t a v e r y

c r u d e n e s t w h i c h i s m a i n l y b u i l t f r o m t h e i n s i d e , on ly t h e t o p b e i n g

laid o n f r o m t h e o u t s i d e . T h e f ema le b u r r o w s i n t o loose soil u n t i l

she c o m e s to a f i rm f o u n d a t i o n , u s u a l l y a s t o n e , w h e r e s h e p r o ­

c e e d s t o m a k e a d o m e - s h a p e d c l ea r ing , t h e s h a p i n g b e i n g d o n e b y

h e r j a w s . T h i s s p a c e i s t h e n p l a s t e r e d f r o m t h e i n s ide w i t h l i qu id

e x c r e m e n t b y m e a n s o f t h e e v e r t e d r e c t u m , t h e a n i m a l m e a n w h i l e

h a v i n g t o a s s u m e s o m e v e r y a w k w a r d p o s i t i o n s d u r i n g t h e p r o c e s s .

O n e m e r g i n g f rom t h e recess s h e p u s h e s h e r w a y i n t o a p o s i t i o n

a s t r i d e t h e o p e n t o p a n d lays h e r eggs . Af t e r c los ing t h e ho l e she

p a y s n o f u r t h e r a t t e n t i o n t o h e r n e s t ( E v a n s , 1910) .

T h e f u n c t i o n o f t h e n e s t b u i l d i n g d e s c r i b e d a b o v e i s t o p r o t e c t

t h e eggs a n d y o u n g f r o m a t t ack b y fungi w h i c h a re a n eve r p r e s e n t

m e n a c e , a s t h e y a re t o t h e y o u n g s t ages o f w o o d l i c e , a n d also f r o m

t h e c a n n i b a l i s t i c p roc l iv i t i e s o f t h e m a l e s o f t h e spec ie s . In a s i m i ­

lar w a y Polymicrodon polydesmoides s p i n s a silk t e n t for t h e p u r p o s e

of m o u l t i n g a n d also to c o v e r i ts c l u s t e r of eggs . Af t e r a m o u l t i t

ea t s t h e silk.

T h e B l a n i u l i d a e lay t h e i r l a rge , e l o n g a t e d eggs s ing ly , h o w e v e r .

T h e S p i r o b o l i d m i l l i p e d e Arctobolus marginatus o f N o r t h A m e r i c a

m a n u f a c t u r e s t h e cases i n w h i c h h e r eggs a r e i n d i v i d u a l l y e n ­

c losed w i t h m a t e r i a l r e g u r g i t a t e d f r o m h e r m o u t h . T h e m o i s t

l u m p i s h e l d b y t h e legs o f t h e e i g h t h t o e l e v e n t h p a i r s a n d s h a p e d

w i t h t h e c o n v e x f ron t o f t h e h e a d . A s h a l l o w b o w l i s m a d e in to

w h i c h a n egg i s la id . T h e s ides o f t h e b o w l a r e t h e n d r a w n u p

ove r t h e egg a n d k n e a d e d t o g e t h e r u n t i l a pe r f ec t s p h e r e i s p r o ­

d u c e d . T h e c o m p l e t e d pe l l e t i s d r o p p e d b y t h e m o t h e r w h o t h e n

s t a r t s t h e n e x t ( L o o m i s , 1933) . I n m a n y spec ies , o n t h e o t h e r h a n d ,

t h e eggs a re n e v e r c o v e r e d .

T h e n u m b e r o f eggs laid b y m i l l i p e d e s va r i e s c o n s i d e r a b l y

M I L L I P E D E S 3 5

a m o n g di f ferent o r d e r s a n d a lso a m o n g di f ferent spec ies o f t h e

s a m e o r d e r . T h e r e i s a t e n d e n c y for t h e size o f t h e egg to d e c r e a s e

i n d i r e c t p r o p o r t i o n a s t h e n u m b e r o f y o u n g p e r b r o o d i nc rea se s .

I t fo l lows f r o m t h i s t h a t t h e d i f ferences i n t h e to ta l a m o u n t o f yo lk

c o n t a i n e d i n v a r i o u s b r o o d s , w h e t h e r t h e y c o n t a i n a l a rge n u m b e r

o f sma l l eggs o r a s m a l l e r n u m b e r o f l a rge eggs t e n d s to be e v e n e d

ou t . Polyxenus lagurus o n l y lays f r o m 10 to 20 eggs w i t h 4 to 8 p e r

nes t , b u t spec ies of Polydesmus lay b e t w e e n 100 a n d 2 0 0 , Oxidus

gracilis up to 3 0 0 , Iulus s p p . lay 60 to 100 o r m o r e , a n d s o m e o f t h e

S p i r o b o l i d a e m a y a lso lay u p t o 300 eggs . T h e m a x i m u m r e c o r d e d

c l u t c h of Arctobolus marginatus in W a s h i n g t o n w a s 2 6 1 .

I n c u b a t i o n o f t h e eggs m a y t a k e severa l w e e k s be fo r e h a t c h i n g

o c c u r s . T h i s p r o c e s s i s ass i s ted by a s t r o n g con ica l e g g - t o o t h s i t ua ­

t e d , i n t h e O p i s t h o s p e r m o p h o r a , o n t h e m i d d l e o f t h e h e a d .

Glomeris marginata seeks no spec ia l p r o t e c t i o n d u r i n g m o u l t i n g ,

b u t d o e s s o i n s o m e loose e a r t h o r o n t h e su r face u n d e r m o s s o r

d e a d l eaves . T h e case o f b o t h P r o t e r o s p e r m o p h o r a a n d O p i s t h o ­

s p e r m o p h o r a i s v e r y d i f fe ren t . T h e m i l l i p e d e s o f t h e s e o r d e r s

b u i l d m o u l t i n g c h a m b e r s w h i c h a r e essen t ia l ly s imi l a r t o t h e i r

n e s t s . I f t h e m o u l t i n g c h a m b e r i s d a m a g e d s o t h a t o t h e r m i l l i p e d e s

can e n t e r , t h e he lp l e s s a n i m a l t h a t h a s j u s t s h e d i ts sk in i s a l m o s t

i n v a r i a b l y e a t e n u p b y t h e i n v a d e r s . Af t e r m o u l t i n g i t i s c u s t o m a r y

for m i l l i p e d e s t o ea t t h e i r cas t e x u v i u m , t h e r e b y r e s t o r i n g lost

s u p p l i e s o f c a l c i u m : f u r t h e r d e v e l o p m e n t d o e s n o t p r o c e e d n o r ­

m a l l y u n l e s s t h e y d o so .

Al l D i p l o p o d a a r e a n a m o r p h i c a n d t h e l a rvae p a s s t h r o u g h a

n u m b e r o f m o u l t s d u r i n g e a c h o f w h i c h t h e n u m b e r o f legs a n d

p o s t - c e p h a l i c s o m i t e s i s i n c r e a s e d . A d d i t i o n a l legs a n d s o m i t e s a re

a d d e d i n t h e e m b r y o n i c r e g i o n b e t w e e n t h e ana l s o m i t e a n d t h e

o n e t h a t w a s las t f o r m e d . C o l o b o g n a t h a , A s c o s p e r m o p h o r a a n d

P r o t e r o s p e r m o p h o r a p a s s t h r o u g h s even larval s tad ia , i n each o f

w h i c h t h e n u m b e r o f leg p a i r s a n d s o m i t e s i s c o n s t a n t for t h e

spec ies o r t h e g r o u p . T h e O p i s t h o s p e r m o p h o r a also n o r m a l l y pas s

t h r o u g h s e v e n larval s t ad ia b u t af ter t h e first o r s e c o n d t h e n u m b e r

o f legs a n d s o m i t e s i s n o t c o n s t a n t for t h e spec ies . I n t h e O n i s -

c o m o r p h a , d e v e l o p m e n t i s h e m i a n a m o r p h i c : a se r ies of a n a ­

m o r p h i c m o u l t s i s fo l lowed b y t h r e e m o u l t s w h i c h a r e u n a c c o m ­

p a n i e d b y inc reases i n t h e n u m b e r o f legs a n d s o m i t e s (Verhoeff ,

3 6 M I L L I P E D E S

FIG

. 11

. S

tages

in

th

e d

evel

op

men

t of

a m

illi

ped

e S

tro

ng

ylo

som

idae

. (A

fter

Sei

fert

, 19

32.)

M I L L I P E D E S 37

1928) . T h e y o u n g e s t l a rvae h a v e t h r e e pa i r s o f legs , t h e n e x t s tage

u sua l l y seven , a n d a t e ach s u b s e q u e n t m o u l t s o m e f o u r m o r e seg­

m e n t s e a c h w i t h e i g h t p a i r s o f legs a re a d d e d o n . T h e t i m e r e ­

q u i r e d for m o u l t i n g inc reases w i t h each s u c c e e d i n g ecdys i s f rom

a few h o u r s for t h e first to severa l w e e k s for t h e last .

Verhoef f ( 1 9 3 3 b , 1939) h a s s h o w n t h a t i n s o m e spec ies o f I u l i d

m i l l i p e d e s t h a t l ive i n co ld c l i m a t e s t h e m a t u r e m a l e s m a y r eg re s s

t o a n i n t e r p o l a t e d i n t e r c a l a r y f o r m l ack ing t h e h i g h l y d i f fe ren t ia ted

g o n o p o d s o f t h e m a t u r e a n i m a l . I n t h e life o f a n i n d i v i d u a l t h e r e

m a y b e a s m a n y a s f o u r p e r i o d s o f s exua l m a t u r i t y a l t e r n a t i n g w i t h

t h r e e i n t e r p o l a t e d s t ages . D u r i n g t h e i n t e r p o l a t e d p e r i o d , g r o w t h

c o n t i n u e s w i t h a n i nc r ea se i n t h e n u m b e r o f s e g m e n t a l g l a n d s .

T h i s cyc le i s r e l a t e d t o season , f u n c t i o n a l m a l e s a p p e a r i n g i n la te

w i n t e r a n d t h e i n t e r p o l a t e d f o r m s i n s u m m e r . I t i s a m e t h o d o f

p r o l o n g i n g life t h r o u g h d r y o r co ld seasons , a n d e n a b l e s a d u l t

m a l e s t o l ive for t w o o r m o r e y e a r s . T h e ac t iv i ty o f t h e tes t i s

a u t o m a t i c a l l y dec l i ne s a t t h e o n s e t o f t h e m o u l t w h i c h in i t i a t e s t h e

i n t e r p o l a t e d s t age a n d t h i s a p p e a r s t o b e c o r r e l a t e d w i t h t h e fact

t h a t t h e c o m p l i c a t e d g o n o p o d s a re m o u l t e d o n l y w i t h g r e a t

difficulty.

B I B L I O G R A P H Y

Identification

ATTEMS , G. ( 1 9 3 7 ) Myriapoda 3 , Polydesmoidea 1 . Das Tierreich, 6 8 , 1 - 3 0 0 .

( 1 9 3 8 ) Idem. 2, Ibid., 6 9 , 1 - 4 8 7 .

( 1 9 4 0 ) Idem. 3, Ibid., 7 0 , 1 - 5 7 7 .

BLOWER, G. ( 1 9 5 2 ) British millipedes with special reference to Yorkshire species. Naturalist, 1 9 5 2 , 1 4 5 - 5 7 .

BROLEMANN , H . W . ( 1 9 3 5 ) Myriapodes . Diplopodes-Chilognathes 1 .

Faune de France, N o . 2 9 , 1 - 3 6 9 , Paris. CHAMBERLIN , R. V. ( 1 9 4 3 ) On Mexican millipedes. Bull. Univ. Utah., 3 4 ,

( 7 ) , 1 - 1 0 3 .

LANG, J . ( 1 9 5 4 ) Mnohonozky—Diplopoda. Fauna C.S.R., 2 , 1 - 1 8 3 .

LATZEL, R. ( 1 8 8 4 ) Die Myriopoden der Oesterreichs-Ungarischen Monar­chic, II. Die Symphylen, Pauropoden und Diplopoden. Wien.

LOHMANDER , H. ( 1 9 2 5 ) Sveriges Diplopoder . Goteb. Kongl. Vet. Handl, 3 0 , ( 2 ) , 1 - 1 1 5 .

SCHUBART, O. ( 1 9 3 4 ) Tausendfussler oder Myriapoda, 1 . Diplopoda. Tieriv. Deuts.,28, 1 - 3 1 8 .

38 M I L L I P E D E S

VERHOEFF, K. W. (1926-31) Diplopoda in H. G. BRONN'S Klass. Ordn. Tierreichs, 5, II (2), 1-1072.

(See also references under Chilopoda, Chap. III)

Biology

BRADE-BIRKS , S . G. (1930) Notes on Myriapods, X X X I I I . T h e economic status of Diplopoda and Chilopoda and their allies. J. S-E. Agric. Coll. Wye, No . 27, 103-46.

BURTT , E. (1947) Exudate from millipedes, with particular reference to its injurious effects. Trop. Dis. Bull., 4 4 , 7-12.

CAUSEY, N. B. (1943) Studies on the life history and the ecology of the hothouse mill ipede, Orthomorpha gracilis (C. L. Koch, 1847). Amer. Midl. Nat., 2 9 , 670-82.

CLOUDSLEY-THOMPSON , J . L. (1949a) T h e enemies of Myriapods. Naturalist, 1 9 4 9 , 137-41 .

(1949b) T h e significance of migration in Myriapods . Ann. Mag. Nat. Hist., (12), 2, 947-62.

(1950a) Economics of the 'spotted snake mill ipede' Blaniulus guttu­latus (Bosc) . Ibid., (12), 3, 1047-57.

(1950b) T h e water relations and cuticle of Paradesmus gracilis (Diplopoda: Strongylosomidae). Quart, J. Micr. Sci., 9 1 , 453-64.

(1951a) Supplementary notes on Myriapoda. Naturalist, 1 9 5 1 , 16-17.

(1951b) Studies in diurnal r h y t h m s — 1 . Rhythmic behaviour in millipedes. J. Exp. Biol., 2 8 , 165-72.

(1951c) On the responses to environmental stimuli, and the sensory physiology of millipedes (Diplopoda). Proc. Zool. Soc. Lond., 1 2 1 , 253-77.

(1954) Problems of dispersal in some terrestrial Ar thropods . Advanc. Sci., 1 1 , 73 -5 .

DAVENPORT , D . , WOOTTON , D . M . and CUSHING , J. E. (1952) T h e biology

of the Sierra luminous millipede Luminodesmus sequoiae Loomis and Davenport . Biol. Bull., 1 0 2 , 100-10.

EATON , T. H. Jr. , (1943) Biology of a mull-forming millipede, Apheloria coriacea (Koch). Amer. Midi. Nat., 2 9 , 713-23.

EVANS , T. J. (1910) Bionomical observations on some British millipedes. Ann. Mag. Nat. Hist., (8), 6, 284-91 .

EVANS, G. O. (1955) A review of the Laelaptid paraphages of the Myria­poda with descriptions of three new species (Acarina: Laelaptidae). Parasitology, 4 5 , 352-68.

FRYER, G. (1957) Observations on some African millipedes. Ann. Mag. Nat. Hist., (12), 1 0 , 4 7 - 5 1 .

LOOMIS , H. F. (1933) Egg-laying and larval stages of a millipede, Arcto­bolus marginatus (Say) Cook, native at Washington. J. Wash. Acad. Sci., 2 3 , 100-9.

M I L L I P E D E S 39

LYFORD , W. H . , Jr . (1943) T h e palatability of freshly fallen forest leaves to millipedes. Ecology, 2 4 , 252-61 .

M A N T O N , S. M. (1954) T h e evolution of Ar thropodan locomotory mechanisms—Part 4. T h e structure, habits and evolution of the Diplo­poda. J. Linn. Soc. (Zool), 4 2 , 299-368.

PALMEN , E. (1949) T h e Diplopoda of Eastern Fennoscandia. Ann. Soc. Zool. Fenn. Vanamo, 1 3 , (6), 1-54.

PERTTUNEN , V. (1953) Reactions of Diplopods to the relative humidi ty of the air. Investigations on Orthomorpha gracilis, Iulus terrestris and Schizophyllum sabulosum. Ibid., 1 6 , (4), 1-69.

REMY , P. (1950a) Les myriapodes et les plantes cultivees (Bibliographic). Bull. Soc. Linn. Lyon., 1 9 , 232-4.

(1950b) On the enemies of Myriapods. Naturalist, 1 9 5 0 , 103-8. SCHUBART, O. (1942) Os myriapodes e suas relacoes com a agricultua. Com

uma bibliografia completa sobre o assunto. Pap. Avul. Dep. Zool. S. Paulo, 2 , 205-34.

SHELFORD, V. E. (1913) T h e reactions of certain animals to gradients of evaporating power of air. A s tudy in experimental biology. Biol. Bull., 2 5 , 79-120.

VERHOEFF, K. W. (1930) Zur Geographie, Okologie und Systematik sudal-penlandischer Chilognathen (116. Diplopoden—Aufsatz) . Z. Morph. Okol. Tiere, 1 8 , 575-668.

(1933a) Revolution bei Diplopoden. Zool. Anz., 1 0 4 , 59-64. (1933b) Wachs tum u n d Lebensverlangerung bei Blaniuliden u n d

uber die Periodomorphose. Z. Morph. Okol. Tiere, 2 7 , 732-49. (1935) Zur biologie der Spirostreptiden. Zool. Anz., 1 0 9 , 288-92. (1939) Wachs tum und Lebensverlangerung bei Blaniuliden und

uber die Periodomorphose. I I . Tic l . Z. Morph. Okol. Tiere, 3 6 , 21-40.

C H A P T E R I I I

C E N T I P E D E S

Classification and distribution A l t h o u g h t h e C h i l o p o d a a re a w i d e l y d i s p e r s e d class , t h e b io logy

o f c e n t i p e d e s h a s a t t r a c t e d c o m p a r a t i v e l y l i t t le a t t e n t i o n f r o m

zoolog is t s w h o h a v e t e n d e d t o conf ine t h e i r a t t e n t i o n s t o t h e sys -

t e m a t i c s o f t h e g r o u p . I n t h e s e a n i m a l s , t h e b o d y i s d i v i d e d i n t o a

va r i ab l e n u m b e r of s o m i t e s , e a c h of w h i c h i s p r o v i d e d w i t h a pa i r

o f l i m b s u s e d for l o c o m o t i o n . T h e h e a d b e a r s a p a i r o f m u l t i -

s e g m e n t e d a n t e n n a e a n d t h r e e p a i r s o f m o u t h - p a r t s . T h e first o f

t h e s e p o s t - o r a l a p p e n d a g e s a re t o o t h e d m a n d i b l e s , t h e s e c o n d a re

fo l iaceous max i l l ae , w h i l e t h e t h i r d a re leg- l ike p a l p s . B e h i n d t h e

h e a d i s t h e f i r s t s e g m e n t o f t h e b o d y , k n o w n a s t h e bas i l a r seg ­

m e n t . I t s a p p e n d a g e s a r e t h e m a x i l l i p e d e s o r t a x o c o g n a t h s . T h e s e

a re p o i s o n - c l a w s w i t h w h i c h t h e p r e y i s c a p t u r e d a n d k i l led . A t t h e

t i p s o f t h e i r s t r o n g , p i e r c i n g t e r m i n a l s e g m e n t s a re t h e orifices o f

t h e d u c t s o f t h e p a i r e d v e n o m - g l a n d s . W h e r e p r e s e n t , t h e eyes a r e

i n t h e f o r m o f c l u s t e r s o f ocell i , e x c e p t i n t h e S c u t i g e r o m o r p h a

w h i c h h a v e c o m p o u n d eyes (see b e l o w ) . T h e n u m b e r o f legs

va r i e s f r o m f i f t e e n t o o v e r a h u n d r e d pa i r s , b u t h o w e v e r m a n y

t h e r e m a y b e , t h e n u m b e r i s a lways o d d . E a c h s o m i t e o f t h e b o d y

i s f l a t t ened w h e n seen in c r o s s - s e c t i o n a n d i s c o m p o s e d ex t e rna l ly

of a do r sa l p l a t e or t e r g i t e a n d a v e n t r a l s t e r n i t e u n i t e d by p l e u r a l

m e m b r a n e s w i t h w h i c h t h e legs a r t i c u l a t e a n d u p o n w h i c h t h e

sp i rac le s l e a d i n g i n t o t h e t r a c h e a u s u a l l y o p e n .

T h e class C h i l o p o d a i s s u b - d i v i d e d i n t o f i v e o r d e r s . T h e f i r s t o f

t h e s e , t h e G e o p h i l o m o r p h a , i n c l u d e s t h e long , w o r m - l i k e c e n t i ­

p e d e s w i t h t h e pa i r s o f legs v a r y i n g i n n u m b e r f r o m 3 1 t o 177.

T h e fore p a r t o f each s o m i t e i s m a r k e d off f r o m t h e h i n d e r p a r t b y

a d i s t i n c t j o i n t , t h e r e is a p a i r of sp i rac les on e a c h s e g m e n t e x c e p t

t h e f i r s t a n d last , a n d t h e a n t e n n a e a re a lways c o m p o s e d o f f ou r -4 0

C E N T I P E D E S 4 1

FIG

. 12

. E

xam

ple

s o

f ce

nti

ped

e fa

mil

ies:

1

. G

eop

hil

idae

, 2

. C

ryp

top

idae

, 3

. S

colo

pen

dri

dae

, 4

. L

ith

ob

iid

ae,

5,

Scu

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ger

idae

. (D

raw

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s n

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e.)

(Aft

er

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s au

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rs.)

42 C E N T I P E D E S

t e e n s e g m e n t s . T h e r e a r e a v e r y la rge n u m b e r o f fami l ies in t h i s

o r d e r w h i c h h a s a w i d e d i s t r i b u t i o n i n all t h e w a r m a n d t e m p e r a t e

c o u n t r i e s o f t h e w o r l d . M o s t o f t h e m are s u b t e r r a n e a n b u t a few

a r e f o u n d u n d e r s t o n e s a n d s e a w e e d b e l o w t i d e m a r k s . T h e

l a r g e s t spec ies , l ike t h e N o r t h Af r i can Orya barbarica, m e a s u r e

a b o u t six o r s even i n c h e s i n l e n g t h , b u t m o s t a re o n l y a n i n c h o r

t w o long . T h e w r i t e r h a s r e c e n t l y d i s c o v e r e d a s m a l l e r spec ies o f

Orya, O . almohadensis, in c e n t r a l T u n i s i a w h i c h m e a s u r e s j u s t ove r

t w o i n c h e s w h e n e x t e n d e d a n d i s sca rce ly l o n g e r t h a n t h e c o m ­

m o n Br i t i sh Haplophilus subterraneus.

FIG. 1 3 . Poison claws of a centipede showing position of poison glands and their ducts .

T h e c e n t i p e d e s o f t h e o r d e r S c o l o p e n d r o m o r p h a differ f rom

t h e G e o p h i l o m o r p h a i n n e v e r h a v i n g m o r e t h a n 2 3 p a i r s o f legs ,

whi le t h e s e g m e n t s o f t h e a n t e n n a e v a r y i n n u m b e r f r o m 1 7 t o 30 .

T h e s o m i t e s a re n o t m a r k e d l y d i v i d e d a n d t h e t e rga l p l a t e o f t h e

bas i l a r s e g m e n t i s fused w i t h t h a t o f t h e first l e g - b e a r i n g s o m i t e .

Sp i r ac l e s a r e n o t f o u n d o n eve ry s e g m e n t o f t h e b o d y . T h i s o r d e r

i s also w i d e l y d i s t r i b u t e d a n d i n c l u d e s t w o m o s t i m p o r t a n t famil ies ,

t h e S c o l o p e n d r i d a e a n d t h e C r y p t o p i d a e , o f w h i c h t h e f o r m e r c o n ­

t a in s a b o u t 16 g e n e r a , i n c l u d i n g m o s t o f t h e l a rge t r o p i c a l a n d

s u b - t r o p i c a l spec ies h a v i n g 21 pa i r s o f legs. T h e p o s t e r i o r p a i r o f

C E N T I P E D E S 43

legs i s u s u a l l y l o n g e r a n d s t o u t e r t h a n t h e o t h e r s , b u t m a y b e

m o d i f i e d a s a n t e n n i f o r m tac t i l e s e n s e - o r g a n s a s i n t h e S o u t h

A m e r i c a n g e n u s Newportia. T h e t e r m i n a l legs m a y b e e x p a n d e d

a n d leaf- l ike a t t h e e n d , f o r m i n g a s t r i d u l a t i n g o r g a n a s in t h e

la rge t r o p i c a l Af r i can g e n u s Alipes, o r s h o r t , t h i ck a n d a r m e d w i t h

a p i e r c i n g c l aw u s e d for h o l d i n g food a s i n t h e A m e r i c a n g e n u s

Theatops.

S o m e of t h e t r o p i c a l spec i e s of Scolopendra a r e c o m m o n l y six or

e igh t i n c h e s in l e n g t h , w h i l e t h e la rges t , S . gigantea f r o m t rop i ca l

A m e r i c a , m e a s u r e s a s m u c h a s a foot . M a n y o f t h e s e a r e a t t r a c ­

t ive ly c o l o u r e d i n t h e l iv ing s t a t e . F o r e x a m p l e , t h e S o u t h Af r i can

Rhysida afra is a d e e p a n d s t r i k i n g s h a d e of b l u e or b l u e w i t h a

g r e e n i s h t i n g e , S . morsitans h a s g r e e n c r o s s b a r s on a ye l l ow b a c k ­

g r o u n d , w h i l e S. cingulata is a beau t i fu l o l ive g r e e n . T h i s spec ies

i s d i s t r i b u t e d w i d e l y t h r o u g h o u t t h e M e d i t e r r a n e a n r e g i o n s o f

E u r o p e , N o r t h Afr ica a n d t h e M i d d l e E a s t , b u t va r i e s c o n s i d e r a b l y

i n size i n different local i t ies . Af r i can a n d As ia t i c s p e c i m e n s m a y

r e a c h a l e n g t h of 18 cm w h e n ful ly e x t e n d e d a n d h a v e a y e l l o w

b o d y a n d b l u e h i n d legs . U n f o r t u n a t e l y t h e y all t e n d t o f ade t o a

u n i f o r m du l l b r o w n c o l o u r w h e n p r e s e r v e d . S . morsitans a n d S .

subspinipes h a v e b e e n t r a n s p o r t e d all ove r t h e t r o p i c s by c o m m e r c e ,

b u t a r e u n a b l e t o e s t ab l i sh t h e m s e l v e s i n t e m p e r a t e l a t i t u d e s .

R e l a t e d g e n e r a a re Ethmostigmus, w h i c h i s a b u n d a n t in Afr ica , a n d

Cormocephalus w h i c h i s e q u a l l y a b u n d a n t i n b o t h t h e E t h i o p i a n

a n d I n d o - A u s t r a l a s i a n r e g i o n s . O n l y t h r e e r e p r e s e n t a t i v e s o f t h e

o r d e r o c c u r in t h e Br i t i sh I s l e s , n a m e l y Cryptops hortensis, C.

anomalans a n d C . parisi. Of t h e s e t h e m o s t c o m m o n is t h e o r a n g e -

c o l o u r e d C . hortensis f r e q u e n t l y f o u n d in p o t t i n g s h e d s a n d u n d e r

t h e b a r k o f t r ee s , e t c .

T h e o r d e r C r a t e r o s t i g m o m o r p h a h a s b e e n e s t a b l i s h e d for t h e

c e n t i p e d e s of t h e g e n u s Craterostigmus w h i c h i s i n t e r m e d i a t e in

m a n y p o i n t s b e t w e e n t h e S c o l o p e n d r o m o r p h a a n d t h e L i t h o -

b i o m o r p h a , a n d , l ike m a n y a n c i e n t arid a n n e c t a n t t y p e s , o c c u r s i n

Aus t r a l a s i a . T h e r e a re o n l y 1 5 p a i r s o f legs a n d s t e r n a a n d t h e

sp i rac les a r e r e d u c e d t o s even p a i r s a s i n t h e L i t h o b i o m o r p h a , b u t

t h e r e a r e 2 1 t e rga l p l a t e s r e p r e s e n t i n g t h e s o m i t e s o f t h e l eg-

b e a r i n g s e g m e n t s o f t h e S c o l o p e n d r o m o r p h a . U n f o r t u n a t e l y

n o t h i n g i s k n o w n o f t h e b io logy o f t h e s e a n i m a l s .

4 4 C E N T I P E D E S

T h e L i t h o b i o m o r p h a a re d i s t i n g u i s h e d f r o m t h e S c o l o p e n d r o ­

m o r p h a b y h a v i n g t h e b o d y c o m p o s e d o f 1 5 l e g - b e a r i n g s o m i t e s , o f

w h i c h o n l y six o r s e v e n posses s sp i r ac le s , t h e t e r g a o f t h o s e w i t h ­

o u t sp i rac les b e i n g g r e a t l y r e d u c e d i n s ize . T h e basa l s e g m e n t s o f

t h e legs a r e s o m e w h a t e n l a r g e d a n d t h e a n t e n n a l s e g m e n t s n u m b e r

f r om 2 0 t o 50 . T h e c e n t i p e d e s o f t h i s o r d e r a r e r e f e r r ed t o t h r e e

famil ies : L i t h o b i i d a e , H e n i c o p i d a e a n d C e r m a t o b i i d a e . T h e y a re

m o s t l y of smal l s ize, t h e l a rges t b e i n g t h e c o n t i n e n t a l Lithobius

fasciatus. Seve ra l spec ies of Lithobius a r e c o m m o n in E n g l a n d , t h e

b e s t k n o w n b e i n g t h e la rge L. forficatus. N e a r l y as l a rge is L.

variegatus w h i c h is easi ly r e c o g n i s e d by i ts a t t r a c t i v e v a r i e g a t e d

c o l o u r p a t t e r n . T h i s spec ies i s o f i n t e r e s t b e c a u s e i t i s f o u n d on ly

i n t h e C h a n n e l I s l a n d s a n d Br i t a in , w h e r e i t o c c u r s m o s t l y i n

s o u t h e r n c o u n t i e s . W e also h a v e o n e spec i e s o f H e n i c o p i d a e ,

Lamyctes fulvicornis, a smal l f o r m d i s t i n g u i s h a b l e f r o m Lithobius

s p p . by t h e p r e s e n c e of a s ingle p a i r o f ocell i i n s t e a d of m a n y , a n d

b y t h e p r e s e n c e o f sp i r ac l e s o n t h e first l e g - b e a r i n g s o m i t e . T h e

C e r m a t o b i i d a e r e s e m b l e t h e H e n i c o p i d a e i n m a n y c h a r a c t e r s a n d

a re n o t e w o r t h y o n a c c o u n t o f t h e a b s e n c e o f p o r e s o n t h e last p a i r

o f legs a n d t h e long , t h i n , m a n y - s e g m e n t e d a n t e n n a e . T h e s e

c h a r a c t e r s t e n d t o l i nk t h e m w i t h t h e S c u t i g e r o m o r p h a . T h e

g e n u s Cermatobius i s f o u n d in t h e M o l u c c a s .

T h e r e m a i n i n g o r d e r , t h e S c u t i g e r o m o r p h a , i s s o m e t i m e s p l a c e d

in a s e p a r a t e s u b - c l a s s , t h e A n a r t i o s t i g m a , r e p r e s e n t e d by a s ing le

fami ly , t h e S c u t i g e r i d a e . I t s r e p r e s e n t a t i v e s a re r e m a r k a b l e for

t h e e x t r a o r d i n a r y l e n g t h o f t h e i r l i m b s a n d for t h e i r e x t r e m e

agi l i ty . T h e y a r e m e d i u m - s i z e d c e n t i p e d e s h a v i n g f i f t e e n p a i r s o f

legs a n d s t e rna l p l a t e s , b u t o n l y e igh t t e rga l p l a t e s . T h e i r eyes a re

c o m p o u n d a n d b u l g i n g , t h e a n t e n n a e w i d e l y s e p a r a t e d a t t h e ba se

a n d exceed ing ly long . T h e sp i rac les l e a d i n g i n t o sacu la r , t u f t ed

t r a c h e a e a r e u n p a i r e d a n d o p e n dorsa l ly u p o n t h e f i r s t s even t e r -

g i tes . T h e s e a n i m a l s a re f o u n d i n all w a r m t rop i ca l a n d t e m p e r a t e

c o u n t r i e s , t h e la rges t , Scutigera longicornis a n d S. clunifera, o c c u r ­

r i n g i n I n d i a a n d s o u t h e r n C h i n a a n d r e a c h i n g t w o o r t h r e e i nches

i n l e n g t h o f h e a d a n d b o d y . T h e r e a re n o i n d i g e n o u s Br i t i sh

spec ies , b u t S . coleoptrata, c o m m o n in s o u t h e r n E u r o p e , w a s o n c e

i n t r o d u c e d i n t o a p a p e r - m i l l in A b e r d e e n w h e r e i t s u c c e e d e d in

e s t a b l i s h i n g itself.

C E N T I P E D E S 45

General behaviour C e n t i p e d e s a r e n o c t u r n a l c r e a t u r e s a n d lack a n i m p e r v i o u s c u t i -

cu l a r w a x - l a y e r ( C l o u d s l e y - T h o m p s o n , 1954) . T h e i r l o c o m o t i o n

h a s l o n g f a sc ina t ed b io log i s t s , b u t on ly r e c e n t l y h a s i ts m e c h a n i c s

b e e n a n a l y s e d i n de ta i l b y m e a n s o f h i g h - s p e e d p h o t o g r a p h y ,

s h o w i n g i t t o be o f e v o l u t i o n a r y a n d f u n c t i o n a l s igni f icance . R a y

L a n k e s t e r , w h o s t u d i e d t h i s m a t t e r i n 1889, r e a c h e d t h e c o n c l u s i o n

t h a t i f t h e a n i m a l s h a d t o se t t l e t h e q u e s t i o n t h e m s e l v e s t h e y w o u l d

n o t ge t on a t a l l ! He e n d e d a l e t t e r t o Nature w i t h t h e fo l lowing

w e l l - k n o w n r h y m e :

A centipede was happy quite Unt i l a toad in fun Said, 'Pray which leg moves after which ?'. T h i s raised her doubts to such a pitch, She fell exhausted in the ditch, Not knowing how to run .

H o w e v e r , M a n t o n (1952 , 1953) h a s r e c e n t l y s h o w n t h a t t h e

l ong G e o p h i l o m o r p h a h a v e b e c o m e spec ia l i sed i n t h e ab i l i ty t o

c h o o s e a n d v a r y t h e i r f o o t h o l d s s o t h a t t h e y m a y o r m a y n o t s h o w

a r e g u l a r r e p e t i t i o n o f t h e l o c o m o t o r y p a t t e r n all a l ong t h e b o d y .

A t t h e s a m e t i m e t h e y a r e a d a p t e d t o b u r r o w i n g ' b y t h e e a r t h w o r m ­

like m e t h o d o f b e c o m i n g " f a t " , t h e ac t ive p r e s s i n g o n t h e soil b e i n g

d o n e b y l o n g i t u d i n a l c o n t r a c t i o n a n d w i d e n i n g o f a s e g m e n t ' .

T h e l egs s e rve a s a n c h o r i n g p o i n t s , l ike t h e c h e t a e o f t h e w o r m ,

a n d w h e n u s e d for w a l k i n g e x e c u t e l a rge ang l e s o f s w i n g t o c o m ­

p e n s a t e for t h e i r s h o r t n e s s . An i nc r ea se i n b u r r o w i n g c a p a c i t y i s

co r r e l a t ed w i t h t h e p r e s e n c e o f l a rge n u m b e r s o f l e g - b e a r i n g s e g ­

m e n t s a n d t h e b u r r o w i n g h a b i t e x p l a i n s m a n y o f t h e m o r p h o ­

logical c h a r a c t e r s o f t h e s e a n i m a l s . T h e h e a d e n d o f a c o n t r a c t e d

a n i m a l c a n b e t h r u s t f o r w a r d m o r e r a p i d l y b y t h e c o n t r a c t i o n o f

t h e m u s c u l a t u r e a n d t e l e s c o p i n g o f t h e s e g m e n t s t h a n b y w a l k i n g .

A c o m b i n a t i o n o f w a l k i n g m o v e m e n t s in s o m e r e g i o n s o f t h e b o d y

w i t h m u s c u l a r c o n t r a c t i o n s a n d e x p a n s i o n s i n o t h e r s r e s u l t s i n a

t h r u s t o r a p u l l b e i n g e x e r t e d o n p a r t s o f t h e b o d y i n w h i c h t h e

legs a re n o t u s e d . T h i s p r o v i d e s a n efficient m e t h o d o f m o v i n g

across g a p s o r p l aces w h e r e f o o t h o l d s a r e d i s c o n t i n u o u s o r sh i f t ing

a n d m u s t a lso b e o f m a j o r i m p o r t a n c e i n w i d e n i n g c rev ices i n t h e

soil.

46 C E N T I P E D E S

I n c o n t r a s t , t h e e v o l u t i o n o f t h e S c o l o p e n d r o m o r p h a a p p e a r s t o

h a v e b e e n as soc ia t ed w i t h a c q u i r i n g i n c r e a s e d s p e e d . F a s t ga i t s

a re pos s ib l e a s t h e r e l a t ive d u r a t i o n o f t h e b a c k s t r o k e o f t h e l i m b s

i s s h o r t e r t h a n i n m o s t o t h e r A r t h r o p o d a . T h e b o d y m a y m o m e n ­

ta r i ly b e s u p p o r t e d b y on ly t w o o r t h r e e legs o n each s ide , b u t

excess ive s agg ing o f t h e b o d y b e t w e e n t h e s e w i d e l y s e p a r a t e d s u p ­

p o r t s i s c o u n t e r e d b y t h e b o d y m u s c u l a t u r e . A t t h e s a m e t i m e

a l t e r n a t e - s i z e d t e r g i t e s a p p e a r t o c o n t r i b u t e a n a n t i - u n d u l a t i o n

m e c h a n i s m w h i c h b e c o m e s n e c e s s a r y a s t h e legs i nc r ea se i n

l e n g t h a n d t h e ga i t b e c o m e s fas ter . T h e s e a c h i e v e m e n t s h a v e b e e n

m a d e a t t h e e x p e n s e o f t h e p r i m i t i v e f lexibil i ty o f l o c o m o t o r y

m o v e m e n t s a s a re f o u n d i n t h e O n y c h o p h o r a a n d w h i c h h a v e b e e n

e x p l o i t e d i n r e l a t ion t o t h e b u r r o w i n g h a b i t o f t h e G e o p h i l o m o r p h a .

T h u s t h e ga i t s o f t h e S c o l o p e n d r o m o r p h a a r e p e r f o r m e d w i t h

g r e a t e r r e g u l a r i t y t h a n t h o s e o f t h e G e o p h i l o m o r p h a , b u t l i t t le

cho i ce of f o o t h o l d s is pos s ib l e .

T h e legs o f t h e L i t h o b i o m o r p h a a n d S c u t i g e r o m o r p h a a re

l o n g e r t h a n t h o s e o f t h e o r d e r s s o far c o n s i d e r e d . T h e ga i t s i n

t h e s e t w o g r o u p s a r e essen t ia l ly s imi la r . O n l y a sma l l r a n g e i s p o s ­

s ible , a n d m o v e m e n t s m u s t b e e x e c u t e d w i t h g r e a t p r e c i s i o n

b e c a u s e t h e fields o f u p t o f o u r success ive legs m a y o v e r l a p . U n ­

d u l a t i o n s o f t h e b o d y a t fas te r s p e e d s a re pa r t i a l ly c o n t r o l l e d in

Lithobius by t h e a l t e r n a t e - s i z e d t e rg i t e s , a n d m o r e c o m p l e t e l y by a

r e d u c t i o n in t e rg i t e n u m b e r in Scutigera i n w h i c h t h e legs a r e o f

different ia l l e n g t h , t h e f o u r t e e n t h p a i r b e i n g a l m o s t d o u b l e t h e

l e n g t h o f t h e first. W i t h t h e g r e a t f leetness o f t h e S c u t i g e r o m o r p h a

a re a s soc ia t ed severa l s t r u c t u r a l a d v a n c e s b e y o n d t h e c o n d i t i o n s

seen i n o t h e r C h i l o p o d a . T h e l o n g legs r e q u i r e a f i rm g r i p on t h e

g r o u n d t o p r e v e n t t h e m f rom s l i p p i n g , a n d i n s t e a d o f t h e s ing le o r

d o u b l e d i g i t i g r a d e s p i n e p r e s e n t i n o t h e r c e n t i p e d e s , t h e leg o f

Scutigera e n d s in a m u l t i - a r t i c u l a t e p l a n t i g r a d e foot , e ach j o i n t p o s ­

sess ing n u m e r o u s g r i p p i n g h a i r s . F a s t r u n n i n g i n d i c a t e s a h i g h

m e t a b o l i c r a t e c o r r e l a t e d w i t h g r e a t e r c o m p l e x i t y o f t h e max i l l a ry

e x c r e t o r y g l a n d , a u n i q u e r e s p i r a t o r y s y s t e m a n d t h e p r e s e n c e o f

an efficient r e s p i r a t o r y c a r r i e r i n t h e b l o o d .

T h e m e c h a n i s m o f b r e a t h i n g a n d b l o o d c i r c u l a t i o n i s s imi l a r t o

t h a t o f s p i d e r s a n d s c o r p i o n s s ince i n t h e A r a c h n i d a t h e b l o o d

m u s t t r a v e r s e t h e i n t e r l a m e l l a r spaces be fo r e r e t u r n i n g t o t h e

C E N T I P E D E S 47

hea r t . In S . coleoptrata t h e l u n g s a re do r sa l a n d s i t u a t e d in t h e

p e r i c a r d i a l cav i ty w h e r e a s p i r a t i o n d u e t o sys to le i s s t r o n g e s t .

T h e y a r e b a t h e d b y b l o o d i n t h e v e n t r o - l a t e r a l l a c u n a e w h i c h a r e

c o n n e c t e d w i t h t h e pe r i ca rd i a l cavi ty b y p u l m o n a r y v e i n s . T h u s

an ac t ive m o d e o f life, s o m e w h a t a n a l a g o u s t o t h a t o f t h e wolf

s p i d e r s w h i c h h u n t t h e i r p r e y i n t h e o p e n , i s a s soc ia t ed w i t h

a n a l a g o u s m o r p h o l o g i c a l s t r u c t u r e s . A t t h e s a m e t i m e t h e p r e s e n c e

of c o m p o u n d eyes in Scutigera, in c o n t r a s t to t h e s i m p l e ocell i of

t h e o t h e r C h i l o p o d a , m a y b e assoc ia ted w i t h fast r u n n i n g af ter

flies a n d o t h e r i n sec t s .

O f c o u r s e t h e G e o p h i l o m o r p h a d o n o t a lways b u r r o w , p a r t i c u ­

lar ly t h e s h o r t e r - b o d i e d s p e c i e s w h i c h o f t en seek s h e l t e r u n d e r

s tones , n o r d o t h e m e m b e r s o f t h e o t h e r o r d e r s r u n fast all t h e

t i m e : o n t h e c o n t r a r y t h e y s p r i n t o n l y occas iona l ly a n d w i t h r e ­

l u c t a n c e . N e v e r t h e l e s s l o c o m o t i o n a p p e a r s t o b e t h e h a b i t w i t h

w h i c h t h e i r e v o l u t i o n h a s b e e n chiefly a s soc ia t ed ( M a n t o n , 1952,

1953) .

C e n t i p e d e s a lways l ive i n d a m p , d a r k a n d o b s c u r e p l a c e s u n d e r

s t ones , fal len leaves , logs , u n d e r b a r k a n d in c rev ices o f t h e soil ,

f r o m w h i c h , l ike w o o d l i c e a n d m i l l i p e d e s , t h e y i s sue f o r t h a t

n i g h t . S inc l a i r (1895) c l a i m e d t h a t i n M a l t a Scutigera d a r t s a b o u t

i n t h e h o t s u n s h i n e a f te r i t s p r e y , b u t i n I n d i a i t i s sa id t o e x h i b i t

a s t r o n g ' d i s l ike ' o f d a y l i g h t a n d h i d e s d u r i n g t h e d a y t i m e in d a r k

p l aces . I t s m o s t c o m m o n h a b i t a t i s u n d e r m a t t i n g c o v e r i n g t h e

floors o f b u n g a l o w s o r o n wa l l s i n d a r k c o r n e r s a n d u n d e r s t o n e s

o u t o f d o o r s . In I t a l y t o o S . coleoptrata a p p e a r s to be p h o t o - n e g a ­

t ive ( C l o u d s l e y - T h o m p s o n , 1949) .

W i t h t h e e x c e p t i o n o f t h e i r eyes w h i c h u s u a l l y d o n o t s e e m t o b e

o f m u c h i m p o r t a n c e , t h e s ense o r g a n s o f c e n t i p e d e s t a k e t h e f o r m

o f h a i r s c o n n e c t e d w i t h n e r v e f i b r e s ; t h e a n i m a l s f i n d t h e i r p r e y b y

m e a n s o f t h e s e ha i r s w h i c h a re sens i t i ve t o t o u c h . T h e y a r e also

v e r y sens i t i ve t o m o i s t u r e a n d c o n t a c t s t i m u l i . T h e w h o l e s u b j e c t

h a s b e e n r e v i e w e d b y C l o u d s l e y - T h o m p s o n ( 1 9 5 2 b ) . A c c o r d i n g

to B a u e r (1953) Lithobius forficatus s h o w s a ' p r e f e r e n c e ' for h i g h

h u m i d i t i e s a n d a g r o u n d t e m p e r a t u r e o f a b o u t 12° C .

A u e r b a c h (1951) h a s f o u n d t h a t t h e d i s t r i b u t i o n o f Bothropolys

multidentatus, Lithobius forficatus a n d Neolithobius voracior in t h e

C h i c a g o a rea o f N o r t h A m e r i c a d o e s n o t fol low a u n i f o r m p a t t e r n .

48 C E N T I P E D E S

T h e f i r s t r e a c h e s a peak o f a b u n d a n c e in w e t fores t c o m m u n i t i e s ,

t h e s e c o n d in d r y fores t , w h i l e X. voracior i s p len t i fu l in t h o s e

local i t ies i n w h i c h floor m o i s t u r e c o n d i t i o n s a r e i n t e r m e d i a t e : a n d

t h i s d i s t r i b u t i o n i s r e l a t e d to t h e di f ferent t i m e s o f su rv iva l o f

t h e t h r e e spec ies w h e n p l a c e d i n d r y air . I t i s o f c o u r s e t r u e t h a t

c e r t a i n c e n t i p e d e s s u c h as Scutigera, Scolopendra a n d Dignathodon

s p p . , a n d in o u r o w n c o u n t r y Lithobius calcaratus, t e n d to i n h a b i t

d r y p l aces , b u t i t i s p r o b a b l e t h a t t h i s p h e n o m e n o n i s a n a l a g o u s t o

t h a t f o u n d i n w o o d l i c e a n d t h a t t h e d i f ferent spec i e s v a r y m e r e l y i n

t h e l e n g t h o f t i m e t h a t t h e y can s u r v i v e a w a y f r o m d a m p n e s s .

R e c e n t l y P a l m e n a n d R a n t a l a (1954) h a v e s u g g e s t e d t h a t t h e o r i e n ­

t a t i o n of t h e G e o p h i l i d c e n t i p e d e Pachymerium ferrugineum in its

n a t u r a l h a b i t a t s , i s chiefly g u i d e d b y r e a c t i o n s t o a i r h u m i d i t y a n d

m o i s t u r e a n d , t o a lesser d e g r e e , t o t e m p e r a t u r e . W h e n t h e re la t ive

h u m i d i t y o f t h e a i r d e c r e a s e s in a n i c h e i n h a b i t e d by t h i s spec ies ,

t h e r e su l t wil l b e a n i n c r e a s e i n l o c o m o t o r y a c t i v i t y a n d o r i e n t a ­

t i o n t o w a r d s m o i s t u r e . I f h i g h t e m p e r a t u r e i s c o m b i n e d w i t h u n ­

u s u a l l y l o w a t m o s p h e r i c h u m i d i t y , t h e i n c r e a s e d de s i cca t i on

c a u s e d wi l l in tens i fy t h e r e s p o n s e s o f t h e a n i m a l t o m o i s t u r e .

M a n y spec ies o f c e n t i p e d e s a r e c a v e - d w e l l e r s a n d a f ew of t h e

G e o p h i l o m o r p h a a r e m a r i n e . T w o Br i t i sh spec i e s a r e f o u n d o n

t h e s e a s h o r e u n d e r s t o n e s a n d s e a w e e d a t l o w t i d e level . T h e

smal l e r , Scolioplanes maritimus, w a s f i rs t d i s c o v e r e d by L e a c h in

1817, w h o w r o t e s o m e w h a t op t imi s t i ca l ly , ' H a b i t a t i n B r i t a n n i a

i n t e r s c o p u l o s a d l i t t o ra m a r i s v u l g i s s i m e ' . I t w a s r e - d i s c o v e r e d

s o m e f i f t y y e a r s l a t e r a t P l y m o u t h a n d h a s s ince t u r n e d u p i n t h e

I s le o f M a n , S o m e r s e t , C o r n w a l l , S u s s e x , C o . D u b l i n a n d o n t h e

coas t o f G a l w a y . I t i s e v i d e n t l y fair ly w i d e l y d i s t r i b u t e d on t h e

N o r t h Sea coas t o f F r a n c e , D e n m a r k , S w e d e n a n d G e r m a n y . T h e

s e c o n d spec ies , Hydroschendyla submarina, i s v e r y m u c h less c o m ­

m o n . I t h a s n e v e r t h e l e s s b e e n f o u n d i n C o r n w a l l , J e r s e y a n d

Y o r k s h i r e , a s wel l a s on t h e coas t s o f F r a n c e , I t a ly , S c a n d i n a v i a ,

N o r t h Af r ica a n d B e r m u d a , w h e r e i t l ives i n m u d d y s i t u a t i o n s

a r o u n d t h e e d g e s o f e r o d e d flat s t ones , a n d i n i so la ted h o n e y ­

c o m b e d b locks o f l i m e s t o n e a b o u t n i n e i n c h e s b e l o w m e a n h i g h

w a t e r ( C h a m b e r l i n , 1920) . Pectinunguis americanus o c c u r s u n d e r

s eaweed , d r i f t w o o d e tc . o n t h e coas t s o f M e x i c o , i n c l u d i n g F l o r i d a

a n d t h e coas t s o f l o w e r Cal i forn ia , a n d o t h e r m a r i n e c e n t i p e d e s

C E N T I P E D E S 49

h a v e b e e n co l l ec ted f r o m t h e C a p e V e r d e I s l a n d s a n d t h e G a l a ­

p a g o s . I n t h e f o r m e r case t h e y i n h a b i t c rev ices i n t h e c r u s t o f w o r m

t u b e s w h i c h cove r all r ocks a t l o w t i d e i n s ide b a y s , a n d i n t h e l a t t e r

la rge e m p t y b a r n a c l e she l l s also a t l ow t i d e level . B o n n e l l (1930)

o b t a i n e d a n u m b e r of Mixophilus indicus f r o m u n d e r s t o n e s a n d

soft m o i s t soil a l ong w i t h v a r i o u s P o l y c h a e t e w o r m s i n t h e b e d o f

t h e C o o u m Rive r , M a d r a s . A s a r e su l t o f e x p e r i m e n t s o n t h e i r

r e s i s t ance t o s u b m e r s i o n he c o n c l u d e d t h a t l i t t le air i s r e q u i r e d

b y t h i s spec ies ; t h e t r a c h e a e s t o r e e n o u g h for 2 4 h o u r s a n d i n

a d d i t i o n a i r i s e n t a n g l e d by a l o o p of t h e p o s t e r i o r e n d of t h e b o d y

a n d i n c h i t i n o u s c h a n n e l s i n t h e coxae o f t h e last legs . I n t h i s

l a t t e r r e s p e c t t h e y a p p e a r to differ f r o m H. submarina a n d S .

maritimus, b o t h o f w h i c h h o w e v e r c a n su rv ive severa l d a y s i m ­

m e r s i o n i n sea w a t e r w i t h o u t a n y ill effects. T h e l i t e r a t u r e o n

m a r i n e m y r i a p o d s h a s b e e n r e v i e w e d b y C l o u d s l e y - T h o m p s o n

(1948 , 1951) .

T h e idea o f c e n t i p e d e s l iv ing i n w a t e r h a s p e r s i s t e d f r o m class i ­

cal t i m e s , for P l i n y w r o t e of a m a r i n e ' S c o l o p e n d r a ' as a v e r y

p o i s o n o u s a n i m a l , b u t t h e r e i s l i t t le d o u b t t h a t h e w a s r e f e r r i ng t o

o n e o f t h e m a r i n e w o r m s . T h e G e r m a n n a t u r a l i s t G e s n e r gave a n

a c c o u n t in 1569 of a s imi l a r ' m a r i n e S c o l o p e n d r a ' w h i c h , soaked

i n oil o r p o u n d e d u p w i t h h o n e y , w a s be l i eved t o cause t h e h a i r t o

fall. C h a r l e s O w e n , in h i s Essay towards a Natural History of Ser­

pents (1752) w r o t e : ' T h e S c o l o p e n d r a i s a l i t t le v e n o m o u s w o r m

a n d a m p h i b i o u s . W h e n i t w o u n d s a n y , t h e r e fo l lows a b l u e n e s s

a b o u t t h e affected p a r t a n d a n i t ch all ove r t h e b o d y l ike t h a t

c a u s e d b y n e t t l e s . I t s w e a p o n s o f m i s c h i e f a re m u c h t h e s a m e w i t h

t h o s e o f t h e s p i d e r on ly la rger ; i t s b i t e i s v e r y t o r m e n t i n g , a n d p r o ­

d u c e s n o t o n l y p r u r i g i n o u s p a i n i n t h e flesh, b u t v e r y of ten d i s ­

t r a c t i o n o f t h e m i n d . T h e s e l i t t le c r e a t u r e s m a k e b u t a m e a n

f igure i n t h e r a n k s o f a n i m a l s , y e t h a v e b e e n t e r r i b l e i n t h e i r ex ­

p lo i t s , p a r t i c u l a r l y i n d r i v i n g p e o p l e o u t o f t h e i r c o u n t r y . T h u s

t h e p e o p l e of R h y t i u m , a c i ty o f C r e t e , w e r e c o n s t r a i n e d to leave

t h e i r q u a r t e r s for t h e m (Ael ian , l ib . X V . , c a p . 2 6 ) . ' T h i s i s t h e

on ly r e c o r d e d i n s t a n c e of a m a s s m i g r a t i o n of c e n t i p e d e s a l t h o u g h

t h e y h a v e a c c o m p a n i e d m i g r a t i n g a r m i e s o f m i l l i p e d e s .

A n u m b e r of cases of p s e u d o p a r a s i t i s m h a v e b e e n r e c o r d e d in

w h i c h b o t h c e n t i p e d e s a n d m i l l i p e d e s h a v e b e e n f o u n d l iv ing i n

D S.S.C.M.

5 0 C E N T I P E D E S

t h e nasal s i n u s o r t h e a l i m e n t a r y cana l o f m a n , i n to w h i c h t h e y

have b e c o m e acc iden ta l l y i n t r o d u c e d . O n occas ions t h e y h a v e b e e n

v o m i t e d u p i n n u m b e r s b y p a t i e n t s w h o a l leged t h a t t h e a n i m a l s

w e r e b r e e d i n g in s ide t h e m . T h e r e i s a c o n s i d e r a b l e l i t e r a t u r e on

t h e s u b j e c t b u t i ts b io logica l i m p o r t a n c e i s s l igh t . T h e e x p l a n a t i o n

p r o b a b l y lies in t h e fact t h a t c e n t i p e d e s s e e m to exe r t a w e i r d fas­

c i n a t i o n o n t h e m o r b i d a p p e t i t e s o f t h e hys t e r i ca l a n d i n s a n e

( J ackson , 1914; S h i p l e y , 1914) .

Food and feeding habits C e n t i p e d e s a re p r i m a r i l y c a r n i v o r o u s b u t c e r t a i n o f t h e G e o ­

p h i l o m o r p h a will o n occas ion feed u p o n p l a n t t i s sues a n d m a y

e v e n be pos i t ive ly i n j u r i o u s t o c r o p s i f p r e s e n t i n sufficient n u m ­

b e r s . T h e y also feed u p o n w o r m s , a n d t h e m a r i n e Hydroschendyla

submarina in t h e B e r m u d a I s l a n d s i s sa id to eat L e o d i c i d s , b i t i n g

t h e m , l ick ing u p t h e i r j u i c e s a n d c a r r y i n g off t h e f r a g m e n t s i n to

w h i c h t h e w o r m s a u t o t o m i s e ( C h a m b e r l i n , 1920) . G e o p h i l i d s a re

n o t easy t o m a i n t a i n i n c ap t i v i t y a n d d o n o t r ead i ly t ake food u n d e r

l a b o r a t o r y c o n d i t i o n s . C o n s e q u e n t l y o u r k n o w l e d g e o f t h e i r feed­

ing h a b i t s i s s o m e w h a t s c a n t y , b u t p r o b a b l y t h e y d e v o u r a va r i e ty

o f sma l l s o i l - i n h a b i t i n g A r t h r o p o d a ( B r a d e - B i r k s , 1929) .

T h e L i t h o b i o m o r p h a wil l occas iona l ly feed o n w o r m s a n d s lugs

t o o , b u t i n sec t s p r o b a b l y f o r m t h e i r s t ap le d ie t : Lithobius forficatus

r ead i ly a c c e p t s flies i n cap t iv i ty . T h i s spec ies h a s b e e n o b s e r v e d o n

a wal l a t n i g h t c a r r y i n g off a w o o d l o u s e in i ts j a w s . I t h a s a lso b e e n

k n o w n t o r e s o r t t o e n t o m o l o g i s t s ' s u g a r p a t c h e s for t h e p u r p o s e o f

c a p t u r i n g t h e luck less i n sec t s w h i c h c o m e for t h e swee t s . S m a l l

m o t h s h a v e n o c h a n c e o f e scape , b u t t h e l a rge r N o c t u i d s s o m e ­

t i m e s s u c c e e d in t e a r i n g t h e m s e l v e s a w a y a l t h o u g h i t i s s u r p r i s i n g

h o w t e n a c i o u s l y t h e c e n t i p e d e s h o l d o n . T h e S c u t i g e r o m o r p h a a re

p r o b a b l y en t i r e ly i n s e c t i v o r o u s , b u t s t u d y o f t h e l i t e r a t u r e s h o w s

t h a t t h e S c o l o p e n d r o m o r p h a h a v e a w i d e r a n g e o f d ie t , a l t h o u g h in

m a n y cases t h e p r ec i s e ident i f ica t ion of spec ies i s d u b i o u s . A p a r ­

t i cu la r ly la rge s p e c i m e n of S. gigas ( pos s ib ly S. gigantea) f rom

T r i n i d a d k e p t for ove r a y e a r in t h e I n s e c t H o u s e o f t h e Zoolog ica l

Soc ie ty o f L o n d o n , fed p r i n c i p a l l y on sma l l m i c e w h i c h i t d e v o u r e d

w i t h a lacr i ty . S c o l o p e n d r a s h a v e b e e n k n o w n , i n I n d i a , t o kill a n d

ea t smal l b i r d s , wh i l e o n e v o r a c i o u s c e n t i p e d e (S. gigantea) w a s

C E N T I P E D E S 51

f o u n d d e v o u r i n g t h e s ide o f a l iv ing t o a d . On t h e o t h e r h a n d ,

s p e c i m e n s of S . morsitans f r o m T e x a s re fused to b i t e t o a d s . M o r e

r ecen t ly , L a w r e n c e (1953) h a s s e e n S . morsitans s p e e d i l y kill sma l l

geckoes o f t h e g e n u s Pachydactylus by b i t i n g t h e m in t h e neck .

O n e l a r g e u n i d e n t i f i e d S c o l o p e n d r a w a s d i s c o v e r e d o n t h e floor o f

a h o u s e at K o k i n e , a s u b u r b of R a n g o o n , w i t h a sma l l s n a k e

w r i t h i n g in i ts c l u t c h e s , f r o m t h e tail o f w h i c h t h e sk in a n d flesh

for a b o u t t w o i n c h e s h a d b e e n c o m p l e t e l y r e m o v e d .

U n d e r l a b o r a t o r y c o n d i t i o n s S . heros f eeds freely u p o n t h e

a g r i c u l t u r a l l y n o x i o u s in sec t s p r o v i d e d : i t p r e f e r s t o r e m a i n u n d e r ­

g r o u n d o n w a r m d a y s b u t i s r es t l e ss o n t h e su r face i n c l o u d y a n d

w e t w e a t h e r . S . viridis re fuses w o o d l i c e a n d e a r t h w o r m s b u t i s

pa r t i a l t o flies; t h e p r e y , o f w h i c h t h e h a r d p a r t s a r e re jec ted , i s

h e l d f i rmly t o t h e m o u t h b y t h e p o i s o n c laws w h i l s t t h e m a n d i b l e s

a n d m a x i l l a e t e a r i t to p i eces . L a w r e n c e (1934) o b s e r v e d a l a rge

S. subspinipes f e e d i n g on a s l u g (Veronicella leydigi), b u t in c a p ­

t iv i ty t h e s a m e spec ies f r o m B o r n e o d o e s n o t t o u c h r a w m e a t ,

w o r m s or v a r i o u s i n sec t s . S . subspinipes i s a b u n d a n t in t h e v ic in i ty

o f t h e t o w n o f T a r r a g o n a i n t h e P h i l i p p i n e I s l a n d s , a n d R e m i n g t o n

(1950) w r o t e : ' A l m o s t e v e r y n i g h t t h e w r i t e r s aw o n e o r t w o o f t h e

g r e a t c h i l o p o d s f eed ing v o r a c i o u s l y o n t h e w i n g e d i n sec t s w h i c h

s w a r m e d i n t o h i s p y r a m i d a l l a b o r a t o r y t e n t , a t t r a c t e d b y t h e e lec ­

t r ic l igh t . T h e c e n t i p e d e s c l i m b e d t h e wa l l s o f t h e t e n t easily,

f a s t ened t h e i r p o w e r f u l ana l legs n e a r t h e v e n t i l a t o r ho l e o f t h e

t e n t p e a k a n d s w u n g t h e i r b o d i e s q u i c k l y t o o n e s ide o r t h e o t h e r

t o se ize i n s e c t s w h i c h a l i g h t e d n e a r b y . '

T h e p r e s e n t w r i t e r k e p t a f e m a l e S . cingulata f o u n d n e a r M a r ­

seil les for severa l m o n t h s in a c rys t a l l i s ing d i s h c o v e r e d w i t h a

shee t o f g lass . S h e w a s fed o n m e d i u m - s i z e d n y m p h a l c o c k r o a c h e s

o f w h i c h o n t h e a v e r a g e s h e a t e a b o u t o n e p e r w e e k t h r o u g h o u t

t h e s u m m e r . A d u l t c o c k r o a c h e s h a d t o b e d i s a b l e d be fo r e she

w o u l d t ack l e t h e m . S h e fed a lso o n s p i d e r s , flies, m o t h s a n d o t h e r

in sec t s a n d c h e w e d u p s o m e w o r m s w h i c h she d i d n o t f inish. S h e

even a t e b e e s a n d w a s p s w h i c h s h e c a u g h t i n m i d - a i r , r e a r i n g u p

t h e fore p a r t o f h e r b o d y t o s n a t c h t h e m w i t h h e r p o i s o n c laws

a s t h e y flew pas t . T h e s e s h e d r o p p e d q u i c k l y a n d w a i t e d u n t i l

h e r p o i s o n h a d h a d t i m e t o t a k e effect ( C l o u d s l e y - T h o m p s o n ,

1955).

52 C E N T I P E D E S

D u r i n g w a r m w e a t h e r she w a s g iven w a t e r dai ly w h i c h she

d r a n k , s o m e t i m e s for p e r i o d s o f severa l m i n u t e s , a n d t h e l a p p i n g

m o v e m e n t s o f h e r m a n d i b l e s a n d max i l l a e c o u l d r ead i ly b e o b ­

s e r v e d t h r o u g h t h e g lass of h e r c o n t a i n e r . In c o n t r a s t , S . clavipes

f r o m C e n t r a l T u n i s i a w e r e pa le , soft a n d c o m p a r a t i v e l y w e a k

c r e a t u r e s w i t h o u t t h e r o b u s t a p p e t i t e of S . cingulata ( C l o u d s l e y -

T h o m p s o n , 1955) .

T h e s m a l l e r C r y p t o p i d a e feed u p o n w o r m s , s o f t - s k i n n e d in ­

sec ts o r a n y a n i m a l sma l l e n o u g h t o b e k i l led b y t h e m .

Enemies C e n t i p e d e s a re c a r n i v o r o u s a n d wil l eat o n e a n o t h e r i f an o p p o r ­

t u n i t y p r e s e n t s itself. Lithobius forficatus m u s t n o t be o v e r c r o w d e d

in cap t iv i ty , o r c a n n i b a l i s m wil l r e su l t , p a r t i c u l a r l y i f o n e of t h e

a n i m a l s i s s m a l l e r t h a n t h e o t h e r s o r h a s b e e n i n j u r e d . I t h a s b e e n

s u g g e s t e d t oo t h a t G e o p h i l i d s f o r m p a r t o f t h e n a t u r a l food o f t h e

C r y p t o p i d a e . C e n t i p e d e s a re p r o b a b l y d i s tas te fu l a n d i t d o e s n o t

a p p e a r l ikely t h a t t h e y a r e e a t e n t o a n y d e g r e e b y s p i d e r s a n d o t h e r

p r e d a t o r y a n i m a l s u n l e s s o t h e r food i s sca rce . S c o r p i o n s h a v e b e e n

k n o w n to kill a n d ea t S . morsitans b u t t h e b i g Scolopendra o f ten

ge t s t h e b e t t e r o f i ts a d v e r s a r y . T h e S c u t i g e r o m o r p h a r ead i ly

a u t o t o m i s e t h e i r legs i f a t t a c k e d , a n d i n s o m e spec ies t h e d e t a c h e d

l i m b s c o n t i n u e t o s t r i d u l a t e , t h e r e b y a t t r a c t i n g a p r e d a t o r ' s a t t e n ­

t ion w h i l e i ts f o r m e r p o s s e s s o r m a k e s i ts e scape .

O n a c c o u n t o f t h e i r r e t i r i n g h a b i t s , c e n t i p e d e s t e n d t o e scape

no t i c e a n d t h e i r p o i s o n also p r o t e c t s t h e m f r o m e n e m i e s . T h e r e

a r e n u m e r o u s s c a t t e r e d a c c o u n t s i n t h e l i t e r a t u r e o f t h e effects o f

t h e b i t e o f t h e l a rge r c e n t i p e d e s , b u t i n m a n y t h e a n i m a l h a s n o t

b e e n a d e q u a t e l y iden t i f i ed a n d i n t h e r e m a i n d e r t h e c o n c l u s i o n s

d r a w n b y t h e a u t h o r s a r e of ten m u c h a t v a r i a n c e . T h u s Scolo­

pendra cingulata i s sa id to c a u s e pa in fu l o e d e m a a n d rea l d i s c o m ­

for t to h u m a n s , b u t S . heros a n d S . viridis p r o d u c e , at m o s t , on ly

t e m p o r a r y s h a r p p a i n . T h e la rge S . subspinipes o f Braz i l p r o d u c e s

i n t e n s e p a i n , b l i s t e r i n g , swe l l ing , local i n f l a m m a t i o n , b u b o s a n d

s u b c u t a n e o u s h a e m o r r h a g e . T h i s spec ies m a y r e a c h a l e n g t h o f 25

c m a n d R e m i n g t o n (1950) w h o w a s b i t t e n b y o n e w h i l e o n t h e

I s l a n d of L e y t e in t h e P h i l i p p i n e s w r o t e t h a t i t c a u s e d a fiery p a i n

w h i c h a t first w a s a l m o s t u n b e a r a b l e a n d d i d n o t d i m i n i s h for

C E N T I P E D E S

a b o u t t w e n t y m i n u t e s . A swol l en , t e n d e r a n d m i l d l y pa in fu l c o n ­

d i t i on p e r s i s t e d for a b o u t t h r e e w e e k s . T h e o n l y a u t h e n t i c case r e ­

c o r d e d in t h e l i t e r a t u r e in w h i c h a c e n t i p e d e b i t e w a s fatal to a

h u m a n i s t h a t o f a s even y e a r o ld ch i l d i n t h e P h i l i p p i n e s w h o w a s

b i t t e n o n t h e h e a d a n d d i e d t w e n t y - n i n e h o u r s l a t e r . B u c h e r l

(1946) h a s p u b l i s h e d t h e r e s u l t s o f e x p e r i m e n t s w i t h t h e five c o m ­

m o n e s t a n d l a rges t Braz i l i an C h i l o p o d s a n d h a s i n c l u d e d a m o r p h o ­

logical a n d h i s to log ica l s t u d y o f t h e p o i s o n a p p a r a t u s . H a v i n g

e x p e r i m e n t e d w i t h m i c e , g u i n e a - p i g s a n d p i g e o n s in j ec t ed w i t h

s o l u t i o n s o f t h e v e n o m a t v a r y i n g c o n c e n t r a t i o n s , h e r e a c h e d t h e

c o n c l u s i o n t h a t t h e p o i s o n o f e v e n t h e l a rges t o f t h e Braz i l i an

spec ies w a s t oo feeb le eve r t o e n d a n g e r t h e life o f m a n o r e v e n

y o u n g c h i l d r e n .

N e v e r t h e l e s s , g i a n t c e n t i p e d e s w h i c h a r e s o a b u n d a n t i n t r o p i c a l

r eg ions a r e d r e a d e d b y t h e h u m a n i n h a b i t a n t s . I n 1798 t h e r e ­

n o w n e d n a t u r a l h i s t o r i a n D o n o v a n w r o t e of Scolopendra morsitans:

' T r a v e l l e r s ag ree t h a t t h e t e m p e r a t e p a r t s o f As ia w o u l d be a t e r ­

res t r ia l p a r a d i s e , w e r e i t n o t for t h e m u l t i t u d e o f t r o u b l e s o m e

insec t s a n d r ep t i l e s w i t h w h i c h t h e y a re in fes ted . I n a wel l cu l t i va ­

t e d c o u n t r y , l ike C h i n a , m a n y o f t h e s e c r e a t u r e s c a n sca rce ly f ind

she l t e r ; b u t s u c h a s h a r b o u r i n t h e wal l s o r f u r n i t u r e o f h u m a n

d w e l l i n g s a re a s a b u n d a n t i n t h a t , a s i n a n y o t h e r c o u n t r y t h a t l ies

w i t h i n o r n e a r t h e t r o p i c s . A m o n g s t t h e l a t t e r , n o n e p r o d u c e m o r e

t e r r i b l e effects t h a n t h e c e n t i p e d e , w h o s e p o i s o n i s a s v e n o m o u s a s

t h a t of t h e s c o r p i o n , w h i c h also is a n a t i v e of C h i n a . ' A sma l l spec i ­

m e n o n l y 8 5 m m l o n g w a s f o u n d b y a zoo logy s t u d e n t o f E x e t e r

U n i v e r s i t y Co l l ege u n d e r a b o u l d e r a t Cass i s , n e a r M a r s e i l l e s , i n

1949. I t b i t h i m o n t h e s e c o n d f inger o f h i s r i g h t h a n d a s h e c a u g h t

it. Af t e r a b o u t a q u a r t e r o f an h o u r t h e ba se o f t h e f inger h a d s w o l ­

len c o n s i d e r a b l y a n d t h e p a i n w a s s imi l a r t o t h a t o f a h o r n e t s t i ng .

W i t h i n a n h o u r t h e w h o l e h a n d h a d swo l l en t o t w i c e i ts n o r m a l

size b u t w a s n o t pa in fu l t o t o u c h . T h e effects h a d q u i t e g o n e t h r e e

d a y s l a t e r ( T u r k , 1951) .

T h e re f ra in o f a T r i n i d a d c a l y p s o r u n s : ' M a n c e n t i p e d e b a d ,

b a d ; w o m a n c e n t i p e d e w o r s e t h a n b a d . ' N e v e r t h e l e s s , I n d i a n ch i l ­

d r e n h a v e b e e n seen t o d r a g h u g e c e n t i p e d e s o u t o f t h e e a r t h a n d

eat t h e m . T h e Af r i can A r a b s d e v o u r S c o l o p e n d r a s a l ive , of ten i n

c o m p a n y w i t h s c o r p i o n s , b r o k e n glass , leaves o f p r i c k l y p e a r a n d

A C E N T I P E D E S

o t h e r u n p l e a s a n t t h i n g s u n d e r t h e in f luence o f r e l ig ious e x c i t e m e n t .

I n S i a m c e n t i p e d e s a re r o a s t e d a n d g iven t o c h i l d r e n suffer ing

f r o m ' t h i n n e s s a n d swo l l en be l ly ' (ma la r i a o r h o o k w o r m ) : a n d

r o a s t e d c e n t i p e d e s p o w d e r e d a n d s o a k e d i n a lcoho l a n d t h e j u i c e o f

b o r a p e t a r e u s e d m e d i c i n a l l y as a s t i m u l a n t .

F e w t e m p e r a t e spec ies a re b i g e n o u g h t o b e ab le t o p e n e t r a t e

t h e h u m a n sk in w i t h t h e i r p o i s o n - c l a w s . Lithobius forficatus

causes a s h a r p p a i n t h a t i s n o t i c e a b l e for s o m e t i m e , b u t s igns

of in ju ry a re ins igni f icant . T h e l o n g - l e g g e d Scutigera forceps

h a s b e e n r e c o r d e d as g i v i n g a b i t e t h a t i s fo l lowed by i n t e n s e

local pa in .

O n t h e w h o l e , a l t h o u g h Buffon, i n a c o n t e m p o r a r y E n g l i s h

t r a n s l a t i o n , w r o t e : 'O f t h e s e h i d e o u s a n d a n g r y insec t s w e k n o w

l i t t le e x c e p t t h e f i g u r e a n d t h e n o x i o u s q u a l i t i e s ' , c e n t i p e d e s a re

for t h e m o s t p a r t c o m p a r a t i v e l y i n n o c u o u s m e m b e r s o f t h e c o m ­

m u n i t y o f a n i m a l s . E v e n t h e la rge S c o l o p e n d r a s d o n o t b i t e u n l e s s

m o l e s t e d a n d wil l a lways t r y t o e scape r a t h e r t h a n f i g h t .

M a n y o f t h e G e o p h i l o m o r p h a , i n c l u d i n g t h e c o m m o n Br i t i sh

Geophilus electricus, G. carpophagus, Necrophlaeophagus longicornis

a n d Scolioplanes crassipes, e x u d e a p h o s p h o r e s c e n t f luid w h e n d i s ­

t u r b e d . T h e p h o s p h o r e s c e n c e m a y b e exc i t ed a t a n y t i m e o f y e a r

b y m e c h a n i c a l s t i m u l a t i o n a n d b y i m m e r s i o n i n w a t e r : i t also

o c c u r s w h e n t h e c e n t i p e d e s a re a t t a c k e d b y a n t s a n d s imi la r

e n e m i e s . I n a u t u m n , a t t h e t i m e o f sexua l m a t u r i t y , c e n t i p e d e s

t e n d t o leave t h e i r b u r r o w s a n d for t h i s r e a s o n a n a b u n d a n c e o f

l u m i n o u s s p e c i m e n s i s f o u n d a t t h a t t i m e o f yea r . T h e l u m i n e s ­

c e n c e i s s i m p l y a p r o t e c t i v e r e a c t i o n a n d i s n o t r e l a t ed to sexual

b e h a v i o u r a s h a s s o m e t i m e s b e e n s u g g e s t e d , for t h e s e a n i m a l s a re

eyeless .

In s o u t h e r n Ca l i fo rn i a t h e l a rge g r e e n i s h Scolopendra heros i s

g rea t ly fea red , n o t o n l y o n a c c o u n t o f i ts p o i s o n o u s b i t e b u t b e c a u s e

i t also p r o d u c e s a r e d d i s h s t r eak w h e r e i t h a s c r a w l e d u p o n t h e

b o d y . L i k e m a n y o t h e r t rop ica l a n d s u b t r o p i c a l S c o l o p e n d r o ­

m o r p h a , i t m a k e s t i n y inc i s ions w i t h i ts n u m e r o u s feet . I n t h e m s e l v e s

t h e s e a re t r i f l ing, b u t w h e n a l a r m e d t h e c e n t i p e d e d r o p s i n t o each

inc i s ion s o m e k i n d o f v e n o m t h a t causes i n t e n s e i r r i t a t i on s o t h a t

t h e affected p a r t b e c o m e s in f l amed a n d t h e t w o r o w s o f p u n c t u r e s

s h o w w h i t e aga ins t t h e f l e s h . N o d o u b t t h e p o i s o n o u s a n d p h o s -

C E N T I P E D E S 5 5

p h o r e s c e n t f l u id s s e c r e t e d n e a r t h e coxae o f t h e legs a r e a d d i t i o n a l

p r o t e c t i v e dev ices t h a t r e n d e r c e n t i p e d e s d a n g e r o u s a n d d i s t a s t e ­

ful to t h e i r e n e m i e s .

W i t h r e g a r d to pa ra s i t e s , t h e c a r n i v o r o u s C h i l o p o d a afford a

s h a r p c o n t r a s t t o t h e v e g e t a r i a n D i p l o p o d a s ince few pa ras i t i c

N e m a t o d a h a v e b e e n r e c o r d e d f r o m t h e m a l t h o u g h t h e y a re s o m e ­

t i m e s in fes ted b y M e r m i t h i d a e . O t h e r p a r a s i t e s t h a t h a v e o c ­

cas iona l ly b e e n f o u n d i n c l u d e b a c t e r i a a n d fungi , P r o t o z o a a n d

N e m a t o m o r p h a ( R e m y , 1950) . T h o m p s o n (1939) d i s s e c t e d s o m e

300 s p e c i m e n s of Lithobius forficatus a n d f o u n d no p a r a s i t e o t h e r

t h a n t w o spec ies o f T a c h i n i d f l i e s . T h e ave rage p a r a s i t i s m w a s

on ly 7 . 5 % , a n d a l m o s t half t h e p a r a s i t i s e d c e n t i p e d e s c o n t a i n e d

m o r e t h a n o n e larva: i n m o s t cases b o t h p a r a s i t e l a rvae d i e d . O n

o n e occas ion h o w e v e r s o m e l a rvae o f t h e P r o c t o t r u p i d w a s p Crypto-

serphus ater w e r e seen i s su ing f r o m t h e b o d y of a Lithobius forfica­

tus w h i c h h a d s u c c u m b e d to t h e i r a t t acks ,

Reproduction and life cycle D e t a i l s o f r e p r o d u c t i o n i n c e n t i p e d e s h a v e n o t o f t en b e e n

closely s t u d i e d , b u t i t a p p e a r s t h a t m a n y spec ies s h o w a r e m a r k ­

ab le d e g r e e o f p a r e n t a l ca re . I n t e m p e r a t e r e g i o n s , egg - l ay ing

u s u a l l y t akes p l ace t h r o u g h o u t t h e s p r i n g a n d s u m m e r a l t h o u g h

c o p u l a t i o n m a y h a v e t a k e n p l ace a s l o n g be fo re a s t h e p r e v i o u s

a u t u m n . I n m a n y o f t h e t r o p i c a l spec ies t h e r e s e e m s t o b e n o

r e g u l a r a n n u a l b r e e d i n g season . T h e sexes a re v e r y s imi l a r a n d c a n

of ten b e d i s t i n g u i s h e d o n l y b y m i c r o s c o p i c e x a m i n a t i o n . I n t h e

L i t h o b i o m o r p h a a n d S c u t i g e r o m o r p h a t h e c l a sp ing o r g a n s a t t h e

p o s t e r i o r e n d o f t h e b o d y a re d i f ferent ly f o r m e d i n t h e t w o sexes ,

t h a t o f t h e female b e i n g u s e d for h o l d i n g t h e egg, t h a t o f t h e m a l e

p r e s u m a b l y for c l a sp ing t h e f emale . D e m a n g e (1956) h a s r e c e n t l y

s h o w n t h a t in Lithobius piceus t h e m a l e c e n t i p e d e d e p o s i t s a

s p e r m a t o p h o r e on a smal l w e b a n d t h i s i s a f t e r w a r d s t a k e n up

b y t h e female . T h e y o u n g o f all t h e o r d e r s leave t h e egg-she l l

w i t h t h e full n u m b e r o f legs w i t h t h e e x c e p t i o n o f t h e L i t h o b i o ­

m o r p h a a n d S c u t i g e r o m o r p h a , w h i c h h a t c h w i t h s even pa i r s o f

legs i n c l u d i n g t h e p o i s o n c laws .

T h e G e o p h i l o m o r p h a a n d C r y p t o p i d a e u sua l l y lay 1 5 t o 3 5

eggs in a loose m a s s w h i c h i s of ten m e r e l y left in t h e soil . In t h e

56 C E N T I P E D E S

G e o p h i l i d Pachymerium ferrugineum, w h i c h h a s a w i d e g e o g r a p h i ­

cal r a n g e in E u r o p e , As ia , Afr ica a n d A m e r i c a , fe r t i l i sa t ion t akes

p l ace i n t h e s p r i n g i n s o u t h e r n F i n l a n d , b u t m a y also o c c u r be fo re

h i b e r n a t i o n . T h e m a i n p e r i o d o f e g g - l a y i n g e x t e n d s f r o m t h e last

w e e k o f M a y t o t h e m i d d l e o f J u l y a n d t h e n u m b e r o f eggs p e r

b r o o d va r i e s b e t w e e n 2 0 a n d 5 5 , a n d i s u s u a l l y 2 5 t o 4 5 . W h e n

d i s t u r b e d d u r i n g b r o o d i n g , t h e f ema le e i t h e r ea t s h e r eggs a n d

y o u n g , o r else a b a n d o n s t h e m , b u t a d o l e s c e n t y o u n g d o n o t s e e m

t o b e a t t a c k e d . I f t h e re la t ive h u m i d i t y d r o p s o n l y 1 - 3 % b e l o w

s a t u r a t i o n , t h e eggs b e g i n t o s h r i n k , o w i n g t o des i cca t i on . I f t h e y

a r e s e p a r a t e d f rom t h e m o t h e r t h e y b e c o m e in fec ted w i t h fungi

w i t h i n a f ew days : i t i s p r o b a b l e t h a t w h e n m o u t h i n g a n d t o u c h i n g

t h e eggs t h e f ema le coa t s t h e m w i t h s o m e fung ic ida l s e c r e t i o n t h a t

p r e v e n t s s p o r e s f r o m d e v e l o p i n g . T h e m a x i m u m size o f t h e y o u n g

a t t h e e n d o f t h e i r first s u m m e r i s 1 6 m m : s o m e o f t h e i n d i v i d u a l s

b e c o m e m a t u r e d u r i n g t h e i r s e c o n d s u m m e r , o t h e r s n o t u n t i l

t h e i r t h i r d . A s t h e size o f t h e m a t u r e f emales va r i e s c o n s i d e r a b l y

t h e l a rges t i n d i v i d u a l s a re p r o b a b l y a t least four y e a r s o ld ( P a l m e n

a n d R a n t a l a , 1954) .

FIG . 14. Parental care in a Scolopendra.

In t h e L i t h o b i o m o r p h a t h e eggs a re laid i n d i v i d u a l l y i n t h e soil

af ter b e i n g c o v e r e d w i t h e a r t h b y t h e female , b u t i n t h e Sco lo ­

p e n d r o m o r p h a t h e y o u n g a re u s u a l l y g u a r d e d b y t h e i r m o t h e r

u n t i l t h e y a r e ab le to shif t for t h e m s e l v e s . O f t e n a r o u g h l y

h o l l o w e d - o u t cav i ty i s m a d e i n soft o r r o t t i n g w o o d b y t h e b o d y

o f t h e m o t h e r be fo re t h e eggs a re la id . T h e p a r e n t c e n t i p e d e t h e n

c u r l s herse l f a r o u n d h e r eggs a n d y o u n g s o t h a t a s s h e lies o n h e r

s ide t h e y a re e n c l o s e d in a ba ske t - l i ke f r a m e w o r k f o r m e d by t h e

C E N T I P E D E S 57

v e n t r a l su r face o f h e r b o d y a n d t h e i n w a r d l y p o i n t i n g legs . T h e

eggs o r y o u n g a re t h u s s a f e g u a r d e d f rom c o n t a c t w i t h t h e soil , a n d

t h e m o t h e r c e n t i p e d e m a i n t a i n s t h i s p o s i t i o n for severa l w e e k s

u n t i l t h e d e p a r t u r e o f t h e a d o l e s c e n t y o u n g ( C o r n w e l l , 1934;

L a w r e n c e , 1947, 1953*) . In t h e case of S . dalmatica i t a p p e a r s t h a t

t h e e a r t h o f t h e ' n e s t ' i s s t u c k t o g e t h e r by s o m e v i s c o u s fluid.

E a r l y w r i t e r s s u c h a s G e r v a i s a n d L u c a s b e l i e v e d t h a t S c o l o p e n ­

d r a s w e r e o v o v i v i p a r o u s b u t t h i s e r r o r w a s l a te r c o r r e c t e d b y

Si lves t r i w h o s u g g e s t e d t h a t t h e m i s t a k e a rose a s a n e r r o n e o u s

i n f e r ence f r o m t h e w a y in w h i c h S . cingulata a s s i d u o u s l y g u a r d s

i ts eggs a n d y o u n g ones .

L i t t l e exac t k n o w l e d g e o f t h e b r e e d i n g h a b i t s o f S c o l o p e n d r o -

m o r p h c e n t i p e d e s i s ava i lab le , a n d t h i s i s p a r t l y d u e t o t h e fact

t h a t i f t h e i n c u b a t i n g m o t h e r s a re d i s t u r b e d t h e y r eac t e i t h e r b y

d e v o u r i n g t h e eggs a n d e m b r y o s o r b y d e s e r t i n g t h e i r b r o o d w h i c h

i s t h e n a t t a c k e d b y fungi ( L a w r e n c e , 1947) . T h u s w h e n a s p e c i m e n

o f S . angulata w a s s e n t w i t h h e r b r o o d f r o m T r i n i d a d to t h e L o n ­

d o n Z o o i n 1894, o n a r r iva l o n l y o n e y o u n g a n d t h e a d u l t w e r e

found , a n d b o t h o f t h e m w e r e d e a d . P a r e n t c e n t i p e d e s feed q u i t e

casua l ly o n t h e i r y o u n g a n d , a t t i m e s , e v e n g r e e d i l y w h e n k e p t

w i t h o u t food.

U n l i k e t h a t o f t h e D i p l o p o d a t h e d e v e l o p m e n t o f c e n t i p e d e s

p r o c e e d s m a i n l y b y e p i m o r p h o s i s . I t i s n o t k n o w n exac t ly h o w

m a n y m o u l t s a re p a s s e d t h r o u g h b y t h e y o u n g c e n t i p e d e s after

l eav ing t h e i r m o t h e r , b u t t h e r e m u s t b e a c o n s i d e r a b l e n u m b e r .

Af te r l eav ing t h e b r o o d c h a m b e r g r o w t h i s c o n t i n u o u s a n d g r a d u a l

a n d i s chiefly c o n c e r n e d w i t h i nc r ea se i n size a n d s t r e n g t h e n i n g

o f t h e c h i t i n o u s e p i d e r m a l s t r u c t u r e s , espec ia l ly t h e m o u t h p a r t s .

T h e L i t h o b i o m o r p h a a n d S c u t i g e r o m o r p h a a t f i r s t c a r r y t h e i r

eggs , w h i c h a re la id s ingly , i n t h e c l a spe r s s i t u a t e d on t h e gen i ta l

s o m i t e , a n d d e v e l o p m e n t i s in i t ia l ly a n a m o r p h i c a n d la te r ep i -

m o r p h i c . T h e f i r s t s e v e n - l e g g e d s t age o f t h e L i t h o b i o m o r p h a las ts

on ly a few h o u r s , af ter w h i c h t h e r e a re f o u r ecdyses a t t h e last o f

w h i c h t h e y o u n g c e n t i p e d e h a s t w e l v e p a i r s o f legs . T h i s c o m ­

ple tes t h e a n a m o r p h i c s tage . T h e e p i m o r p h i c p h a s e cons i s t s o f four

s tages , in all o f w h i c h t h e r e a re f i f t een pa i r s o f legs , a n d t h e sexual ly

m a t u r e a d u l t e m e r g e s f r o m t h e last o n e . T h e size o f Lithobius

forficatus after l eav ing t h e egg m a y inc rease f rom 3 to 24 mm

58 C E N T I P E D E S

a n d t h e n u m b e r o f a n t e n n a l s e g m e n t s a n d t e e t h o n t h e max i l l i -

p e d e s also inc reases . T h e t i m e t a k e n t o c o m p l e t e t h e v a r i o u s

s t ages differs c o n s i d e r a b l y , t h e s e c o n d b e i n g 10 to 14 days , t h e

t h i r d 8 0 t o 8 4 d a y s . T h e w h o l e d e v e l o p m e n t f r o m egg t o m a t u r e

c e n t i p e d e r e q u i r e s a b o u t t h r e e yea r s , s o t h a t la rva l a n d i m m a t u r e

c e n t i p e d e s a re u s u a l l y f o u n d t o g e t h e r w i t h sexua l ly m a t u r e f o r m s .

In Scutigera coleoptrata t h e l a rvae h a t c h w i t h fou r p a i r s of legs

a n d t h e r e a r e five m o r e larval s t ages w i t h 5 , 7 , 9 , 11 a n d 13 pa i r s

o f legs r e spec t ive ly . T h i s a n a m o r p h i c s t age i s s u c c e e d e d by an

e p i m o r p h i c o n e o f fou r a d o l e s c e n t s t ages each w i t h fifteen p a i r s o f

legs . T h e first t h r e e larval s t ages r e q u i r e a b o u t t h r e e w e e k s for

t h e i r c o m p l e t i o n . C e n t i p e d e s a re l o n g - l i v e d c r e a t u r e s a n d spec i ­

m e n s of Lithobius forficatus h a v e b e e n k n o w n to l ive for up to 5 to 6

y e a r s (Verhoeff, 1937a, b ) .

B I B L I O G R A P H Y

Identification

ATTEMS , C. G. (1926) Progoneata, Chilopoda in KUKENTHAL , W. &

KRUMBACH , T . Handbuch der Zoologie, Berlin, 4 , (1-4), 1-402. (1928) T h e Myriapoda of South Africa. Ann. S. Afr. Mus. 2 6 ,

1-431. (1929) Myriapoda, Geophi lomorpha. Das Tierreich, 5 2 , 1-388 (1930) Chilopoda, Scolopendromorpha. Ibid., 5 4 , 1-308.

BLOWER, G. (1955) Yorkshire centipedes. Naturalist, 1 9 5 5 , 1 3 7 - 4 6 . BRADE-BIRKS , S. G. (1939) Notes on Myriapoda X X X V I . Sources for

description and illustration of the British fauna. J. S-E. Agric. Coll. Wye, No . 44, 156-79.

BROLEMANN , W. H. (1932) Chilopodes. Faune de France, 2 5 , 1 - 4 0 5 . CHAMBERLIN , R. V. (1920) T h e Myriapoda of the Australian region.

Bull. Mus. Comp. Zool., 6 4 , 1 - 2 6 9 . CLOUDSLEY-THOMPSON , J . L. (1952) Collecting centipedes and milli­

pedes. Bull. Amat. Ent. Soc, 1 1 , 5-8 . LATZEL, R. (1880) Die Myriopoden der Oesterreichish-Ungarischen

Monarchic 1. Die Chilopoden. Wien. VERHOEFF, K. W. (1902-28) Chilopoda in H. G. BRONN'S Klass. Ordn.

Tierreichs, 5, II (1), 1-725. W A N G , Y. M. (1951) T h e Myriapoda of the Phil ippine Islands. Serica 1,

1-80.

Biology

AUERBACH, S. I. (1951) T h e centipedes of the Chicago area with special reference to their ecology. Ecol. Monogr., 2 1 , 97-124.

C E N T I P E D E S 59

BAUER, K. (1955) Sinnesokologische Untersuchungen an Lithobius for­ficatus. Zool. Jahrb. (Zool.), 6 5 , 267-300.

BONNELL , B. (1930) Geophil id centipedes from the bed of the Cooum River (Madras) . J. Asiat. Soc. Bengal, (N.S.) , 2 5 , 181-4.

BUCHERL, W. (1946) Acao do veneno dos Escolopendromorfos do Brasil sobre alguns animais de laboratorio. Mem. Inst. Butanan. S. Paulo, 1 9 , 181-97.

CLOUDSLEY-THOMPSON, J. L. (1945) Behaviour of the common centipede, Lithobius forficatus. Nature, Lond., 1 5 6 , 537-8.

(1948) Hydroschendyla submarina (Grube) in Yorkshire: with an historical review of the marine Myriapoda. Naturalist, 1 9 4 8 , 149-52.

(1949) A note on the Myriapods and Arachnids of nor thern Italy. Ent.Mon. Mag., 8 5 , 285.

(1951) Supplementary notes on Myriapoda. Naturalist, 1 9 5 1 , 16-17.

(1952a) T h e biology of centipedes and millipedes. Discovery, 1 3 , 18-21 .

(1952b) T h e behaviour of centipedes and mil l ipedes—1. Responses to environmental stimuli. Ann. Mag. Nat. Hist., (12), 5, 417-34.

(1954) T h e ecological significance of diurnal rhythms in terrestrial Arthropoda. Sci. Prog., 4 2 , 46-52 .

(1955) Some aspects of the biology of centipedes and scorpions.

Naturalist, 1 9 5 5 , 1 4 7 - 5 3 .

CORNWELL , W. S. (1934) Notes on the egg-laying and nesting habits of certain species of Nor th Carolina myriapods and various phases of their

life histories. J. Elisha Mitchell Sci. Soc, 1 4 9 , 289-91 .

DEMANGE , J . -M. (1956) Contr ibut ion a l 'etude de la biologie, en cap-tivite, de Lithobius piceus gracilitarsis Brol. (Myriapode-Chilpode) . Bull. Mus. Hist. nat. Paris, (2), 2 8 , 388-93.

JACKSON, A. R. (1914) A preliminary list of the Myriapods of the Chester district. Lanes. Nat., 6, 450-8 .

LAWRENCE, R. F. (1947) Some observations on the post-embryonic devel­opment of the Natal forest centipede Cormocephalus midtispinus (Kraep.) . Ann. Natal. Mus., 1 1 , 139-56.

LAWRENCE , T. C. (1934) Notes on the feeding habits of Scolopendra sub­spinipes Leach (Myriapoda). Proc. Hawaii Ent. Soc, 8, 497-8 .

M A N T O N , S. M. (1952) T h e evolution of Ar thropodan locomotory mechanisms—Part 3. T h e locomotion of the Chilopoda and Pauropoda. J. Linn. Soc. (Zool), 4 2 , 1 1 8 - 6 7 .

(1953) Locomotory habits and the evolution of the larger Ar thro­podan groups in Evolution. Symp. Soc. Exp. Biol, 7, 339-76.

PALMEN , E. (1949) T h e Chilopoda of Eastern Fennoscandia. Ann. Soc. Zool. Fenn. Vanamo, 1 3 , (4), 1-45.

60 C E N T I P E D E S

PALMEN, E. and RANTALA , M. (1954) On the life-history and ecology of Pachymeriurn ferrugineum (C. L. Koch) (Chilopoda, Geophilidae). Ibid., 1 6 , (3), 1-44.

REMINGTON , C. L. (1950) T h e bite and habits of a giant centipede (Scolopendra subspinipes) in the Philippine Is. Amer. J. Trop. Med., 3 0 , 453-5 .

REMY , P. A. (1950) On the enemies of Myriapods. Naturalist, 1 9 5 0 , 1 0 3 - 8 . SCHUBART, O. (1955) Tausendfiisser als Nahrung im Tierreich. Nach.

Nat. Mus. Aschaffenburg, 4 9 , 1 - 2 9 . SHIPLEY , A. E. (1914) Pseudoparasit ism. Parasitology, 6 , 351-2. SINCLAIR , F. G. (1895) Myriapods: in HARMER, S. F. and SHIPLEY , A. E.

The Cambridge Natural History, 5, 29-80. T U R K , F . A. (1951) Myriapodological Notes, I I I . T h e iatro-zoology,

biology and systematics of some tropical 'Myr iapods ' . Ann. Mag. Nat. Hist., (12), 4, 35-48.

VERHOEFF, K. W. (1937a) Zur Kenntnis der Li thobiiden. Arch. Natur-gesch. (N.F. ) , 6, 171-257.

(1937b) Zur Biologie der Scutigera coleoptrata, und uber die j i in-geren Larvenstadien. Z. wiss. Zool., 1 5 0 , 262-82.

C H A P T E R I V

O T H E R ' M Y R I A P O D S '

I T HAS a l r e a d y b e e n p o i n t e d o u t t h a t t h e D i p l o p o d a a n d C h i l o p o d a

w e r e f o r m e r l y a s soc ia t ed w i t h t h e less fami l ia r P a u r o p o d a a n d

S y m p h y l a a n d r e g a r d e d a s o r d e r s o f a c lass ' M y r i a p o d a ' , c o m p o s e d

o f A r t h r o p o d a p o s s e s s i n g b o d i e s f o r m e d o f m a n y s imi l a r s o m i t e s

e a c h p r o v i d e d w i t h a t leas t o n e p a i r o f legs . I t i s n o w rea l i sed ,

h o w e v e r , t h a t t h e ' M y r i a p o d a ' i n c l u d e d a n u n n a t u r a l a s s e m b l a g e

o f super f ic ia l ly s imi l a r b u t u n r e l a t e d g r o u p s w h i c h a r e n o w c o n ­

s i d e r e d a s s e p a r a t e c lasses , h a v i n g n o m o r e r e l a t i o n s h i p t o o n e

FIG. 1 5 . Pauropoda and Symphyla. Left, Scutigerella sp. (body length 4 m m ) ; right, Pauropus sp. (body length 1 .5 mm.)

a n o t h e r t h a n t o t h e C r u s t a c e a , I n s e c t a a n d A r a c h n i d a . I n d e e d ,

t h e r e i s s t r o n g r e a s o n t o s u s p e c t t h a t t h e m o d e r n S y m p h y l a a re

c losely a l l ied to t h e e x t i n c t a n c e s t o r s o f insec t s .

Class PAUROPODA

T h e P a u r o p o d a r e s e m b l e t h e D i p l o p o d a i n h a v i n g t h e orifice o f

t h e r e p r o d u c t i v e o r g a n s o n t h e fore p a r t o f t h e b o d y , t h a t i s t o say

i n t h e t h i r d s o m i t e b e h i n d t h e h e a d , a n d i n t h e fu s ion o f t h e t w o

61

62 O T H E R ' M Y R I A P O D S '

ad jo in ing t e rg i t e s to r e p r e s e n t a s ingle s o m i t e ; b u t differ f rom

t h e m in t h e s t r u c t u r e o f t h e t w o pa i r s o f j a w s , i n h a v i n g t h e e n d o f

t h e a n t e n n a e b r a n c h e d a n d i n t h e posses s ion o f o n l y t w e l v e s o m i t e s

a n d t e n pa i r s o f l i m b s of w h i c h n i n e h a v e a l o c o m o t o r y func t ion ,

t h e first pa i r b e i n g r e d u c e d t o m e r e b u d s . I n a d d i t i o n t h e legs a re

ve ry w i d e l y s p a c e d , t r a c h e a e a re a b s e n t a n d five pa i r s o f l o n g tac t i le

b r i s t l e s a re a t t a c h e d t o t h e s ides o f t h e b o d y .

P a u r o p o d s a re m i n u t e A r t h r o p o d a m e a s u r i n g o n l y a b o u t o n e -

t w e n t i e t h o f a n i n c h i n l e n g t h . T h e first w a s d i s c o v e r e d b y L u b ­

b o c k i n 1886. T h e y h a v e s ince b e e n f o u n d i n E u r o p e , As ia a n d

A m e r i c a w h e r e t h e y i n h a b i t d a m p s i t u a t i o n s b e n e a t h d e c a y i n g

leaves , logs a n d so on . In s o m e (Pauropus s p p . ) w h i c h a re m o r e

ac t ive i n t h e i r m o v e m e n t s , t h e b o d y i s n a r r o w , c o m p a r e d w i t h its

l e n g t h ; b u t in t h e m o r e s lugg i sh f o r m s (Eurypauropus s p p . ) i t i s

v e r y w i d e , i ts s ides a n d f ron t b e i n g p r o d u c e d so a s t o concea l t h e

legs a n d h e a d . A t t h e p r e s e n t t i m e six fami l ies a re k n o w n t o sc ience ,

b u t l i t t le i n f o r m a t i o n i s ava i lab le a b o u t t h e i r eco logy a n d d i s t r i b u ­

t i on o t h e r t h a n t h a t t h e y a re be l i eved t o b e g e n e r a l l y d i s t r i b u t e d

e x c e p t i n t h e a rc t i c , a n t a r c t i c a n d d e s e r t r e g i o n s o f t h e w o r l d .

I n d e e d , o w i n g t o t h e i r c o n c e a l e d h a b i t s t h e y a r e s o m e t i m e s b e ­

l ieved t o b e r a r e , b u t S t a r l i n g (1944) e s t i m a t e d a n a n n u a l ave rage

of 1,672,704 p e r ac re ( to a d e p t h of 5 i nches ) in oak s t a n d s on clay

soil a n d 2 ,178 ,000 i n p i n e s t a n d s o n s a n d y l o a m i n t h e D u k e

F o r e s t , N o r t h C a r o l i n a . F i v e t i m e s a s m a n y P a u r o p o d s w e r e f o u n d

in oak h u m u s on clay soil a s i n t h e s a m e level u n d e r p i n e s t a n d s

o n s a n d y soil , a n d h i s o b s e r v a t i o n s s u g g e s t e d t h a t m o i s t u r e a n d

t e m p e r a t u r e a re t h e t w o m a i n fac tors t h a t affect t h e d i s t r i b u t i o n o f

t he se a n i m a l s . T h e g r e a t e s t n u m b e r w a s co l l ec ted f ro m s a n d y soil

w h e n t h e m o i s t u r e p e r c e n t a g e o f t h e o v e n - d r y w e i g h t w a s 1 1 - 2 0 % .

I n clay soil P a u r o p o d s a p p e a r e d t o p r e f e r 2 1 - 3 0 % o f m o i s t u r e .

T h e o p t i m u m r a n g e o f t e m p e r a t u r e b a s e d o n ac t iv i ty a n d m o r t a l i t y

r a t e w h e n P a u r o p o d a w e r e p l a c e d i n c o n s t a n t t e m p e r a t u r e c a b i n e t s

w a s f o u n d t o b e 1 6 - 2 0 ° C : t h e o p t i m u m , b a s e d o n field o b s e r v a ­

t i ons , 1 7 - 2 3 ° C . S u m m e r a p p e a r s t o b e t h e m o s t f a v o u r a b l e season

for d e v e l o p m e n t a n d ac t iv i ty , a n d eggs w e r e o b t a i n e d i n J u n e a n d

J u l y . A c o r r e l a t i o n a p p e a r s t o exis t b e t w e e n o p t i m u m t e m p e r a t u r e

for fungal g r o w t h a n d a h i g h i n c i d e n c e in P a u r o p o d d i s t r i b u t i o n

w h i c h m a y b e r e l a t ed t o t h e i r f eed ing h a b i t s .

O T H E R ' M Y R I A P O D S ' 63

L i t t l e i s k n o w n c o n c e r n i n g t h e food o f P a u r o p o d s . S p e c u l a t i o n s

h a v e b e e n m a d e t h a t t h e s lowly m o v i n g spec i e s feed o n d e c a y i n g

p l a n t a n d a n i m a l m a t e r i a l , w h e r e a s t h e m o r e agile t y p e s m a y c o n ­

s u m e m i c r o s c o p i c a n i m a l s ( L a t z e l 1884) . A spec ies of Pauropus

h a s b e e n seen f e e d i n g o n d e a d f l i e s f l o a t i n g i n a p u d d l e . N o d o u b t

m o s t spec ies feed e i t h e r o n f resh sap o r t h e s e m i - l i q u i d p r o d u c t s

o f d e c a y i n g w o o d . H a r r i s o n (1914) o b s e r v e d P a u r o p o d s b r o w s i n g

' on p a r t i c l e s o f soil i n w h i c h n o t h i n g in t h e w a y o f food c o u l d be

d i s t i n g u i s h e d ' , a n d c o n c l u d e d t h a t t h e y w e r e h u m u s - f e e d e r s , w h i l e

S t a r l i n g (1944) o b s e r v e d t h a t P. carolinensis a te t h e m y c e l i a of

m o u l d s g r o w i n g o n d e c a y i n g leaf p a r t i c l e s b u t d i d n o t a p p e a r t o

feed o n d e a d a n i m a l m a t e r i a l s u c h a s C o l l e m b o l a , D i p t e r a a n d

o t h e r P a u r o p o d a t h a t w e r e p l a c e d a t t h e i r d i sposa l .

A c c o r d i n g t o T i e g s (1947) , P a u r o p o d a a re p r e y e d u p o n b y ca r ­

n i v o r o u s m i t e s a n d f a l s e - s c o r p i o n s w h i c h f r e q u e n t l y t ake tol l o f

l a rvae a n d e v e n o f a d u l t s . N e m a t o d e s h a v e n e v e r b e e n f o u n d i n

P a u r o p o d a a n d n o t h i n g else a p p e a r s t o b e k n o w n o f t h e i r e n e m i e s .

T h e eggs a r e d e p o s i t e d s ing ly o r i n c l u m p s i n s e c l u d e d c rev ices

o f d a m p a n d d e c o m p o s i n g v e g e t a t i o n . L i k e D i p l o p o d a , t h e y o u n g

o f P a u r o p o d s h a t c h w i t h t h r e e p a i r s o f legs , af ter w h i c h t h e y p a s s

t h r o u g h f o u r success ive la rva l s t ages b e f o r e a t t a i n i n g t h e n i n e -

legged a d u l t c o n d i t i o n . T h e n e w l y h a t c h e d Pauropus huxleyi i s

o n e s e v e n t y - s e c o n d o f an i n c h i n l e n g t h a n d h a s s ix legs , t h r e e

la rge do r sa l p l a t e s a n d t w o la te ra l h a i r s . D e v e l o p m e n t p r o c e e d s

s lowly a n d r e s e m b l e s t h a t o f t h e D i p l o p o d a i n b e i n g a n a m o r p h i c . I n

P. silvaticus t h e egg h a t c h e s af ter 1 2 - 1 3 days , r u p t u r e b e i n g a s ­

s i s ted by s t o u t c u t t i n g se tae o f t h e e m b r y o l o g i c a l cu t i c l e . A

q u i e s c e n t ' p u p o i d ' s t age w i t h t w o pa i r s o f r u d i m e n t a r y l i m b s

e m e r g e s w h i c h las ts on ly 3 - 4 d a y s a n d i s fo l lowed b y four s u c ­

cess ive larval s t ages w h i c h h a v e 3 , 5 , 6 a n d 8 pa i r s of legs a n d r e ­

q u i r e a p p r o x i m a t e l y 2 , 4 , 5 a n d 3 w e e k s r e spec t i ve ly to d e v e l o p .

T h e p e r i o d f r o m egg t o a d u l t i n t h i s spec ies i s t h u s a b o u t f o u r t e e n

w e e k s i n d u r a t i o n , a n d t h e a d u l t s d o n o t m o u l t aga in ( T i e g s ,

1947) .

T h e life h i s to r i e s of Pauropus carolinensis, P. amicus a n d Eury-

pauropus spinosus a p p e a r to be s imi la r . T h e eggs a re la id in g r o u p s

of f r o m 3 to 12, e ach egg b e i n g pe r fec t ly sphe r i ca l , p e a r l y w h i t e

a n d 0 .17 m m i n d i a m e t e r . T h e o u t e r m e m b r a n e , w h i c h i s o p a q u e .

64 O T H E R ' M Y R I A P O D S '

i s c o v e r e d w i t h m i n u t e p u s t u l a t i o n s . O n t h e twe l f th d a y t h e o u t e r

m e m b r a n e b r e a k s a n d t h e e m b r y o pa r t i a l ly e m e r g e s : i ts a n t e r i o r

e n d b e c o m e s free w h i l e t h e p o s t e r i o r e n d i s sti l l e n c l o s e d i n t h e

m e m b r a n e . T h e e m b r y o i s c o v e r e d b y o n e e m b r y o n i c m e m b r a n e

w h i c h b e a r s o u t g r o w t h s t h a t cove r t h e a n t e n n a e a n d t h r e e pa i r s

o f legs a re v is ib le i n s ide . T h e e m b r y o r e m a i n s m o t i o n l e s s i n t h i s

c o n d i t i o n for t h r e e d a y s a n d t h e n , b y dorsa l s p l i t t i n g o f t h e s e c o n d

cu t ic le , i s sues o u t a s a n ac t ive ly m o v i n g h e x a p o d larva w i t h t w o

tac t i l e se tae ( H a r r i s o n , 1914) . T h e r e m a i n i n g i n s t a r s h a v e 5 , 6 , 8

a n d 9 legs r e spec t ive ly a n d t h e n u m b e r of t ac t i l e b r i s t l e s a re 3 , 4 , 4

a n d 5 . Before m o u l t i n g t h e a n i m a l s b e c o m e s o m e w h a t r ig id b u t

r e m a i n u p r i g h t t h r o u g h o u t t h e p r o c e s s . T h e h e a d a n d a n t e n n a e

a re b e n t v e n t r a l l y a n d w h e n t h e p r o c e s s , w h i c h t akes o n l y a b o u t

twen ty - f ive m i n u t e s , i s a l m o s t c o m p l e t e , v i g o r o u s p r o p u l s i o n s ,

w h i c h f i r s t free t h e h e a d , e n a b l e t h e w h i t e , m o i s t a n d w e a k a n i m a l

to d r a g itself f r o m its o ld cu t ic le .

Class SYMPHYLA

T h e r e p r o d u c t i v e o r g a n s o f t h e S y m p h y l a , l ike t h o s e o f t h e

P a u r o p o d a , o p e n u p o n t h e t h i r d s o m i t e b e h i n d t h e h e a d , b u t

o t h e r w i s e t h e t w o c lasses a re v e r y d i s s imi l a r . I n t h e S y m p h y l a t h e

a n t e n n a e a re v e r y l o n g a n d m a n y j o i n t e d , t h e r e a r e f o u r pa i r s o f

p e c u l i a r l y m o d i f i e d j a w s a n d t h e h e a d b e a r s a p a i r o f t r a c h e a l

sp i r ac l e s . T h e r e a re t w e l v e pa i r s o f w a l k i n g legs , b u t t h e n u m b e r

o f t e rga l p l a t e s , n a m e l y f i f t een , t h e f i r s t b e i n g v e r y smal l , i s g r e a t e r

t h a n t h e n u m b e r o f legs a n d n o t less a s i n t h e D i p l o p o d a a n d

P a u r o p o d a . T h e basa l s e g m e n t s o f t h e legs o f t h e t h i r d t o twe l f th

l e g - b e a r i n g s e g m e n t s a r e p r o v i d e d w i t h a p r o t r u s i b l e sac t h o u g h t

t o h a v e a r e s p i r a t o r y f u n c t i o n , w h e r e a s in P a u r o p o d s t h e r e i s b u t

a s ingle p a i r on t h e f loor of t h e c o l l u m or f i r s t p o s t - c e p h a l i c seg­

m e n t . W i t h t h e las t s o m i t e a r t i c u l a t e s a pa i r o f ta i l - l ike p r o c e s s e s

u p o n w h i c h s p i n n i n g g l a n d s o p e n , a n d j u s t i n f ron t o f t h e m i s a

pap i l la c a r r y i n g a t ac t i l e ha i r . S y m p h y l a a re sma l l , pa l l i d a r t h r o ­

p o d s r e s e m b l i n g t i ny c e n t i p e d e s i n a p p e a r a n c e a n d ac t iv i ty , t h a t

l ive i n d a m p p l aces u n d e r s t o n e s , d e a d leaves , e t c . T w o famil ies

a re k n o w n , S c u t i g e r e l l i d a e a n d S c o l o p e n d r e l l i d a e , b o t h o f w h i c h

a re r e p r e s e n t e d i n t h e B r i t i s h f auna .

T h e class S y m p h y l a h a s h e l d t h e i n t e r e s t o f m a n y n a t u r a l i s t s

O T H E R ' M Y R I A P O D S ' 65

s ince a b o u t t h e m i d d l e o f t h e e i g h t e e n t h c e n t u r y a n d n u m e r o u s

a r t ic les h a v e b e e n p u b l i s h e d w h i c h dea l w i t h i ts m e m b e r s . N e a r l y

all o f t h e s e a r e c o n c e r n e d p r i n c i p a l l y w i t h t h e t a x o n o m y , a n a t o m y

a n d p h y l o g e n e t i c r e l a t i o n s h i p s o f t h e g r o u p w h i l e a few of t h e

l a te r p a p e r s c o n s i d e r i t s ecologica l a n d e c o n o m i c a s p e c t s . T h e

f i rs t spec ies w a s d e s c r i b e d in 1763 as Scolopendra nivea by S c o p u l i ,

w h o e v i d e n t l y l i t t le r ea l i sed t h a t t h e o r g a n i s m p o s s e s s e d c h a r a c ­

t e r s s o d i s t i n c t f r o m t h o s e o f t h e C h i l o p o d a t h a t e v e n t u a l l y i t

w o u l d be p l a c e d i n a c lass by itself. I n 1839 G e r v a i s n a m e d t h e

s e c o n d spec ies , w h i c h he co l l ec t ed n e a r P a r i s , Scolopendrella nota-

cantha a n d i n 1847 h e p l a c e d t h i s g e n u s i n t h e G e o p h i l i d a e : b u t

M e n g e i n 1851 s u g g e s t e d t h a t Scolopendrella s h o u l d be c o n s i d e r e d

a s t r a n s i t i o n a l b e t w e e n t h e S c o l o p e n d r i d a e a n d t h e L e p i s m i d a e !

T h e b e s t - k n o w n spec ies , Scutigerella immaculata, o c c u r s on b o t h

s ides o f t h e A t l a n t i c , a n d in A m e r i c a h a s r i s e n to t h e r a n k o f a

s e r ious e c o n o m i c p e s t ( M i c h e l b a c h e r , 1938) . S i n c e 1920 , n u m e r o u s

i m p o r t a n t p a p e r s h a v e b e e n p u b l i s h e d o n t h i s sub j ec t .

S. immaculata i s w i d e l y d i s t r i b u t e d in t h e N o r t h e r n H e m i s p h e r e

b u t i s k n o w n to o c c u r o n l y in a s ing le local i ty , B u e n o s A i r e s ,

s o u t h o f t h e e q u a t o r . I t d o e s n o t a p p e a r t o b e w i d e s p r e a d i n Afr ica

b u t h a s b e e n r e p o r t e d f r o m severa l local i t ies i n A lge r i a a n d T u n i s i a ,

a n d h a s b e e n f o u n d i n t h e A l p s a t a h e i g h t o f 9 ,842 ft. T h e r e a r e n o

def in i te r e c o r d s o f i t f r o m As ia o r A u s t r a l i a . N o t h i n g c a n be sa id o f

i ts s o u t h e r n l im i t s , b u t i t p r o b a b l y e x t e n d s wel l i n t o t h e t r o p i c s

s ince t h e c l i m a t e o f t h e H a w a i i a n I s l a n d s s e e m s wel l s u i t e d t o i ts

d e v e l o p m e n t . O t h e r spec ies o f S y m p h y l a a r e f o u n d w i d e s p r e a d

t h r o u g h o u t t h e w o r l d : t h e i r n o r t h e r n d i s t r i b u t i o n s e e m s t o b e

l i m i t e d b y e x p e c t e d m i n i m u m t e m p e r a t u r e s o f a b o u t 1 5 ° F - .

U n d e r e x p e r i m e n t a l c o n d i t i o n s Scutigerella immaculata c a n w i t h ­

s t a n d a t e m p e r a t u r e o f 20° C for l o n g p e r i o d s b u t s e e m s u n a b l e to

s u r v i v e f reez ing for a n y l e n g t h o f t i m e i f p r e v i o u s l y h e l d a t r o o m

t e m p e r a t u r e . I f k e p t a t 4 .5° C first h o w e v e r i t m a y w i t h s t a n d 0 ° C

for m o n t h s ( M i c h e l b a c h e r , 1938) .

M a n y spec ies a r e wel l d i s t r i b u t e d i n t h e t r o p i c s a n d a l t h o u g h

n o n e h a s y e t b e e n r e c o r d e d f r o m C h i n a o r S ibe r i a , t h e y p r o b a b l y

o c c u r t h e r e t oo .

S y m p h y l a a r e nega t ive ly p h o t o t a c t i c b u t t h e r e s p o n s e i s n o t

v e r y s t r o n g l y d e v e l o p e d for t h e y a p p e a r t o c o m e t o t h e su r face o f E S.S.C.M.

6 6 O T H E R ' M Y R I A P O D S '

t h e soil t o feed w i t h o u t h e s i t a t i o n a t a n y h o u r o f t h e day . I t i s n o t

u n c o m m o n t o f i n d t h e m ly ing pe r fec t ly m o t i o n l e s s o n t h e sur face

o f t h e g r o u n d w h e r e t h e y a re fully e x p o s e d t o t h e s u n l i g h t . W h e n

i n m o t i o n t h e a n t e n n a e a r e k e p t c o n s t a n t l y m o v i n g , b u t w h i l e

f eed ing t h e y a re , a s a r u l e , h e l d b a c k w a r d s . S y m p h y l a can r u n

v e r y r a p i d l y w h e n d i s t u r b e d a n d q u i c k l y r e t r e a t i n t o t h e soil . I f

t h e i r a n t e n n a e a re t o u c h e d w i t h a c a m e l ' s h a i r b r u s h o r o t h e r

i n s t r u m e n t t h e y r e v e r s e t h e i r c o u r s e w i t h l i g h t n i n g s p e e d . I n

t u r n i n g r o u n d t h e p o s t e r i o r e n d o f t h e b o d y i s h e l d st i l l a n d ac ts

a s a p ivo t (Verhoeff, 1934) . T h e v e r y y o u n g , h o w e v e r , n e v e r c o m e

t o t h e su r face o f t h e soil a n d a p p a r e n t l y d o n o t feed u n t i l t h e y h a v e

m o u l t e d a s e c o n d t i m e . S y m p h y l a a r e n o t r e s t r i c t e d t o a n y p a r ­

t i cu l a r level o f t h e soil , a n d m a y be f o u n d f r o m t h e su r face to a

d e p t h o f fou r feet o r m o r e . M o i s t u r e i s t h e m o s t i m p o r t a n t fac tor

d e t e r m i n i n g t h e i r ve r t i ca l d i s t r i b u t i o n , b u t t e m p e r a t u r e , soil t e x ­

t u r e , s t r u c t u r e a n d v e g e t a t i o n also in f luence t h e m .

S y m p h y l a a p p e a r t o b e v e g e t a r i a n s a n d t o p r e f e r d e c a y i n g a n d

s u c c u l e n t m a t e r i a l s a l t h o u g h t h e y wil l feed o n m a n y k i n d s o f

l ower p l a n t life. N e w p o r t i n 1845 t h o u g h t t h a t t h e y m u s t b e ca r ­

n i v o r o u s , p r e y i n g p e r h a p s o n t h e m i c r o s c o p i c P o d u r i d a e t o b e

f o u n d i n t h e s a m e p l aces , b u t D u b o s c q , s o m e y e a r s la te r , n o t e d t h e

a b s e n c e of a p o i s o n g l a n d in Scolopendrella. Scutigerella immaculata

n o r m a l l y feeds u p o n d e c a y i n g v e g e t a b l e m a t t e r b u t m a y a t t ack

l iv ing p l a n t s , of ten d o i n g v e r y m u c h d a m a g e t o f i e l d a n d g lass ­

h o u s e c r o p s s u c h a s y o u n g s e e d l i n g s , a s p a r a g u s , l i m a b e a n s , peas ,

t o m a t o e s a n d c u l t i v a t e d f l o w e r s . I t h a s con ica l t a s t e sens i l lae a t t h e

a p e x o f t h e s e c o n d m a x i l l a e ( c o n s i d e r e d t o b e h o m o l o g o u s w i t h

t h e g n a t h o c h i l a r i u m o f D i p l o p o d a ) , b u t t h e s e a r e s i m p l e r i n s t r u c ­

t u r e a n d c o n s i d e r a b l y f ewer i n n u m b e r t h a n t h o s e o f m i l l i p e d e s .

P o p u l a t i o n s t u d i e s i n t h e f i e l d a n d g r e e n h o u s e s s h o w t h a t S y m ­

p h y l a m a y b e p r e s e n t i n l a rge n u m b e r s , s o m e t i m e s a s m a n y a s 2 2

mi l l i on p e r ac re o u t o f d o o r s , a n d 90 m i l l i o n p e r ac re i n g lass ­

h o u s e s . S u i t a b l e m e t h o d s for c h e c k i n g d a m a g e i n g r e e n h o u s e s

cons i s t o f u s i n g r a i sed b e n c h e s , s t e a m t r e a t m e n t , i n sec t i c ides a n d

soil f u m i g a t i o n ( M i c h e l b a c h e r , 1938) .

As i n t h e case o f t h e P a u r o p o d a , l i t t le i s k n o w n o f t h e p r e d a t o r s

o f t h e s e c r e a t u r e s , b u t C h i l o p o d s a re sa id t o b e a m o n g t h e m o s t

i m p o r t a n t o f t h e i r n a t u r a l e n e m i e s . A la rge G a m a s i d m i t e h a s b e e n

O T H E R ' M Y R I A P O D S ' 6 7

o b s e r v e d to seize a S y m p h y l i d w i t h i ts j a w s a n d c a r r y i t r a p i d l y

a w a y : v a r i o u s g r e g a r i n e s h a v e b e e n f o u n d in Scutigerella immacu­

lata, Hanseniella hova a n d H. agilis a n d t h e r e is a s ing le r e c o r d of a

n e m a t o d e i n t h e first n a m e d spec i e s ( R e m y , 1950) .

M a n y S y m p h y l a lay a c l u m p of eggs in a c r ev ice or h o l l o w of

t h e soil , a t t a c h i n g t h e m to i ts wa l l by a s h o r t s ta lk so t h a t t h e eggs

a re free f r o m c o n t a c t w i t h t h e s ides o r floor o f t h e s h e l t e r t h e r e b y

o b t a i n i n g s o m e p r o t e c t i o n f r o m fung i a n d o t h e r e n e m i e s . I n Scuti­

gerella immaculata, 4 - 2 5 eggs a r e la id ( F i l i n g e r , 1931) : in Han­

seniella agilis 3 - 8 . T h e y o u n g h a t c h w i t h six o r s even p a i r s o f legs

af ter an a v e r a g e p e r i o d o f a b o u t e l even d a y s : t h e r e a re five f u r t h e r

s tages e a c h h a v i n g o n e m o r e p a i r o f l egs t h a n t h e last , u p t o t h e

n u m b e r o f e l even . F r o m t h i s e l e v e n - l e g g e d la rva , t h e a d u l t e m e r g e s

af ter a f i na l m o u l t . A c c o r d i n g to F i l i n g e r (1931) t h e first m o u l t

o c c u r s w i t h i n o n e t o f o u r d a y s , u s u a l l y af ter 2 4 - 3 6 h o u r s , t h e

s u c c e e d i n g o n e s a t i n t e r v a l s o f a b o u t e i g h t d a y s . S e x u a l m a t u r i t y

i s r e a c h e d af ter 4 0 - 6 0 days . D u r i n g m o u l t i n g a sp l i t o c c u r s b e ­

t w e e n t h e h e a d a n d t h e f i r s t b o d y s e g m e n t , b u t a s t h e w h o l e

cu t i c l e i s soft i t i s n o t u s u a l l y cas t in o n e p i e c e as in m o s t o t h e r

m y r i a p o d s , b u t i s m o u l t e d i r r e g u l a r l y i n s t r i p s a n d t a t t e r e d f rag­

m e n t s a t v a r i o u s p o i n t s o f t h e b o d y .

M i c h e l b a c h e r (1938) f o u n d t h a t S . immaculata m o u l t s f r o m

t i m e to t i m e d u r i n g i t s e n t i r e life, a n d s ince i t m a y l ive for a

p e r i o d o f fou r y e a r s o r m o r e , t h e m a x i m u m n u m b e r o f m o u l t s

p r o b a b l y e x c e e d s f i f t y . T h e m o u l t i n g c h a r a c t e r i s t i c s o f d i f ferent

i n d i v i d u a l s v a r y g rea t ly : a sex f ac to r i s p r e s e n t a n d s o m e e v i d e n c e

h a s b e e n o b t a i n e d w h i c h i n d i c a t e s t h a t a g e n e t i c f ac to r m a y a lso

b e i n v o l v e d . O t h e r fac tors w h i c h in f luence m o u l t i n g a r e : t y p e o f

food , t e m p e r a t u r e , h u m i d i t y a n d m u t i l a t i o n . A b o v e a n d b e l o w

28° C t h e m o u l t i n g r a t e d e c r e a s e s . T h e ear l ies t t h a t e g g - l a y i n g w a s

o b s e r v e d t o b e g i n w a s b e t w e e n t h e s e v e n t h a n d e i g h t h m o u l t s

w h i c h w o u l d i n d i c a t e t h a t t h i s i s a b o u t t h e t i m e o f s e x u a l m a t u r i t y .

I n m o s t cases h o w e v e r eggs a r e n o t p r o d u c e d u n t i l a m u c h la te r

da t e . O v i p o s i t i o n o c c u r s a s h o r t t i m e be fo re m o u l t i n g . A t b i r t h ,

t h e spec i e s of Scutigerella so far i n v e s t i g a t e d h a v e b e e n f o u n d to

h a v e s ix p a i r s o f legs a n d s ix a n t e n n a l s e g m e n t s , w h e r e a s Han­

seniella s p p . h a v e seven p a i r s o f legs a n d six a n t e n n a l s e g m e n t s

( T i e g s , 1945) . I t i s s u r p r i s i n g t o f i n d t h e s e d i f ferences i n s o h o m o -

6 8 O T H E R ' M Y R I A P O D S '

F I G . 1 6 . Stages in the development of Scutigerella immaculata. (After Michelbacher, 1938.)

o v e r t h e d e c a y i n g v e g e t a t i o n o n w h i c h i t f eeds , b u t t h e r e a f t e r b e ­

c o m e s m o r e ac t ive . A f t e r 7 - 1 2 d a y s i t r e t r e a t s t o t h e s h e l t e r o f

s o m e s e c l u d e d c rev ice a n d t h e r e m o u l t s . W i t h t h e s i x t h m o u l t

t h e o r g a n i s m rece ives all i t s m o r p h o l o g i c a l p a r t s , b u t c o m p l e t e

d i f fe ren t i a t ion d o e s n o t o c c u r u n t i l a m u c h l a t e r p e r i o d , t h e l ife-

h i s t o r y b e i n g r a t h e r c o m p l e x . A f t e r each m o u l t m o r e s e g m e n t s

a r e u s u a l l y a d d e d t o t h e a n t e n n a e a n d b r o k e n a n t e n n a e a r e r e ­

g e n e r a t e d . T h i s h a s b e e n o b s e r v e d i n i n d i v i d u a l s n e a r l y t h r e e

y e a r s o ld . A s a l r e a d y m e n t i o n e d , t h e t o t a l life s p a n m a y exceed

f o u r y e a r s .

g e n e o u s a g r o u p a s t h e S y m p h y l a . T h e l a rva s lowly a n d l a b o r i o u s l y

w o r k s i ts w a y o u t o f t h e egg t h r o u g h t h e c u t m a d e i n t h e b l a s t o d e r ­

m i c cu t i c le a n d c h o r i o n b y t h e t w o p a i r s o f s h a r p s p i n e s a t t h e

b a s e s o f t h e a n t e n n a e . T h e s e s p i n e s a r e p a r t o f t h e e m b r y o n i c

cu t i c l e a n d a r e r e j ec t ed w i t h t h e l a t t e r a t ec los ion . D u r i n g t h e

first f ew h o u r s o f f r e e d o m t h e l a rva e n l a r g e s , e v i d e n t l y b y i n g e s ­

t i o n o f f l u id f r o m w i t h o u t . F o r t h e first d a y i t c r awl s s l ugg i sh ly

O T H E R ' M Y R I A P O D S ' 6 9

B I B L I O G R A P H Y Identification

ATTEMS , C. G . ( 1 9 2 6 ) Progoneata, Chilopoda in KUKENTHAL , W. and

KRUMBACH , T. Handbuch der Zoologie, Berlin, 4 , ( 1 - 4 ) , 1 - 4 0 2 . BAGNALL , R. S. ( 1 9 1 4 ) A synopsis of the British Symphyla, with de­

scriptions of new species. Trans. Nat. Hist. Soc. Northumb., (NS) , 4, 1 7 - 4 1 .

HANSEN , H. J . ( 1 9 0 2 ) On the genera and species of the order Pauropoda. Vidensk. Medd., 1 9 0 2 , 3 2 3 - 4 2 4 .

( 1 9 0 3 ) T h e genera and species of the order Symphyla. Quart. J. micr. Sci., 4 7 , 1 - 1 0 1 .

LATZEL, R. ( 1 8 8 4 ) Die Myriapoden der Osterreichisch-Ungarischen Monar­chic 2. Die Symphylen, Pauropoden und Diplopoden. Wien.

MICHELBACHER, A. E. ( 1 9 4 2 ) A synopsis of the genus Scutigerella (Sym­phyla: Scutigerellidae). Ann. Ent. Soc. Amer., 3 5 , 2 6 7 - 8 8 .

REMY , P. ( 1 9 3 8 ) Pauropodes de France, d'Allemagne et des Balkans avec description de quatre formes nouvelles. Bull. Soc. Hist. nat. Metz., 3 5 , 1 5 3 - 7 8 .

STARLING, J. H. ( 1 9 4 3 ) Pauropoda from the Duke forest. Proc Ent. Soc Wash., 4 5 , 1 8 3 - 2 0 0 .

VERHOEFF, K . W . ( 1 9 3 4 ) Symphyla u n d Pauropoda in H . G . BRONN'S

Klass. Ordn. Tierreichs, 5, II ( 3 ) , 1 - 2 0 0 .

Biology

FILINGER, G. A. ( 1 9 2 8 ) Observations on the habit and control of the garden centipede Scutigerella immaculata Newport , a pest of greenhouses. J. Econ. Ent., 2 1 , 3 5 7 - 6 0 .

( 1 9 3 1 ) T h e garden centipede Scutigerella immaculata Newpor t . Bull Ohio Agr. Exp. Sta., N o . 4 8 6 , 1 - 3 3 .

HARRISON , L. ( 1 9 1 4 ) On some Pauropoda from New South Wales. Proc Linn. Soc N.S.W., 3 9 , 6 1 5 - 3 4 .

KENYON, F . C . ( 1 8 9 5 ) T h e morphology and classification of the Pauro­poda, with notes on the morphology of the Diplopoda. Tufts Coll. Stud., N o . 4 , 7 7 - 1 4 6 .

MICHELBACHER, A. E. ( 1 9 3 8 ) T h e biology of the garden centipede Scuti­gerella immaculata. Hilgardia, 1 1 , 5 5 - 1 4 8 .

STARLING, J. H. ( 1 9 4 4 ) Ecological studies of the Pauropoda of the Duke forest. Ecol. Monogr., 1 4 , 2 9 1 - 3 1 0 .

TIEGS , O. W. ( 1 9 4 5 ) T h e post-embryonic development of Hanseniella agilis (Symphyla) . Quart. J. Micr. Sci., 8 5 , 1 9 1 - 3 2 8 .

( 1 9 4 7 ) T h e development and affinities of the Pauropoda, based on a study of Pauropus silvaticus. Ibid., 8 8 , 1 6 5 - 2 6 7 , 2 7 5 - 3 3 6 .

WILLIAMS , S. R. ( 1 9 0 7 ) Habi ts and structure of Scutigerella immaculata (Newport) . Proc. Boston Nat. Hist. Soc, 3 3 , 4 6 1 - 8 5 .

C H A P T E R V

S C O R P I O N S

Classification and distribution A l t h o u g h d i f ferent i n s ize , all s c o r p i o n s a r e m o r e o r less a l ike i n

g e n e r a l a p p e a r a n c e a n d a r e easi ly d i s t i n g u i s h e d f r o m o t h e r A r a c h -

n i d a by a c o m b i n a t i o n o f c h a r a c t e r s t h a t a re a lways p r e s e n t . T h e i r

m o s t s t r i k i n g f ea tu r e s a re t h e la rge p e d i p a l p s f u r n i s h e d w i t h s t o u t

FIG. 1 7 . Examples of scorpion families: 1. Buthidae, 2. Scorpion-idae, 3. Chactidae. (Drawings not to scale.) (After various authors.)

che l ae o r c laws a n d t h e d iv i s ion o f t h e a b d o m e n i n t o t w o p o r t i o n s :

a b r o a d p r e - a b d o m e n c o n s i s t i n g of s even s e g m e n t s w h i c h a re as

w i d e o r w i d e r t h a n t h e c e p h a l o t h o r a x o r p r o s o m a , a n d a s l e n d e r

ta i l - l ike p o s t - a b d o m e n . At t h e e n d of t h e tai l i s a s t ing , s o m e w h a t

7 0

S C O R P I O N S 7 1

c u r v e d a n d p o i n t e d . I t s b a s e i s e n l a r g e d a n d c o n t a i n s a p a i r o f

p o i s o n g l a n d s w h i c h o p e n n e a r t h e t i p . O n t h e v e n t r a l s ide o f t h e

a b d o m e n , i m m e d i a t e l y b e h i n d t h e gen i t a l o p e r c u l a , i s s i t u a t e d a

p a i r o f c o m b - l i k e o r g a n s k n o w n a s ' p e c t i n e s ' w h i c h a r e n o t f o u n d

in a n y o t h e r a n i m a l s . E a c h p e c t i n e a r t i cu l a t e s w i t h a c h i t i n o u s

p l a t e r e p r e s e n t i n g t h e s e c o n d s t e r n i t e a n d i s p r o v i d e d w i t h c o m ­

p l e x m u s c u l a t u r e . I t s c o m p o n e n t s f o r m t h r e e l o n g i t u d i n a l se r ies .

O f t h e s e t h e back i s c o m p o s e d o f t h r e e p a r t s , t h e p r o x i m a l b e i n g

t h e longes t , w h i l e t h e l ame l l ae o r t e e t h c o m p r i s e t h e t h i r d ser ies

a n d a r e i n s e r t e d b e t w e e n t h e c o n s t i t u e n t s o f t h e m e d i a n r o w .

FIG. 1 8 . Ventral view of a scorpion showing pectines.

T h e s e l a m e l l a e v a r y i n n u m b e r f r o m t h r e e t o m o r e t h a n for ty

d e p e n d i n g u p o n t h e sex a n d spec ies o f t h e s c o r p i o n , a n d a re

r i ch ly s u p p l i e d w i t h n e r v e s .

T h e d o r s a l su r f ace o f t h e p r o s o m a i s c o v e r e d b y a c o m p a c t a n d

u n s e g m e n t e d sh i e ld o r c a r a p a c e w h i c h b e a r s a p a i r o f m e d i a n a n d

f r o m t h r e e t o five p a i r s o f la te ra l s i m p l e eyes . T h e m o u t h i s v e n t r a l

in p o s i t i o n a n d i s s i t u a t e d b e t w e e n an a n t e r i o r a n d a p o s t e r i o r l ip .

I n f ron t a n d a b o v e t h e b a s e o f t h e p e d i p a l p s a r e a p a i r o f s h o r t

che l a t e che l i ce rae u s e d for m a s h i n g a n d s h r e d d i n g t h e food, w h i l e

72 S C O R P I O N S

t h e f i r s t t w o o f t h e f o u r p a i r s o f w a l k i n g legs h a v e m a x i l l a r y p l a t e s

a n d h a r b o u r g l a n d s t h a t s ec r e t e d iges t ive e n z y m e s .

S c o r p i o n s l ive i n h o t a n d t rop ica l c o u n t r i e s . I n E u r o p e severa l

spec ies a re f o u n d i n G r e e c e , I t a ly , S p a i n a n d t h e Ba lkans a n d a t

leas t o n e h a s a r a n g e e x t e n d i n g i n t o s o u t h e r n G e r m a n y . O n t h e

A m e r i c a n c o n t i n e n t t h e y a r e f o u n d f r o m P a t a g o n i a t o t h e m o r e

s o u t h e r n o f t h e U n i t e d S t a t e s . T h e i r g e o g r a p h i c a l d i s t r i b u t i o n ha s

b e e n m a d e t h e s u b j e c t o f severa l s t u d i e s a n d i s i n t e r e s t i n g b e c a u s e

s c o r p i o n s a r e a v e r y a n c i e n t g r o u p , a r e n o t r e a d i l y d i s p e r s e d t o n e w

local i t ies a n d c o n s e q u e n t l y a re o f g r e a t i m p o r t a n c e i n b i o g e o g r a p h i -

cal r e s e a r c h . T h e y a re a b s e n t f r o m m a n y i s l ands , i n c l u d i n g N e w

Z e a l a n d .

T h e o r d e r i s d i v i d e d i n t o six fami l ies , o f w h i c h t h e m o s t i m p o r ­

t a n t i s t h e B u t h i d a e w i t h m o r e t h a n 600 spec ies i n c l u d i n g Buthus

occitanus, t h e c o m m o n ye l low s c o r p i o n o f F r a n c e a n d t h e M e d i ­

t e r r a n e a n r eg ion , a n d Androctonus australis t h e f a t - t a i l ed s c o r p i o n

of N o r t h Afr ica , w h i l e t h e spec i e s of Centrurus a n d Tityus a r e

N e o t r o p i c a l . T h e D i p l o c e n t r i d a e a r e f o u n d i n t h e Pa l aea r c t i c

r eg ion , t h e isle o f S o k o t r a i n t h e G u l f o f A d e n a n d M e x i c o , t h e

S c o r p i o n i d a e i n Afr ica , M a d a g a s c a r , As ia a n d A u s t r a l i a , w h i l e t h e

Ve jov idae o c c u r m o s t l y i n As ia a n d A m e r i c a . T h e C h a c t i d a e h a v e

a s o m e w h a t s imi l a r d i s t r i b u t i o n a n d i n c l u d e t h e sma l l b l ack Euscor-

pius s p p . o f s o u t h e r n E u r o p e a n d t h e M e d i t e r r a n e a n , w h i l e t h e

B o t h r i u r i d a e l ive in A u s t r a l i a . M o s t spec ies h a v e a v e r y l i m i t e d

r a n g e , e x c e p t i n g Isometrus maculatus, w h i c h is u b i q u i t o u s in t h e

w a r m e r p a r t s o f t h e g l o b e , a n d Scorpio maurus w h i c h e x t e n d s f rom

t h e A t l a n t i c t o I n d i a . F e w a re f o u n d a t h i g h a l t i t u d e s , b u t S .

maurus a n d Buthus occitanus o c c u r in t h e A t l a s M o u n t a i n s a n d

Euscorpius germanus i n t h e T y r o l . On m o r p h o l o g i c a l g r o u n d s t h e

B u t h i d a e c a n b e s e p a r a t e d f r o m t h e r e m a i n i n g fami l ies o f s co r ­

p i o n s , a n d i t i s b e l i e v e d t h a t t h e t w o g r o u p s m a y h a v e evo lved i n ­

d e p e n d e n t l y , p e r h a p s e v e n s ince t h e S i l u r i a n e p o c h .

General behaviour S c o r p i o n s r e s e m b l e o t h e r A r a c h n i d a a n d in sec t s i n h a v i n g a n

i m p e r v i o u s i n t e g u m e n t a n d efficient p o w e r s o f w a t e r r e t e n t i o n .

( C l o u d s l e y - T h o m p s o n , 1956) . T h e y a re m a r k e d l y n o c t u r n a l b u t

t h i s h a b i t c a n n o t b e d i c t a t e d p r i m a r i l y b y t h e n e e d t o avo id d r y a i r .

S C O R P I O N S 73

I n d e e d , S e r g e n t (1947) h a s s h o w n t h a t t h e n e g a t i v e r e a c t i o n s t o

l igh t of Androctonus australis, Buthus occitanus a n d Scorpio maurus

are less m a r k e d t h a n a r e t h e i r pos i t i ve ly t h i g m o t a c t i c r e s p o n s e s , s o

i t i s p r o b a b l e t h a t t h e i r n o c t u r n a l b e h a v i o u r h a s a n ecological

r a t h e r t h a n a phys io log ica l s ign i f icance . S c o r p i o n s a r e essen t ia l ly

i n h a b i t a n t s o f w a r m c l i m a t e s a n d b e c o m e s l u g g i s h i n co ld w e a t h e r ,

a l t h o u g h t h e y c a n w i t h s t a n d f r eez ing for severa l w e e k s ( V a c h o n ,

1953) .

T h e i r l ives a re c o m p a r a t i v e l y s i m p l e : n o t e v e n t h e m o s t p r i m i ­

t ive f o r m s o f a n i m a l a s soc ia t ion a r e k n o w n a n d all spec ies lead

s t r ic t ly i n d i v i d u a l l ives a n d u s u a l l y e i t h e r avo id e a c h o t h e r o r

f i g h t t o t h e d e a t h . T h e fact t h a t a g g r e g a t i o n s a r e s o m e t i m e s f o u n d

i n c e r t a i n a r eas i s n o t d u e t o social i n s t i n c t s — t h e s e a r e c o n ­

s p i c u o u s l y a b s e n t — b u t t o t h e fact t h a t t h e y o u n g d o n o t s ca t t e r far

f rom t h e i r p l a c e o f b i r t h . F a b r e ' s (1907) c l a im t h a t w h e n t w o are

f o u n d b e n e a t h t h e s a m e s t o n e t h e y a r e e i t h e r m a t i n g o r else o n e i s

d e v o u r i n g t h e o t h e r m a y b e a n e x a g g e r a t e d g e n e r a l i s a t i o n , b u t i s

p r o b a b l y n o t e n t i r e l y w i t h o u t f o u n d a t i o n .

S o m e s c o r p i o n s (e .g . Euscorpius s p p . ) n o r m a l l y f r e q u e n t d a m p

places , o t h e r s (e .g . Pandinus, Palamnaeus s p p . ) a re fo res t d w e l l e r s

w h i l s t p e r h a p s t h e b e s t k n o w n (e .g . Scorpio, Buthus, Androctonus

s p p . ) a r e i n h a b i t a n t s o f d r y a n d d e s e r t r e g i o n s . M o s t s c o r p i o n s d o

n o t d r i n k , b u t m o i s t u r e l ov ing spec i e s s u c h as Euscorpius italicus

are sens i t ive b o t h t o d r o u g h t a n d t o excess ive m o i s t u r e (Bo t t , 1951 ;

C l o u d s l e y - T h o m p s o n , 1951) . S c h u l t z e (1927) h o w e v e r f o u n d t h a t

t h e l a rge P h i l i p p i n e fores t s c o r p i o n Palamnaeus longimanus h a d to

be g i v e n a c e r t a i n a m o u n t o f w a t e r eve ry day , a n d i t w a s a s t o n i s h ­

ing w h a t l a rge a m o u n t s o f w a t e r t h i s c r e a t u r e w o u l d d r i n k . T h e

s c o r p i o n w o u l d t a k e u p d r o p s o f w a t e r f r o m g r o o v e s i n b a r k ,

d r o p s s c a t t e r e d o n i ts b o d y o r s ip w i t h i ts m a n d i b l e s w a t e r t h a t h a d

a c c u m u l a t e d b e t w e e n t h e c h e l a e — t h a t is, i t w o u l d m o v e t h e l a t t e r

c lose to t h e m a n d i b l e s ' i n t h e w a y a m a n h o l d s a glass in h i s h a n d

a n d b r i n g s i t t o w a r d s h i s m o u t h ' . A t t h e s a m e t i m e , S e r g e n t (1946)

ha s s h o w n t h a t a l t h o u g h A. australis is a spec ies p a r t i c u l a r l y a d a p ­

t ed to a d r y c l ima te , i t d o e s n o t avo id w a t e r a n d c a n res is t p r o ­

l o n g e d i m m e r s i o n ( 3 1 % s u r v i v e d 24 h o u r s ) , w h i l e S . maurus c an

s u r v i v e i m m e r s i o n for u p t o 4 8 h o u r s ( 6 7 % ) .

F r o m h is i n t e r e s t i n g s t u d i e s V a c h o n (1952 , 1953) h a s r ecen t ly

74 S C O R P I O N S

s u g g e s t e d t h a t s ince m o d e r n s c o r p i o n s r e p r e s e n t t h e r e m a i n s o f a n

a n c i e n t f auna , t h e y o r ig ina l ly l ived u n d e r q u i t e d i f ferent c o n d i t i o n s

o f t e m p e r a t u r e a n d h u m i d i t y . T h e y a re v e r y r e s p o n s i v e t o m i c r o ­

c l ima t i c v a r i a t i o n s a n d each spec ies s e e m s t o h a v e t o l ive a n d r e ­

p r o d u c e itself w i t h i n s t r i c t l y l i m i t e d a n d c h a r a c t e r i s t i c ecological

c o n d i t i o n s . N e v e r t h e l e s s , s c o r p i o n s h a v e m a n a g e d t o s u r v i v e i n

c o n d i t i o n s o f h e a t a n d d r o u g h t la rge ly o n a c c o u n t o f t h e i r n o c ­

t u r n a l h a b i t s a n d s u b t e r r a n e a n h a b i t a t s . T h u s t h e B u t h i d a e a re

u s u a l l y f o u n d i n s h a l l o w s c r a p e s u n d e r rocks w h i c h t h e y d ig w i t h

t h e i r che l ae a n d legs ( L a n k e s t e r 1883) . A c c o r d i n g t o P o c o c k (1893)

Parabuthus capensis s t a n d s on i ts first a n d f o u r t h p a i r s of legs u s i n g

t h e t i p s o f t h e che l ae a s p r o p s w h i l e i t k icks s a n d b a c k w a r d s w i t h

i ts d i s e n g a g e d legs . Euscorpius s p p . do n o t d ig , b u t h a n g u p s i d e

d o w n u n d e r p i eces o f w o o d , e t c . o r h i d e u n d e r r o c k s , w h i l e Palam­

naeus a n d Scorpio s p p . d i g d e e p ho l e s ( u p to 75 cm in t h e case of S .

maurus w h o s e e n l a r g e d p e d i p a l p s a re p r o b a b l y spec ia l ly a d a p t e d

for t h i s p u r p o s e ) . S c o r p i o n s o f t h e g e n u s Hadrurus in A r i z o n a

f r e q u e n t l y d ig d o w n t w o o r t h r e e feet i n s a n d y w a s t e s a n d r ive r

b a n k s . H e r e t h e y r e m a i n even t h o u g h t h e b u r r o w h a s co l l apsed

' a p p a r e n t l y f i nd ing n o difficulty i n b r e a t h i n g ' ( S t r a h n k e , 1945) .

H o w e v e r , M i l l o t a n d P a u l i a n (1943) h a v e s h o w n t h a t A . australis

can w i t h s t a n d t h e b l o c k i n g o f s even o f i t s e i g h t l u n g s for m a n y

m o n t h s w i t h o u t m u c h ill effect, a n d i t i s e v i d e n t t h a t s c o r p i o n s

h a v e c o n s i d e r a b l e r e s p i r a t o r y r e se rves .

Food and feeding habits N o d o u b t t h e ab i l i ty t o s u r v i v e for l o n g p e r i o d s w i t h o u t food i s

o f g r ea t se rv ice t o s c o r p i o n s l iv ing u n d e r t h e h a z a r d o u s c o n d i t i o n s

o f d e s e r t r e g i o n s . T h u s a we l l - f ed Hadrurus s p . m a y r e m a i n b u r i e d

for fou r o r five m o n t h s , a n d in e x p e r i m e n t s s p e c i m e n s h a v e l ived

for n i n e m o n t h s w i t h o u t food o r w a t e r ( S t r a h n k e , 1945) , w h i l e ac ­

c o r d i n g to W a t e r m a n (1950) t h e W e s t I n d i a n Tityus trinitatis c a n

su rv ive t h r e e o r f o u r m o n t h s w i t h o u t food p r o v i d e d t h a t w a t e r i s

ava i lab le . A. australis c a n s u r v i v e six m o n t h s ' s t a r v a t i o n a n d B.

occitanus h a s l ived for up t o 368 d a y s w i t h o u t f eed ing . F a b r e

(1907) r e m a r k e d t h a t t h e a p p e t i t e of B . occitanus w a s v e r y s l ight

a n d L a n k e s t e r (1883) f o u n d g r ea t difficulty in f eed ing A. australis.

O n t h e o t h e r h a n d t h e w r i t e r h a s f o u n d t h a t t h e s a m e spec ies i n

S C O R P I O N S 75

cap t iv i t y feeds r ead i ly o n c o c k r o a c h e s , e a t i ng a t leas t o n e p e r week

d u r i n g t h e s u m m e r m o n t h s , a l t h o u g h t h e y d o n o t t o u c h h a r d

bee t l e s s u c h as Blaps s p p . a n d Akis spinosa u n l e s s s t a r v e d

( C l o u d s l e y - T h o m p s o n , 1955a) .

M o r e s e g m e n t a l a p p e n d a g e s h a v e b e e n b r o u g h t i n t o se rv ice a s

m o u t h p a r t s i n s c o r p i o n s t h a n i n o t h e r A r a c h n i d s . T h e r e i s t h e

u s u a l a s soc ia t ion o f t h e che l i ce rae , l a b r u m a n d p e d i p a l p coxae ,

a n d in a d d i t i o n t h e u n d e r l ip i s c o m p o s e d o f e n d i t e l obes o f t h e

coxae o f b o t h t h e first a n d s e c o n d p a i r s o f legs . T h e p r e y i s p i c k e d

t o p i e c e s b y a l t e r n a t e m o v e m e n t s o f t h e che l i ce rae a n d t h e j u i c e s

a n d soft t i s sues a re d r a w n i n t o t h e t i n y m o u t h b y t h e p u m p i n g

ac t ion o f t h e p h a r y n x . I n c o n s e q u e n c e f eed ing i s s l ow a n d t akes

several h o u r s .

T h e food o f s c o r p i o n s cons i s t s chiefly o f s p i d e r s , h a r v e s t m e n ,

f l i e s , c o c k r o a c h e s , g r a s s h o p p e r s , c r i cke t s , m a n t i d s , bu t t e r f l i e s , a n t s ,

bee t l e s ( a d u l t a n d la rvae) , m y r i a p o d s a n d e v e n smal l m i c e . A c c o r d ­

ing to S t r a h n k e (1945) Hadrurus s p . wil l eat r ead i ly of soft-

b o d i e d i n sec t s b u t re jec t s w o o d l i c e a n d h a r v e s t m e n ( w h e n h u n g r y

t h e y wi l l e v e n t ack le h a r d b e e t l e s a n d sma l l l i za rds ) , w h e r e a s

Euscorpius germanus ea t s b l u e b o t t l e s , f l ies, sma l l c o c k r o a c h e s , w o o d -

lice, s p i d e r s a n d c e n t i p e d e s ( P o c o c k , 1893) .

S c h u l t z e (1927) f o u n d t h a t v a r i o u s spec ies o f B l a t t i d a e s e e m e d

to be f a v o u r e d by Palamnaeus longimanus b u t t h a t c r i cke t s , e a rwigs

a n d c e r t a i n l a rvae o f C o l e o p t e r a w e r e also t a k e n a t t i m e s . T h i s

spec ies i s u s u a l l y f o u n d in o ld o r v i r g i n fores t u n d e r loose b a r k o f

d e a d s t a n d i n g t r e e s , u n d e r d e c a y i n g t r u n k s o f t r e e s a n d logs , o r i n

cavi t ies o f r o t t e n s t u m p s l o c a t e d i n t h e j u n g l e , m o s t l y i n r a t h e r

h u m i d a n d d a m p p laces , w h e r e s u c h in sec t s a b o u n d .

A c c o r d i n g t o V a c h o n (1953) i t i s n o t en t i r e ly c lear h o w t h e sco r ­

p i o n first d e t e c t s i t s p r e y . T h e eyes a re t o o c r u d e t o b e o f m u c h

ass i s t ance a n d in a n y case t h e s c o r p i o n i s a n o c t u r n a l a n i m a l , for

w h i c h v i sua l i m p r e s s i o n s c a n b e o f n o g r e a t s igni f icance . O t h e r

sense o r g a n s m u s t t h e r e f o r e b e c o n c e r n e d , n o t a b l y t h e s e n s o r y

ha i r s o r t r i c h o b o t h r i a f o u n d o n l y o n t h e p e d i p a l p s . ' T h e s e a re

r ich ly s u p p l i e d w i t h n e r v e s , a n d can d e t e c t m i n u t e a i r c u r r e n t s

s u c h a s t h o s e c a u s e d b y m o v e m e n t s o f t h e p r e y . T h e y a re , i n fact

like t i n y r ece iv ing se ts , p o i n t i n g i n all d i r e c t i o n s a n d s p r e a d o u t

a long t h e p e d i p a l p i , w h i c h w h e n e x t e n d e d ac t a s h u g e a n t e n n a e . '

7 6 S C O R P I O N S

W h e n h u n g r y , t h e a n i m a l m o v e s s lowly f o r w a r d s u p p o r t e d b y i ts

h i n d legs w i t h c laws o p e n a n d e x t e n d e d a n d tai l r a i sed a n d p o i n t ­

ing f o r w a r d s . ' O f t e n t h e s c o r p i o n wil l t h e n he s i t a t e a n d t h e f i n a l

act o f c a p t u r e s e e m s a l m o s t a cc iden t a l an ac t o f de fence r a t h e r

t h a n o f a t t ack . I f t h e p r e y i s ac t ive , t h e s c o r p i o n m a y even w i t h ­

d r a w for a t i m e , b u t i t w a i t s p a t i e n t l y a n d f ina l ly ach i eves i ts a i m . '

S c o r p i o n s p r o b a b l y d o n o t u sua l l y g o t o seek t h e i r food . I n s t e a d ,

t h e y wa i t for t h e i n sec t s t h a t c o m e t o t h e i r la i rs t o h i d e . S o m e scor ­

p i o n s s u c h as E. italicus a n d P. longimanus a p p e a r s e l d o m , if ever ,

t o u s e p o i s o n t o kill t h e i r p r e y ( C l o u d s l e y - T h o m p s o n , 1951 ;

S c h u l t z e , 1927) a n d t h e s t i n g i s u s e d on ly as a de fens ive w e a p o n .

On t h e o t h e r h a n d , S. maurus, B. occitanus a n d A. australis will

lash o u t w i t h t h e i r s t i ng a t t h e s l igh tes t p r o v o c a t i o n , a l t h o u g h i f

t h e p r e y i s c o m p a r a t i v e l y q u i e t i t m a y be d e v o u r e d al ive.

Enemies T h e g r e a t e s t t h r e a t s t o t h e s c o r p i o n ' s ex i s t ence a re p r o b a b l y

food s h o r t a g e , d r o u g h t a n d h u m a n ac t iv i t ies . F r o m a n c i e n t t i m e s

m a n h a s feared , m a l i g n e d a n d h a t e d t h e a n i m a l s o n a c c o u n t o f t h e i r

p o i s o n . N e v e r t h e l e s s , t h e r e a re o t h e r e n e m i e s w h i c h a lso d e s t r o y

t h e m . I n t h e t r o p i c a l r a i n fores t s o f Afr ica a n d A m e r i c a s c o r p i o n s

a re s o m e t i m e s c a u g h t b y r a i d i n g a r m i e s o f d r i v e r a n t s . A l t h o u g h

m a n y t i m e s t h e size o f t h e i r t o r m e n t o r s , t h e s c o r p i o n s r a p i d l y s u c ­

c u m b t o t h e i r a t t acks , a r e o v e r p o w e r e d a n d d i s m e m b e r e d . V a r i o u s

c e n t i p e d e s , s p i d e r s , So l i fugae , l i za rds , s n a k e s a n d b i r d s h a v e b e e n

r e c o r d e d a s p r e d a t o r s a n d Af r i can b a b o o n s h a v e b e e n o b s e r v e d

c a t c h i n g la rge s c o r p i o n s , t e a r i n g off t h e i r tai l a n d g reed i ly d e v o u r ­

ing t h e res t o f t h e b o d y . I t h a s also b e e n r e p o r t e d t h a t c e r t a i n

na t ives o f Afr ica enjoy e a t i n g l ive s c o r p i o n s ! In a d d i t i o n m a n y

s c o r p i o n s a re i n v e t e r a t e c a n n i b a l s . A m o n g t h e few p a r a s i t e s k n o w n

a re v a r i o u s m i t e s a n d n e m a t o d e w o r m s w h i c h a re un l ike ly t o b e

v e r y h a r m f u l .

T h e p e c t i n e s a l r e a d y m e n t i o n e d a re k n o w n t o r e p r e s e n t t h e

m o d i f i e d a p p e n d a g e s of t h e n i n t h s o m i t e of t h e b o d y ( = t h i r d

m e s o s o m a l s e g m e n t ) b u t t h e i r f u n c t i o n h a s l o n g r e m a i n e d p r o ­

b l ema t i ca l . T h e y h a v e b e e n r e g a r d e d a s e x t e r n a l r e s p i r a t o r y o r g a n s

a n d e x t e r n a l gen i ta l ia , a n d i t h a s b e e n c l a i m e d t h a t t h e l ame l l ae o f

t h e m a l e a n d female s c o r p i o n b e c o m e i n t e r l o c k e d a n d se rve t o h o l d

S C O R P I O N S 77

t h e t w o sexes t o g e t h e r d u r i n g m a t i n g . A n a l t e r n a t i v e s u g g e s t i o n

ha s b e e n m a d e t h a t t h e i r f u n c t i o n i s t o c l ean t h e e x t r e m i t i e s o f t h e

p e d i p a l p s , legs a n d ta i l . I n 1883 L a n k e s t e r m a d e e x p e r i m e n t s o n

t h e t ac t i l e s ense o f t h e p e c t i n i f o r m a p p e n d a g e s , a n d w r o t e : ' T h e y

a p p e a r e d t o m e t o posses s n o spec ia l s ens i t i venes s . W h e n t h e y

w e r e p i n c h e d w i t h fo rceps , t h e s c o r p i o n s s h o w e d n o s ign o f d i s ­

c o m f o r t . I t i s q u i t e p o s s i b l e t h a t t h e y m a y a c q u i r e a h e i g h t e n e d

sens ib i l i ty a t t h e b r e e d i n g s ea son , a n d s e r v e a s g u i d e s t o t h e m a l e

a n d f ema le in effect ing c o p u l a t i o n . ' A few y e a r s la te r , n e r v e t e r ­

m i n a t i o n s w e r e d i s c o v e r e d i n t h e l a m e l l a e o f t h e p e c t i n e s o f s co r ­

p i o n s b y G a u b e r t , w h o w r o t e : T l es t i n c o n t e s t a b l e q u e l e u r r i chesse

en ne r f s en fait d e s o r g a n e s sens i t i f s . '

P o c o c k (1893) s u g g e s t e d t h a t t h e p e c t i n e s w e r e t ac t i l e o r g a n s o f

s o m e i m p o r t a n c e . H e p o i n t e d o u t t h a t t h e i r s i t u a t i o n n e a r t h e

gen i t a l a p e r t u r e , t h e i r l a rge r s ize i n m a l e s a n d t h e m o d i f i c a t i o n o f

t h e i r basa l p o r t i o n i n f ema les o f t h e s a m e spec i e s i n d i c a t e d s o m e

sexua l f u n c t i o n . A p a r t f r o m t h i s h e c o n s i d e r e d t h a t i t w a s h i g h l y

p r o b a b l e t h a t t h e y w e r e use fu l o r g a n s o f t o u c h i n o t h e r a s p e c t s o f

life, e n a b l i n g t h e i r p o s s e s s o r t o l e a r n t h e n a t u r e o f t h e su r f ace ove r

w h i c h i t w a s w a l k i n g . H e a d d e d : I n f a v o u r o f t h i s v i e w m a y b e

a d d u c e d t h e fact t h a t t h e s e a n i m a l s h a v e b e e n s e e n t o t o u c h t h e

g r o u n d w i t h t h e i r c o m b s . M o r e o v e r , i t i s a v e r y n o t i c e a b l e c i r c u m ­

s t a n c e t h a t s c o r p i o n s w h i c h , l ike Euscorpius, c r e e p a l o n g w i t h t h e i r

be l l ies c lose t o t h e g r o u n d , h a v e v e r y s h o r t c o m b s w h i l e i n o t h e r s

w h i c h , l ike Parabuthus, s t a n d h i g h u p o n t h e i r legs , t h e c o m b s a re

e x c e e d i n g l y l ong . I o n c e n o t i c e d a Parabuthus m a r c h i n g o v e r a

p i ece o f d e a d c o c k r o a c h . W h e n s h e h a d hal f c r o s s e d it , i n s t e a d o f

g o i n g s t r a i g h t a h e a d a s w a s e x p e c t e d , s h e h a l t e d a b r u p t l y , b a c k e d

a l i t t le a n d s t o o p i n g d o w n s t a r t e d t o d e v o u r t h e f r a g m e n t . F r o m

t h e h e i g h t a t w h i c h t h e b o d y w a s b e i n g c a r r i e d , I a m p e r s u a d e d

t h a t n o p o r t i o n o f t h e l o w e r su r face , e x c e p t t h e c o m b s , c o u l d h a v e

c o m e i n t o c o n t a c t w i t h t h e p i e c e o f food; s o t h e r e c a n b e l i t t le

d o u b t t h a t i t s p r e s e n c e w a s d e t e c t e d b y t h e o r g a n s i n q u e s t i o n . '

S h o r t l y a f t e r w a r d s i t w a s s u g g e s t e d t h a t t h e p e c t i n e s o f s co r ­

p i o n s , l ike t h e spec ia l s e n s e o r g a n s of Limulus, a n d of Galeodes a n d

o t h e r A r a c h n i d s w e r e p r o b a b l y t o b e a c c r e d i t e d w i t h t h e f u n c t i o n s

o f e q u i l i b r a t i o n a n d a u d i t i o n , b u t W a r b u r t o n (in H a r m e r a n d

S h i p l e y , 1909)* s u p p o r t e d P o c o c k ' s (1893) v i e w .

7 8 S C O R P I O N S

F r o m a de t a i l ed h i s to log ica l s t u d y o f t h e p e c t i n e s , S c h r o d e r c o n ­

c l u d e d t h a t t h e y w e r e c h e m o t a c t i c o r g a n s a n d h a d a d o u b l e f u n c ­

t i on a s r e c e p t o r s for t a s t e a n d sme l l a n d w e r e p e r h a p s also u s e d

d u r i n g m a t i n g as a s t i m u l a t o r y o r g a n (Wollustorgane) in t h e r e c o g ­

n i t i o n o f t h e sexes . W i t h sti l l m o r e i m a g i n a t i o n , U b i s c h a t t r i b u t e d

t o t h e m a n aux i l i a ry ro le i n r e s p i r a t i o n . S h e s u g g e s t e d t h a t w i t h

t h e i r c o m p l e x m u s c u l a t u r e , t h e p e c t i n e s c o u l d b e u s e d a s fans t o

b l o w f resh a i r ac ross t h e l u n g - b o o k s w h i l e t h e s c o r p i o n w a s i n i ts

stuffy r e t r e a t , a n d t h a t t h e y s e r v e d t o v e n t i l a t e t h e l u n g - b o o k s

w h e n t h e a n i m a l r e s t e d o n t h e g r o u n d b y l i f t ing t h e p r e - a b d o m e n

a n d t h u s p e r m i t t i n g a i r t o p a s s f reely b e n e a t h t h e b o d y .

O n t h e o t h e r h a n d , S c h u l t z e (1927) o b s e r v e d i n t h e case o f t h e

l a rge P h i l i p p i n e fores t s c o r p i o n Palamnaeus longimanus t h a t w h i l e

g i v i n g b i r t h t o y o u n g t h e p e c t i n e s o f t h e m o t h e r s c o r p i o n ' w e r e

c a r r i e d in a ve r t i ca l p o s i t i o n p o i n t i n g d o w n w a r d s , s e e m i n g l y to

se rve a s h o l d e r s o r b r a c e r s ' .

F ina l l y , L a w r e n c e (1953 )* w r o t e : ' T h e p e c t i n e s o f s c o r p i o n s h a v e

b e e n i n t e r p r e t e d e i t h e r a s t ac t i l e o r s t i m u l a t o r y o r g a n s d u r i n g

c o u r t s h i p , o r a s o r g a n s o f sme l l . T h e l a t t e r s e e m s t o b e t h e m o r e

l ikely e x p l a n a t i o n e x c e p t t h a t t h e i r p o s i t i o n i s p e c u l i a r i n t h e a r t h r o ­

p o d a , w h e r e t h e s e o r g a n s a r e g e n e r a l l y l oca t ed o n t h e a n t e n n a e o r

l egs ' . A f t e r r e v i e w i n g s o m e o f t h e f u n c t i o n s t h a t h a v e b e e n a t t r i b u ­

t e d t o t h e p e c t i n e s , M i l l o t a n d V a c h o n (in G r a s s e , 1949 )* c o n ­

c l u d e d w i t h jus t i f i ab le c a u t i o n : ' T o u t e s ces h y p o t h e s e s n e fon t q u e

m a s q u e r n o t r e c o m p l e t e i g n o r a n c e . '

As a r e su l t of e x p e r i m e n t s c a r r i e d o u t on Buthus occitanus,

Androctonus australis a n d Euscorpius germanus, in w h i c h it w a s

f o u n d t h a t t h e r e s p o n s e o f t h e s c o r p i o n s t o a v i b r a t i n g t u n i n g fork

d e c r e a s e d m a r k e d l y after t h e p e c t i n e s h a d b e e n p a i n t e d over , i t h a s

r e c e n t l y b e e n s u g g e s t e d t h a t t h e f u n c t i o n o f t h e s e o r g a n s l ies i n

t h e p e r c e p t i o n o f g r o u n d v i b r a t i o n s ( C l o u d s l e y - T h o m p s o n , 1955b) .

P r o b a b l y t h e y a re u s e d m o r e a s a w a r n i n g o f d a n g e r t h a n i n t h e

d e t e c t i o n of p r e y .

I t i s a w e l l - k n o w n fact t h a t a n u m b e r of t h e l a r g e r spec ies s u c h

as t h e g r e e n i s h - b l a c k Palamnaeus swammerdami of s o u t h e r n I n d i a

wi l l f r e q u e n t l y e m i t a u d i b l e s o u n d s u n d e r t h e s t i m u l u s o f fear o r

o f a n g e r . T h e s o u n d i s sa id t o b e a l m o s t a s l o u d as , a n d v e r y s imi la r

t o t h a t m a d e b y b r i sk ly a n d c o n t i n u o u s l y d r a w i n g t h e t i p o f t h e

S C O R P I O N S 7 9

i n d e x r inger b a c k w a r d s a n d f o r w a r d s in a d i r e c t i o n t r a n s v e r s e to

i ts coa r se e d g e s ove r t h e e n d s of t h e t e e t h of a v e r y f i n e - t o o t h e d

c o m b . T h e s t r i d u l a t o r y a p p a r a t u s cons i s t s o f a s c r a p e r o n t h e flat

o u t e r face o f t h e basa l s e g m e n t o f t h e p e d i p a l p s a n d a r a s p on t h e

e q u a l l y flat i n n e r face o f t h e c o r r e s p o n d i n g s e g m e n t o f t h e f i r s t

p a i r o f l egs . T h e s c r a p e r i s t o l e r a b l y th i ck ly , b u t r egu l a r ly , b e s e t

w i t h s t o u t con ica l s h a r p s p i n u l e s l ike a t i g e r ' s c a n i n e , on ly m o r e

c u r v e d t o w a r d s t h e p o i n t s , s o m e o f w h i c h t e r m i n a t e i n a long ,

l i m p ha i r , w h i l e t h e r a s p i s s t u d d e d w i t h m i n u t e t u b e r c l e s s h a p e d

l ike t h e t o p s o f m u s h r o o m s .

T h e r e i s n o e v i d e n c e t h a t s c o r p i o n s o r l a rge s p i d e r s c a n h e a r t h e

s o u n d s t h a t t h e i r o w n s t r i d u l a t i n g o r g a n s p r o d u c e , a n d P o c o c k

(1896) p o i n t s o u t t h a t m a n y p o i s o n o u s a n i m a l s i n c l u d i n g w a s p s a n d

snakes a r e f r e q u e n t l y r e n d e r e d c o n s p i c u o u s b y b r i g h t a n d s t a r i n g

c o l o u r s o r b y s o u n d - p r o d u c i n g o r g a n s w h i c h , w h e n i n ac t ion ,

s e rve a s a d a n g e r s igna l t o m e d d l e s o m e i n t r u d e r s , w a r n i n g t h e m

t o b e w a r e o f hos t i l e i n t e r f e r e n c e . I n t h i s w a y t h e p o i s o n o u s f o r m s

a r e n o t d e s t r o y e d b y c a r n i v o r o u s c r e a t u r e s i n m i s t a k e for o t h e r

h a r m l e s s a n d e d i b l e spec i e s . T h e e x i s t e n c e o f s t r i d u l a t o r y o r g a n s

i m p l i e s t h e ex i s t ence o f a n a u d i t o r y sense , n o t neces sa r i l y i n t h e

p e r f o r m e r s t h e m s e l v e s , b u t o n l y i n t h e e n e m i e s t h a t m i g h t o t h e r -

FIG. 1 9 . Stridulatory apparatus of a scorpion. 1. Coxa of claw with rasp. 2. Coxa of first leg wi th scraper. (After Pocock, 1 8 9 6 . )

wise d e s t r o y t h e m . T h e fact t h a t m o n k e y s , w h i c h a r e p a r t i a l t o a

d ie t o f s c o r p i o n s a n d skilful e n o u g h t o h a n d l e t h e m w i t h o u t d a m a g e ,

p a y n o h e e d t o t h e h i s s i n g w h e n s e a r c h i n g for t h e s e a n i m a l s b e ­

n e a t h s t o n e s d o e s n o t d e t r a c t f r o m t h e t h e o r y . D e s p i t e t h e i r w a r n ­

ing c o l o u r s , b e e s a r e d e v o u r e d b y f rogs a n d t o a d s a n d t h e c o b r a i s

80 S C O R P I O N S

ki l led b y t h e m o n g o o s e — i n d e e d , few spec ies a r e d e v o i d o f p r e ­

d a t o r y e n e m i e s . N e v e r t h e l e s s , t h e ex i s t ence o f p o i s o n , c o u p l e d

w i t h t h e p r e s e n c e o f a p o s e m a t i c s o u n d p r o d u c t i o n , wil l d e t e r

m a n y p o t e n t i a l e n e m i e s , t h e r e b y i m p a r t i n g a n e v o l u t i o n a r y a d ­

v a n t a g e t o t h e i r p o s s e s s o r s .

Poison T h e p o i s o n o f s c o r p i o n s h a s a t t r a c t e d a t t e n t i o n s ince ear l ies t

t i m e s a n d o b s e r v a t i o n s a s t o i ts effects o n m a n a n d o t h e r v e r t e ­

b r a t e s h a v e of ten b e e n m a d e . U n f o r t u n a t e l y t h e s e h a v e b e e n s o m e ­

w h a t conf l ic t ing a n d scient i f ical ly a c c u r a t e d a t a h a s b e e n o b t a i n e d

o n l y c o m p a r a t i v e l y r e c e n t l y . O n e s o u r c e o f e r r o r h a s b e e n lack o f

k n o w l e d g e o f t h e phys io log ica l s t a t e o f t h e a n i m a l o n w h i c h t h e

o b s e r v a t i o n w a s m a d e , o f t h e q u a n t i t y o f p o i s o n in jec ted b y t h e

s c o r p i o n i n t o t h e w o u n d a n d i ts r e l a t i on t o t h e to t a l w e i g h t o f t h e

v i c t i m . A n o t h e r h a s b e e n i n a c c u r a t e a n d u n c e r t a i n d e t e r m i n a t i o n s

o f t h e spec ies o f s c o r p i o n , for i t i s k n o w n t h a t d i f ferent spec ies

v a r y g r e a t l y i n t h e d e g r e e o f v i r u l e n c e a n d t y p e o f t h e i r p o i s o n .

E x a c t k n o w l e d g e c a n b e o b t a i n e d o n l y u n d e r carefu l ly c o n t r o l l e d

l a b o r a t o r y e x p e r i m e n t s w h i c h m a y b e s u p p l e m e n t e d b y field o b ­

s e r v a t i o n s p r o v i d e d t h a t t h e s c o r p i o n i s iden t i f i ed b y a n e x p e r t .

S u c h o b s e r v a t i o n s h a v e led t o t h e c o n c l u s i o n t h a t a t leas t t w o

t y p e s o f p o i s o n exis t . O n e o f t h e s e i s local in effect a n d c o m p a r a ­

t ive ly h a r m l e s s to m a n : i t i s exempl i f i ed by t h e E u r o p e a n Eus­

corpius italicus a n d t h e A m e r i c a n Centruroides vittatus. T h e o t h e r

t y p e i s n e u r o t o x i c r e s e m b l i n g s o m e k i n d s o f s n a k e v e n o m a n d can

be e x t r e m e l y d a n g e r o u s . I t is f o u n d in Buthus occitanus a n d An­

droctonus australis in N o r t h Afr ica a n d in Centruroides sculpturatus

a n d C . gertschi i n N o r t h A m e r i c a . P o i s o n for e x p e r i m e n t s m a y b e

o b t a i n e d i n p u r e f o r m w i t h o u t i n ju ry t o t h e s c o r p i o n b y e lec t r ica l

s t i m u l a t i o n . I t h a s b e e n f o u n d t h a t B . occitanus o f s o u t h e r n F r a n c e

p r o d u c e s a t o n e t i m e a b o u t 8 mg o f fluid p o i s o n : c u r i o u s l y e n o u g h

t h e s a m e spec ies f r o m N o r t h Afr ica i s sa id t o b e m u c h m o r e

d a n g e r o u s , w h i l e t h e s t i n g of A. australis h a s b e e n k n o w n to kill a

m a n in a b o u t f o u r h o u r s , a d o g in s even m i n u t e s a n d h a s a tox ic i ty

a l m o s t e q u a l to t h a t of a cob ra .

T h e s y m p t o m s c a u s e d b y s c o r p i o n p o i s o n o f t h e less v i r u l e n t

t y p e cons i s t m o s t l y o f s u d d e n s h a r p p a i n fo l lowed b y n u m b n e s s o f

S C O R P I O N S 8 1

t h e l i m b a n d local swe l l ing : t h e s e pas s a w a y w i t h i n a n h o u r o r t w o .

C e r t a i n s c o r p i o n s h a v e r e d u c e d p o i s o n g l a n d s a n d t h e i r v e n o m

m a y h a v e n o effect w h a t s o e v e r . N o t s o w i t h spec ies w h o s e p o i s o n

i s n e u r o t o x i c . H e r e t h e s y m p t o m s r e s e m b l e p o i s o n i n g w i t h s t r y c h ­

n i n e . In t h e case o f t h e A m e r i c a n C . sculpturatus t h e v e n o m d o e s

n o t p r o d u c e a swe l l ing or d i s c o l o r a t i o n a t t h e s i te o f t h e s t ing .

F i r s t , a fee l ing o f t i g h t n e s s d e v e l o p s in t h e t h r o a t so t h a t t h e

v i c t i m t r i e s t o c lear h i s t h r o a t o f a n i m a g i n a r y p h l e g m . T h e

t o n g u e d e v e l o p s a fee l ing of t h i c k n e s s a n d s p e e c h b e c o m e s diffi­

cu l t . T h e v i c t i m n e x t b e c o m e s res t l ess a n d t h e r e m a y b e s l ight ,

i n v o l u n t a r y t w i t c h i n g o f t h e m u s c l e s . S m a l l c h i l d r e n a t t h i s s tage

wil l n o t b e sti l l : s o m e a t t e m p t t o c l i m b u p t h e wal l o r t h e s ides o f

t h e i r co t . A ser ies of s n e e z i n g s p a s m s is a c c o m p a n i e d by a c o n t i n ­

u o u s flow o f f luid f rom n o s e a n d m o u t h w h i c h m a y f o r m a c o p i o u s

f ro th . O c c a s i o n a l l y t h e r a t e o f h e a r t - b e a t i s c o n s i d e r a b l y i n c r e a s e d .

C o n v u l s i o n s fol low, t h e a r m s a r e flailed a b o u t a n d t h e e x t r e m i t i e s

b e c o m e q u i t e b l u e be fo re d e a t h o c c u r s . T h i s c o m p l e x p a t t e r n o f

r e a c t i o n s m a y las t f r o m 4 5 m i n u t e s t o 1 0 o r 1 2 h o u r s . I n t h o s e

a d u l t s a n d c h i l d r e n w h o r ecove r , t h e effects o f t h e v e n o m pe r s i s t

l onges t a t t h e o r ig ina l s i te o f t h e s t i ng , w h i c h m a y b e h y p e r s e n s i t i v e

for s eve ra l days , so t h a t o n l y a s l igh t b u m p wil l s e n d pa in fu l o r

t i n g l i n g s e n s a t i o n s t h r o u g h o u t t h e i m m e d i a t e s u r r o u n d i n g area .

T h e effect o f s c o r p i o n p o i s o n on d i f fe ren t a n i m a l s va r i e s a g o o d

deal . H e d g e h o g s , j e r b o a s a n d f e n n e c foxes a r e p rac t i ca l ly i m m u n e ,

b u t g u i n e a - p i g s a n d d o g s a re espec ia l ly s u s c e p t i b l e . B i r d s a r e q u i t e

sens i t ive a s a r e f rogs a n d f ishes . T h e p o i s o n h a s a h a e m o l y t i c

ac t ion d e s t r o y i n g r e d b l o o d c o r p u s c l e s a n d also c o n t a i n s a d e n o s i n e

t r i - p h o s p h a t a s e i n l a rge q u a n t i t i e s . A n t i - s c o r p i o n s e r u m s a re p r o ­

d u c e d i n v a r i o u s c e n t r e s i n c l u d i n g Alge r i a , M e x i c o , Braz i l , A r i z o n a

a n d L o n d o n .

Mating habits I n s c o r p i o n s t h e t w o sexes a r e d i s t i n c t a n d s h o w s l i gh t b u t

v is ible d i f ferences i n t h e r e l a t ive p r o p o r t i o n s o f t h e b o d y . T h e

m a l e i s m o r e s l e n d e r a n d h a s a l o n g e r ta i l . I t also h a s a p a i r of

o r g a n s u s e d i n c o p u l a t i o n , b u t v i s ib le o n l y w h e n t h e a n i m a l i s

t u r n e d o n i ts b a c k . I n a d d i t i o n t o t h e n o w t h o r o u g h l y d i s c r e d i t e d

l e g e n d o f t h e i r su ic ida l t e n d e n c i e s , s c o r p i o n s a p p e a r t o a r o u s e

F S.S.C.M.

82 S C O R P I O N S

p o p u l a r i n t e r e s t for a n u m b e r o f r e a sons , n o t t h e least b e i n g t h e i r

c u r i o u s m a t i n g h a b i t s . C o u r t s h i p t akes t h e f o r m o f a d a n c e ( ' p r o ­

m e n a d e a d e u x ' ) first o b s e r v e d by M a c c a r y in 1810 a n d la ter

d e s c r i b e d b y F a b r e (1907) , Ser fa t a n d V a c h o n (1950) a n d T h o r n ­

t o n (1956) . On f ind ing a female , t h e m a l e g r a s p s h e r p e d i p a l p a l

c l aws w i t h h i s a n d wa lks s i d e w a y s o r b a c k w a r d s w h i l e s h e fol lows,

FIG 20. Courtship dance of scorpions. (After Vachon, 1 9 5 3 . )

usua l l y w i t h o u t r e l u c t a n c e . In Buthotus alticola t h e p r o m e n a d e i s

p r e c e d e d b y a m a n o e u v r e d u r i n g w h i c h t h e t w o a n i m a l s face each

o t h e r , fo rc ib ly s t r a i g h t e n t h e b a c k p a r t s o f t h e i r b o d i e s a n d c o m ­

p r e s s t h e i r a b d o m e n s t o t h e g r o u n d , w h i l s t t h e i r ta i ls , e x t e n d e d

u p w a r d s , a re c o n t i n u o u s l y e n t w i n e d a n d t h e n d i s e n g a g e d . T h e

p r o m e n a d e w h i c h fo l lows i s s o m e w h a t less e n e r g e t i c a n d t h e ta i l s

o f t h e t w o a n i m a l s a r e r a i sed b u t s u p p l e . T h e m a l e d i r ec t s o p e r a ­

t i o n s w h i l e h i s m a t e fo l lows p lac id ly a s h e l eads t h e d a n c e . T h e

p r o c e s s m a y last severa l h o u r s a n d in t h e case of Buthus occitanus

t h e tai ls m a y aga in b e e n t w i n e d b u t o f c o u r s e w i t h o u t hos t i l e i n t e n t .

S C O R P I O N S 83

A t l e n g t h t h e m a l e e i t h e r d ig s a h o l e w i t h o u t en t i r e ly q u i t t i n g

i ts h o l d of t h e f emale , o r else l eads h e r to a s u i t a b l e r e t r e a t i n t o

w h i c h b o t h d i s a p p e a r . T r u e c o p u l a t i o n t akes p l ace , w h i c h i s r a r e

i n t h e A r a c h n i d a . I n t h e c o u r s e o f t h i s ac t t h e m a l e p r o t r u d e s ce r ­

t a in spec ia l o r g a n s a l r e a d y r e f e r r e d to a n d t h e s e f o r m a t e m p o r a r y

p e n i s w i t h w h i c h h e i n s e r t s t h e s p e r m a n d finally p l a c e s i n p o s i t i o n

a vag ina l p l u g — a k i n d o f p o s t n u p t i a l h y m e n ( V a c h o n , 1953) .

A f t e r w a r d s t h e f emale n o t i n f r e q u e n t l y ea t s h i m .

In t h e S o u t h Af r i can Opisthopthalmus latitnanus t h e classical

' a r b r e d r o i t ' i s e i t h e r a b s e n t o r o n l y f leet ingly p r e s e n t , w h i l e t h e

' p r o m e n a d e a d e u x ' d o e s n o t u s u a l l y last l o n g e r t h a n a n h o u r . T h e

m a l e h o l d s t h e che l i ce rae o f t h e f emale a n d n o t , a s i n o t h e r spec ies ,

h e r p e d i p a l p s . T h e p r o m e n a d e t akes p l ace i n a l i m i t e d a rea a n d i f

t h e g r o u n d i s r o u g h t h e m a l e c lea rs t h e soil p a r t i c l e s f r o m t h e

space i n w h i c h t h e p a i r a r e d a n c i n g . S h o r t l y af ter t h e s t a r t , t h e

gen i ta l o p e r c u l a o f t h e f emale o p e n s a n d a l i t t le l a t e r t h a t o f t h e

m a l e also o p e n s a s t h e e x t r u s i o n o f a s p e r m a t o p h o r e b e g i n s . As

s o o n a s t h i s i s c lear o f t h e gen i t a l a p e r t u r e o f t h e m a l e he m o v e s

b a c k s l igh t ly s o t h a t i t l ies f reely o n t h e g r o u n d . H e t h e n j e r k s t h e

f e m a l e v io len t ly , d r a w i n g h e r ove r t h e s p e r m a t o p h o r e a n d half

l i f t ing h e r a t t h e s a m e t i m e . S h e l o w e r s h e r b o d y ove r t h e c a p s u l e

o f t h e s p e r m a t o p h o r e , w h i c h b e c o m e s i n s e r t e d i n h e r gen i t a l a p e r ­

t u r e .

T h u s in O. latimanus t h e r e i s no t r u e c o p u l a t i o n b u t a fer t i l isa­

t i o n m e c h a n i s m s imi l a r t o t h a t f o u n d i n f a l s e - s co rp ions . T h e ' p r o ­

m e n a d e a d e u x ' r e su l t s i n t h e f ema le b e i n g j e r k e d b a c k a n d fo r th

u n t i l s h e i s i n t h e c o r r e c t p o s i t i o n ove r t h e s p e r m a t o p h o r e w h i c h

she t h e n p i cks u p ( A l e x a n d e r , 1956) . 1

Reproduction and life cycle T h e fer t i l i sed eggs d e v e l o p i n s i d e t h e m o t h e r a n d t h e y o u n g a re

b o r n a l ive . T h e c o u r s e o f d e v e l o p m e n t va r i e s a c c o r d i n g t o w h e t h e r

t h e eggs a re r i ch in yolk , a s in t h e B u t h i d a e , o r l ack ing in yolk , a s

1 Since this account was wri t ten, similar information has been ob ­tained on the mat ing habits of the Chact idae, Bothr iur idae and Buthidae as well as the Scorpionidae. It therefore seems likely that inseminat ion by means of spermatophores occurs th roughout the order and that t rue copulation may not take place as previously supposed (Alexander, 1957).

84 S C O R P I O N S

i n t h e S c o r p i o n i d a e . I n t h e f i r s t case t h e eggs p a s s q u i c k l y i n t o t h e

o v i d u c t a n d d e v e l o p t h e r e , t h e e m b r y o s c o n s u m i n g t h e yo lk w i t h

w h i c h t h e y a re f i l l e d ; i n t h e s e c o n d , t h e fer t i l i sed egg r e m a i n s i n

p lace a n d b e c o m e s c losely c o m m i n g l e d w i t h t h e m a t e r n a l t i s sues .

At t h e e n d of i ts d e v e l o p m e n t each e m b r y o lies in a d i v e r t i c u l u m

w h i c h possesses a t u b u l a r e x t e n s i o n l ike an u m b i l i c a l c o r d a l o n g

FIG. 2 1 . Developing embryos of scorpion (family Scorpionidae) showing 'bottle and teat ' . (After Vachon, 1 9 5 3 . )

w h i c h p a s s n u t r i e n t f l u i d s f r o m t h e wal l o f t h e m o t h e r ' s i n t e s t i n e .

T h e s e a re t r a n s f o r m e d b y g l a n d u l a r s e c r e t i o n s a n d t h e n led t h r o u g h

t h e t u b e t o t h e m o u t h o f t h e e m b r y o w h i c h h a s a w e l l - d e v e l o p e d

p h a r y n x w i t h w h i c h i t s u c k s t h e m a t e r n a l f l u i d ( V a c h o n , 1950a) .

T h e che l i ce rae o f t h e e m b r y o s c o r p i o n e n d i n c o n t r a c t i l e ves i cu la r

o r g a n s w h i c h ac tua l ly t a k e h o l d o f t h e t ea t a n d c a r r y i t t o t h e

m o u t h !

I n m a n y spec ies t h e y o u n g a r e b o r n d u r i n g t h e n i g h t , s o m e ­

t i m e s in t w o b a t c h e s s e p a r a t e d by an in t e rva l o f a d a y , b u t in

Buthotus alticola b i r t h h a s b e e n o b s e r v e d f r o m 7.0 to 9.0 a .m .

(Se r fa t a n d V a c h o n , 1950) . A c c o r d i n g t o F a b r e (1907) a n d W a t e r ­

m a n (1950) t h e y o u n g , w h i c h a re b o r n e n v e l o p e d i n t h e i r c h o r i o n ,

a r e f reed b y t h e i r m o t h e r , b u t t h i s u n l i k e l y h y p o t h e s i s h a s b e e n

d i s p r o v e d in B. occitanus, a n d in B. alticola by Ser fa t a n d V a c h o n

(1950) w h o s t a t e t h a t t h e y o u n g free t h e m s e l v e s w i t h o u t p a r e n t a l

a ss i s t ance , w h i l e in Euscorpius f lav icaudis t h e y o u n g e scape by lacer ­

a t i n g t h e c h o r i o n w i t h t h e i r s t i n g s ( C l o u d s l e y - T h o m p s o n , 1955a) .

T h e p r o c e s s o f m o u n t i n g t h e m o t h e r ' s b a c k m a y t a k e u p t o t w o

h o u r s a s t h e l i t t le s c o r p i o n s a re ve ry p l u m p a n d w e a k ( C l o u d s l e y -

T h o m p s o n , 1951 ; S c h u l t z e , 1927) . H e r e t h e y r e m a i n u n t i l af ter

t h e i r f i r s t m o u l t . In P . longimanus t h i s p e r i o d las ts a b o u t t e n d a y s

S C O R P I O N S 8 5

( S c h u l t z e , 1927) . in E . carpathicus f o u r t e e n d a y s ( B e r l a n d , 1932)* ,

in E. italicus t e n to t w e l v e d a y s ( C l o u d s l e y - T h o m p s o n , 1951) ,

w h i l s t in E. germanus i t t ake s a b o u t s i x t een d a y s ( C l o u d s l e y -

T h o m p s o n , 1955a) . N o d o u b t h o w e v e r t h e l e n g t h o f t i m e d e p e n d s

m u c h u p o n t h e s ea son a n d t e m p e r a t u r e a t w h i c h t h e a n i m a l s a re

l iv ing . T h e m o t h e r s c o r p i o n ca r r i e s h e r y o u n g a r o u n d b u t d o e s

n o t feed t h e m : t h e y exis t o n t h e n o u r i s h m e n t w h i c h t h e y d e r i v e

f r o m d i g e s t i n g t h e e m b r y o n i c yolk . Q u i t e w h i t e a n d m e a s u r i n g

on ly a f ew m i l l i m e t r e s in l e n g t h , t h e y r e m a i n p l ac id ly on h e r back ,

of ten c o m p l e t e l y h i d i n g h e r b o d y f r o m v i e w s o t h a t on ly t h e a p ­

p e n d a g e s a n d tail r e m a i n v i s ib l e . I f t h e y s h o u l d h a p p e n to fall off,

t h e y m a k e b u t feeb le efforts t o c l i m b b a c k a n d t h e s t i m u l u s for

t h i s i s o f s h o r t d u r a t i o n a n d i n h i b i t e d b y l igh t . T h e i r t a r s i possess

a spec ia l ly m o d i f i e d p a d w h i c h e n a b l e s t h e m t o c l i m b t o t h e i r

m o t h e r ' s back .

Af te r t h e first m o u l t t h e y o u n g a c q u i r e t h e typ ica l s c o r p i o n - l i k e

a p p e a r a n c e af ter w h i c h t h e y r e m a i n w i t h t h e i r m o t h e r for a d a y

o r t w o l o n g e r be fo re finally s c a t t e r i n g . G r o w t h i s a c c o m p a n i e d b y

m o u l t i n g a s i n all A r t h r o p o d a ; t h e o ld sk in c racks a r o u n d t h e ca ra ­

p a c e a n d i s s h e d c o m p l e t e l y , i n c l u d i n g t h e l i n ing o f t h e m i d g u t

a n d h i n d g u t a n d o f t h e f o u r p a i r s o f l u n g - b o o k s s i t u a t e d o n t h e

v e n t r a l s ide o f t h e t h i r d t o s ix th p r e - a b d o m i n a l s e g m e n t s . T h e

to ta l n u m b e r o f m o u l t s o f m o s t spec ies i s n o t exac t ly k n o w n a n d

m a y v a r y s o m e w h a t e v e n i n t h e s a m e spec ies , b u t i t i s b e l i e v e d

t h a t t h e r e a re e igh t s t ad i a in Palamnaeus longimanus a n d s even in

Androctonus australis.

B I B L I O G R A P H Y Identification GOUGH , L . H . and HIRST , S. ( 1 9 2 7 ) Key to identification of Egyptian

scorpions. Min. Agr. Egypt Tech. Sci. Bull., No . 7 6 , 1 - 8 . KRAEPELIN , K. ( 1 8 9 9 ) Scorpiones und Pedipalpi. Das Tierreich., 8, 1 - 2 6 5 .

MELLO-LEITAO ( 1 9 4 5 ) Escorpioes Sul-Americanos. Arq. Mus. Nac.

Brasil, 4 0 , 1 - 4 6 8 .

POCOCK, R. I. ( 1 9 0 0 ) The Fauna of British India, including Ceylon and Burma. Arachnida. London .

VACHON, M. ( 1 9 5 2 ) Etudes sur les Scorpions. Alger. WERNER, F . ( 1 9 3 5 ) Scorpiones, in H . G. BRONN'S Klass.Ordn. Tierreichs,5,

I V ( 4 ) , 1 - 3 1 6 .

86 S C O R P I O N S

Biology

ALEXANDER, A. J. (1955) Mat ing in scorpions. Nature, Lond., 1 7 8 , 867-8 . (1957) T h e cour tship and mat ing of the scorpion Opisthophthahnus

latimans. Proc. Zool. Soc. Lond., 1 2 8 , 529-44. BERLAND , L. (1945) Les Scorpions. Paris. BOTT , R. (1951) Beobachtungen am sudeuropaischen Skorpion (Euscor­

pius italicus). Natur. u. Volk., 8 1 , 290-3 . CLOUDSLEY-THOMPSON , J . L. (1951) Notes on Arachnida, 16 .—The

behaviour of a scorpion. Ent. Mon. Mag., 8 6 , 1 0 5 . (1955a) Some aspects of the biology of centipedes and scorpions.

Naturalist, 1 9 5 5 , 147-53. (1955b) On the function of the pectines of scorpions. Ann. Mag.

Nat. Hist., (12),8, 556-60. (1956) Studies in diurnal rhy thms, V I . Bioclimatic observations in

Tunis ia and their significance in relation to the physiology of the fauna, especially woodlice, centipedes, scorpions and beetles. Ann. Mag. Nat. Hist.,(12), 9, 305-29.

FABRE, J. H. (1907) Souvenirs entomologiques, Ser. 9, Paris. LANKESTER, E. R. (1883) Notes on the habits of the scorpions Androctonus

funestris Ehr. and Euscorpius italicus Roes. J .Linn. Soc. (Zool.), 1 6 , 4 5 5 - 6 2 . MILLOT , J. and PAULIAN , R. (1943) Valeur fonctionelle des poumons des

scorpions. Bull. Soc. zool. Fr., 5 8 , 97 -8 . PETRUNKEVITCH, A. (1947) Scorpion. Encyclopaedia Britannica. POCOCK, R. I. (1893) Notes upon the habits of some living scorpions.

Nature, Lond., 4 8 , 1 0 4 - 7 . (1896) H o w and why scorpions hiss. Nat. Sci., 9, 17-25.

SCHULTZE, W. (1927) Biology of the large Phil ippine forest scorpion. Philippine J. Sci.. 3 2 , 375-89.

SERFAT, A. and VACHON , M. (1950) Quelques remarques sur la biologie d 'un scorpion de l 'Afghanistan: Buthotus alticola (Pocock). Bull. Mus. Hist. Nat. Paris, (2), 2 2 , 215-18.

SERGENT, E. (1946) Les scorpions et Teau. Arch. Inst. Pasteur d'Algerie, 2 4 , 76-9; 304-5.

(1947) Abris des scorpions. Ibid., IS, 206-9. STRAHNKE , H. L. (1945) Scorpions of the genus Hadrurus Thore l l . Amer.

Mus. Nov., No. 1298, 1-9. THORNTON , I. W. B. (1956) Notes on the biology of Leiurus quinquestriatus

(H. E . , 1929) (Scorpiones, Buthidae) . Brit. J. Anim. Behav., 4, 92 -3 . VACHON , M. (1950) Remarques preliminaires sur l 'alimentation les

organes cheliceriens le biberon et la tetine de l 'embryon du scorpion: Ischnurus ochropus C. L. Koch (Scorpionidae). Arch. Zool. exp. gen., 8 6 , 137-56.

(1953) T h e biology of scorpions. Endeavour, 1 2 , 80-9 . WATERMAN , J. A. (1950) Scorpions in the Wes t Indies with special

reference to Tityus trinitatis. Caribbean Med. J., 1 2 , 167-77.

C H A P T E R V I

S O L I F U G A E

Classification and distribution T h e A r a c h n i d s o f t h e O r d e r Sol i fugae o r S o l p u g i d a , s o m e t i m e s

k n o w n a s ' f a l s e - s p i d e r s ' o r ' w i n d - s c o r p i o n s ' , a re a m o n g t h e m o s t

f o r m i d a b l e of t h e t e r r e s t r i a l i n v e r t e b r a t e s . A superf ic ia l r e s e m ­

b l a n c e t o t r u e s p i d e r s i s b e l i e d b y t h e s e g m e n t e d a b d o m e n w i t h o u t

s p i n n e r e t s , w h i l s t t h e legs o f t h e f o u r t h p a i r cha rac t e r i s t i ca l l y b e a r

five 'ma l l eo l i ' o r ' r a c q u e t o r g a n s ' w h o s e f u n c t i o n i s u n k n o w n , a l ­

t h o u g h i t h a s b e e n s u g g e s t e d t h a t t h e y m a y se rve t o s u p p o r t t h e

FIG. 22. Examples of Solifugid families: 1. Rhagodidae, 2. Hexi-sopodidae, 3. Galeodidae, 4. Eremobatidae, 5. Ammotrechidae.

(Drawings not to scale.) (After various authors.) 87

88 S O L I F U G A E

a b d o m e n . I t i s m o r e l ikely h o w e v e r t h a t t h e y a r e s ense o r g a n s

a n a l o g o u s w i t h t h e p e c t i n e s o f s c o r p i o n s . T h e h a i r y b o d y i s d i v i d e d

in to t w o p a r t s , a p r o s o m a o r c e p h a l o t h o r a x a n d an o p i s t h o s o m a o r

a b d o m e n w h i c h a re s e g m e n t e d a n d u n i t e d t o o n e a n o t h e r w i t h o u t

a n a r r o w p e d i c l e a s i s f o u n d in s p i d e r s . T h e che l i ce rae a r e ex ­

t r e m e l y wel l d e v e l o p e d , f o r m i n g t w o p o w e r f u l p i n c e r s w i t h w h i c h

t h e p r e y i s d e s t r o y e d . S o m e t i m e s t h e s e a re a s l o n g a s t h e e n t i r e

p r o s o m a a n d t h e y a re p o s s i b l y for t h e i r s ize t h e m o s t f o r m i d a b l e

j a w s i n t h e a n i m a l w o r l d . T h e p e d i p a l p s h a v e t h e n o r m a l six seg­

m e n t s a n d e n d , n o t in a c law, b u t in a p e c u l i a r suc to r i a l o r g a n to

b e d i s c u s s e d b e l o w .

T h e legs o f t h e So l i fugae a r e q u i t e c h a r a c t e r i s t i c . T h e first pa i r

a re l ong a n d r a t h e r feeble . T h e y a re n o t u s e d for w a l k i n g b u t a r e

ca r r i ed s t r e t c h e d o u t i n f ron t a n d u s e d a s a d d i t i o n a l tac t i le o r g a n s ,

a h a b i t f o u n d also i n t h e ' w h i p - s c o r p i o n s ' . T h e r e m a i n i n g legs a re

t r u e a m b u l a t o r y l i m b s , t h o s e o f t h e f o u r t h pa i r , w h i c h a r e t h e

s t r o n g e s t o f all , b e a r i n g t h e mal leo l i . T h e r e a r e o n l y t h r e e o f t h e s e

t o each h i n d leg i n t h e fami ly H e x i s o p o d i d a e , w h i c h i n c l u d e s t h e

c u r i o u s , s h o r t - l e g g e d Chelypus s p p .

T h e size o f t h e b o d y va r i e s f r o m o n e t o five c e n t i m e t r e s i n

l e n g t h , a n d t h e l a rge r spec ies s u c h as Galeodes arabs a n d G. ara-

neoides w h o s e f o r m i d a b l e a p p e a r a n c e i s e n h a n c e d by t h e i r u n u s u a l

h a i r i n e s s a n d b u l k , c a n w i t h t h e i r l i m b s s p a n a w i d t h o f five i n c h e s .

M o s t spec ies a re u n i f o r m l y ye l low o r b r o w n i n c o l o u r w h i l e t h o s e

of t h e g e n e r a Rhagodes a n d Dinorhax a re b lack . A few, h o w e v e r ,

h a v e a p a t t e r n of l o n g i t u d i n a l b l ack s t r i p e s on a y e l l o w b a c k g r o u n d ,

o r t h e r e v e r s e w i t h occas iona l r e d d i s h t i n t s .

P r e d o m i n a n t l y i n h a b i t a n t s o f ho t , d r y a n d d e s e r t a reas , t h e

Sol i fugae a re a l m o s t en t i r e ly conf ined t o t r o p i c a l a n d s u b t r o p i c a l

r e g i o n s . I n E u r o p e on ly six spec ies o c c u r a n d t h e s e a r e f o u n d i n

w a r m e r p a r t s s u c h a s s o u t h - e a s t S p a i n , G r e e c e , t h e B a l k a n s a n d

t h e v ic in i ty o f t h e Black Sea . T e n fami l i e s a re k n o w n to sc ience o f

w h i c h t w o , t h e E r e m o b a t i d a e a n d A m m o t r e c h i d a e , a re u n i q u e l y

N e a r c t i c , w h i l e t h e r e m a i n d e r a re r e s t r i c t e d t o t h e O l d W o r l d .

O f t h e s e t h e C e r o m i d a e a n d H e x i s p o d i d a e a re f o u n d i n Afr ica

s o u t h o f t h e E q u a t o r , t h e S o l p u g i d a e i n Afr ica a n d I r a q , w h i l e t h e

D a e s i i d a e a re d i s t r i b u t e d t h r o u g h o u t Afr ica , A r a b i a , As ia M i n o r ,

Pe r s i a a n d s o u t h e r n E u r o p e . T h e R h a g o d i d a e a n d G a l e o d i d a e a r e

S O L I F U G A E 89

r e s t r i c t e d t o a n a rea n o r t h o f t h e E q u a t o r r a n g i n g f r o m M o r o c c o t o

I n d i a a n d T u r k e s t a n : t h e r e m a i n i n g fami l ies , t h e K a r s c h i i d a e a n d

M e l a n o b l o s s i i d a e , h a v e a s o m e w h a t d i s c o n t i n u o u s d i s t r i b u t i o n in

Afr ica a n d Asia .

Sol i fugae a r e p a r t i c u l a r l y a b u n d a n t i n Afr ica , b u t n o n e a re

f o u n d i n M a d a g a s c a r a n d t h e y a re also a b s e n t f r o m A u s t r a l i a a n d

N e w Z e a l a n d .

General behaviour T h e s e a n i m a l s a re lovers o f w a r m t h a n d a re n e v e r f o u n d i n cold

or t e m p e r a t e c o u n t r i e s , a l t h o u g h o n e spec ies , Gylippus rickmersi,

i n h a b i t s t h e 10 ,000 foot p l a t e a u o f t h e P a m i r i n C e n t r a l Asia ,

n o r t h o f t h e H i n d u K u s h M o u n t a i n s . E v e n w h e r e t h e y t h r i v e ,

t h e y h i d e a w a y o r h i b e r n a t e t h r o u g h o u t t h e w i n t e r s e a s o n . T h e y

avo id fe r t i l e oases a n d s e e m t o p r e f e r u t t e r l y n e g l e c t e d r e g i o n s

w h e r e t h e soil i s b r o k e n a n d b a r e , b u t t h i s i s n o t b e c a u s e t h e y c a n ­

n o t exis t i n p r o x i m i t y w i t h m a n . O n t h e c o n t r a r y , t h e y f r e q u e n t l y

e n t e r t h e t e n t s o f t r ave l l e r s t o c a t c h f l i e s a n d o t h e r i n sec t s . A c ­

c o r d i n g t o A e l i a n , a n a rea o f E t h i o p i a w a s d e s e r t e d b y i ts i n h a b i ­

t a n t s on a c c o u n t o f t h e a p p e a r a n c e o f an i n c r e d i b l e n u m b e r o f

s c o r p i o n s a n d P h a l a n g i u m s ' b u t P l i n y , i n q u o t i n g t h e s a m e s to ry ,

r e p l a c e d P h a l a n g i u m ' by ' S o l f u g a ' . Gluvia dorsalis is sa id to be a

famil iar s igh t in t h e s t r e e t s o f M a d r i d a n d t h e spec ies Mummucia

variegata a n d Pseudocleobis morsicans o f ten r u n a b o u t in t h e s t r ee t s

o f S a n t i a g o w h e r e t h e y a r e k n o w n a s ' A r a n h a s de l So l ' ( s u n -

s p i d e r s ) . T h e m a j o r i t y o f Sol i fugae , a s t h e i r n a m e i n d i c a t e s , a re

h o w e v e r , n o c t u r n a l a n d h i d e a w a y u n d e r s t o n e s o r i n c rev ices o f

t h e soil d u r i n g t h e d a y t i m e . I t h a s b e e n s u g g e s t e d t h a t t h i s h a b i t

m a y b e c o r r e l a t e d w i t h a low t e m p e r a t u r e t o l e r a n c e , b u t t h e m a t t e r

ha s n o t b e e n t e s t e d e x p e r i m e n t a l l y .

H i n g s t o n (1925) h a s d e s c r i b e d t h e p r o c e s s o f b u r r o w i n g in a

P e r s i a n spec ies of Galeodes (G. arabs or G. araneoides). No g r e a t

skill i s e x h i b i t e d , a n d t h e p r o c e d u r e i s l a b o r i o u s e v e n in f r iable

soil . W h e r e t h e s a n d i s loose , a f u r r o w i s p l o u g h e d w i t h t h e

p o i n t e d m a n d i b l e s , t h e soil b e i n g r a k e d b a c k w i t h t h e h a i r y legs .

T h e a n i m a l faces i ts e x c a v a t i o n w i t h o u t s t r e t c h e d l i m b s ; t h e l ong

p e d i p a l p s a r e t h r u s t f o r w a r d t o e x p l o r e t h e way ; t h e first p a i r o f

legs a lso i s a d v a n c e d , b u t i t i s t h e s e c o n d p a i r t h a t fulfils t h e p u r -

90 S O L I F U G A E

p o s e o f r akes . T h e s e a r e p u s h e d i n t o t h e loose s a n d , t h e i r e n d s

b e i n g t u r n e d i n w a r d s s o a s t o g a t h e r i t i n a r m f u l s . T h e r a k i n g s a re

r e p e a t e d i n s u c h r a p i d succes s ion t h a t t h e s a n d c o m e s s p o u t i n g

f r o m b e n e a t h t h e a b d o m e n in a r h y t h m i c a l se r ies o f j e t s . F r o m

t i m e to t i m e t h e Sol i fug id r eve r se s i ts p o s i t i o n , l ower s itself i n t o

t h e excava t ion , t h r u s t s i t s b o d y i n t o t h e p l ace w h e r e i t p r e v i o u s l y

r a k e d , a n d shove l s u p t h e d e b r i s w i t h i ts b r o a d h e a d , espec ia l ly

a n y o f t h e l a rge r f r a g m e n t s w h i c h i t c a n n o t so easi ly d i s lodge w i t h

i ts r akes . T h e n i t aga in t u r n s a b o u t a n d r e s u m e s t h e scuffling w i t h

i ts s e c o n d pa i r o f legs . S o m e t i m e s t h e f ema le s m e r e l y c u t a c i rc le

i n t h e soil w i t h t h e i r j a w s a n d k ick t h e l o o s e n e d f r a g m e n t s a w a y

(Pocock , 1898) . Eremobates formicaria c o n s t r u c t s i ts b u r r o w in t h e

s a m e m a n n e r a s Galeodes, b u t i n s t e a d o f u s i n g a c o m m o n b u r r o w

t h r o u g h o u t t h e b r e e d i n g season , a n e w o n e i s c o n s t r u c t e d a l m o s t

eve ry n i g h t ( T u r n e r , 1916) .

Food and feeding habits Sol i fugae a re exc lus ive ly p r e d a t o r y a n d c a r n i v o r o u s , h a v i n g a n

e x t r a o r d i n a r y vo rac i t y . T h e y wil l c o n t i n u e f eed ing u n t i l t h e i r a b ­

d o m e n s a r e so d i s t e n d e d t h a t t h e y c a n sca rce ly m o v e . A y o u n g

Galeodes sca rce ly 5 mm l o n g h a s b e e n s een to d e v o u r ove r 100 flies

i n 2 4 h o u r s . A l t h o u g h in sec t s , i n c l u d i n g e v e n h a r d bee t l e s , f o r m

t h e i r s t ap l e d ie t , So l i fugae wil l kill a n d ea t l a rge s p i d e r s , s c o r p i o n s

a n d l i za rds . T h e y h a v e also b e e n o b s e r v e d t o kill m i c e a n d smal l

b i r d s . Seve ra l spec ies s u c h as Solpuga sericea a n d S. lineata b u r r o w

in to t h e g r o u n d to c a t c h t e r m i t e s w h i l e a C a l i f o r n i a n spec ies o f

Eremobates ki l ls b e e s , e n t e r i n g t h e h ive s in s e a r c h o f p r e y . T h e

smal l n o c t u r n a l spec ies E . pallipes f r o m C o l o r a d o is sa id to h u n t

b e d - b u g s .

T h e p r e y i s p r o b a b l y fo l lowed by s igh t in s o m e spec ies , for a

b l i n d Galeodes h a s difficulty in l o c a t i n g i ts v i c t i m s , b u t t h e n o c ­

t u r n a l S o u t h Af r i can Solpugyla globicornis s e a r c h e s a t r a n d o m w i t h

i ts p e d i p a l p s a n d first p a i r o f legs s t r e t c h e d f o r w a r d , a n d s igh t i s

n o t u s e d . I t i s pos s ib l e t h a t t h e o l fac tory s ense m a y also b e u s e d i n

o r i e n t a t i o n , as o n e s p e c i m e n w a s o b s e r v e d t r y i n g to ge t h o l d o f a

snai l t h a t h a d r e t r e a t e d i n t o i ts shel l (Bo lwig , 1952) . T h e l o n g -

l egged f o r m s can r u n a t g r e a t s p e e d so t h a t t h e y r e s e m b l e ba l l s o f

y e l l o w t h i s t l e d o w n b l o w n ove r t h e dese r t . Of t en w h e n g o i n g a t

S O L I F U G A E 9 1

full s p e e d , t h e y s t o p a b r u p t l y a n d b e g i n h u n t i n g a b o u t like a d o g

c h e c k e d i n m i d - c o u r s e b y t h e s c e n t o f g a m e . W h e n g o r g e d w i t h

food o r w h e n p r e g n a n t , h o w e v e r , t h e y a re fat a n d s lugg i sh . S o m e

spec ies h a v e b e e n k n o w n t o c l i m b t r e e s i n s e a r c h o f in sec t s a n d

o t h e r p r e y . I t i s p r o b a b l e t h a t t h e ab i l i ty t o m o v e i s t h e m a i n a t t r i ­

b u t e b y w h i c h l iv ing p r e y i s d i s t i n g u i s h e d f r o m n o n - l i v i n g , for i n

cap t iv i t y a d e a d in sec t wi l l be a t t a c k e d on ly i f s u i t a b l y m o v e d

( T u r n e r , 1916) .

T h e r e h a s b e e n m u c h c o n t r o v e r s y a s t o t h e p o i s o n o u s p r o p e r t i e s

w i t h w h i c h t h e s e c r e a t u r e s h a v e b e e n w i d e l y c r e d i t e d . L i c h t e n s t e i n

(1797) h a s e n d e a v o u r e d t o s h o w t h a t t h e m i c e w h i c h p l a g u e d t h e

Ph i l i s t i nes ( 1 S a m . v . 6 ) w h e n t h e y c a p t u r e d t h e ' a rk o f t h e C o v e ­

n a n t ' m a y h a v e b e e n Galeodes arabs, a n d i t i s c e r t a i n ly t r u e t h a t

t h e i r h a i r y b o d i e s a n d r a p i d m o v e m e n t s g ive t o m a n y spec ies a

m o u s e - l i k e a p p e a r a n c e . T h i s a u t h o r a lso s u g g e s t e d t h a t t h e

' e m e r o d s ' w i t h w h i c h t h e y w e r e p l a g u e d r e f e r r e d t o t h e sores

c a u s e d by t h e b i t e s o f t h e s e a n i m a l s , for So l i fugae h a v e b e e n

k n o w n t o a t t ack t r ave l l e r s a s l eep i n t h e d e s e r t a t n i g h t . O l iv i e r

(1807) d i sbe l i eved t h e awful r e p o r t s o f t h e A r a b s , w h o w e r e t e r r i ­

fied a t t h e s igh t o f t h e w i n d - s c o r p i o n s , w h i c h a p p e a r e d i n t h e t e n t s

a t n i g h t a n d w h o t o l d y a r n s , e a c h m o r e h o r r i b l e t h a n t h e last , a s t o

t h e i r d a n g e r o u s b i t e s . H e d i d a d m i t , h o w e v e r , t h a t w i t h such j a w s

t h e r e s u l t s w o u l d p r o b a b l y b e m o s t pa in fu l . P e o p l e h a v e b e e n b i t ­

t en a c c i d e n t a l l y b y t h e a n i m a l s g e t t i n g u n d e r t h e i r c l o t h e s a n d t h e

effect i s s o m e t i m e s seve re . T h e i n h a b i t a n t s o f B a k u o n t h e C a s p i a n

Sea be l i eve t h a t a local spec i e s is e spec ia l ly p o i s o n o u s af ter i ts

w i n t e r s l eep , a n d t h e y r u b t h e w o u n d w i t h t h e ca rcass o f t h e a n i m a l

af ter first s t e e p i n g i t in b o i l i n g oil , in o r d e r to n e u t r a l i s e t h e effects

o f t h e v e n o m . O n t h e o t h e r h a n d , t h e S o m a l i s d o n o t r e g a r d t h e m a s

n o x i o u s — i n d e e d , t h e y h a v e n o n a m e i n t h e i r l a n g u a g e for a n y t h i n g

so u n i m p o r t a n t ! H u t t o n (1843) r e c o r d s t h e case o f a l i za rd b i t t e n

by a Galeodes w h i c h r e c o v e r e d in t h r e e days , a n d o t h e r a u t h o r s

have s e a r c h e d in va in for p o i s o n g l a n d s s u c h a s t h o s e in t h e j a w s o f

spiders.* B e r n a r d (1897) s u g g e s t e d t h a t p o i s o n i n g m i g h t r e s u l t f r o m

a s i m p l e e x u d a t i o n o f t ox ic e x c r e t o r y m a t t e r t h r o u g h t h e seta l p o r e s

w h i c h , h e be l i eved , c o u l d b e t r a c e d a l o n g t h e t i p s o f t h e j a w s .

P h i s a l i x ( 1 9 2 2 ) * r e c o r d s a n u m b e r of cases of Sol i fugae b i t i n g

m e n a n d c o n c l u d e s t h a t i n v i e w o f t h e sever i ty o f t h e effects w h i c h

9 2 S O L I F U G A E

m a y occas iona l ly r e su l t i n d e a t h , t h e poss ib i l i t y o f p o i s o n c a n n o t

b e en t i r e ly e l i m i n a t e d . A l t h o u g h t h e m a t t e r h a s n o t ye t b e e n fully

t e s t e d e x p e r i m e n t a l l y , i t i s n o w gene ra l l y a s s u m e d t h a t Sol i fugae

a re n o t v e n o m o u s s ince a n u m b e r o f p e o p l e h a v e a l l owed t h e m ­

selves t o be b i t t e n w i t h o u t a n y ill effects. On t h e few occas ions

t h a t p o i s o n i n g d o e s o c c u r , i t i s m o s t p r o b a b l y d u e to in fec t ion o f

t h e w o u n d .

I n t h e s i l ence o f t h e n i g h t , t h e d e s e r t So l i fugae r ace a b o u t , c o n ­

d u c t t h e i r a m o u r s a n d g l u t t h e m s e l v e s o n i n n u m e r a b l e in sec t s t o

s u p p l y t h e i r r e q u i r e m e n t s d u r i n g t h e w i n t e r s l eep .

T h e S o u t h Af r i can Solpuga caffra is a l a rge spec ies w i t h m a s s i v e

p o w e r f u l j a w s set i n a v e r y w i d e h e a d - p l a t e . T h e m e t h o d o f c a t c h ­

ing i n sec t s s e e m s to d e p e n d on c o n t a c t a n d w i t h i n a c e r t a i n cr i t ical

d i s t a n c e t h e p r e y i s se ized w i t h a s h o r t s p r i n g a n d l i g h t n i n g s n a p

o f t h e j a w s . A c r i cke t i s s e l d o m m i s s e d , b u t m o r e ac t ive g r a s s ­

h o p p e r s s o m e t i m e s e s c a p e t h e first a t t e m p t t o c a t c h t h e m . W h i l e

b e i n g e a t e n t h e c r a c k l i n g s o u n d o f t h e h a r d e r p a r t s o f a n i n sec t ' s

cu t i c l e a s t h e y a r e c r u s h e d in t h e che l i ce rae c a n be h e a r d f r o m a

d i s t a n c e o f severa l f e e t ! T h e p o i n t e d e x t r e m i t i e s o f t h e j a w s a re

of ten u s e d t o p i e r c e t h e b o d y o f t h e p r e y ( L a w r e n c e , 1949) a n d I

h a v e o b s e r v e d t h e s a m e w h e n Rhagodes s p . f eeds o n la rge M y g a l o -

m o r p h s p i d e r s .

T h e p r e y w h e n c a u g h t i s u s u a l l y h e l d c r o s s - w a y s b y b o t h j a w s .

M a s t i c a t i o n a n d m a c e r a t i o n i s a fair ly c o m p l i c a t e d p r o c e d u r e s ince

t h e r e a r e s i m u l t a n e o u s m o v e m e n t s o f t h e j a w s i n t w o p l a n e s ;

first t h e r e i s t h e o p e n i n g a n d c los ing of t h e j a w s a l t e rna t e ly , a

m o v e m e n t i n t h e ve r t i ca l p l a n e ; a t t h e s a m e t i m e t h e p r e y i s

g r o u n d b e t w e e n t h e che l i ce rae , t h e left a n d r i g h t s ides m o v i n g

a l t e rna t e ly b a c k w a r d s a n d f o r w a r d s p r o d u c i n g a h o r i z o n t a l m o v e ­

m e n t . T h e p r e y i s s p e e d i l y r e d u c e d t o a soft p u l p a n d p r e s s e d

aga ins t t h e m o u t h o p e n i n g w h e r e m o s t o f i t i s a b s o r b e d in a s e m i ­

fluid c o n d i t i o n . E v e n h a r d , c h i t i n o u s p a r t s , a l t h o u g h u sua l l y r e ­

j e c t e d , m a y a t t i m e s b e d e v o u r e d .

M o s t v i c t i m s a re o v e r p o w e r e d w i t h ease , b u t occas iona l ly So l i ­

fugae e n c o u n t e r a m o r e p o w e r f u l a d v e r s a r y s u c h as a c e n t i p e d e ,

s c o r p i o n o r a n o t h e r Sol i fug id w h i c h will n o t s u b m i t w i t h o u t a

s t u b b o r n fight. H i n g s t o n (1925) g ives a g r a p h i c a c c o u n t o f s u c h

c o m b a t s in Galeodes arabs a n d G. araneoides. He be l i eves t h a t t h e s e

S O L I F U G A E 9 3

spec ies h a v e n o t m u c h facu l ty o f v i s ion , t a s t e o r h e a r i n g , b u t h is

e x p e r i m e n t s a re o p e n t o t h e o b j e c t i o n t h a t h e w a s t e s t i n g t h e

r e s p o n s e s o f t h e a n i m a l s t o u n n a t u r a l s t i m u l i w h i c h t h e y d o n o t

e n c o u n t e r i n t h e i r n o r m a l life. T h e chief s e n s e i s t h a t o f t o u c h ,

w h i c h i s l oca t ed i n t h e i n n u m e r a b l e ha i r s w i t h w h i c h t h e b o d y i s

cove red . T h e c o n t e s t i s u s u a l l y m o r e a n e x h i b i t i o n o f swi f tness

t h a n o f a n y p a r t i c u l a r s t r a t eg ica l skill , t h e v i c t i m b e i n g q u i c k l y

m a c e r a t e d b y t h e j a w s o f i ts f e roc ious e n e m y .

D u e l s b e t w e e n r ival So l i fug ids a re u sua l ly m o r e p r o l o n g e d . T h e

c o m b a t a n t s r u s h a t e a c h o t h e r , t h e i r p e d i p a l p s t a k i n g t h e i m ­

m e d i a t e shock a n d w a r d i n g off t h e p o n d e r o u s j a w s . A f t e r t h i s t h e

c o n t e s t b e c o m e s v e r y v a r i a b l e . S o m e t i m e s t h e a n i m a l s r ock f r o m

s ide t o s ide , t h e i r b o d i e s k e p t a p a r t b y t h e i r p r o j e c t i n g p e d i p a l p s

l ike w r e s t l e r s a t a r m ' s l e n g t h w a i t i n g for a c h a n c e to s e c u r e a g r i p .

A t o t h e r s t h e y c o m e q u i c k l y i n t o c loser a p p o s i t i o n a n d t h e i r j a w s

i n t e r l ock a s t h e y s t r u g g l e to ge t a v i ta l g r i p . G i v e n t h e s l igh tes t

o p p o r t u n i t y o n e wil l d r i v e i t s che l i c e r ae i n t o t h e soft p a r t s o f i ts

o p p o n e n t a n d t h e s t r u g g l e e n d s . N o t i n f r e q u e n t l y h o w e v e r t h e

i n t e r l o c k i n g j a w s a re d i s e n g a g e d a n d t h e w r e s t l e r s s p r i n g a p a r t

on ly t o c h a r g e aga in , w h e n o n e m a y o v e r w h e l m t h e o t h e r .

S a v o r y ( 1 9 2 8 ) * w r i t e s t h a t d u r i n g t h e G r e a t W a r So l i fugae b e ­

c a m e fami l i a r t o t h e t r o o p s i n E g y p t a n d t h e N e a r E a s t w h e r e

Galeodes arabs i s c o m m o n . T h e so ld ie r s n a m e d t h e m g e r r y ­

m a n d e r s ' a n d a d m i r e d t h e m for t h e i r fe roc i ty . A t o n e t i m e t h e

m e n s t a t i o n e d a t A b o u k i r k e p t p e t Sol i fugae a n d m a t c h e d t h e m

l ike f igh t ing cocks . E a c h C o m p a n y h a d i ts c h a m p i o n a n d b e t s

w e r e freely la id on t h e r e s u l t s o f t h e f igh ts . S ize i s n o t a lways a

dec i s ive f ac to r a n d i t s o m e t i m e s h a p p e n s t h a t a s m a l l e r i n d i v i d u a l

se izes i ts o p p o n e n t b e t w e e n i ts t o o w i d e l y - o p e n e d j a w s a n d c o n ­

q u e r s by h o l d i n g on in a p o s i t i o n in w h i c h t h e b i g c r e a t u r e i s q u i t e

he lp l e s s . C o m b a t s w i t h s c o r p i o n s u sua l l y r e s u l t i n t h e d e a t h o f t h e

l a t t e r b e f o r e t h e y h a v e t i m e t o u s e t h e i r s t i ngs . I n 1942 i n L i b y a ,

my t r o o p c o r p o r a l k e p t a s h o r t - l e g g e d , b lack Rhagodes in a b i s c u i t

t i n o n t h e b a c k o f h i s t a n k a n d fed i t a l m o s t en t i r e ly o n s c o r p i o n s .

I n a d d i t i o n t o t h e i r u s e a s buffers i n t h e h o u r o f b a t t l e , w h e n

t h e y a re o f s u p r e m e i m p o r t a n c e , t h e p e d i p a l p s a r e u s e d a s i m ­

p l e m e n t s o f f eed ing . T h e y a re s t r e t c h e d f o r w a r d l ike l o n g a r m s t o

seize p i eces o f food w i t h t h e i r t e r m i n a l s u c k e r s . T h e m o r s e l s a r e

9 4 S O L I F U G A E

t h e n t r a n s f e r r e d t o t h e j a w s . W h e n d r i n k i n g , t h e t i p s a re b r o u g h t

t o g e t h e r , t h r u s t i n to t h e f lu id a n d t h e n e m p l o y e d like a p a i r o f

h a n d s t o lift t h e l i q u i d i n t o t h e m o u t h ( H i n g s t o n , 1925) . T h e pa lpa l

o r g a n s w e r e o r ig ina l ly d e s c r i b e d b y L i c h t e n s t e i n (1797) a s o r g a n s

o f scen t , b u t l a te r i t w a s c l a i m e d t h a t t h e y w e r e s u c k e r s . T o w a r d s

t h e e n d o f t h e last c e n t u r y h o w e v e r , i t w a s s u g g e s t e d o n m o r p h o ­

logical g r o u n d s t h a t t h e ea r l i e r v i ew w a s t h e c o r r e c t o n e a n d H e y -

m o n s (1902) c l a i m e d t h a t t h e m a l e Sol i fugae r e c o g n i s e d t h e females

by t h e sense o f sme l l , t h e r e c e p t o r o r g a n s for w h i c h lay in t h e

ta rs i o f t h e p e d i p a l p s . A f t e r a m p u t a t i o n o f t h e s e o r g a n s , m a l e s in ­

va r i ab ly f led w h e n i n t r o d u c e d i n t o t h e p r e s e n c e of a f ema le . I t i s

n o t s u r p r i s i n g , h o w e v e r , t h a t t h e m a t i n g i n s t i n c t s h o u l d b e d e s ­

t r o y e d b y t h i s c r i p p l i n g t r e a t m e n t .

Sol i fugae c a n c l i m b up g lass o r o u t o f a b u c k e t by m e a n s o f t h e i r

p e d i p a l p s w h o s e o r g a n s a re u n d o u b t e d l y s u c k e r s ( C l o u d s l e y -

T h o m p s o n , 1954) .

Enemies L i t t l e i s k n o w n o f t h e e n e m i e s o f Sol i fugae , b u t D i s t a n t (1892)

in t h e T r a n s v a a l s aw a wag ta i l a t t ack a Solpuga hostilis a n d P o c o c k

(1898) s u g g e s t s t h a t t h e y a re p r o b a b l y e a t e n b y i n s e c t i v o r o u s

b i r d s , smal l m a m m a l s a n d r ep t i l e s . T h e y h a v e r e c e n t l y b e e n f o u n d

i n t h e s t o m a c h c o n t e n t s o f a n Af r i can S t e p p e B u z z a r d . E n e m i e s also

i n c l u d e l a rge l i za rds , o t h e r r ep t i l e s a n d o t h e r Sol i fugae t oo , for

c a n n i b a l i s m i s b y n o m e a n s u n k n o w n .

T h e n i n t h s o m i t e o f So l i fugae i s s u p p r e s s e d i n t h e a d u l t a n d t h e

p r o s o m a i s j o i n e d t o t h e o p i s t h o s o m a ac ross i ts w h o l e w i d t h .

N e v e r t h e l e s s , t h e r e i s a g r e a t f l ex ib i l i ty b e t w e e n t h e t w o p a r t s o f

t h e b o d y a n d t h e a b d o m e n can b e ra i sed u n t i l i t i s a l m o s t ver t i ca l .

T h i s ac t i on i s c o m m o n in life a n d r e su l t s in a s c o r p i o n - l i k e a p ­

p e a r a n c e , p a r t i c u l a r l y i n t h e s h o r t - l e g g e d b lack R h a g o d i d a e . I t

h a s b e e n s u g g e s t e d ( C l o u d s l e y - T h o m p s o n , 1949) t h a t t h i s b e ­

h a v i o u r m a y be a f o r m o f m i m i c r y ; a t a n y r a t e , t h a t r a i s ing t h e

a b d o m e n i n t h i s f a sh ion m a y b e a n asse t i n d e t e r r i n g a n a t t acke r .

A t t h e s a m e t i m e t h i s v u l n e r a b l e m e m b e r i s k e p t a w a y f r o m d a n g e r

a n d t h e foe i s p r e s e n t e d w i t h a p a i r o f g a p i n g j a w s s u r r o u n d e d by

f i v e p a i r s o f s t r o n g l i m b s a r m e d w i t h l ong b r i s t l e s , s h o r t s p i n e s

a n d s h a r p c laws.

S O L I F U G A E 95

Sol i fugae c a n s t r i d u l a t e a n d m a k e g r u n t i n g s o u n d s b y r u b b i n g

t o g e t h e r a p a i r o f h o r n y r i d g e s on t h e i n n e r sur face o f t h e che l i ­

ce rae . An e n r a g e d Galeodes h a s b e e n sa id t o ' s c r e e c h ' a n d t h i s , l ike

F I G . 23. Galeodes arabs in defensive at t i tude. (After Millot and Vachon, 1949.)

t h e h i s s i n g of s c o r p i o n s a n d s n a k e s , i s p r o b a b l y a f o r m of a d v e r t i s e ­

m e n t a n d a w a r n i n g t o e n e m i e s .

T h e o n l y pa r a s i t e o f Sol i fugae so far r e c o r d e d i s t h e I n d i a n

P o m p i l i d w a s p Salius sycophanta w h i c h h a s b e e n seen , af ter a p r o ­

l o n g e d s t r u g g l e , to s t i ng a Galeodes a n d d r a g i t to a h o l e in w h i c h

w e r e a f t e r w a r d s f o u n d no less t h a n f ive Galeodes all d e p r i v e d of

t h e i r legs a n d w i t h a s ing le egg a t t a c h e d t o t h e h a i r o n t h e u n d e r ­

s ide o f t h e i r s t o m a c h s . Al l w e r e q u i t e d e a d e x c e p t for t h e las t

w h i c h w a s still m o v i n g feebly.

Mating habits Sexua l d i f ferences i n Sol i fugae a re n o t s t r i k ing . T h e m a l e i s

s m a l l e r a n d o f l i gh t e r b u i l d t h a n t h e f emale , b u t h i s legs a re l o n g e r .

96 S O L I F U G A E

T h e y p r o b a b l y s t a n d h i m i n g o o d s t ead a t m a t i n g t i m e w h e n t h e

f emale i s a l leged to kill a n d d e v o u r h e r less p o w e r f u l m a t e i f s h e

c a n ! T h e j a w s o f t h e m a l e a re less b u l k y t h a n t h o s e o f t h e f ema le

w h i c h a re u s e d t o d ig b u r r o w s i n w h i c h t h e eggs a re la id . T h e y a re

less s t r o n g l y t o o t h e d a n d b e a r on t h e i r u p p e r s ide a p e c u l i a r w h i p ­

like s t r u c t u r e o f u n k n o w n f u n c t i o n k n o w n a s t h e f l age l l um.

M a t i n g t akes p l ace a t d u s k o r d u r i n g t h e n i g h t : i t i s r a p i d a n d

b r u t a l . A c c o r d i n g to H e y m o n s (1902) w h o o b s e r v e d i t i n Galeodes

caspius d u r i n g a j o u r n e y ac ros s t h e s t e p p e s of T u r k e s t a n , t h e m a l e

c o u r t s h i s m a t e by s t r o k i n g he r , t h u s r e d u c i n g h e r to a s t a t e o f

l e t h a r g y . H e t h e n seizes h e r w i t h h i s che l i ce rae , p e d i p a l p s a n d

legs , u s u a l l y w i t h o u t h a r m i n g he r , ca r r i e s h e r for s o m e l i t t le d i s ­

t a n c e a n d lays h e r o n h e r s ide . Af te r m a s s a g i n g h e r v e n t r a l su r face

for s o m e t i m e w i t h h i s j a w s , h e o p e n s h e r gen i t a l orifice w h o s e

e d g e s h a v e b e c o m e swo l l en f rom t h e s e a t t e n t i o n s , lifts h i s a b d o m e n

a n d e m i t s a m a s s o f s p e r m a t o z o a w h i c h falls t o t h e g r o u n d . G a t h e r ­

ing t h i s w i t h h i s che l i ce rae , he forces i t i n t o t h e vag ina o f t h e fe­

m a l e , c loses t h e s ides a n d h o l d s t h e m s h u t for a w h i l e . T h e n h e

b o u n d s off a n d flees be fo re she can c a t c h h i m . A m a l e can effect

severa l c o p u l a t i o n s i n succes s ion b u t af ter t h e first t h e s p e r m a t i c

m a s s i s c o m p a r a t i v e l y sma l l a n d h e d ies s h o r t l y a f t e r w a r d s .

T h e s e a c t i o n s a re p u r e l y reflex, b e c a u s e i f t h e a n i m a l s a re s e p a r a ­

t e d d u r i n g c o p u l a t i o n t h e m a l e wil l c o n t i n u e h i s m a s s a g i n g m o v e ­

m e n t s aga ins t t h e h a n d o f t h e o b s e r v e r , j u s t a s t h o u g h t h e f emale

w e r e sti l l t h e r e . A l t h o u g h t h e to ta l ac t m a y last for severa l m i n u t e s ,

c e r t a i n de ta i l s a re e x t r e m e l y r a p i d a n d i t i s difficult to see exac t ly

w h a t i s o c c u r r i n g ; for e x a m p l e , i t i s n o t q u i t e c lea r h o w t h e m a s s

o f s p e r m a t o z o a i s g a t h e r e d u p a n d i n t r o d u c e d i n t o t h e gen i t a l

orifice of t h e female .

Reproduction and life cycle Afte r fer t i l i sa t ion t h e f emale d e v e l o p s a n e n o r m o u s a p p e t i t e for

t w o o r t h r e e w e e k s . T h e r e fo l lows a p e r i o d o f i n t e n s e t u n n e l l i n g

o p e r a t i o n s d u r i n g w h i c h a d e e p b u r r o w i s c o n s t r u c t e d , m o s t l y a t

n i g h t . In Solpuga caffra e g g - l a y i n g las ts for s o m e 3 1 / 2 -4 1 / 2 h o u r s

( L a w r e n c e , 1949) , s o m e 200 eggs b e i n g p r o d u c e d . I n t h e sma l l e r

S. hostilis t h e n u m b e r i s u n d e r 100. D u r i n g l a b o u r t h e female lies

o n h e r s ide r a t h e r l is t lessly w h i l e t h e eggs s l ip f r o m h e r a t r e g u l a r

PLATE la. A group of woodlice. T o p row: Ligia oceanica, Ligidium hypno-rum, Hemilepistus reaumtiri and Armadillidium vulgare. Bottom row: Oniscus asellus, Porcellio scaber, Androniscus dentiger and Philoscia muscorum.

T h e halfpenny gives the scale. (Photo: J. L. Cloudsley-Thompson.)

PLATE lb. Ligia oceanica (length 2-3 cm), Platyarthrus hoffmannseggi (length 3 mm) and Oniscus asellus (length 16 m m ) . (From W e b b and

Sillem, 1906.)

PLATE IVb. G i a n t t r o p i c a l m i l l i p e d e (Spirostrephis s p . ) . ( S h e l l p h o t o ­

g r a p h s . )

PLATE I V A . F l a t - b a c k e d m i l l i p e d e (Polydesmus angustus).

PLATE V b . T h e c o m m o n c e n t i p e d e (Lithobius forficatus). T h e s p e c i m e n

h a s l o s t s o m e l e g s . ( S h e l l p h o t o g r a p h . )

PLATE V A . A m e r i c a n h o u s e c e n t i p e d e (Scutigera forceps). (Photo: H u g h

S p e n c e r . )

PLATE VIa. Scolopendra cingulata

PLATE VIb. Head of S. cingulata. (Photos: J. L . Cloudsley-Thompson.)

PLATE V I I b . N e w l y b o r n s c o r p i o n s e s c a p i n g f r o m t h e i r c h o r i o n s . (Photos:

E . A . R o b i n s . )

PLATE V I I A . F a t - t a i l e d s c o r p i o n (Androctonus australis). T h e h a l f p e n n y

g i v e s t h e s c a l e . {Photo: J . L . C l o u d s l e y - T h o m p s o n . )

PLATE V I I I a . Euscorpius italicus with newly born young.

PLATE V I I I B . E. italicus, the same female protecting her young just after their first moult . T h e cast skins can be seen on the mother ' s back. (Photos:

J. L. Cloudsley-Thompson.)

PLATE IXa. Left, Androctonus australis, one of the most deadly species in the world. Right, ignoring a hard desert beetle (Akis spinosa). (Photos:

J. L. Cloudsley-Thompson.)

PLATE 1X6. Left, black scorpion (Androctonus aeneas). (Photo: J. L. Cloudsley-Thompson.) Right, pectine of scorpion much enlarged. (Photo:

E. A. Robins.)

PLATE Xb. Solpuga caffra, f e m a l e d e p o s i t i n g e g g s . (Photo: R . A . H o l l i d a y . )

PLATE X « . L e f t , r a c q u e t o r g a n s o f S o l i f u g i d ; r i g h t , p e c t i n e o f s c o r p i o n .

{Photos: E . A . R o b i n s . )

PLATE X I A . Solifugids fighting. (Photo: Richard L. Cassell.)

PLATE Xlb. Whip-scorpion (Thelyphomis candatus). (Photo: E. A. Robins.)

PLATE X I I b . H a r v e s t s p i d e r s . L e f t , Trogulus tricarumtus; r i g h t , Nemas-

toma chrysomelas. (Photos: c o p y r i g h t , J . H . P . S a n k e y . )

PLATE X I I a . L e f t , M y g a l o m o r p h s p i d e r ; r i g h t , F a l s e - s c o r p i o n (Toxochernes

panzeri).

PLATE X I I I A . T h e j u m p i n g s p i d e r (Phidippus audax).

PLATE X I 1 1 6 . J u m p i n g s p i d e r (Phidippus audax) c l i m b i n g u p t h e s a f e t y -

l i n e . (Photos: W a l k e r v a n R i p e r . )

PLATE XlVa. W o l f s p i d e r (Lycosa s p . ) w i t h e g g s a c .

PLATE XlVb. L e f t , Amaurobius ferox ( m a l e ) ; r i g h t , Scytodes thoracica

( f e m a l e c a r r y i n g e g g s a c ) . (Photos: J . L . C l o u d s l e y - T h o m p s o n . )

PLATE X V 7 . Argiope bruennichi female on web. Left, ventral; right, dorsal view. T h e narrow ribbons of silk or s tabi l imentum help to camou­

flage the spider. (Photos: J. L. Cloudsley-Thompson.)

PLATE XVb. Brown tick (Rhipicephalus appendiculatus). Male left; female right. (Shell photograph.)

PLATE X V I a . B o n t t i c k (Amblyomma hebraeum). C l o s e u p v i e w o f h e a d

a n d m o u t h p a r t s o f m a l e .

PLATE X V I b . R e d s p i d e r m i t e s (Paratetranychus pilosus). A d u l t s , e g g s

a n d h a t c h e d e g g c a s e s o n u n d e r s i d e o f a p p l e l e a f . ( S h e l l p h o t o g r a p h s . )

PLATE X V I I a . B i g b u d m i t e (Eriophiyes ribis). I n f e c t e d b u d o n t o p w i t h

n o r m a l b u d u n d e r n e a t h .

PLATE X V I I b . B i g b u d m i t e (EriopJiyes ribis) r e m o v e d f r o m b l a c k c u r r a n t

b u d . ( S h e l l p h o t o g r a p h s . )

S O L I F U G A E

in t e rva l s : s h e i s l i m p a n d m o t i o n l e s s e x c e p t for r h y t h m i c c o n t r a c ­

t i o n s o f h e r b o d y a t a r a t e o f a p p r o x i m a t e l y o n e p e r t w o s e c o n d s .

T h e eggs o f Galeodes m a y n u m b e r m o r e t h a n 2 0 0 . T h e y a r e i n t h e

f o r m o f w h i t e a n d g l i s t e n i n g s p h e r e s t h a t reflect t h e s u n l i g h t w i t h a

beau t i fu l m e t a l l i c l u s t r e a s i f m a d e o f m o t h e r - o f - p e a r l : t h e y a d h e r e

to o n e a n o t h e r in c o m p a c t h e a p s . In Solpuga caffra t h e eggs a r e of a

l ight , b u t d i r t y ye l l ow co lou r , w h i l e in S . hostilis t h e r e a r e d a r k e r

m a r k i n g s . W i t h i n a d a y o r t w o af ter o v i p o s i t i o n t h e f ema le b e g i n s

to t a k e an i n t e r e s t in f eed ing . Eremobates formicaria lays m o r e t h a n

o n e b a t c h o f sma l l w h i t e s p h e r i c a l eggs p e r s eason , b u t c loses t h e

m o u t h o f t h e b u r r o w a n d leaves t h e m t o t h e i r fate .

T h e a p p e a r a n c e a n d d e t a i l e d s t r u c t u r e o f t h e n e w l y h a t c h e d

first l a rva a p p e a r s t o v a r y c o n s i d e r a b l y i n d i f ferent g e n e r a . I n

Galeodes t h e y o u n g l a rvae e m e r g e f r o m t h e eggs w i t h i n a d a y o r

t w o af ter t h e y a r e la id . A t first t h e y a r e soft, w h i t e a n d he lp l e s s .

T h e y a r e u n a b l e t o m o v e , b u t af ter t w o o r t h r e e w e e k s , d u r i n g

w h i c h t h e y a re c lose ly g u a r d e d b y t h e i r m o t h e r , t h e first m o u l t

t ake s p l a c e a n d f r o m t h e n o n t h e y o u n g c r e a t u r e s r a p i d l y b e c o m e

m o r e ac t ive . T h e i r i n t e g u m e n t h a r d e n s a n d p r o g r e s s i v e l y a s s u m e s

t h e v a r i o u s e x t e r n a l c h a r a c t e r s o f t h e m a t u r e a n i m a l . E v e n t u a l l y

t h e y d i s p e r s e . T h e n u m b e r o f m o u l t s a n d t h e l e n g t h o f t i m e r e ­

q u i r e d t o r e a c h t h e a d u l t c o n d i t i o n i s n o t k n o w n w i t h c e r t a i n t y i n

a n y spec ies o f t h e o r d e r Sol i fugae .

B I B L I O G R A P H Y Identification

KRAEPELIN, K. ( 1 9 0 1 ) Arachnoidea: Palpigradi u n d Solifugae. Das Tierreich, 1 2 , 1 - 1 5 9 .

M U M A , M . H . ( 1 9 5 1 ) T h e Arachnid Order Solpugida i n the Uni ted States. Bull. Amer. Mus. Nat. Hist., 9 7 , ( 2 ) , 3 1 - 1 4 2 .

ROEWER, C. F. ( 1 9 3 4 ) Solifugae, in H. G. BRONN'S Klass. Ordn. Tier-reichs, 5 , iv ( 4 ) , 1 - 6 0 8 .

( 1 9 4 1 ) Solifugen 1 9 3 4 - 4 6 . Veroff. deuts. Kolon.-Ubersee-Mus., 3 , 9 7 - 1 9 2 .

Biology

BERNARD, A. ( 1 8 9 7 ) 'Wind-scorpions ' , a brief account of the Galeodidae. Sci. Prog. (N.S.) , 1 , 3 1 7 - 4 3 .

BOLWIG , N. ( 1 9 5 2 ) Observations on the behaviour and mode of orienta­tion of hunt ing Solifugae. J. Ent. Soc. S. Afr., 1 5 , 2 3 9 - 4 0 .

G S.S.C.M

9 8 S O L I F U G A E

CLOUDSLEY-THOMPSON, J . L . ( 1 9 4 9 ) Notes on Arachnida, 9 . — D o Solifugae mimic scorpions? Ent. Mon. Mag., 8 5 , 4 7 .

( 1 9 5 4 ) Notes on Arachnida, 2 2 . — T h e function of the palpal organ of Solifugae. Ibid., 9 0 , 2 3 6 - 7 .

DISTANT , W . L . ( 1 8 9 2 ) Are the Solpugidae poisonous? Nature, Lond., 4 6 , 2 4 7 .

HEYMONS, R. ( 1 9 0 2 ) Biologische Beobachtungen an asiatischen Solifugen. Abh.preuss. Akad. Wiss., 1 9 0 , 1 - 6 5 .

HINGSTON, R. W. ( 1 9 2 5 ) Nature at the Desert's Edge. London . 1 9 2 - 2 6 1 . H U T T O N , T. ( 1 8 4 3 ) Observations on the habits of a large species of

Galeodes. Ann. Mag. Nat. Hist., 1 2 , 8 1 - 5 . LAWRENCE, R. F. ( 1 9 4 9 ) Observations on the habi ts of a female Solifuge,

Solpuga caffra Pocock. Ann. Transvaal Mus., 2 1 , 1 9 7 - 2 0 0 . LICHTENSTEIN , A . A. H. ( 1 7 9 7 ) Gat tungen Solpuga u n d Phalangium in

HERBST, J. F. W. Natursystem der ungefliigelten Insekten, Berlin. LONNBERG , E. ( 1 8 9 9 ) Some biological observations on Galeodes and

Buthus. K. vetensk. Akad. Forh., 5 6 , 9 7 7 - 8 3 . OLIVIER , G. A. ( 1 8 0 7 ) Voyage dans l' Empire Ottoman, l' Egypte et la

Perse, 3 , Paris.

POCOCK, R. I . ( 1 8 9 8 ) T h e nature and habits of Pliny's Solpuga. Nature, Lond., 5 7 , 6 1 8 - 2 0 .

TURNER, C. H. ( 1 9 1 6 ) Notes on the feeding, behaviour and oviposition of a captive American false-spider {Eremobates formicaria). J. Anim. Behav., 6 , 1 6 0 - 8 .

C H A P T E R V I I

F A L S E - S C O R P I O N S

Classification and distribution T h e o r d e r P s e u d o s c o r p i o n e s , C h e l o n e t h i o r C h e r n e t e s c o m p r i s e s

sma l l A r a c h n i d s w h i c h r e s e m b l e s c o r p i o n s i n t h e f o r m o f t h e i r

p e d i p a l p s a n d o f t h e i r b o d y , e x c e p t t h a t t h e h i n d p a r t o f t h e a b ­

d o m e n i s n o t n a r r o w a s i s t h e p o s t - a b d o m e n o r m e t a s o m a o f s co r -

F I G . 24. Examples of False-scorpion families: 1. Chthoniidae, 2. Neobisiidae, 3. Cheiridiidae, 4. Chernetidae, 5. Cheliferidae.

(After various authors.)

p i o n s a n d t h e y h a v e n o c a u d a l s t i ng . T h e do r sa l su r face o f t h e

p r o s o m a or c e p h a l o t h o r a x i s f o r m e d of a l a rge sc le r i t e b e a r i n g t h e

eyes , w h e n t h e s e a re p r e s e n t , a n d six p a i r s o f a p p e n d a g e s : t h e

99

1 0 0 F A L S E - S C O R P I O N S

che l i ce rae , p e d i p a l p s a n d f o u r p a i r s o f legs . T h e che l i ce rae a r e p r e -

ora l i n p o s i t i o n a n d a r e c o m p o s e d o f t w o s e g m e n t s . T h e i r f i n g e r s

b e a r a ser ies o f c o m p l i c a t e d s t r u c t u r e s k n o w n as t h e s e r r u l a e a n d

l a m i n a e . T h e s e r r u l a e x t e r i o r i s kee l - l ike , se t w i t h fine t e e t h a n d

a t t a c h e d fo r v a r y i n g d e g r e e s o f i t s l e n g t h t o t h e m o v a b l e f i n g e r

wh i l e t h e s e r r u l a i n t e r io r , a t t a c h e d t o t h e b a s e o f t h e f i x e d f i n g e r ,

i s e v e n m o r e v a r i a b l e in f o r m . A f lage l lum, f o r m e d of se tae w h o s e

n u m b e r a n d s h a p e a r e v a l u a b l e t a x o n o m i c c h a r a c t e r s , i s a l so a t ­

t a c h e d t o t h e f i x e d f i n g e r .

T h e m o u t h i s s i t u a t e d b e t w e e n t h e basa l s e g m e n t s o f t h e s ix-

s e g m e n t e d p e d i p a l p s . T h e s e a re e n o r m o u s l y d e v e l o p e d a n d r e ­

s e m b l e t h e c l aws o f s c o r p i o n s . T h e y s e r v e a s p r e h e n s i b l e o r g a n s t o

c a p t u r e a n d kill t h e p r e y a n d b e a r s e n s o r y h a i r s o r se tae . T h e i m ­

m o v a b l e f inger o f t h e c h e l a e h a s a r o w of c u t t i n g t e e t h a l o n g i t s

i n n e r e d g e , t h e las t o f w h i c h i s c o n s i d e r a b l y e n l a r g e d . T h r o u g h

t h i s p a s s e s t h e d u c t o f t h e e l o n g a t e d p o i s o n g l a n d w h i c h i tself i s

e m b e d d e d i n t h e s u b s t a n c e o f t h e f i n g e r . I n c e r t a i n fami l ies b o t h

f i n g e r s a r e e q u i p p e d w i t h p o i s o n g l a n d s . T h e c o x a e o f t h e p e d i ­

p a l p s a re e x t e n d e d f o r w a r d s o a s t o f o r m m a s t i c a t o r y p l a t e s , o r

t h e y m a y b e a r d i s t i n c t e n d i t e s w i t h w h i c h t h e p r e y i s h e l d i n f ron t

o f t h e m o u t h d u r i n g f e e d i n g . T h e f o u r p a i r s o f w a l k i n g legs differ

f r om t h o s e o f o t h e r A r a c h n i d a i n t h a t t h e t i b i a i s u n d i v i d e d s o t h a t

t h e r e i s n o pa te l l a . A t t h e s a m e t i m e i n m a n y spec i e s t h e f e m u r i s

d i v i d e d i n t o t w o m o r e o r less d i s t i n c t s e g m e n t s . T h e n u m b e r o f

t a r sa l j o i n t s i s o f g r e a t s y s t e m a t i c i m p o r t a n c e a n d i s t h e ch ie f

c h a r a c t e r u p o n w h i c h t h e t h r e e s u b - o r d e r s o f t h e P s e u d o s c o r p i o n e s

a r e d i f fe ren t ia ted .

T h e o p i s t h o s o m a o r a b d o m e n i s b r o a d l y a t t a c h e d t o t h e c e p h a l o -

t h o r a x a n d cons i s t s o f 12 s e g m e n t s , t h e las t o f w h i c h i s sma l l a n d

f o r m s a c i r c u m a n a l r i n g . T h e gen i t a l orifice i s s i t u a t e d b e t w e e n

t h e s e c o n d a n d t h i r d s t e r n i t e s , t h e s e c o n d f o r m i n g a n o p e r c u l u m

w h i l e t h e f i r s t s t e r n i t e i s m u c h r e d u c e d .

T h e o r d e r P s e u d o s c o r p i o n e s c o n t a i n s o v e r 1,500 spec i e s b e l o n g ­

i n g t o t h r e e s u b - o r d e r s all o f w h i c h a r e r e p r e s e n t e d i n t h e B r i t i s h

f auna . F a l s e - s c o r p i o n s a re d i s t r i b u t e d all ove r t h e w o r l d w i t h t h e

e x c e p t i o n o f t h e a rc t i c a n d a n t a r c t i c r e g i o n s . A t p r e s e n t , n i n e t e e n

fami l ies h a v e b e e n d e s c r i b e d , b u t t h e o r d e r i s still b y n o m e a n s

wel l k n o w n a n d o t h e r s m a y y e t b e d i s c o v e r e d . S o m e g e n e r a h a v e a

F A L S E - S C O R P I O N S 1 0 1

w o r l d - w i d e d i s t r i b u t i o n , o t h e r s a re r a r e a n d local . As a r u l e t h e y

a r e s o b e r - c o l o u r e d a n i m a l s , t h e i r l ive ry c o n s i s t i n g o f v a r i o u s s h a d e s

o f y e l l o w a n d b r o w n .

A w i d e v a r i e t y of h a b i t a t s a re co lon i s ed , t h e m a j o r i t y of s p e c i e s i n ­

h a b i t i n g soil a n d d e c a y i n g v e g e t a t i o n w h i l e o t h e r s l ive u n d e r s t o n e s

a n d t h e b a r k of t r e e s . N o n e i s pa r a s i t i c : Chelifer cancroides h a s o c ­

cas iona l ly b e e n r e c o r d e d o n m a n b u t i t i s p r o b a b l y m e r e l y p h o r e t i c

(see b e l o w ) . T h i s spec ie s , Allochernes italicus, Cheiridium museorum,

e tc . , f r e q u e n t l y l ive in h u m a n h a b i t a t i o n s . Microbisium femoratum

l ives exc lus ive ly in m o s s a n d m e m b e r s o f t h e g e n u s Neobisium a r e

n e a r l y a lways f o u n d i n m o s s a n d h u m u s : t h e spec ies o f Chthonius

a re n e a r l y a lways f o u n d u n d e r s t o n e s w h i l e t h e g e n u s Chernes

i n c l u d e s b a r k - i n h a b i t i n g f o r m s . S p e c i e s s u c h as Microbisium dumi-

cola a n d Neobisium sylvaticum t h a t w a l k in t h e o p e n on p l a n t s a n d

b u s h e s a r e e x t r e m e l y r a r e , b u t c a v e r n i c o l o u s f a l s e - s c o r p i o n s a re

re la t ive ly n u m e r o u s , a l t h o u g h t h e y b e l o n g a l m o s t exc lus ive ly t o

t h e g e n e r a Neobisium, Roncus a n d Chthonius. Q u i t e a n u m b e r of

spec ies a re m y r m e c o p h i l o u s a n d l ive i n t h e n e s t s o f a n t s : D o n i s -

t h o r p e ( 1 9 2 7 ) * r e c o r d s t h e fo l lowing a m o n g s t t h e B r i t i s h fauna ,

Chthonius ischnocheles, Neobisium muscorum, Roncus lubricus, Micro-

creagris cambridgei, Pselaphochernes scorpioides a n d Allochernes

wideri. Neobisium maritimum, Chthonius halberti a n d t h e la rge

Garypus beauvoisi h a v e a l i t to ra l d i s t r i b u t i o n a n d a r e f o u n d in c r a c k s

in rocks b e t w e e n t i d e - m a r k s on t h e sea s h o r e w h i l e Neobisium

muscorum a n d severa l o t h e r spec ies o c c u r i n d a m p s e a w e e d a t t h e

w a t e r ' s e d g e .

A n u m b e r of spec ies s u c h as Withius subruber, Cheiridium museo­

rum a n d Toxochernes panzeri a r e of ten a s soc i a t ed w i t h s t o r e d food

p r o d u c t s i n w a r e h o u s e s , w h e r e t h e y i n h a b i t e x t r e m e l y d r y e n v i r o n ­

m e n t s : t h e y also o c c u r i n b i r d s ' n e s t s i n h o l l o w t r e e s . I n v i e w o f

t h e i r sma l l s ize i t i s o b v i o u s t h a t t h e i r p o w e r s o f w a t e r - r e t e n t i o n

m u s t be e x t r e m e l y efficient. A n u m b e r o f o t h e r spec ies a re pa r t i a l

t o h e a p s o f m a n u r e a n d o n e o r t w o c l ing t o t h e legs o f flies a n d

o t h e r a r t h r o p o d s a s a m e a n s o f d i spe r sa l (see b e l o w ) . T h e we l l -

k n o w n ' b o o k - s c o r p i o n ' Cheiridium museorum, a l r e a d y m e n t i o n e d ,

h a s b e e n k n o w n t o l ive i n h u m a n h a b i t a t i o n s s ince t h e t i m e o f

Ar i s t o t l e , for he w r o t e : In b o o k s o t h e r sma l l a n i m a l s a r e f o u n d ,

s o m e o f w h i c h a r e l ike s c o r p i o n s w i t h o u t ta i l s , ' a n d i n t h i s c o u n t r y

102 F A L S E - S C O R P I O N S

H o o k e (1664) d r e w a p i c t u r e p o s s i b l y o f t h e s a m e spec ies in h i s

f a m o u s b o o k Micrographia.

General behaviour All false s c o r p i o n s a r e of sma l l s ize, s e l d o m e x c e e d i n g 7 or 8 mm

in l e n g t h . T h e g i a n t Garypus beauvoisi o f C o r s i c a a n d t h e M e d i ­

t e r r a n e a n i s o n l y a q u a r t e r o f an i n c h in l e n g t h , a n d t h e l a rges t

B r i t i sh spec ie s , t h e h a n d s o m e Dendrochernes cyrneus, is o n l y 3.6

m m l o n g . B e c a u s e t h e y a r e s o sma l l a n d h a v e shy , r e t i r i n g h a b i t s ,

p s e u d o s c o r p i o n s a r e l i t t le k n o w n a n d s e l d o m f o u n d u n l e s s spec ia l ly

s o u g h t . T h i s i s a p i ty , for t h e y a re i n t e r e s t i n g c r e a t u r e s a n d m a n y

a s p e c t s o f t h e i r b i o l o g y w o u l d p r o v i d e s u i t a b l e s u b j e c t s fo r s t u d y

b y b o t h a m a t e u r a n d p ro fes s iona l zoo log is t s .

M o s t p s e u d o s c o r p i o n s a r e m a r k e d l y p h o t o - n e g a t i v e a n d d o n o t

of ten v e n t u r e i n t o t h e o p e n . T h e y m a y b e co l l ec ted b y h a n d f r o m

r o t t i n g leaves a n d f r o m u n d e r t h e b a r k o f t r e e s , b u t t h i s m e t h o d

t e n d s t o b e l a b o r i o u s for t h e y a r e b y n o m e a n s p l en t i fu l . T h e m o s t

effective m e t h o d en ta i l s t h e u s e o f t h e Ber l e se F u n n e l , b u t a s i m p l e r

w a y i s t o s ca t t e r fal len leaves , m o s s a n d o t h e r v e g e t a b l e d e b r i s o n t o

a s h e e t of n e w s p a p e r or a w h i t e t a b l e t o p . D e s p i t e t h e i r sma l l s ize,

t h e c r e a t u r e s c a n t h e n b e easi ly r e c o g n i s e d b y t h e i r s q u a r i s h s h a p e :

t h e y g e n e r a l l y c r o u c h m o t i o n l e s s , t h e i r legs a n d che l ae d r a w n i n

u n t i l t h e y a r e t o u c h e d , w h e n t h e y a t o n c e p r o c l a i m t h e i r n a t u r e b y

r u n n i n g b a c k w a r d s . F a l s e - s c o r p i o n s wa lk s lowly w i t h a n a i r o f i m ­

p re s s ive d i g n i t y a n d c a l m d e l i b e r a t i o n w h i c h d i s t i n g u i s h e s t h e m

f r o m m o s t o f t h e o t h e r sma l l a r t h r o p o d s t h a t i n h a b i t t h e s a m e t y p e

o f local i ty , t h e i r e n o r m o u s p e d i p a l p s s p r e a d o u t i n f r o n t o f t h e m

like t h e a n t e n n a e o f an insec t . If, a s t h e y p r o c e e d , t h e y h a p p e n to

t o u c h s o m e o t h e r a n i m a l w i t h t h e l o n g se tae o n t h e i r e x t e n d e d

p a l p s , t h e y d a r t s i d e w a y s o r b a c k w a r d s w i t h s u r p r i s i n g s p e e d ,

look ing r a t h e r l ike a s t a r t l e d crayf ish. T h i s s u d d e n r e t r e a t i s h i g h l y

cha rac t e r i s t i c for n o t m a n y a n i m a l s c a n go b a c k w a r d s a s easi ly a s

fo rwards , a n d v e r y f ew m o r e r a p i d l y .

I t h a s b e e n p o i n t e d o u t t h a t a few spec ies i n h a b i t a c o m p a r a ­

t ively d r y e n v i r o n m e n t , b u t t h e m a j o r i t y a r e e x t r e m e l y s u s c e p t i b l e

t o des i cca t ion a n d m u s t b e p r o v i d e d w i t h m o i s t u r e i f k e p t i n

cap t iv i ty . S o m e spec ies a r e l i g h t - s h y , b u t in Chelifer cancroides no

nega t i ve p h o t o t a x i s h a s b e e n o b s e r v e d a l t h o u g h t h e a n i m a l s t e n d

F A L S E - S C O R P I O N S 103

to p r e f e r a r o u g h sur face to wa lk on . T h a n k s to t h e a r o l i u m , a

t r u m p e t - s h a p e d m e m b r a n o u s s u c k e r b e n e a t h t h e c l aws o f t h e

w a l k i n g legs , f a l s e - sco rp ions a r e ab l e t o c l i m b ver t i ca l ly a n d wa lk

u p s i d e - d o w n o n t h e u n d e r su r faces o f s t o n e s a n d logs . I f t h e y

s h o u l d h a p p e n t o fall o n t h e i r b a c k s , h o w e v e r , t h e y c a n on ly r i g h t

t h e m s e l v e s w i t h difficulty b y a r c h i n g t h e i r b o d i e s a n d r o c k i n g

f rom s ide t o s ide , o r b y g r a s p i n g s o m e n e a r b y ob jec t w i t h t h e i r

c laws.

T h e p h e n o m e n o n o f t h e u t i l i s a t ion o f a n o t h e r a n i m a l for t r a n s ­

p o r t , t o w h i c h t h e n a m e ' p h o r e s y ' i s c o m m o n l y a p p l i e d , i s p e r h a p s

a p a r t i c u l a r t y p e o f c o m m e n s a l i s m . An e x a m p l e i s a f forded by

Limosina sacra, a B o r b o r i d fly, n u m b e r s of w h i c h c o n s t a n t l y r i d e

o n t h e b a c k s o f d u n g b e e t l e s i n N o r t h Afr ica , a p p a r e n t l y for t h e

p u r p o s e o f o v i p o s i t i n g in t h e p a r t i c u l a r l y c h o i c e a s s e m b l a g e o f

faecal m a t t e r t h a t t h e bee t l e s col lec t a n d c o n s o l i d a t e . I n a s imi la r

way , b i r d - l i c e ( M a l l o p h a g a ) a r e f r e q u e n t l y c o n v e y e d f r o m o n e

h o s t to a n o t h e r by t h e H i p p o b o s c i d fly Ornithomyia avicularia.

A b o u t t w e n t y - f i v e spec ies o f p s e u d o s c o r p i o n a r e k n o w n t o o b t a i n

t r a n s p o r t f r o m o n e p l ace t o a n o t h e r o n o t h e r a n i m a l s s u c h a s

D i p t e r a , H y m e n o p t e r a , C o l e o p t e r a , H e m i p t e r a , O r t h o p t e r a a n d

o t h e r in sec t s , h a r v e s t - s p i d e r s a n d b i r d s . Be ie r (1948) p r o v i d e s a

usefu l s u m m a r y o f t h e ex t ens ive l i t e r a t u r e n o t on ly o n p h o r e s y

b u t a lso on o t h e r t y p e s o f a s soc ia t ion i n w h i c h f a l s e - sco rp ions a re .

c o n c e r n e d . H e l is ts t h e spec ies t h a t h a v e b e e n f o u n d i n h a b i t i n g

t h e n e s t s o f b i r d s a n d m a m m a l s , t e r m i t e s , a n t s a n d o t h e r H y m e n ­

o p t e r a , a n d t a b u l a t e s t h e C h e r n e t e s t h a t h a v e b e e n r e c o r d e d a s

a t t a c h e d t o t h e e x t r e m i t i e s o f t h e l i m b s a n d t o t h e b o d i e s o f in sec t s

a n d o t h e r a r t h r o p o d s . T h e m o s t i m p o r t a n t p h o r e t i c spec ies i n

E u r o p e is Lamprochernes nodosus w h i c h is n o t i n f r e q u e n t l y f o u n d

a t t a c h e d t o t h e legs o f housef l ies i n s u m m e r a n d a u t u m n a l t h o u g h

i t also c l ings to hover - f l i e s a n d o t h e r i n sec t s . F a l s e - s c o r p i o n s o c ­

cas ional ly r i d e o n t h e b a c k s o f bee t l e s , s h e l t e r i n g u n d e r t h e i r

e ly t ra . Cordylochernes scorpioides is a w e l l - k n o w n e x a m p l e f re ­

q u e n t l y p h o r e t i c on t h e b e e t l e Acrocinus longimanus in t r op i ca l

A m e r i c a .

V a r i o u s e x p l a n a t i o n s o f t h e p h o r e t i c h a b i t h a v e b e e n s u g g e s t e d ,

b u t i n m o s t cases i t s e e m s t h a t t h i s b e h a v i o u r i s e i t h e r acc iden ta l

o r m o t i v a t e d b y h u n g e r . O n l y f emale f a l s e - sco rp ions a re p h o r e t i c ,

104 F A L S E - S C O R P I O N S

a n d t h e spec ies i n v o l v e d a re t h o s e t h a t i n h a b i t fal len leaves a n d

d e b r i s , n o t t h o s e t h a t l ive u n d e r s t o n e s a n d b e n e a t h b a r k ( V a c h o n ,

1947a) .

T h e ab i l i ty o f f a l s e - sco rp ions t o s p i n w a s d e n i e d b y s o m e o f t h e

ear l ie r w r i t e r s , b u t i t i s n o w k n o w n t h a t t h e y c o n s t r u c t ne s t s

p a r t l y o r w h o l l y o f silk f r o m t h e i r o w n b o d i e s . T h e a n i m a l s u sua l l y

enc lose t h e m s e l v e s i n t h e s e n e s t s for m o u l t i n g , for b r o o d p u r ­

p o s e s a n d , i n s o m e cases , for h i b e r n a t i o n . S u c h n e s t s a r e c lo sed

cells o f s p u n t i s sue w i t h o r w i t h o u t an e x t e r n a l cove r o f e x t r a n e o u s

m a t t e r . T h e y a r e r o u g h l y c i r cu l a r i n s h a p e a n d m a y b e a t t a c h e d

a b o v e a n d b e l o w t o t h e sol id su r faces o f n a r r o w c rev ices . W h e n

t h e y a r e a t t a c h e d on o n e s ide on ly t h e y h a v e a free, c o n v e x roof

a n d m a y b e fixed h e r e a n d t h e r e t o s u r r o u n d i n g ob jec t s . T h e e x ­

t e r n a l c o v e r i n g , i f p r e s e n t , cons i s t s o f e a r t h or v e g e t a b l e f ibres

w h i c h a re n o t b o u n d t o t h e s t r u c t u r e b u t a r e f i rmly a t t a c h e d t o it ,

b u t t h e i n t e r i o r i s s m o o t h a n d a lways free f r o m fore ign m a t t e r .

T h e s p u n t i s sue i s t h i n a n d d e n s e , c o m p o s e d o f i n n u m e r a b l e

t h r e a d s , c r o s s e d a n d r e c r o s s e d a n d coa lesced i n i r r e g u l a r c o n ­

fus ion w i t h o u t i n t e r s p a c e s .

T h e silk i s d e r i v e d f r o m g l a n d s i n t h e c e p h a l o t h o r a x w h o s e

d u c t s t r a v e r s e t h e che l i ce rae t o t h e a p e x o f t h e m o v a b l e f inger .

T h e y o p e n a t t h e t i p s o f t h e b r a n c h e s o f t h e ga lea o r o n o r n e a r

t h e m a r g i n o f a t u b e r c l e w h i c h r e p l a c e s t h a t s t r u c t u r e i n s o m e

g r o u p s . T h e s p i n n i n g i s d o n e w i t h t h e che l i ce rae b u t t h e p r e s e n c e

o r a b s e n c e o f t h e ga lea d o e s n o t a p p e a r t o b e a s soc i a t ed w i t h

d i f ferences o f m e t h o d o r i n t h e t i s sue : t h e s e r r u l a e , e t c . a r e n o t

c o n c e r n e d . N e s t b u i l d i n g i s c a r r i e d o u t f r o m w i t h i n . T h e c o n ­

s t r u c t i o n o f an e x t e r n a l f r a m e w o r k i s t h e first task , a n d w h e r e t h i s

h a s a c o a t i n g o f e x t r a n e o u s m a t e r i a l s , t h e a n i m a l f r e q u e n t l y goes

o u t t o col lec t t h e m . T h e y a re p i c k e d u p i n t h e p e d i p a l p s , t r a n s ­

f e r r ed t o t h e che l i ce rae a n d a t t a c h e d t o t h e nes t b y t h e a p p l i c a t i o n

o f silk t o t h e i r i n n e r su r faces . T h e silk i s d r a w n f r o m t h e galea o r

t u b e r c l e i n severa l v i sc id a n d v e r y fine t h r e a d s w h i c h m a y r e m a i n

s e p a r a t e o r m a y coalesce , a n d t h e s p i n n i n g i s a c c o m p a n i e d b y

c o n t i n u o u s f o r w a r d a n d b a c k w a r d m o v e m e n t s o f t h e b o d y a n d

b y la tera l m o v e m e n t s o f t h e che l i ce rae . A t first, w h e n a t t a c h m e n t s

a re b e i n g m a d e f r o m p lace t o p l ace , t h e t h r e a d s u s u a l l y d o coalesce ,

b u t a f t e r w a r d s t h e a n i m a l se t t l es d o w n t o l o n g c o n t i n u e d s p i n n i n g

F A L S E - S C O R P I O N S 105

a n d t h e silk i s r a p i d l y b r u s h e d o n t o t h e i n t e r i o r o f t h e nes t , first i n

o n e p lace , t h e n i n a n o t h e r . T h e a n i m a l c o n t i n u e s a t w o r k g r a d u a l l y

i m p r i s o n i n g itself, for d a y s or e v e n w e e k s u n t i l a d e n s e t i s s u e i s

p r o d u c e d ove r eve ry p a r t o f t h e i n s ide o f i ts a b o d e ( K e w , 1914) .

Food and feeding habits P s e u d o s c o r p i o n s a re exc lus ive ly c a r n i v o r o u s a n d feed o n l iv ing

o r r e c e n t l y k i l led p r e y s u c h a s C o l l e m b o l a , P s o c i d s , T h y s a n u r a ,

D i p t e r a , o t h e r sma l l i n sec t s , S y m p h y l a a n d A r a c h n i d s . U n l i k e

s p i d e r s , t h e y a r e n o t u s u a l l y c a n n i b a l i s t i c i f food i s ava i l ab le b u t an

i n j u r e d or a i l ing i n d i v i d u a l h a s a p o o r c h a n c e of su rv iva l . I t i s

d o u b t f u l i f t h e p r e y i s ac t ive ly s o u g h t af ter , b u t r a t h e r t h a t fa lse-

s c o r p i o n s lie i n wa i t , w i t h t h e i r c l aws o p e n , u n t i l s o m e s u i t a b l e

a n i m a l a c c i d e n t a l l y b r u s h e s aga in s t t h e i r s e n s o r y h a i r s , w h e n i t

i s se ized w i t h e x t r e m e r a p i d i t y . I t i s sa id t h a t s o m e spec i e s o f

Chthonius c a n ac tua l ly l eap u p o n t h e i r p r e y . T h e ro le o f t h e p o i s o n

g l a n d s i n t h e p a l p s i s n o t e n t i r e l y c lear . S o m e t i m e s t h e p r e y i s

p a r a l y s e d i m m e d i a t e l y b u t n o t i n f r e q u e n t l y i t i s c o n v e y e d t o t h e

che l i ce rae w h i l s t st i l l s t r u g g l i n g . O c c a s i o n a l l y o n e f a l s e - s co rp ion

h a s b e e n o b s e r v e d to r o b a n o t h e r o f i ts food af ter a s h o r t s t r u g g l e

( V a c h o n in G r a s s e , 1949) .*

T h e p r o t o n y m p h i s t h e m o s t ac t ive i n s t a r a n d i s q u i t e b o l d a n d

fear less in i ts b e h a v i o u r : i t wi l l e v e n t a k e food d i r ec t ly f r o m a p r o b e .

T h e la te r s t ages d o n o t feed s o r ead i ly a n d a d u l t s m a y ea t on ly

o n c e or t w i c e a m o n t h . L e v i (1948) f o u n d t h a t in Chelifer can-

croides, a d u l t s fed o n c e a w e e k in cap t i v i t y s e e m e d to be in b e t t e r

c o n d i t i o n t h a n t h o s e c a u g h t i n t h e w o o d s . D u r i n g f eed ing t h e

p e d i p a l p s m a y b e v i b r a t e d , p o s s i b l y b y t h e a c t i o n o f t h e p h a r y n g e a l

p u m p ( C h a m b e r l i n , 1931) .

T h e A r g e n t i n e f a l s e - sco rp ion Sphenochernes schulzi r e c e n t l y d e s ­

c r i b e d by T u r k (1953) i s v e r y c o m m o n in t h e n e s t s o f a l e a f - c u t t i n g

an t , Acromyrmex lundi. T h e s e p s e u d o s c o r p i o n s live b u r i e d in t h e

m a t e r i a l o f t h e n e s t a n d s e e m i n g l y d o n o t n o r m a l l y e m e r g e e x c e p t

for t h e i r p r e y . T h e y h o l d t h e i r p e d i p a l p s o p e n a l m o s t c o n t i n u o u s l y ,

c a t c h i n g a t t h e legs o f t h e a n t s a s t h e y r u n pas t , a n d h o l d i n g fast

u n t i l t h e a n t d ies f r o m t h e effect o f t h e i r p o i s o n . T h e a t t a cke r s ,

a n d t h e r e a r e u s u a l l y m o r e t h a n o n e , t h e n p r o b e t h e i r v i c t i m w i t h

t h e i r che l i ce rae , a n d p r o c e e d to suck t h e b o d y f lu ids . I t i s a c u r i o u s

106 F A L S E - S C O R P I O N S

fact t h a t t h e s e a t t a cks t a k e p l ace on ly in day l igh t . I f a vesse l c o n ­

t a i n i n g C h e r n e t i d s a n d c a p t u r e d a n t s i s d a r k e n e d t h e a n t s a re

re leased , w h e r e a s i n t h e l igh t t h e h o l d o f t h e C h e r n e t i d s i s so

s t r o n g a n d p e r s i s t e n t t h a t t h e y will n o t let g o e v e n w h e n w h i r l e d

a b o u t . T h e a t t a cks o f t h e p s e u d o s c o r p i o n a re m o s t c l u m s y , a n d

th i s i s t h o u g h t t o b e t h e r e a s o n t h a t t h e a n t spec ies c o n t i n u e s t o

su rv ive . T h e a n t s n e v e r s u c c e e d i n f ree ing t h e m s e l v e s f r o m t h e i r

a t t a cke r s b y b i t i n g . M o r e r e c e n t l y V a c h o n (1954) h a s r e c o r d e d a n

e x t r a o r d i n a r y assoc ia t ion b e t w e e n Ellingsenius hendrickxi a n d b e e s

i n t h e Be lg ian C o n g o . T h i s c u r i o u s l y o r n a m e n t e d a n d s c u l p t u r e d

spec ies i s v e r y c o m m o n a t T s h i b i n d a a n d K a t a n a w h e r e i t passes

i ts w h o l e life cycle i n b e e h ives . T h e f a l s e - sco rp ions of ten a t t a c h

t h e m s e l v e s t o t h e legs o f t h e b e e s a n d s o m e t i m e s n u m b e r s c o m b i n e

t o a t t ack b o t h w o r k e r s a n d q u e e n s , w h i c h a r e k i l led a n d e a t e n l ike

o r d i n a r y p r e y . The Ellingsenius forces i ts che l i ce rae i n t o t h e a r t i c u ­

l a t ions o f t h e legs o f t h e b e e a t i n t e r s e g m e n t a l m e m b r a n e s a n d

FIG . 25. Ellingsenius hendrickxi. (After Vachon, 1954.)

feeds u p o n it, h o l d i n g on by its che l i ce rae on ly . I f t h e s e b e c o m e

unf ixed , h o w e v e r , t h e p e d i p a l p s a re u s e d t o r e g a i n c o n t r o l .

Af te r a m e a l a f a l se - sco rp ion can of ten be s een to c lean its

m o u t h - p a r t s a n d che l i ce rae . T h i s h a b i t i t s h a r e s w i t h s p i d e r s a n d

h a r v e s t m e n , w h i c h s imi la r ly p a s s t h e i r p a l p s o r legs t h r o u g h t h e i r

j a w s . S i n c e t h e p r e y i s d i g e s t e d ex t e rna l ly b y m e a n s o f e n z y m e s

a n d t h e n s u c k e d in in s o l u t i o n , i t i s essen t ia l t h a t t h e severa l c h a n n e l s

a n d g r o o v e s i n t h e m o u t h - p a r t s s h o u l d b e k e p t free f r o m sol id

F A L S E - S C O R P I O N S 107

pa r t i c l e s . I n a d d i t i o n t o t h i s h o w e v e r , f a l s e - s c o r p i o n s a r e r e m a r k ­

ab l e in t h a t t h e y also c l ean t h e i r che l i ce rae be fo r e a m e a l ( V a c h o n ,

1948) . F o r e x a m p l e , w h e n Dactylochelifer latreillei s en se s i ts p r e y

i t b e g i n s t o c l ean i ts che l i ce rae w i t h i ts p e d i p a l p s . O n c a p t u r e ,

t h e p r e y i s g r a s p e d b y t h e p e d i p a l p s . O f t e n b o t h a re u s e d , b u t t h e

h o l d o f o n e o f t h e m i s s o o n r e l i n q u i s h e d a n d t h e p r e y i s h e l d aloft

b y t h e o t h e r . T h e free p a l p t h e n c o n t i n u e s t o c l ean t h e m o u t h ­

p a r t s . Af t e r a few m i n u t e s t h e p r e y , w h i c h b y n o w m a y wel l b e

inac t ive , i s a p p l i e d t o t h e che l i ce rae w h i c h b y t h e i r c o m b i n e d

a c t i o n m a k e a s m a l l w o u n d . T h e m o u t h - p a r t s a r e i n s e r t e d u n t i l

t h e l a b r u m a p p e a r s t o p e n e t r a t e s l igh t ly i n t o t h e w o u n d . W h e n

f ixat ion t o t h e che l i c e r ae i s c o m p l e t e t h e p e d i p a l p s re lease t h e i r

g r i p a n d t a k e u p a c h a r a c t e r i s t i c f lexed a t t i t u d e . D u r i n g f eed ing

i t c a n b e s e e n t h a t l i q u i d i s f lowing b o t h i n a n d o u t o f t h e p r e y .

As s u c k i n g p r o c e e d s a s o f t - s k i n n e d insec t b e c o m e s q u i t e flaccid,

o n l y t o b e c o m e s u d d e n l y t u r g i d d u e t o t h e e x u d a t i o n f r o m t h e

f a l s e - s co rp ion of a l i q u i d p r e s u m a b l y c o n t a i n i n g d iges t i ve e n z y m e s .

T h e m e a l m a y las t for a n h o u r o r m o r e b e f o r e t h e p r e y i s finally

d i s c a r d e d a n d t h e m o u t h - p a r t s aga in c l e a n e d ( G i l b e r t , 1951) .

T h e f eed ing b e h a v i o u r of Neobisium muscorum a n d N. mariti-

mum i s s imi la r , e x c e p t t h a t t h e food i s ac t ive ly k n e a d e d by t h e

che l i ce rae , w h i c h r e m a i n c o m p a r a t i v e l y still in D. latreillei, a n d

c o n s i d e r a b l e u s e i s m a d e o f t h e p e d i p a l p s i n food c a p t u r e . I n

Chthonius ischnocheles, h o w e v e r , t h e p r e y i s d i s a b l e d by t h e c h e l i ­

ce rae . T h i s m a y b e c o r r e l a t e d w i t h t h e u n u s u a l l y l a rge che l i ce rae

a n d t h e a b s e n c e o f a p a l p a l v e n o m a p p a r a t u s in t h e g e n u s Chthonius.

T h e che l i ce rae , by a c h e w i n g ac t i on , m a k e a w o u n d a n d t h i s i s

q u i c k l y e x t e n d e d s o t h a t t h e p r e y b e c o m e s i m m o b i l i s e d w i t h i n

t w o o r t h r e e m i n u t e s . F e e d i n g i s a c c o m p a n i e d b y a n i n c e s s a n t

k n e a d i n g o f t h e p r e y , o n e che l i ce ra b e i n g c l e n c h e d i n t h e w o u n d

w h i l e t h e o t h e r i s c losed r o u n d it, a t t h e s a m e t i m e d i g g i n g f u r t h e r

i n w a r d s . T h i s a l t e r n a t e i n s e r t i o n o f each che l i ce ra c o n t i n u e s a t

i n t e r v a l s o f a b o u t o n e s e c o n d : a t t i m e s t h e c l e n c h i n g o f t h e c h e l i ­

ce rae i s n o t a l t e r n a t e , o n e o f t h e m o p e n i n g a n d c los ing severa l

t i m e s i n succes s ion . C h a m b e r l i n (1931) m e n t i o n s t h a t t h e m o d i f i ­

ca t i on o f t h e s e r r u l a e s e e m s t o pa ra l l e l t h e p r e h e n s i l e o r n o n -

p r e h e n s i l e f u n c t i o n s o f t h e che l i ce rae , a n d G i l b e r t (1951) s u g g e s t s

t h a t t h e r e m a y b e a co r r e l a t i on b e t w e e n g e n e r a i n w h i c h t h e se r -

108 F A L S E - S C O R P I O N S

r u l a e a r e f ixed t h r o u g h o u t t h e i r l e n g t h t o t h e che l ice ra l f ingers a n d

t h o s e w h o s e che l i c e r ae a r e i nac t i ve d u r i n g f e e d i n g . A t t h e s a m e

t i m e i t i s p o s s i b l e t h a t t h e pos se s s ion o f pa r t i a l ly free s e r r u l a e in

Xeobisium a n d Chthonius is a s soc ia t ed w i t h t h e m a i n t e n a n c e of a

l i qu id film b e t w e e n t h e f a l s e - s co rp ion a n d i ts p r e y , d e s p i t e t h e

fact t h a t t h e che l i ce rae a r e m o v i n g .

Enemies O w i n g t o t h e i r s ec r e t i ve h a b i t s , f a l s e - s c o r p i o n s h a v e few e n e m i e s

a l t h o u g h L e v i (1948) h a s r e c o r d e d t h a t t h e y m a y b e e a t e n b y a n t s .

T h e y d o n o t of ten fall v i c t i m t o s p i d e r s : t h e i r p o i s o n - b e a r i n g

p e d i p a l p s h e l p t h e m t o h o l d t h e i r o w n aga in s t spec ies o f t h e i r o w n

size, w h i l s t t h e y a r e l ikely t o r e m a i n u n n o t i c e d b y m a n y s p i d e r s o f

a l a rge r s ize . T h e y d o n o t a p p e a r t o b e d i s tas te fu l h o w e v e r , a n d

B r i s t o w e ( 1 9 4 1 ) * h a s fed Chthonius ischnocheles a n d Lamprochernes

nodosus t o a n u m b e r o f s p i d e r spec ie s . T h e y m a y also be e a t e n by

h a r v e s t - s p i d e r s ( C l o u d s l e y - T h o m p s o n , 1955) .

W i t h t h e e x c e p t i o n o f six n e m a t o d e w o r m s o f t h e g e n u s Hexa-

meris f o u n d in a f emale Roncus s p . w h o s e ova r i e s w e r e a t r o p h i e d ,

n o p a r a s i t e s o f p s e u d o s c o r p i o n s a r e k n o w n .

Mating habits I n m a l e f a l s e - s c o r p i o n s t h e ga lea o r s p i n n e r e t o n t h e m o v a b l e

f inger o f t h e che l i ce rae i s p o o r l y d e v e l o p e d c o m p a r e d w i t h t h a t o f

t h e f ema le ; t h e a b d o m i n a l t e r g i t e s m a y b e p r o v i d e d w i t h s t r o n g

la tera l kee l s as in Chelifer cancroides a n d t h e c laws of t h e p e d i p a l p s

a re m o r e r o b u s t a n d h a v e a w i d e r g a p e . L a t e r a l gen i t a l sacs a re

p r e s e n t u n d e r t h e gen i t a l o p e r c u l u m close t o t h e gen i t a l a p e r t u r e .

I n s o m e spec ies t h e s e a r e c a p a b l e o f b e i n g e x t r u d e d . T h e y r e a c h

t h e i r h i g h e s t d e v e l o p m e n t i n t h e C h e l i f e r i d a e w h e r e t h e y c a n b e

c o m p l e t e l y e v a g i n a t e d a n d c o n s t i t u t e t h e ' r a m ' s - h o r n o r g a n s ' o f

m a n y a u t h o r s , a t e r m p r o p o s e d b y M e n g e .

T h e p a i r i n g of Dendrochernes cyrneus a n d Dactylochelifer latreil-

lei h a s b e e n d e s c r i b e d b y K e w (1914) . T h e m a l e s a r e d i f ferent ly

e q u i p p e d : D. latreillei h a s an e l a b o r a t e gen i t a l a rea , l o n g r a m ' s -

h o r n o r g a n s a n d m u c h m o d i f i e d legs o f t h e first pa i r , w h i l e D .

cyrneus h a s a less e l a b o r a t e gen i t a l a rea , no r a m ' s - h o r n o r g a n s a n d

no mod i f i ed legs . B o t h a r e d e s t i t u t e o f i n t r o m i t t e n t o r g a n s o f

F A L S E - S C O R P I O N S 109

c o p u l a t i o n a n d fe r t i l i sa t ion i s effected by m e a n s of a s p e r m a t o -

p h o r e . T h e m a l e a n d f e m a l e face o n e a n o t h e r i n w a l k i n g pos i t i on ,

t h e m a l e g r a s p i n g o n e o r b o t h o f t h e p e d i p a l p s o f t h e female w i t h

o n e o r b o t h o f h i s o w n . T h e r e i s a fo r ced c o u r t s h i p d u r i n g w h i c h

t h e m a l e m a k e s d i s p l a y o f def in i te c h a r a c t e r . A t l e n g t h h e e x t r u d e s

a s p e r m a t o p h o r e w h i c h i s a t t a c h e d to t h e s u b s t r a t e in f ron t o f t h e

female w h e r e i t s t a n d s e r ec t o r o b l i q u e l y . T h e m a l e t h e n r e t i r e s

a n d t h e f e m a l e m o v e s f o r w a r d u n t i l h e r gen i t a l o p e n i n g c o m e s i n t o

c o n t a c t w i t h t h e s p e r m a t o p h o r e w h i c h i s r e c e i v e d w i t h o u t de lay .

C o u r t s h i p va r i e s i n t h e t w o spec ies c o r r e l a t e d w i t h t h e i r m o r p h o ­

logical d i f ferences . D. latreillei h o l d s t h e f ema le w i t h b o t h p a l p s

a n d m a k e s d i sp l ay w i t h h i s r a m ' s - h o r n o r g a n s , r e l eas ing h e r j u s t

be fo r e e x t r u d i n g a s p e r m a t o p h o r e . W h e n s h e c o m e s f o r w a r d h e

F I G . 26. Courtship dance of false-scorpions. (After Vachon, 1938.)

se izes h e r by t h e gen i t a l o p e n i n g w i t h h i s first p a i r o f legs a n d

e x e c u t e s a ser ies o f p u l l i n g m o v e m e n t s by w h i c h t h e r e c e p t i o n o f

t h e m a l e p r o d u c t i s fac i l i t a ted . T h e a n i m a l s t h e n s e p a r a t e a n d g o

t h e i r d i f ferent w a y s . In D . cyrneus t h e m a l e h o l d s h i s m a t e w i t h

o n e p e d i p a l p on ly , t h e o t h e r b e i n g s h a k e n i n h e r face, a n d h i s first

legs a r e m o v e d r a p i d l y , b e i n g l if ted a n d r e p l a c e d in a p e c u l i a r

f a sh ion . T h e female , w h o i s a p p a r e n t l y ' m u c h i m p r e s s e d ' b y t h e s e

ac t ions , i s n o t r e leased d u r i n g e x t r u s i o n o f t h e s p e r m a t o p h o r e

w h i c h s h e t akes q u i c k l y w i t h o u t t h e m a l e se iz ing h e r gen i t a l o p e n ­

ing . A f t e r a p e r i o d o f r e p o s e t h e w h o l e p r o c e s s m a y be r e p e a t e d a

110 F A L S E - S C O R P I O N S

n u m b e r o f t i m e s a n d a l a rge n u m b e r o f s p e r m a t o p h o r e s a r e t h u s

p r o d u c e d a n d r ece ived i n q u i c k s u c c e s s i o n .

In Chelifer cancroides, a c c o r d i n g to V a c h o n (1938) , a n u p t i a l

d a n c e t a k e s p l ace d u r i n g w h i c h t h e m a l e v i g o r o u s l y d i sp l ays a n d

r e t r a c t s h i s r a m ' s - h o r n o r g a n s a n d w a v e s h i s p e d i p a l p s i n t h e air

l ike t h e a r m s o f a s w i m m e r . T h e d a n c e cons i s t s o f a t leas t t h r e e set

f i g u r e s w h i c h a re r e p e a t e d r h y t h m i c a l l y for s o m e m i n u t e s o r l o n g e r

i f t h e f e m a l e i s u n r e s p o n s i v e . St i l l d a n c i n g , he a p p r o a c h e s h i s m a t e ,

d e p o s i t s a s p e r m a t o p h o r e a n d t h e n r e t r e a t s , s lowly m o v i n g h i s

p a l p s . O b e d i e n t t o t h i s s igna l , t h e f ema le a d v a n c e s u n t i l s h e s t a n d s

a b o v e t h e s p e r m a t o p h o r e w h i c h s h e i n t r o d u c e s i n t o h e r s p e r m a -

t h e c a e . T h e m a l e t h e n l o w e r s h i s h e a d b e n e a t h t h a t o f h i s m a t e ,

g r i p s t h e f e m u r s o f h e r p a l p s w i t h h i s o w n c l aws a n d t a p s h e r

gen i t a l r e g i o n w i t h h i s a n t e r i o r l egs , t h u s e n s u r i n g t h a t t h e s p e r m a ­

t o z o a f r o m t h e s p e r m a t o p h o r e a re p r o p e r l y s e c u r e d .

Reproduction and life cycle I t h a s b e e n k n o w n s ince t h e t i m e o f F a b r i c i u s i n 1793 t h a t t h e

eggs o f Chelifer w e r e r e t a i n e d b e n e a t h t h e a b d o m e n o f t h e m o t h e r ,

b u t L u b b o c k i n 1861 w a s t h e f i r s t t o o b s e r v e t h a t t h e y w e r e e n ­

c losed i n a t r a n s p a r e n t , s t r u c t u r e l e s s m e m b r a n e a t t a c h e d t o t h e

a b d o m e n a n d t h a t l a rge m o t i o n l e s s y o u n g s imi la r ly r e t a i n e d w e r e

n o u r i s h e d b y a m i l k y fluid p r o v i d e d b y t h e m o t h e r . T e n y e a r s l a te r

M e t s c h n i k o f f d i s c o v e r e d t h a t d e v e l o p m e n t i n v o l v e d a m e t a m o r ­

p h o s i s i n c l u d i n g i m m o b i l e l a rvae w h i c h w e r e p r o v i d e d a n t e r i o r l y

w i t h a s t r o n g l y m u s c u l a r s u c k i n g - a p p a r a t u s a n d B a r r o i s s h o w e d

t h a t t h e l a rvae u n d e r w e n t t w o d i s t i n c t p e r i o d s o f e m b r y o g e n e s i s .

T h e eggs a n d l a t e r t h e l a rvae m a y b e a r r a n g e d i n a f l a t d i s c i n

t h o s e spec ies w h e r e t h e f ema le c o n t i n u e s a n ac t ive ex i s t ence d u r i n g

ges t a t i on , for e x a m p l e i n m o s t o f t h e Che l i f e r i dae ; b u t w h e r e t h e

female c o n s t r u c t s a n e s t i n w h i c h s h e seals herse l f up a n d r e m a i n s

inac t ive u n t i l t h e d e v e l o p m e n t o f t h e y o u n g i s c o m p l e t e , t h e y a r e

u sua l l y i n a m u l b e r r y - l i k e m a s s . A c c o r d i n g t o K e w (1929) i n t h e s e

f a l se - sco rp ions t h e e n o r m o u s l y d i s t e n d e d females i m p r i s o n t h e m ­

selves i n b r o o d n e s t s w h e r e t h e y r e m a i n h i d d e n f r o m v iew. A few

h o u r s be fo r e t h e eggs a re la id a n i n c u b a t i o n c h a m b e r o r b r o o d - s a c

m a k e s i t s a p p e a r a n c e a c c o m p a n i e d b y p e c u l i a r m u s c u l a r m o v e ­

m e n t s o f t h e m o t h e r ' s b o d y . I t i s a de l i ca te , t r a n s p a r e n t m e m b r a n e

F A L S E - S C O R P I O N S 111

a n d looks l ike a m i n u t e m u s h r o o m , i ts s ta lk j o i n e d to t h e o v i d u c t ,

a n d t h e eggs a r e la id i n t o i t . T h e i r n u m b e r m a y v a r y f r o m five t o

fo r ty o r m o r e . A f t e r a few d a y s t h e y o u n g e s c a p e f r o m t h e e g g -

m e m b r a n e b u t s t ay in s ide t h e b r o o d - s a c .

T h e s e first l a rvae h a v e a s u c k i n g b e a k a n d r e m a i n a t t a c h e d t o t h e

gen i t a l orifice o f t h e f ema le t h r o u g h w h i c h t h e y a re fed on a k i n d

o f u t e r i n e m i l k s e c r e t e d b y t h e t r a n s f o r m e d ova r i e s o f t h e m o t h e r ,

w h o s e a b d o m e n g r a d u a l l y s h r i n k s a s t h e l a rvae g r o w . T h e y swel l

s o m u c h t h a t V a c h o n d e s c r i b e s t h e m a s ' l a rvae gonf lees ' a n d t h e

b r o o d - m a s s b e c o m e s m o r e b u l k y t h a n t h e m o t h e r ' s b o d y w h e n c e

i t p r o j e c t s b r o a d l y on e a c h s ide a n d of ten a lso p o s t e r i o r l y . By

d e g r e e s a n d w i t h o u t m u c h f u r t h e r i n c r e a s e i n s ize t h e s e d e u t e m -

b r y o s c o m p l e t e t h e i r d e v e l o p m e n t . B e h i n d t h e o ld la rva l s t r u c t u r e s

t h e che l i c e r ae a p p e a r a n t e r i o r l y a n d w i d e a p a r t w h i l e do r sa l ly t h e

a b d o m i n a l s e g m e n t s w i t h t h e i r se tae b e c o m e d i s t i n c t . L a t e r a l l y

a n d v e n t r a l l y t h e p a l p s a n d legs b e c o m e c lear ly d i f f e ren t i a t ed .

F o u r o r five w e e k s a f te r t h e e x t r u s i o n o f t h e eggs s o m e p o w e r o f

m o v e m e n t i s a t t a i n e d a n d t h e y o u n g e m e r g e f r o m t h e b r o o d - m a s s ,

t h e d e b r i s o f w h i c h r e m a i n s a t t a c h e d t o t h e i r m o t h e r .

T h e y o u n g , o r p r o t o n y m p h s , e m e r g e w i t h i n a b o u t a d a y . I n

s o m e spec i e s s u c h as Garypus minor a n d t h e B r i t i s h Chthonius

ischnocheles, Neobisium carpenteri, N. maritimum, N. muscorum,

Toxochernes panzeri, Chernes cimicoides a n d Dendrochernes cyrneus,

20 or m o r e y o u n g a re p r o d u c e d , in Chelifer cancroides, 7 to 39 , b u t

t h e fami l ies of t h e s m a l l e r Cheiridium museorum n u m b e r o n l y 2 to 5

i n d i v i d u a l s .

I n s o m e spec i e s t h e p r o t o n y m p h s r i d e o n t h e i r m o t h e r s ' b a c k s

l ike y o u n g s c o r p i o n s a n d wol f s p i d e r s , b u t t h e y a r e ac t ive , g r e e d y

l i t t le c r e a t u r e s a n d s o o n d i s p e r s e .

W h e n y o u n g p s e u d o s c o r p i o n s e m e r g e f r o m t h e b r o o d - m a s s t h e y

r e s e m b l e m i n i a t u r e c o p i e s o f t h e i r p a r e n t s . T h e y m o u l t t h r e e t i m e s

on ly , for w h i c h p u r p o s e t h e y u s u a l l y enc lose t h e m s e l v e s i n m o u l t ­

ing n e s t s , b e f o r e r e a c h i n g t h e a d u l t s t age . D u r i n g t h i s t i m e t h e y

i nc r ea se t h e i r l e n g t h b y a b o u t o n e a n d a half t i m e s , t h e spec ia l

s t r u c t u r e s o f t h e che l i ce rae d e v e l o p a n d t h e n u m b e r o f h a i r s w i t h

w h i c h t h e b o d y i s c o v e r e d i nc r ea se s c o n s i d e r a b l y . A p e r i o d o f

q u i e s c e n c e l a s t ing s o m e t e n t o fifteen d a y s p r e c e d e s t h e a c t u a l

m o u l t i n g p r o c e s s a n d t h e a n i m a l s d o n o t leave t h e i r n e s t s u n t i l

112 F A L S E - S C O R P I O N S

t h e y a r e a l m o s t fully c o l o u r e d ; t h a t i s t o say, w i t h i n t e n o r t w e l v e

days . P a i r i n g m a y o c c u r w i t h i n a b o u t a f o r t n i g h t o f t h e final

m o u l t .

A c c o r d i n g t o V a c h o n ( 1 9 4 7 b ) t h e dif ferent i n s t a r s o f fa lse-

s c o r p i o n s can b e r e c o g n i s e d a s fo l lows: t h e p r o t o n y m p h a lways ha s

f o u r t r i c h o b o t h r i a (o r l o n g s e n s o r y ha i r s ) o n t h e che l ae o f t h e p e d i ­

p a l p s ( o n e o n t h e m o v a b l e f inger , t h r e e o n t h e fixed f inger) , t h e

d e u t o n y m p h h a s e igh t ( t w o o n t h e m o v a b l e f inger , s ix o n t h e

f ixed), t h e t r i t o n y m p h h a s t e n ( t h r e e o n t h e m o v a b l e f inger , s even

o n t h e f ixed) w h i l e t h e a d u l t h a s t w e l v e t r i c h o b o t h r i a ( four o n t h e

m o b i l e f inger a n d e igh t o n t h e fixed f inger) . T h i s r u l e h o l d s g o o d

for all spec i e s i n w h i c h t h e a d u l t h a s t w e l v e t r i c h o b o t h r i a o n each

of i ts c laws .

In Chernes cimicoides f ema les p r o d u c e t h e i r eggs in t h e s u m m e r ,

b u t y o u n g m a y b e f o u n d t h r o u g h o u t t h e yea r . T h e larval s tages

a re p a s s e d t h r o u g h i n t h e a u t u m n a n d t h e y o u n g u s u a l l y h i b e r n a t e

be fo r e o r af ter t h e i r s e c o n d m o u l t . T h e y r e a p p e a r t h e fo l lowing

s p r i n g a n d t h e final m o u l t t ake s p l a c e i n ear ly s u m m e r , t h e e n t i r e

life cyc le l a s t ing for a y e a r . L e v i (1948) f o u n d t h a t in W i s c o n s i n

t h e life cyc le of Chelifer cancroides a lso o c c u p i e s a yea r , b u t V a c h o n

(1938) f o u n d t h a t i n F r a n c e t h e s a m e spec ies t ook t w o y e a r s t o

r e a c h m a t u r i t y . A p s e u d o s c o r p i o n h a s b e e n k n o w n t o l ive i n c a p ­

t iv i ty for a p p r o x i m a t e l y 3 1 / 2 y e a r s ( S t r e b e l , 1937) .

B I B L I O G R A P H Y

Identification

BEIER, M . ( 1 9 3 2 ) Pseudoscorpionidea. Das Tierreich, 57, 1 - 2 5 8 ; 58, 1 - 2 9 4 .

CHAMBERLIN, J . C . ( 1 9 3 1 ) T h e Arachnid order Chelonethida. Publ. Stanf. Univ. (Biol.), 7 , 1 - 2 8 4 .

EVANS , G. O. and BROWNING, E . ( 1 9 5 4 ) Synopses of the British Fauna,

No. 10—Pseudoscorpiones. London: Linn. Soc. K E W , H. W. ( 1 9 1 1 ) A synopsis of the false-scorpions of Britain and

Ireland. Proc. R. Irish Acad. ( B ) , 29, 3 8 - 6 4 . ( 1 9 1 6 ) Idem. Supplement . Ibid. ( B ) , 33, 7 1 - 8 5 .

ROEWER, C. F . ( 1 9 3 7 - 4 0 ) Chelonethi oder Pseudoskorpione in H . G.

BRONN'S Klass. Ordn. Tierreichs, 5, IV ( 6 ) , 1 - 3 5 4 .

Biology

BEIER, M . ( 1 9 4 8 ) Phoresie und Phagophil ie bei Pseudoscorpionen. Ost.

Zool. Z., 1 , 4 4 1 - 9 7 .

F A L S E - S C O R P I O N S 113

CLOUDSLEY-THOMPSON, J. L. (1956) Notes on Arachnida, 25.—An u n ­usual case of phoresy by false-scorpions. Ent. Mon. Mag., 9 2 , 71 .

GILBERT , O. (1951) Observations on the feeding of some British false-scorpions. Proc. Zool. Soc. Lond., 1 2 1 , 547-55.

KEW, H. W. (1911) On the pairing of Pseudoscorpiones. Proc. Zool. Soc. Lond., 1 9 1 1 , 376-90.

(1914) On the nests of Pseudoscorpiones: with historical notes on the spinning organs and observations on the building and spinning of nests. Ibid., 1 9 1 4 , 93 -111 .

(1929) On the external features of the development of the Pseudo­scorpiones: with observations on the ecdyses and notes on the> im­mature forms. Ibid., 1 9 2 9 , 33-8 .

LEVI, H. W. (1948) Notes on the life history of the Pseudoscorpion Chelifer cancroides (Linn.) (Chelonethida). Trans. Amer. Micr. Soc, 6 7 , 290-8 .

STREBEL, O. (1937) Beobachtungen am einheimischen Biicherskorpion Chelifer cancroides L. (Pseudoscorpiones). Beitr. naturh. Forsch. Sudzu. Dtsch., 2 , 143-55.

TURK , F. A. (1953) A new genus and species of pseudoscorpion with some notes on its biology. Proc Zool. Soc Lond., 1 2 2 , 951-4 .

VACHON, M. (1938) La reproduct ion et le developpement des Pseudo­scorpions. Ann. Sci. nat. Zool., (11), 1 , 1 - 2 0 9 .

(1947a) Nouvelles remarques a propos de la phoresie des Pseudo­scorpions. Bull. Mus. Hist. nat. Paris, (2), 1 9 , 84 -7 .

(1947b) Comment reconnaitre Page chez les Pseudoscorpions (Arachnides). Ibid., (2), 1 9 , 271-4 .

(1948) Quelques remarques sur la 'nettoyage des pattes machoires ' et les glandes salivaires, chez les Pseudoscorpions (Arachnides). Ibid., (2), 2 0 , 1 6 2 - 4 .

(1954) Remarques sur un Pseudoscorpion vivant dans les ruches d'Abeilles au Congo Beige, Ellingsenius hendrickxi n. sp. Ann. Mus. Congo. Tervuren, 1, 284-7.

H S.S.C.M

C H A P T E R V I I I

W H I P - S C O R P I O N S A N D O T H E R S

IN THE p r e s e n t c h a p t e r , f i ve sma l l o r d e r s o f A r a c h n i d a a r e c o n ­

s i d e r e d w h o s e affinities h a v e l o n g b e e n d i s p u t e d , a n d w h o s e n a t u r a l

h i s t o r y a n d w a y o f life a r e sti l l l a rge ly u n k n o w n . T h e t h r e e o r d e r s

T h e l y p h o n i d a , S c h i z o m i d a a n d P h r y n i c h i d a w e r e for m a n y y e a r s

r e c o g n i s e d a s s u b - o r d e r s o f t h e o r d e r P e d i p a l p i a n d w e r e k n o w n a s

F I G . 27. Examples of Palpigradi, Thelyphonida and Schizomida. (Drawings not to scale.) (After various authors.)

U r o p y g i H o l o p e l t i d i a , U r o p y g i S c h i z o p e l t i d i a a n d A m b l y p y g i o r

T a r a n t u l i d a e r e spec t ive ly . H o w e v e r , i n 1948 , P e t r u n k e v i t c h r a i sed

t h e m t o o r d i n a l r a n k a n d t h u s t h e y a r e h e r e t r e a t e d , a l t h o u g h

M i l l o t (in G r a s s e , 1949)* sti l l r e g a r d s t h e S c h i z o m i d a as a s u b ­

o r d e r o f t h e U r o p y g i .

114

W H I P - S C O R P I O N S A N D O T H E R S 115

Order PALPIGRADI

Classification and distribution T h e P a l p i g r a d i o r M i c r o t h e l y p h o n i d a a r e t i n y c r e a t u r e s r e s e m ­

b l i n g , a s t h e i r a l t e r n a t i v e n a m e s u g g e s t s , m i n i a t u r e w h i p - s c o r p i o n s .

T h e p r o s o m a a p p e a r s t o cons i s t o f on ly t w o s e g m e n t s w h e n seen

f rom a b o v e , t h e t e r g u m o f t h e s e g m e n t b e a r i n g t h e f o u r t h p a i r o f

a p p e n d a g e s f o r m i n g p a r t o f t h e c a r a p a c e ; b u t v e n t r a l l y t h e r e a r e

four s t e r n i t e s . T h e che l i ce rae a r e t h e o n l y c h e l a t e a p p e n d a g e s a s

t h e p e d i p a l p s a r e leg- l ike a n d t e r m i n a t e in a p a i r o f c l aws . E y e s

a r e a b s e n t a n d t h e m o u t h i s a m e r e sli t b e t w e e n t h e b a s e s o f t h e

che l i ce rae . T h e a b d o m e n i s d i s t i n c t l y s e g m e n t e d a n d i s t e r m i n a t e d

by a s l e n d e r f l age l lum c o n s i s t i n g o f 15 s e g m e n t s . T h e e x t e r n a l r e ­

p r o d u c t i v e o r g a n s o f t h e a d u l t s a r e q u i t e c o m p l i c a t e d a n d a r e

b o r n e o n t h e s e c o n d a n d t h i r d a b d o m i n a l s e g m e n t s .

T h e o r d e r c o m p r i s e s b u t a s ing le fami ly , t h e K o e n e n i i d a e , c o n ­

t a i n i n g a b o u t t w e n t y spec i e s i n f o u r g e n e r a . T h e s e m i n u t e A r a c h ­

n i d a a r e w i d e l y d i s t r i b u t e d i n s o u t h e r n E u r o p e , Afr ica , A m e r i c a

f r o m Ca l i fo rn ia t o C h i l e , S i a m a n d A u s t r a l i a .

Biology P a l p i g r a d i s h o w a m a r k e d a v o i d a n c e o f l i gh t a n d a re u s u a l l y

f o u n d u n d e r h a l f - b u r i e d s t o n e s a n d i n o t h e r d a m p a n d s h e l t e r e d

p laces i n c o m p a n y w i t h s p r i n g - t a i l s , m y r i a p o d s , w o o d l i c e a n d

o t h e r r e t i r i n g a n i m a l s . A few spec i e s s u c h as Koenenia spelaea, K.

draco a n d K. pyrenaica a r e t r o g l o d y t e s a n d h a v e p a r t i c u l a r l y e l o n g a ­

t e d l i m b s w i t h a b u n d a n t s e n s o r y h a i r s . M i c r o - w h i p - s c o r p i o n s a p ­

p e a r t o b e d e p e n d e n t u p o n m o i s t c o n d i t i o n s a n d a r e e x t r e m e l y

s u s c e p t i b l e t o de s i cca t i on . D u r i n g p e r i o d s o f d r o u g h t t h e y m a k e

t h e i r w a y d e e p i n t o t h e soil .

P a l p i g r a d i c a n m o v e w i t h g r e a t agi l i ty , t h e i r p e d i p a l p s ass i s t ing

t h e o t h e r l i m b s i n l o c o m o t i o n w h i l e t h e i r f l a g e l l u m i s h e l d h o r i z o n ­

ta l ly b e h i n d t h e b o d y . F r o m t h e s t r u c t u r e o f t h e i r che l i ce rae i t i s

e v i d e n t t h a t t h e s e a n i m a l s a re c a r n i v o r o u s , b u t i n v i e w o f t h e i r

m i n u t e s ize t h e r e c a n b e few o t h e r a n i m a l s s m a l l e n o u g h t o b e

s u i t a b l e a s p r e y . W h e e l e r (1900) f o u n d t h a t t h e a l i m e n t a r y cana l o f

Koenenia mirabilis, a spec ie s o c c u r r i n g in T e x a s , c o n t a i n e d on ly

m a t e r i a l r e s e m b l i n g yo lk pa r t i c l e s a n d c o n c l u d e d t h a t i t w a s a d -

1 1 6 W H I P - S C O R P I O N S A N D O T H E R S

m i r a b l y c o n s t r u c t e d for s u c k i n g t h e eggs o f o t h e r m i n u t e a r t h r o ­

p o d s s u c h a s S y m p h y l a a n d P a u r o p o d s , b u t t h i s h y p o t h e s i s ha s

b e e n c o n t e s t e d . N o p r e d a t o r s h a v e y e t b e e n r e c o r d e d , a l t h o u g h t h e

s a m e a u t h o r f o u n d a t t a c h e d t o t h e v e n t r a l su r face o f t h e p r o s o m a o f

ce r t a in i n d i v i d u a l s , a n e c t o - p a r a s i t e o f u n k n o w n n a t u r e , t h e y o u n g

fo rms o f w h i c h w e r e u n i - s e g m e n t e d a n d t h e a d u l t s t h r e e - s e g m e n t e d .

Of t h e m a t i n g h a b i t s a n d life cyc le o f t h e P a l p i g r a d i v e r y l i t t le i s

k n o w n , t h o u g h i t i s b e l i e v e d t h a t i n d i v i d u a l s c a n r e c o g n i s e o n e

a n o t h e r b y scen t . I n c e r t a i n spec ies t h e m a l e s a p p e a r t o o u t n u m b e r

t h e f ema le s , w h i l e in o t h e r s , s u c h as K. mirabilis, m a l e s a r e ex­

t r e m e l y r a r e . In t h e y o u n g s t ages of Prokoenenia wheeleri t h e r e are

f ewer ha i r s , f ewer che l i ce ra l t e e t h a n d f ewer f lagellar s e g m e n t s

t h a n in t h e a d u l t s . In c e r t a i n spec i e s , a p a i r o f eve r s ib l e sacs h a v e

b e e n d e s c r i b e d o n e a c h o f t h e f o u r t h t o s ix th a b d o m i n a l s t e r n i t e s .

T h e s e v a r y i n n u m b e r a n d p o s i t i o n d u r i n g g r o w t h a n d m a y r e ­

p r e s e n t a p r i m i t i v e a n d v e r y s i m p l e t y p e o f b r e a t h i n g o r g a n .

Order THELYPHONIDA

Classification and distribution I n t h e i r g e n e r a l f o r m , t h e T h e l y p h o n i d a b e a r s o m e s l igh t r e s e m ­

b l a n c e t o s c o r p i o n s . T h e y c a n easi ly b e d i s t i n g u i s h e d , h o w e v e r ,

b y t h e f o r m o f t h e p e d i p a l p s , t h e first p a i r o f legs a n d t h e a b d o m e n ,

w h i c h b e a r s a s l e n d e r c a u d a l a p p e n d a g e f r o m w h i c h t h e n a m e

' w h i p - s c o r p i o n ' i s d e r i v e d . T h e s e s t r a n g e A r a c h n i d s a re gene ra l l y

o f l a rge s ize, v a r y i n g f r o m 2 5 t o 7 0 m m i n l e n g t h . T h e e l o n g a t e d

p r o s o m a i s c o v e r e d by a do r sa l c a r a p a c e a n d h a s t h r e e t h o r a c i c

s t e r n i t e s . T h e che l i ce rae a re c o m p o s e d o f t w o s e g m e n t s a n d a re

n o t che l a t e , w h i l e t h e p e d i p a l p i a r e p o w e r f u l l i m b s o f six s e g m e n t s .

T h e i r coxae a r e fu sed b e l o w t h e m o u t h a n d h a v e n o m a s t i c a t i n g

func t i on , b u t each t r o c h a n t e r h a s a l a rge s e m i c i r c u l a r p r o c e s s on

i ts i n n e r s i d e a r m e d w i t h s h a r p t e e t h . T h e p r o c e s s e s c a n b e

p r e s s e d a g a i n s t e ach o t h e r a n d a re wel l a d a p t e d t o c r u s h i n g t h e

p r ey , w h i c h i s d e t e c t e d b y t h e l o n g a n t e r i o r legs . T h e s e a r e n o t

u s e d for w a l k i n g b u t a r e h e l d s t r e t c h e d o u t i n f ron t a s t ac t i l e

o r g a n s . T h e r e i s o n e p a i r o f m e d i a n a n d t h r e e pa i r s o f la te ra l eyes

b u t t h e s e a re feeble a n d s e r v e on ly t o d i s t i n g u i s h b e t w e e n l igh t

a n d d a r k n e s s .

W H I P - S C O R P I O N S A N D O T H E R S 117

T h e a b d o m e n i s c o m p o s e d o f 1 2 s e g m e n t s , o f w h i c h t h e last

t h r e e a re sma l l a n d a n n u l a r , f o r m i n g a p y g i d i u m w h i c h b e a r s t h e

long , w h i p - l i k e t e l son .

R e p r e s e n t a t i v e s o f t h e o r d e r a r e d i s p e r s e d s o m e w h a t u n e v e n l y

t h r o u g h o u t t h e t r o p i c s : t h e g e n u s Hypoctonus i s f o u n d in M a l a y a ,

Typopeltis in C o c h i n c h i n a a n d J a p a n , w h i l e Thelyphonus h a s an

I n d o - o c e a n i c d i s t r i b u t i o n . T h e la rges t spec ies b e l o n g t o t h e g e n u s

Mastigoproctus w h i c h , a p p r o p r i a t e l y e n o u g h , is exc lus ive ly

A m e r i c a n .

General behaviour T h e T h e l y p h o n i d a a r e n o c t u r n a l p r e d a t o r s a n d u s u a l l y s p e n d

t h e d a y - t i m e h i d i n g u n d e r logs a n d s t o n e s o r s h e l t e r i n g i n t h e i r

b u r r o w s . A c c o r d i n g to P e r g a n d e (1886) , Mastigoproctus giganteus

a p p e a r s to se lec t a p l ace for d i g g i n g w h e r e t h e r e i s a l r e a d y a smal l

d e p r e s s i o n i n t h e soil . W i t h i t s f r o n t legs la id b a c k w a r d s , i t t h e n

s c r a p e s a q u a n t i t y of s a n d i n t o a h e a p w i t h i ts p o w e r f u l p e d i p a l p s ,

g r a s p s t h i s w i t h b o t h p e d i p a l p s a n d , m o v i n g b a c k w a r d s for s o m e

d i s t a n c e f r o m i ts b u r r o w , t u r n s r o u n d a n d d e p o s i t s i ts l oad . A f t e r

p a t t i n g a n d s m o o t h i n g i t s o m e w h a t w i t h o n e o r o t h e r o f i ts p a l p s ,

i t r e s t s for a m o m e n t w i t h o n l y t h e a n t e n n a e - l i k e first legs p l ay ing ,

' a s i f i n t h o u g h t ' . T h e n , t u r n i n g r o u n d , i t r e t r a c e s i t s w a y t o t h e

o p e n i n g , a lways u s i n g i ts l ong , s l e n d e r legs c a u t i o u s l y t o d i s ­

cove r i t s p a t h . O n r e a c h i n g t h e b u r r o w i t goes t h r o u g h t h e s a m e

p e r f o r m a n c e a s b e f o r e . T h e c h a n n e l w h e n d u g r e a c h e s a l e n g t h

o f 7.5 to 10 cm a n d t akes severa l d a y s to c o m p l e t e , a s t h e a n i m a l

of ten r e s t s m o t i o n l e s s for h o u r s , o r goes o u t on a h u n t i n g ex­

p e d i t i o n .

A sma l l spec ies , Labochirus proboscideusy is fair ly a b u n d a n t in

t h e l o w - l y i n g j u n g l e s o f t h e K a n d y d i s t r i c t o f C e y l o n a n d i s k n o w n

to e x t e n d to a c o n s i d e r a b l y h i g h e r a l t i t u d e . I t i s f o u n d u n d e r

s t o n e s a n d logs o f d e c a y i n g w o o d in t h e n e i g h b o u r h o o d o f w a t e r ­

c o u r s e s a n d i n o t h e r p a r t s o f t h e j u n g l e w h e r e t h e soil i s t h o r o u g h l y

m o i s t e n e d b y t h e r a i n s , b u t d o e s n o t o c c u r o n m a r s h y g r o u n d .

T h i s spec ies d igs a b u r r o w for i tself b e n e a t h t h e s t o n e s u n d e r

w h i c h i t l ives ( G r a v e l e y , 1 9 1 1 , 1915) . Thelyphonus sepiaris, w h i c h

also i n h a b i t s C e y l o n is, h o w e v e r , m u c h b e t t e r ab l e t o w i t h s t a n d

d r o u g h t . I t l ives in d r i e r s i t u a t i o n s a n d wil l s u r v i v e in a d r y cage

118 W H I P - S C O R P I O N S A N D O T H E R S

w i t h o u t w a t e r for severa l w e e k s w i t h o u t a p p a r e n t d i s c o m f o r t . I t

a p p e a r s , t o o , to be o f a s o m e w h a t less t i m i d d i spos i t i on .

Food and feeding habits W h i p - s c o r p i o n s feed chiefly on in sec t s s u c h a s c o c k r o a c h e s ,

g r a s s h o p p e r s , c a t e rp i l l a r s a n d t e r m i t e s , a s we l l a s w o r m s a n d s lugs ,

w h i c h t h e y se ize q u i c k l y w i t h t h e i r s h a r p p e d i p a l p s . A c c o r d i n g t o

G r a v e l e y (1915) i t i s a l m o s t i m p o s s i b l e to o b s e r v e t h e f e e d i n g o f

t h e n o c t u r n a l C e y l o n spec ies Labochirus proboscideus in i ts n a t u r a l

h a u n t s . E v e n in c a p t i v i t y i t i s v e r y s h y o f a n y l i g h t af ter e m e r g i n g

f rom i ts h i d i n g p l a c e in s e a r c h o f food , b u t wil l ea t a s of ten as

su i t ab l e p r e y i s p r o v i d e d . I t wi l l a c c e p t w i n g e d t e r m i t e s , sma l l

l ocus t s a n d r o a c h e s , espec ia l ly w h e n t h e s e a re d i s a b l e d , b u t i s

easily ' f r i g h t e n e d ' b y l a r g e r i n sec t s a n d b y v e r y ac t ive o n e s . T h e

p r e y i s se ized b e t w e e n t h e p e d i p a l p s a n d h e l d b e t w e e n t h e m a n d

t h e p r o s o m a : l i t t le u s e a p p e a r s t o b e m a d e o f t h e che l ae . T h e

che l i ce rae a r e p r o v i d e d w i t h b r u s h e s o f h a i r s w h i c h m a y s e r v e t o

filter t h e b l o o d o f t h e d i s m e m b e r e d p r e y . T h e y a r e also u s e d i n

c l e a n i n g t h e t e r m i n a l s e g m e n t s o f t h e legs . T h e a n t e n n i f o r m first

legs a r e g e n e r a l l y h e l d d i r e c t e d f o r w a r d s a n d u s u a l l y s o m e w h a t

o u t w a r d s i n a n a r c h e d p o s i t i o n . A s t h e a n i m a l m o v e s a l o n g t h e y

a re l o w e r e d a l t e r n a t e l y f r o m t i m e t o t i m e u n t i l t h e t i p c o m e s i n

c o n t a c t w i t h t h e g r o u n d , a n d t h e n r a i sed a g a i n . I t i s n o t k n o w n for

ce r t a in w h e t h e r t h i s spec i e s d r i n k s w a t e r a s s o m a n y o t h e r s d o ,

b u t i t i s h i g h l y p r o b a b l e .

W h e n h u n t i n g , t h e l a rge A m e r i c a n Mastigoproctus giganteus

m o v e s s lowly a n d c a u t i o u s l y w i t h i ts f o r m i d a b l e p a l p s o u t s t r e t c h e d

a n d o p e n , fee l ing a n d t o u c h i n g all ob jec t s a b o u t i t w i t h i t s s e n s o r y

first legs , u n t i l i t d i s c o v e r s an i n s e c t w h i c h i t g r a s p s . T h e p r e y i s

t h e n c a r r i e d i n t o t h e b u r r o w as a ca t ca r r i e s a m o u s e . A l t e r n a t e

s t r i k ing a n d g r a p p l i n g m o v e m e n t s o f t h e p a l p s c a r r y t h e a t t a c h e d

p r e y f i rmly t o w a r d s t h e che l i ce rae . T h i s l a rge spec i e s h a s b e e n

k n o w n t o eat sma l l f rogs a n d t o a d s , b u t o n t h e w h o l e T h e l y p h o n i d a

a re v e r y t i m i d c r e a t u r e s . N e v e r t h e l e s s , w h e n i n t r o d u c e d t o o n e

a n o t h e r i n c lose q u a r t e r s , t h e y e n g a g e i n f i e r c e b a t t l e s i n w h i c h

o n e o r b o t h o f t h e c o n t e s t a n t s i s f r e q u e n t l y k i l led o r m u t i l a t e d .

In cap t iv i ty , s p e c i m e n s of Thelyphonus skimkewitchii feed read i ly

o n d e a d insec t s , f i r s t careful ly a n d s lowly e x a m i n i n g t h e ob jec t

W H I P - S C O R P I O N S A N D O T H E R S 119

be fo re t a k i n g i t u p i n t h e i r che l ae . L i v e i n sec t s a r e r a r e ly c a u g h t

a n d t h e y d o n o t a t t e m p t t o i n t e r f e re w i t h bee t l e s a n d g r a s s h o p p e r s

l a rge r t h a n t h e m s e l v e s . O n t h e o t h e r h a n d a m o t h wil l b e d e v o u r e d

a l m o s t c o m p l e t e l y a n d a d ragonf ly e a t e n all b u t t h e w i n g s . Bes ides

insec t s , t h e y wil l ea t sma l l p i eces o f o v e r - r i p e b a n a n a ( F l o w e r ,

1901) . M a r x (1892) f o u n d t h a t v e r y y o u n g M. giganteus w o u l d n o t

ea t f l i e s b u t fed o n sma l l c o c k r o a c h e s .

T h e a n t e r i o r legs o f T h e l y p h o n i d a s e rve a s fee lers : t h e y a re

sens i t ive n o t on ly t o t o u c h , b u t a lso t o c h e m i c a l s a n d m o i s t u r e .

T h e de l i cacy o f t h e i r r e s p o n s e c a n b e i l l u s t r a t ed b y b r e a t h i n g

o n t h e m w h e n t h e y a r e a t r e s t — e v e n t h i s s l i gh t s t i m u l u s i n t h e case

of Mastigoproctus i s e n o u g h to s e n d t h e m i n t o res t l e ss ac t iv i ty . I f

a n a n i m a l w h i c h i s a imles s ly w a n d e r i n g a b o u t s h o u l d h a p p e n t o

ge t t h e t i p of o n e of t h e s e l i m b s i n t o a d i s h of w a t e r , i t wil l i m ­

m e d i a t e l y s w i n g a b o u t , t h r u s t i ts o t h e r feeler i n t o t h e w a t e r , c l a m ­

b e r half i n t o t h e d i sh a n d b e g i n g r e e d i l y t o s c o o p w a t e r i n t o i ts

m o u t h w i t h i ts che l i ce rae . I f v e r y d i l u t e h y d r o c h l o r i c ac id i s s u b ­

s t i t u t e d for w a t e r , a c l e a r - c u t a v o i d a n c e r e a c t i o n i s o b t a i n e d

( P a t t e n , 1917) .

A l t h o u g h i t i s be l i eved t h a t n o n e o f t h e ' P e d i p a l p s ' i s p o i s o n o u s ,

a n d no p o i s o n g l a n d s h a v e b e e n f o u n d i n a n y o f t h e s e o r d e r s , M .

giganteus i s g r ea t l y f ea red in s o m e of t h e s o u t h e r n U n i t e d S t a t e s on

a c c o u n t o f i ts s u p p o s e d l y v e n o m o u s p o w e r s . I t i s g iven t h e local

n a m e o f ' g r a m p u s ' a n d c a n inflict w o u n d s i n t h e h u m a n sk in w i t h

t h e s h a r p s p i n e s o n i ts p e d i p a l p s . T h e l y p h o n i d a p r o t e c t t h e m s e l v e s

w h e n d i s t u r b e d b y d i s c h a r g i n g f r o m t h e ana l r e g i o n a d u s t - l i k e

c l o u d h a v i n g a s t r o n g o d o u r of ace t ic ac id in spec ies s u c h as Thely­

phonus caudatus, T. sepiaris a n d Hypoctonus oatesi, w h i l e t h e o d o u r

of t h e r e p u g n a t o r i a l f luid f r o m T . linganus i s sa id to r e s e m b l e t h a t

of c h l o r i n e gas . I f a w h i p - s c o r p i o n be m o l e s t e d w i t h a f inger b e a r ­

ing a c u t o r r a w s c r a t c h , t h i s c u t o r s c r a t c h wil l p r o b a b l y b e g i n to

s m a r t v io l en t ly f r o m ac id e jec ted f r o m n e a r t h e b a s e o f t h e ta i l , b u t

t h i s i s t h e w o r s t t h e y c a n d o .

T h e n a m e ' v i n e g a r o n e ' b y w h i c h T h e l y p h o n i d a a re k n o w n i n

p a r t s o f t h e s o u t h e r n U n i t e d S t a t e s w a s o r ig ina l ly b e s t o w e d o n

t h e m b y se t t l e r s f r o m t h e F r e n c h W e s t I n d i e s , a n d a r o s e f r o m t h e

v i n e g a r - l i k e , ac id s e c r e t i o n t h e y e x u d e w h e n a p p r o a c h e d . A b l ack ­

s m i t h i n 1877 i s r e p o r t e d t o h a v e c r u s h e d o n e t o h i s u p p e r left

120 W H I P - S C O R P I O N S A N D O T H E R S

b r e a s t . Bl i s te rs r e s u l t e d f r o m t h e ac id s ec re t i on w h i c h e x t e n d e d

ove r t h e w h o l e o f h i s ches t . F l o w e r (1901) a lso h a d a c u r i o u s ex­

p e r i e n c e w i t h a s p e c i m e n of Thelyphonus skimkewitchii in B a n g ­

kok. T h i s spec ies i s k n o w n in S i a m e s e a s ' M e n g p o n - m e n n ' ( i .e .

s t i n k i n g s c o r p i o n ) : i t i s chiefly to be seen d u r i n g t h e r a i n y season

a n d g ives off a fa in t a n d c h a r a c t e r i s t i c sme l l . He w r o t e : ' S e e i n g a

Thelyphonus o f t h i s spec ies r u n n i n g on t h e g r o u n d , I p i c k e d i t up

b y t h e c e p h a l o t h o r a x b e t w e e n t h e first f inger a n d t h u m b o f m y

left h a n d ; i t a t o n c e b e n t i ts t h r e a d - s h a p e d tail ove r i ts b a c k (as a

s c o r p i o n does ) a n d also s c r a t c h e d a b o u t m y f ingers w i t h i ts legs ,

b u t t h e p i n c e r s d id n o t t o u c h m e ; I t h o u g h t n o t h i n g o f i ts ta i l , e tc .

u n t i l I felt a s h a r p p a i n a n d f o u n d t h e a n i m a l had s o m e h o w s t u n g

m e . I w e n t s t r a i g h t i n t o m y h o u s e , a n d a l r e a d y t h e first j o i n t o f m y

f inger w a s v e r y swol l en a n d in f l amed , t h e r e b e i n g a r a p i d l y g r o w ­

i n g w h i t e l u m p , a n d t h e r e s t w a s r ed ; a t o n e s p o t w a s a f resh

p u n c t u r e as i f a n e e d l e h a d b e e n d r i v e n in , in a h o r i z o n t a l d i r ec t i on ,

a n d g o n e s o m e l i t t le w a y u n d e r t h e sk in . Af te r c u t t i n g a n d s q u e e z ­

ing t h e w o u n d , I p u t my f inger i n t o a s t r o n g s o l u t i o n o f p e r m a n ­

g a n a t e o f p o t a s h , w h i c h a t o n c e r e l i eved t h e p a i n a n d s t o p p e d t h e

swel l ing , b u t t h e l i t t le w o u n d c o n t i n u e d t o s m a r t for s o m e h o u r s .

S i n c e t h e n I h a v e b e e n carefu l n e v e r to let a Thelyphonus t o u c h

m e . '

G r a v e l e y (1915) h o w e v e r c o u l d h a r d l y be l i eve t h a t t h i s s t i ng

was rea l ly d u e to t h e T . skimkewitchii a s he h a d f r e q u e n t l y h a n d l e d

o t h e r spec ies w i t h o u t r ece iv ing a n y h a r m a n d i t i s p r o b a b l e t h a t

t h e a n i m a l w a s b l a m e d unfa i r ly .

Mating habits and life cycle T h e e x t e r n a l a p p e a r a n c e o f t h e sexes i s a l m o s t iden t i ca l a n d t h e y

can of ten be d i s t i n g u i s h e d on ly by m e a n s o f smal l d i f ferences in

t h e s t r u c t u r e o f t h e gen i t a l s t e r n i t e s . T h e c o u r t s h i p o f Thelyphonus

sepiaris h a s b e e n d e s c r i b e d by G r a v e l y (1915) . I t cons i s t s of a

c u r i o u s sexua l p a r a d e r e m i n i s c e n t o f t h a t o f t h e s c o r p i o n s . T h e

m a l e g r i p s t h e a n t e n n i f o r m first legs o f t h e f ema le in h i s p e d i p a l p s

a n d h o l d s t h e i r e x t r e m i t i e s i n h i s che l i ce rae . H e t h e n wa lks b a c k ­

w a r d s , t h e f emale fo l lowing . Before l o n g s h e ra ises h e r a b d o m e n

i n t h e air a n d t h e m a l e c o m m e n c e s t o s t r oke h e r gen i t a l s e g m e n t

w i t h h i s e l o n g a t e d f ron t legs . T h e s e a re u sua l l y p a s s e d b e t w e e n

W H I P - S C O R P I O N S A N D O T H E R S 1 2 1

t h e t h i r d a n d f o u r t h legs o f t h e female , b u t s o m e t i m e s p a s s b e ­

h i n d h e r b a c k legs . T h e i r t i p s a re g e n e r a l l y c ro s sed . A t t h e s a m e

t i m e t h e che l ae o f t h e m a l e a re h e l d o p e n a n d a r e m o v e d s l igh t ly

ove r t h e dorsa l su r face o f t h e a b d o m e n o f t h e f emale .

W h e n t h e f ema le i s p r e g n a n t , s h e seeks she l t e r . Thelyphonus

caudatus d igs a b u r r o w s o m e 40 cm in d e p t h a n d s l igh t ly e n l a r g e d

a t i ts e x t r e m i t y . T h e e n t r a n c e i s c o n c e a l e d w i t h leaves a n d o t h e r

d e b r i s . T h e f ema le ins ta l l s he r se l f a t t h e b o t t o m o f t h e b u r r o w

w h e r e s h e lays s o m e 2 0 t o 3 5 ye l l owi sh eggs . T h e s e a r e r e t a i n e d i n

a t r a n s p a r e n t m e m b r a n e fixed b e n e a t h h e r gen i t a l s t e r n i t e . T h e y

a r e c o m p a r a t i v e l y l a rge , m e a s u r i n g a b o u t 3 m m i n d i a m e t e r , a n d

a r e p r o t e c t e d f r o m d e s i c c a t i o n by a q u a n t i t y o f l i q u i d p r o d u c e d a t

t h e t i m e o f t h e i r e m i s s i o n .

T h e f ema le r e m a i n s m o t i o n l e s s i n h e r r e t r e a t for severa l w e e k s .

T h e exac t i n c u b a t i o n p e r i o d i s n o t k n o w n h o w e v e r , a s cap t ive

f emales u s u a l l y d e v o u r t h e i r eggs . T h e y o u n g free t h e m s e l v e s b y

c u t t i n g t h e e g g - s a c w i t h spec ia l s p i n e s o n t h e i r legs . T h e y a r e

y e l l o w i s h - w h i t e i n c o l o u r a n d v e r y di f ferent i n a p p e a r a n c e f r o m

t h e a d u l t s . Af t e r a w h i l e t h e y c l i m b s lowly on t o t h e i r m o t h e r ' s

b a c k a n d c l ing t o h e r o p i s t h o s o m a a n d t h e b a s e o f h e r b a c k legs

b y m e a n s o f t h e a d h e s i v e d iscs w i t h w h i c h t h e i r ta rs i a re f u r n i s h e d .

H e r e t h e y r e m a i n u n t i l af ter t h e first m o u l t w h e n t h e y a c q u i r e t h e

typ ica l f o r m a n d r e s e m b l e m i n i a t u r e a d u l t s . N o w t h e y leave t h e i r

m o t h e r w h o h a s b e c o m e so t h i n a n d w e a k a s a r e s u l t o f h e r p r o ­

l o n g e d vigi l t h a t s h e falls i n t o a s t a t e o f l e t h a r g y f r o m w h i c h s h e

d o e s n o t r ecove r . T h e d e v e l o p m e n t o f t h e y o u n g i s e x t r e m e l y s low.

T h e y u n d e r g o t h r e e m o r e m o u l t s a t yea r ly i n t e rva l s be fo r e b e ­

c o m i n g a d u l t ( S t r u b e l l , 1926) .

Order SCHIZOMIDA

Classification and distribution S c h i z o m i d a , s o m e t i m e s k n o w n a s S c h i z o n o t i d a e o r T a r t a r i d a e ,

differ f r o m t h e T h e l y p h o n i d a , w i t h w h i c h t h e y a r e of ten g r o u p e d ,

in t h e i r sma l l s i z e — t h e y m e a s u r e f r o m 5 to 7 mm in l e n g t h — a n d

i n h a v i n g t h e c a r a p a c e s u b d i v i d e d i n t o t h r e e u n e q u a l d iv i s ions ,

t h e p r o p e l t i d i u m , m e s o p e l t i d i u m a n d m e t a p e l t i d i u m . T h e last

122 W H I P - S C O R P I O N S A N D O T H E R S

t w o a r e p r e s e n t a s free t e rg i t e s , a p r i m i t i v e c o n d i t i o n , a n d b e l o n g

t o t h e s e g m e n t s b e a r i n g t h e t h i r d a n d f o u r t h p a i r s o f legs r e s p e c ­

t ively . M e d i a n eyes a r e l a c k i n g b u t a p a i r o f la te ra l eyes m a y be

p r e s e n t w h i c h a re r e d u c e d t o sma l l pa l e a r ea s o f cu t i c le i n s o m e

f o r m s . T h e p e d i p a l p s a re c lawless , r a p t a t o r y , r a t h e r r o b u s t a n d

of ten a r m e d w i t h c h a r a c t e r i s t i c s p i n e s a n d se tae , w h i l e t h e legs o f

t h e first p a i r a re l o n g a n d s l e n d e r a n d u s e d l ike a n t e n n a e a s t ac t i l e

sense o r g a n s . T h e a b d o m e n i s aga in c o m p o s e d o f t w e l v e s e g m e n t s ,

t h e las t t h r e e b e i n g sma l l , a n n u l a r a n d f o r m i n g a p y g i d i u m w h i c h

b e a r s a s h o r t c a u d a l a p p e n d a g e m a d e u p o f o n e t o t h r e e , o r o c ­

cas iona l ly four , s e g m e n t s . In t h e m a l e s i t i s of ten fused i n t o a

s ingle r o u n d e d o r e l o n g a t e k n o b .

T h r e e g e n e r a o n l y a r e f o u n d in t h e o r d e r : Schizomus a n d Trithy-

reus h a v e a w i d e t r o p i c a l a n d e q u a t o r i a l d i s t r i b u t i o n , w h i l e Stenoch-

rus c o n t a i n s a s ing le spec ies f r o m P o r t o R i c o . O n e or t w o spec ies

h a v e b e e n d e s c r i b e d f r o m s p e c i m e n s i n t r o d u c e d i n t o h o t - h o u s e s

i n t e m p e r a t e c o u n t r i e s ( C l o u d s l e y - T h o m p s o n , 1949) . T h e g e n e r a

Schizomus a n d Trithyreus c a n be d i s t i n g u i s h e d by t h e fact t h a t t h e

p o s t e r i o r free s e g m e n t o f t h e p r o s o m a i s d i v i d e d by a l o n g i t u d i n a l

s u t u r e i n t h e la t te r .

Biology S c h i z o m i d a a r e a b s o l u t e l y n o c t u r n a l i n t h e i r h a b i t s a n d s p e n d

t h e d a y i n d a m p , d a r k r e t r e a t s u n d e r leaves , s t o n e s a n d logs , o r

d e e p i n t h e soil w h e r e t h e g r o u n d i s m o i s t . I n C e y l o n , Schizomus

crassicaudatus i s f o u n d o n l y u n d e r b r i c k s , e t c . , on o r c lose to o p e n

g r o u n d m o r e or less s h a d e d by t r e e s , w h i l e S . vittatus a n d Trithy­

reus paradenigensis o c c u r a m o n g d e a d leaves espec ia l ly w h e r e t h e s e

f o r m a l aye r o f c o n s i d e r a b l e d e p t h a n d a r e m a t t e d t o g e t h e r b y

funga l h y p h a e . A l t h o u g h t h e y m a k e n o a t t e m p t t o d r i n k , t h e y a re

v e r y s u s c e p t i b l e t o de s i cca t i on . I n a d d i t i o n , t h e y a r e s t r o n g l y

p h o t o - n e g a t i v e a n d a r e v e r y sens i t ive t o tac t i l e a n d v i b r a t o r y

s t i m u l i . T h e y can r u n s u r p r i s i n g l y fast a n d , w h e n t o u c h e d i n

f ron t , e s cape b y a s u d d e n j u m p b a c k w a r d s . A p p r o a c h i n g ob jec t s

a p p e a r of ten t o b e p e r c e i v e d — p r o b a b l y b y m e a n s o f v i b r a t i o n s —

be fo re t h e y a r e a c t u a l l y t o u c h e d . T h e e l o n g a t e d f r o n t p a i r o f legs ,

h i g h l y sens i t ive tac t i l e s ense o r g a n s , a r e c a r r i e d aloft a n d n o t u s e d

i n w a l k i n g . L i t t l e i s k n o w n o f t h e b io logy o f S c h i z o m i d a . T h e y p r o -

W H I P - S C O R P I O N S A N D O T H E R S 1 2 3

b a b l y feed o n sma l l a r t h r o p o d s s u c h a s C o l l e m b o l a , T h y s a n u r a ,

S y m p h y l a a n d p o s s i b l y sma l l a n t s s u c h as Monomorium pharaonis

w i t h w h i c h t h e y a r e f r e q u e n t l y a s soc i a t ed ( C l o u d s l e y - T h o m p s o n ,

1949) . I n c a p t i v i t y t h e y s h o w cann iba l i s t i c p roc l iv i t i e s . A n a l s t ink

g l a n d s p r o d u c e ace t ic ac id , o r s i m i l a r c o m p o u n d s , w h i c h a re u s e d

i n de fence . T h e a n i m a l s h a v e n o f i x e d a b o d e , b u t l ive i n n a t u r a l

ho le s a n d c rev ices i n t h e soi l .

M a l e s of Schizomus latipes h a v e n o t ye t b e e n f o u n d , a l t h o u g h

t h e w r i t e r h a s e x a m i n e d o v e r fo r ty s p e c i m e n s o f t h i s spec ies .

P o s s i b l y t h e y h a v e a s h o r t life a n d d i e s o o n af ter m a t i n g .

T h e b r e e d i n g h a b i t s o f S c h i z o m i d a a r e l i t t le k n o w n a n d a p p e a r

to h a v e b e e n o b s e r v e d o n l y in t h e case of S . crassicaudatus. A c ­

c o r d i n g to G r a v e l e y (1915) a c a p t i v e s p e c i m e n c o n s t r u c t e d a l i t t le

FIG. 2 8 . Schizomus crassicaudatus, female guarding her eggs. (After Gravely, 1915.)

cav i ty a b o u t 1 5 m m b e l o w t h e su r face o f t h e soi l . T h e n e s t h a d n o

o p e n i n g a n d t h e Schizomus n e v e r lef t i t u n t i l t h e eggs d i s a p p e a r e d

t h r e e w e e k s la te r . I t w a s l i ned w i t h soil c e m e n t e d t o g e t h e r . T h e

eggs w e r e s e v e n i n n u m b e r , f l a t t ened a t t h e i r po le s , g l i s t e n i n g

w h i t e a n d n o t e n c l o s e d i n a b r o o d p o u c h . T h e y w e r e a r r a n g e d i n a

s p h e r i c a l m a s s a t t a c h e d t o t h e a b d o m e n o f t h e f ema le i n t h e r e g i o n

o f h e r gen i t a l a p e r t u r e . As a r u l e she r e s t e d on t h e s ide o f t h e nes t ,

1 2 4 W H I P - S C O R P I O N S A N D O T H E R S

h e r b o d y b e n t a t r i g h t ang les , w i t h t h o r a x ve r t i ca l a n d a b d o m e n

h o r i z o n t a l .

Order PHRYNICHIDA ( = AMBLYPYGI)

Classification and distribution T h e P h r y n i c h i d a differ f r o m o t h e r T e d i p a l p s ' i n l ack ing any

c a u d a l a p p e n d a g e a n d i n h a v i n g t h e o p i s t h o s o m a j o i n e d t o t h e

c e p h a l o t h o r a x by a s l e n d e r p e d i c e l . T h e c a r a p a c e i s e n t i r e w i t h a

p a i r o f m e d i a n , a n d t h r e e p a i r s o f la te ra l eyes , a n d t h e r e a re t h r e e

FIG. 2 9 . Phrynichida ( = Amblypygi) , Charon grayi (after Kano, 1 9 3 7 ) and Charinus milloti (after Millot, 1 9 4 9 . ) (Body lengths,

2 cm.)

t h o r a c i c s t e r n i t e s . T h e p e d i p a l p s a r e s t o u t r a p t a t o r y o r g a n s a r m e d

wi th s t r o n g s p i n e s a n d t e r m i n a t i n g i n a m o v a b l e h o o k . T h e flexible

t ip o f t h e legs o f t h e first p a i r i s v e r y l o n g a n d c o m p o s e d o f m a n y

s e g m e n t s : i t i s u s e d as a t ac t i l e s e n s e o r g a n . W i t h t h e i r f l a t t ened

b o d i e s a n d s o m b r e c o l o u r s , t h e s e a n i m a l s b e a r a superf ic ia l r e s e m ­

b l a n c e t o c r a b s p i d e r s . T h e a b d o m e n i s c o m p o s e d o f t w e l v e seg­

m e n t s , t h e last o n e f o r m i n g a p y g i d i u m . T h e size va r i e s f r o m 8 to

4 5 m m i n l e n g t h .

T h e d i s t r i b u t i o n o f t h e ta i l less w h i p - s c o r p i o n s i s la rge ly c o n ­

d i t i o n e d b y t h e i r w a t e r r e q u i r e m e n t s a n d t h e y a re f o u n d on ly i n

t h e m o r e h u m i d r e g i o n s o f t h e t r o p i c s a n d s u b - t r o p i c s . T h e r e a re

t w o fami l ies , t h e C h a r o n t i d a e a n d t h e T a r a n t u l i d a e . T h e f o r m e r

W H I P - S C O R P I O N S A N D O T H E R S 125

i s c o m p o s e d m o s t l y of sma l l e r , c a v e r n i c o l o u s f o r m s h a v i n g a d i s ­

t r i b u t i o n i n s o u t h e r n a n d e a s t e r n As ia a n d t h e Pacif ic i s l ands ,

w h i l e t h e l a t t e r c o n t a i n s t h r e e s u b - f a m i l i e s : t h e P h r y n i c i n a e w h i c h

a re f o u n d i n Afr ica , I n d i a a n d C e y l o n , t h e D a m o n i n a e w h i c h

o c c u r i n Afr ica a n d S o u t h A m e r i c a , a n d t h e T a r a n t u l i n a e w h i c h

a re en t i r e ly A m e r i c a n .

Biology A s a l r e a d y m e n t i o n e d , m o s t o f t h e P h r y n i c h i d a l ive i n h u m i d

r e g i o n s u n d e r logs a n d s t o n e s , o r i n c r ev i ce s a m o n g rocks , w h e r e

t h e y c a n m o v e freely. U n l i k e t h e T h e l y p h o n i d a w h i c h r e s t o n t h e

g r o u n d i f t h e ob jec t u n d e r w h i c h t h e y a r e s h e l t e r i n g i s l i f ted u p ,

t h e y a r e u s u a l l y t o b e f o u n d c l i n g i n g t o i t s u n d e r su r face . T h e y

will d a r t r o u n d t h e s t o n e b e n e a t h w h i c h t h e y w e r e h i d i n g i n o r d e r

t o e v a d e c a p t u r e , b u t s e l d o m t r y t o e s c a p e t o o t h e r s t o n e s . T h e

ta i l less w h i p - s c o r p i o n s a r e aga in n o c t u r n a l c a r n i v o r e s a n d s p e n d

t h e d a y h i d i n g i n t h e i r d a r k r e t r e a t s . W h e n s u d d e n l y e x p o s e d t o

t h e l igh t , t h e y d o n o t a t o n c e f l e e , b u t f reeze i n t o i m m o b i l i t y . I f

t o u c h e d , h o w e v e r , t h e y c a n r u n w i t h s u r p r i s i n g s p e e d . T h e i r

m o v e m e n t s a r e s o m e w h a t u n p r e d i c t a b l e ; t h e y u s u a l l y m o v e s ide ­

w a y s l ike c r a b s p i d e r s , w a l k i n g w i t h t h e six p o s t e r i o r legs ex­

t e n d e d s i d e w a y s w h i l e t h e first p a i r a r e w a v e d l ike a n t e n n a e a n d

e x p l o r e t h e su r f ace ove r w h i c h t h e a n i m a l s a r e t r ave l l i ng . W h e n ,

t h e c r e a t u r e s a r e a t res t , h o w e v e r , t h e s e legs m a y b e s lowly r o t a t e d ,

o n e f o r w a r d s a n d t h e o t h e r b a c k w a r d s , so a s t o s w e e p a l a rge a rea

r o u n d t h e b o d y . T h e y r e s e m b l e t h e w r i t h i n g o f t e n t a c l e s r a t h e r

t h a n t h e m o r e typ ica l m o v e m e n t s o f a r t h r o p o d a n t e n n a e . T h e

e x t r e m e t i p i s u s e d t o t o u c h t h e su r face w h i c h i s b e i n g inves t ­

iga ted a n d t h i s i s d o n e w i t h t a p p i n g m o v e m e n t s o f e x t r e m e de l i ­

cacy.

T h a n k s t o t h e i r t a r sa l pu lv i l l i , t h e C h a r o n t i d a e c a n c l i m b

ver t i ca l su r faces a n d r u n a b o u t u n d e r n e a t h t h e ce i l ings o f caves .

Charinides bengalensis, for e x a m p l e , c a n c l i m b a ver t i ca l s h e e t of

p o l i s h e d g lass a n d e v e n wa lk ac ros s t h e l o w e r su r face of a h o r i z ­

on ta l s h e e t w h i l e t h e T a r a n t u l i d a e , l ack ing pulv i l l i , c a n n o t d o

th i s .

A n u m b e r o f spec ies h a v e b e c o m e d o m e s t i c a t e d a n d l ive in d a r k

c o r n e r s o f h o u s e s i n t r o p i c a l r e g i o n s . E x a m p l e s a re a f forded b y

126 W H I P - S C O R P I O N S A N D O T H E R S

Phrynichus ceylonicus in I n d i a , Paracharon caecus in P o r t u g u e s e

G u i n e a , Masicodamon allanieus in M o r o c c o a n d Damon medius

a n d D . variegatus i n F r e n c h W e s t Afr ica a n d S o u t h Afr ica r e s p e c ­

t ive ly . A c c o r d i n g t o L a w r e n c e (1949) t h e las t spec i e s p r o b a b l y

o c c u r s i n all b u i l d i n g s i n P i e t e r m a r i t z b u r g i n t h e v e n t i l a t i o n a reas

b e l o w f l o o r - l e v e l . S p e c i m e n s a re also v e r y c o m m o n i n o u t h o u s e s ,

b e n e a t h s t o r e d f u r n i t u r e , p a c k i n g cases a n d o t h e r l a rge w o o d e n

s t r u c t u r e s w h i c h h a v e b e e n left u n d i s t u r b e d . I n p a r k s a n d g a r d e n s

t h e y of ten l ive u n d e r o ld t r e e s t u m p s o r fa l len t r u n k s o f t r ee s ,

w h i l e i n m o r e o p e n c o u n t r y t h e y a r e c o m m o n u n d e r s t o n e s a n d i n

c rev ices o f r o c k s . I t i s p r o b a b l e t h a t t h e m o r e d o m e s t i c a t e d spec ies

a re b e t t e r ab l e to w i t h s t a n d d r y c o n d i t i o n s , a n d Phrynichus ceyloni­

cus, a spec ies t h a t d o e s n o t b u r r o w , c a n l ive for t w o or t h r e e w e e k s

in a b a r e cage , w h i l e t h e v a r i e t y pusillus a p p e a r s to be con f ined to

m o i s t j u n g l e s of t h e l o w e r h i l l s of C e y l o n a n d d ies in a few d a y s i f

n o t s u p p l i e d w i t h m o i s t soil ( G r a v e l e y , 1915) .

Al l P h r y n i c h i d a a re p r e d a t o r y , f e e d i n g on a v a r i e d se l ec t ion of

insec t s s u c h a s c o c k r o a c h e s , c r i cke t s , g r a s s h o p p e r s , t e r m i t e s , w o o d -

lice a n d t h e l ike. T h e y a r e v e r y ' n e r v o u s ' a n i m a l s , a p p r o a c h t h e i r

p r e y c a u t i o u s l y a n d t h e n seize i t s u d d e n l y , g r i p p i n g i t w i t h t h e i r

p e d i p a l p s . In Phrynichus ceylonicus b o t h p a l p s a re s h o t f o r w a r d

i n a n y a t t e m p t t o c a t c h t h e p r e y , b u t c a p t u r e i s u s u a l l y effected

b e t w e e n t h e t e r m i n a l c l aw a n d t h e s p i n e n e a r t h e e n d o f t h e t ib ia

o f t h e p e d i p a l p on o n e s ide on ly . S p i n e s a re a r r a n g e d to f o r m a v e r y

effective ' h a n d ' , t h e t e r m i n a l c l aw b e i n g a p p o s a b l e t o t h e p r o x i m a l

o f t w o l o n g do r sa l s p i n e s a t t h e d is ta l e n d o f t h e t ib ia a n d t h e s p i n e

o n t h e p e n u l t i m a t e j o i n t t o t h e d is ta l o f t h e s e . A s t h e c l aw a n d all

t h r e e s p i n e s a re r ig id a n d s h a r p l y p o i n t e d i t m i g h t b e s u p p o s e d

t h a t o n c e t h e p r e y i s g r a s p e d , e scape w o u l d b e q u i t e i m p o s s i b l e .

T h e s t r e n g t h n e c e s s a r y t o r e t a i n t h e p r e y a p p e a r s t o b e l ack ing ,

h o w e v e r , a n d e v e n a s o f t - b o d i e d c r i cke t m a y b e a t t a c k e d u n ­

successful ly , t i m e af ter t i m e . B u t o n c e w i t h i n r e a c h o f t h e che l i ­

ce rae , all c h a n c e of e s c a p e v a n i s h e s .

T h e p r e y , w h i c h f r e q u e n t l y r e m a i n s al ive for a t i m e , i s h e l d b e ­

t w e e n t h e p e d i p a l p s , of ten w i t h t h e t e r m i n a l f i n g e r e m b e d d e d i n

i ts t i s sue s , w h i l s t p a r t s o f i t a re s c o o p e d i n t o t h e m o u t h b y t h e

t e r m i n a l s e g m e n t s o f t h e che l i ce rae w h o s e saw- l ike a r m a t u r e m a y

be o f u s e in s e v e r i n g p ieces o f s u i t a b l e s ize f r o m t h e m a i n m a s s .

W H I P - S C O R P I O N S A N D O T H E R S 127

S u c h p i eces a r e m a s t i c a t e d b y c o m b i n e d ve r t i ca l a n d l o n g i t u d i n a l

m o v e m e n t s o f t h e s e a p p e n d a g e s w h i c h r u b i t a g a i n s t t h e g n a t h o -

b a s e s o f t h e p e d i p a l p s .

U n l i k e Phrynichus ceylonicus, Charinides bengalensis c a p t u r e s its

p r e y b e t w e e n t h e t w o s e c o n d a p p e n d a g e s a s t h e t e r m i n a l c l aw o f

t h e p a l p c a n n o t b e c losed a g a i n s t t h e s p i n e s a t t h e e n d o f t h e t ib i a .

T h e c a p t u r e i s e x t r e m e l y s u d d e n a n d c a n o n l y b e o b s e r v e d w i t h

difficulty. W h e n d r i n k i n g , d r o p s o f w a t e r a r e c o n v e y e d b y t h e

p a l p s t o t h e che l i ce rae , o r t h e s e o r g a n s m a y b e i n s e r t e d d i r ec t ly

i n t o t h e w a t e r w h i c h i s t a k e n u p w i t h m o v e m e n t s l ike t h o s e e m ­

p l o y e d in m a s t i c a t i o n .

T h e a p p e n d a g e s a r e of ten c l e a n e d b y t h e che l i ce rae a s i n false-

s c o r p i o n s a n d g r e a t ca re i s t a k e n t o k e e p t h e i r t i p s free f r o m d i r t .

I n t h e case o f t h e p e d i p a l p s t h i s m a y b e c o r r e l a t e d w i t h t h e p r e s e n c e

o n t h e t e r m i n a l s e g m e n t s o f a n e l a b o r a t e s y s t e m o f s p i n e s , c l u b b e d

ha i r s a n d p i t s w h i c h m a y p e r h a p s c o n s t i t u t e a n o r g a n o f t a s t e . I t i s

n o t u n l i k e l y t o o t h a t t h e p u l v i l l u s on t h e t a r s i o f C . bengalensis a n d

t h e p a d in P . ceylonicus m u s t be k e p t pe r fec t ly c l ean i f t h e y a r e

t o b e u s e d effectively a n d t ac t i l e o r g a n s m a y b e c o n c e n t r a t e d i n

t h i s r e g i o n . T h a t t h e a n t e n n i f o r m first legs s h o u l d b e k e p t c lean

i s c lea r ly n e c e s s a r y on a c c o u n t o f t h e i r f u n c t i o n a s feelers . T h e

e x t e n t t o w h i c h v i s ion i s u s e d i n s eek ing p r e y i s u n c e r t a i n

( G r a v e l e y , 1915) . P h r y n i c h i d a u s u a l l y fast for severa l d a y s af ter

e ach m e a l .

T h e s e c o n d a r y sex d i f ferences o f t h e P h r y n i c h i d a a r e e x t r e m e l y

smal l , a n d i n m o s t spec ies t h e r e i s l i t t le t o d i s t i n g u i s h t h e m a l e s

f r o m t h e f ema les . In Charon grayi, h o w e v e r , w h i c h h a s a w i d e d i s ­

t r i b u t i o n i n e a s t e r n As ia , t h e f e m u r o f t h e p e d i p a l p i n t h e m a l e

i s l o n g e r t h a n t h o s e o f t h e s e c o n d , t h i r d a n d f o u r t h w a l k i n g legs ,

w h i l e i n t h e f ema le i t i s s h o r t e r . M a t i n g h a b i t s h a v e n o t y e t b e e n

o b s e r v e d i n a n y o f t h e P h r y n i c h i d a . D u r i n g t h e b r e e d i n g season ,

t he f ema les o f t h e spec ies c a r r y a n egg sac o n t h e i r a b d o m e n s .

T h e n u m b e r o f eggs m a y v a r y f r o m 7 t o 8 0 o r m o r e , d e p e n d i n g o n

t h e size o f t h e m o t h e r ( T a k a s h i m a , 1950) . T h e eggs a r e q u i t e

la rge , m e a s u r i n g 2 to 3 mm in d i a m e t e r a n d p r o b a b l y in all spec ies

a re c a r r i e d b y t h e m o t h e r i n a c a p s u l e a t t a c h e d t o t h e v e n t r a l s u r ­

face o f h e r a b d o m e n . B o t h eggs a n d e m b r y o s a r e c losely p a c k e d i n

t h i s egg sac, t h e p r e s s u r e in t h e con f ined a rea g i v i n g a s u b a n g u l a r

128 W H I P - S C O R P I O N S A N D O T H E R S

o u t l i n e t o s o m e o f t h e c o n t i g u o u s eggs . T h e c o n t e n t s o f t h e sac

are n o t a r r a n g e d i n r e g u l a r r o w s , e i t h e r l o n g i t u d i n a l l y o r t r a n s ­

verse ly , b u t in t h e S o u t h Af r i can Damon variegatus a r e t w o layers

d e e p ( L a w r e n c e , 1949) .

A c c o r d i n g t o G r a v e l e y (1915) all t h e I n d i a n a n d C e y l o n e s e

spec ies a p p e a r t o b r e e d a t a b o u t t h e s a m e t i m e o f yea r . T h e

e m b r y o s a re c a r r i e d u n d e r t h e a b d o m e n w h e r e t h e y a r e s u p p o r t e d

b y a m e m b r a n e s e c r e t e d for t h e p u r p o s e . T h e n u m b e r o f eggs

var ies f r o m 15 to 60 or m o r e . Charinides bengalensis b r e e d s in

J u l y a n d A u g u s t a n d s o m e t i m e s ear l ie r . T h e n e w l y h a t c h e d y o u n g

a re en t i r e ly w h i t e : l ike y o u n g s c o r p i o n s t h e y c l ing t o t h e do r sa l

su r face a n d t h e s ides o f t h e a b d o m e n o f t h e i r m o t h e r u n t i l af ter

t h e i r f i r s t m o u l t . I m m e d i a t e l y af ter t h e f i r s t m o u l t t h e c a r a p a c e i s

a l i t t le ove r 1 mm in w i d t h , b u t d u r i n g t h e f i r s t y e a r i ts w i d t h i s

d o u b l e d . D u r i n g t h e s e c o n d y e a r i t i n c r e a s e s t o a b o u t 2 . 5 m m a n d

d u r i n g t h e t h i r d t o 3 m m o r m o r e . T h e a d u l t s ize i s a p p r o x i m a t e l y

3.5 m m .

FIG. 30 Ricinulei. (After Berland, 1 9 5 5 , and Millot, 1 9 4 9 . )

Order RICINULEI

T h e R ic inu l e i o r P o d o g o n a t a a r e smal l A r a c h n i d s , 4 t o 1 0 m m

in l e n g t h w i t h a s h o r t m a s s i v e b o d y a n d a r e m a r k a b l y h a r d , t h i c k

a n d d e e p l y g r a n u l a t e d i n t e g u m e n t . T h e p r o s o m a i s c o v e r e d b y a

W H I P - S C O R P I O N S A N D O T H E R S 1 2 9

n o n - s e g m e n t e d c a r a p a c e a t t h e f r o n t e d g e o f w h i c h i s a m o b i l e

h o o d o r c u c u l l u s w h i c h fits d o w n t i g h t l y o v e r t h e che l i ce rae . N o

t r u e eyes a r e p r e s e n t , b u t v a g u e p a l e s p o t s o n e a c h s ide o f t h e ca ra ­

p a c e m a y wel l r e p r e s e n t ves t ig ia l eyes . T h e p e d i p a l p s a r e o f six

s e g m e n t s a n d a re r e m a r k a b l e i n t h a t t h e i r coxal s e g m e n t s a r e fused

i n t h e m i d - l i n e : t h e y a r e c h e l a t e a s a r e t h e t w o - s e g m e n t e d che l i ­

ce rae . T h e p r o s o m a i s j o i n e d t o t h e o p i s t h o s o m a b y a n a r r o w

ped ice l , b u t t h i s i s h i d d e n f r o m v i e w b y e x p a n s i o n s o f t h e b a s e o f

t h e a b d o m e n w h i c h fits v e r y c lose ly aga in s t t h e p r o s o m a , t h e

j u n c t u r e f o r m i n g a c o u p l i n g dev ice . T h e l iv ing a n i m a l i s ab le t o

d i s e n g a g e t h e c a r a p a c e f r o m t h e a b d o m e n s o t h a t t h e gen i t a l

orifice i s e x p o s e d d u r i n g m a t i n g a n d o v i p o s i t i o n . T h e o p i s t h o s o m a i s

c o m p o s e d o f n i n e s e g m e n t s o f w h i c h o n l y t h e first f o u r a r e wel l

d e n n e d , w h i l e t h e las t t h r e e f o r m a sma l l p y g i d i u m . T h e legs a re

s h o r t a n d s t o u t , t h e t h i r d p a i r b e i n g m o d i f i e d a s c o p u l a t o r y o r g a n s

in m a t u r e m a l e s , a c h a r a c t e r o t h e r w i s e f o u n d o n l y in c e r t a i n m i t e s .

T h e o r d e r i s l i m i t e d to a s ing le fami ly , t h e R i c i n o i d i d a e (or

C r y p t o s t e m m i d a e ) a n d c o n t a i n s o n l y t w o g e n e r a , Ricinoides a n d

Cryptocellus. Of t h e s e t h e first i s r e p r e s e n t e d by s ix W e s t Af r i can

spec ies , t h e s e c o n d by s e v e n spec ies h a v i n g a d i s t r i b u t i o n f r o m

T e x a s t o t h e A m a z o n b a s i n . A f t e r t h e d i s c o v e r y i n 1838 , o f t h e

first s p e c i m e n s o f t h e s e v e r y r a r e a n i m a l s , o n l y 3 2 w e r e f o u n d

u n t i l , n e a r l y a c e n t u r y l a t e r i n t h e B r i t i s h C a m e r o o n s no less t h a n

317 s p e c i m e n s of Ricinoides sjostedti w e r e o b t a i n e d . I t i s n o t e n ­

t i re ly s u r p r i s i n g , t h e r e f o r e , t h a t t h e b i o l o g y o f t h e s e p e c u l i a r

c r e a t u r e s i s p rac t i ca l ly u n k n o w n , a l t h o u g h s p e c i m e n s h a v e b e e n

k e p t a l ive a t t h e B r i t i s h M u s e u m ( N a t u r a l H i s t o r y ) for o v e r a y e a r

( F i n n e g a n , 1935) .

R i c inu l e i a p p e a r g e n e r a l l y t o l ive u n d e r d a m p , fal len leaves i n

e q u a t o r i a l fo res t s . C e r t a i n M e x i c a n spec ies a r e c a v e r n i c o l o u s a n d

s p e c i m e n s of Cryptocellus dorotheae h a v e b e e n f o u n d s h o r t l y after

r a i n s i n t h e s a n d y soil o f t h e R i o G r a n d e R i v e r Val ley . T h e y w e r e

t aken f r o m u n d e r s l abs o f c o n c r e t e , h e a v y s h e e t i r o n a n d roof ing

m a t e r i a l w h i c h h a d n o t b e e n d i s t u r b e d for severa l y e a r s . T h e

c r e a t u r e s a r e v e r y s lugg i sh a n d h a v e a s l ow a n d c u r i o u s gai t .

T h e y m o v e w i t h c o n s i d e r a b l e d e l i b e r a t i o n a n d s e e m t o feel t h e i r

way a l o n g w i t h t h e i r f ron t p a i r o f legs , t h e i r m o v e m e n t s r e s e m ­

b l i n g t h o s e o f a t i ck c r a w l i n g o v e r t h e g r o u n d , S u d d e n i l l u m i n -

I S.S.C.M.

1 3 0 W H I P - S C O R P I O N S A N D O T H E R S

a t ion or s l igh t v i b r a t i o n s of t h e soil s e n d t h e m i n t o a ca t a l ep t i c

s t a te .

N o t h i n g i s k n o w n o f t h e life h i s t o r y a n d d e v e l o p m e n t o f t h e s e

r a r e A r a c h n i d s b e y o n d t h e fact t h a t t h e y a r e o v i p a r o u s , t h e eggs

h a t c h i n g i n t o a s ix - legged la rva l f o r m as in A c a r i .

B I B L I O G R A P H Y Identification

EWING , H. E. ( 1 9 2 9 ) A synopsis of the American Arachnids of the primitive order Ricinulei. Ann. Ent. Soc. Amer., 2 2 , 5 8 3 - 6 0 0 .

GRAVELEY, F. H. ( 1 9 1 6 ) T h e evolution and distribution of the Indo-Australian Thelyphonidae , with notes on the distinctive characters of various species. Rec. Ind. Mus., 1 2 , 5 9 - 8 9 .

KASTNER, A. ( 1 9 3 2 ) Pedipalpi Latreille in KUKENTHAL, W . a n d KRUMBACH,

T. Handbuch der Zoologie, Berlin, 3, ( 2 ) , 1 - 7 6 . ( 1 9 3 2 ) Palpigradi Thorel l . Ibid., 7 7 - 9 8 . ( 1 9 3 2 ) Ricinulei Thorel l . Ibid., 9 9 - 1 1 6 .

KRAEPELIN, K . ( 1 8 9 9 ) Scorpiones und Pedipalpi . Das Tierreich, 8 , 1 - 2 6 5 .

( 1 9 0 1 ) Palpigradi. Ibid., 1 2 , 1 - 3 .

POCOCK, R. I. ( 1 9 0 0 ) The Fauna of British India, including Ceylon and Burma. Arachnida. London .

ROEWER, C. F. ( 1 9 3 4 ) Palpigradi in H. G. BRONN'S Klass. Ordn. Tierreichs, 5 , I V ( 8 ) , 6 4 0 - 7 2 3 .

WERNER, F . ( 1 9 3 5 ) Pedipalpi. Ibid., 3 1 7 - 4 9 0 .

Biology

CLOUDSLEY-THOMPSON, J . L . ( 1 9 4 9 ) Notes on Arachnida, 1 1 . — S c h i ­zomida in England. Ent. Mon. Mag., 8 5 , 2 6 1 .

FINNEGAN , S. ( 1 9 3 5 ) Rarity of the archaic Arachnids Podogona (Ricinulei). Nature, Lond., 1 3 6 , 1 8 6 .

FLOWER, S. S. ( 1 9 0 1 ) Notes on the millipedes, centipedes, scorpions etc of the Malay Peninsula and Siam. J. Straits Brit. Asiat. Soc, 3 6 , 1 - 4 8 .

GRAVELEY, F. H. ( 1 9 1 1 ) Pedipalpi of Ceylon. Spolia Zeylandica, 7 , 4 3 - 7 . ( 1 9 1 5 ) Notes on the habits of Indian insects, myriapods and arach­

nids. Rec. Ind. Mus., 1 1 , 4 8 3 - 5 3 9 .

LAWRENCE, R. F. ( 1 9 4 9 ) Notes on the whip-scorpions (Pedipalpi) of South Africa. Trans. Roy. Soc. S. Africa, 3 2 , 2 7 5 - 8 5 .

MARX, G. ( 1 8 9 2 ) Contr ibut ions to the life-history of Arachnida. Proc. Ent. Soc. Wash., 2, 2 5 2 - 4 .

PATTEN , B. M. ( 1 9 1 7 ) Reactions of the whip-tail scorpion to light. J. Exp. Zool, 2 3 , 2 5 1 - 7 5 .

PERGANDE, T. ( 1 8 8 6 ) [Habits of a specimen of Thelyphonus}. Proc. Ent. Soc. Wash., 1 , 4 2 - 4 .

W H I P - S C O R P I O N S A N D O T H E R S 1 3 1

STRUBELL, A. ( 1 9 2 6 ) Thelyphonus caudatus L., Eine biologische Skizze. Verh. Nat. Ver. Bonn., 8 2 , 3 0 1 - 1 4 .

TAKASHIMA , H. ( 1 9 5 0 ) Notes on Amblypygi found in territories adjacent to Japan. Pacific Sci., 4, 3 3 6 - 8 .

WHEELER, W. M. ( 1 9 0 0 ) A singular Arachnid (Koenenia mirabilis Grassi) occurring in Texas . Amer. Nat., 3 4 , 8 3 7 - 5 0 .

C H A P T E R I X

H A R V E S T - S P I D E R S

Classification and distribution T h e o r d e r O p i l i o n e s o r P h a l a n g i d e a i n c l u d e s t h e h a r v e s t m e n ,

t h e m a j o r i t y o f w h i c h c a n b e r e c o g n i s e d b y t h e i r l ong , s l e n d e r legs

a n d s e g m e n t e d a b d o m e n w h i c h i s j o i n e d t o t h e c e p h a l o t h o r a x

ac ros s t h e w h o l e b r e a d t h a n d n o t b y a n a r r o w p e d i c e l a s i n s p i d e r s .

T h e c e p h a l o t h o r a x i s c o m p o s e d o f six s e g m e n t s a n d i s o f ten s e p a r ­

a t e d f r o m t h e a b d o m e n b y a fair ly d e e p g r o o v e . T h e c a r a p a c e i s

u s u a l l y s m o o t h a n d , i n m o s t spec ie s , b e a r s t w o eyes , a l t h o u g h t h e s e

m a y occas iona l ly b e a b s e n t . T h e eyes a r e n e a r l y a lways s i t u a t e d o n

a p r o m i n e n t o c u l a r t u b e r c l e n e a r t h e m i d d l e o f t h e c e p h a l o t h o r a x ,

o n e l o o k i n g o u t a t e a c h s ide . N e a r t h e a n t e r i o r m a r g i n o f t h e p r o ­

s o m a o p p o s i t e t h e a t t a c h m e n t o f t h e first p a i r o f legs t h e r e a r e t w o

sma l l o p e n i n g s l e a d i n g to a p a i r o f o d o r i f e r o u s g l a n d s : t h e g l a n d s

t h e m s e l v e s c a n , i n s o m e spec i e s , b e s e e n t h r o u g h t h e c a r a p a c e

w h e n t h e y look l ike a n e x t r a p a i r o f eyes . T h e che l i ce rae a r e t h r e e -

s e g m e n t e d , t h e las t t w o s e g m e n t s f o r m i n g p i n c e r s , w h i l e t h e p e d i ­

p a l p s a r e o f s ix s e g m e n t s . T h e i r coxae b e a r g n a t h o b a s e s w h i c h

f o r m p a r t o f a c o m p l e x m o u t h . T h e p e d i p a l p s a r e s h o r t a n d leg­

l ike; t h e y a re chiefly s e n s o r y o r g a n s for u s e i n c o n t a c t w i t h ob j ec t s

c lose t o t h e b o d y , a n d t h e y also h e l p i n g r a s p i n g t h e f o o d a n d

b r i n g i n g i t t o t h e j a w s . I n s o m e g e n e r a t h e y e n d i n a c l aw w h i c h

m a y b e s m o o t h o r t o o t h e d , b u t i n o t h e r s n o c l aw i s f o u n d .

T h e b o d i e s o f h a r v e s t - s p i d e r s a r e u s u a l l y c o v e r e d w i t h s p i n e s ,

p o i n t e d t u b e r c l e s a n d b r i s t l e s . T h e r e i s o f ten a d o u b l e r o w a l o n g

t h e c e n t r e o f t h e o c u l a r t u b e r c l e a n d i n s o m e g e n e r a o f P a l p a t o r e s

(see b e l o w ) a g r o u p f o r m s a t r i d e n t in t h e m i d d l e o f t h e fo r e - ed g e

o f t h e c e p h a l o t h o r a x a n d i s a n i m p o r t a n t d i a g n o s t i c c h a r a c t e r . O n

t h e u n d e r s i d e o f t h e b o d y t h e c o x a e o f t h e legs a l m o s t m e e t i n t h e

m i d d l e s o t h a t t h e r e i s n o s t e r n u m a s i n s p i d e r s .

132

H A R V E S T - S P I D E R S 1 3 3

T h e a b d o m e n i s c o m p o s e d o f t e n s e g m e n t s , b u t t h e s e c a n b e

d i s t i n g u i s h e d o n l y i n t h e m o s t p r i m i t i v e s u b - o r d e r , t h e C y p h o -

p h t h a l m i : i n o t h e r O p i l i o n e s n o t m o r e t h a n n i n e t e r g i t e s a re

a p p a r e n t . A u n i q u e p e c u l i a r i t y of h a r v e s t - s p i d e r s lies in t h e fact

t h a t t h e t e r g i t e a n d s t e r n i t e o f t h e s a m e s e g m e n t a r e n o t a lways

p l a c e d ve r t i ca l ly o p p o s i t e o n e a n o t h e r . T h e a n u s h a s b e e n b r o u g h t

f o r w a r d v e n t r a l l y s o t h a t t h e t e r g i t e p r i m i t i v e l y a b o v e i t n o w lies

b e h i n d , a n d t h e s t e r n i t e p r i m i t i v e l y b e l o w i s n o w p l a c e d i m m e d ­

iate ly i n f ron t . C o n s e q u e n t l y m o s t O p i l i o n e s h a v e s h o r t a n d

r o u n d e d b o d i e s . T h e m a j o r i t y o f spec i e s h a v e c r y p t i c , o r c o n c e a l ­

i n g co lo ra t i on , b e i n g u s u a l l y b r o w n o r g r ey , o f ten w i t h a c e n t r a l

d a r k b a n d w h i c h se rves t o b r e a k u p t h e o u t l i n e o f t h e a n i m a l ' s

s h a p e a n d r e n d e r s i t i n c o n s p i c u o u s aga in s t i ts n a t u r a l b a c k g r o u n d .

FIG. 3 1 . Examples of harvest-spider families: 1 . (Suborder) Cy-phophthalmi , 2 . Phalangodidae, 3 . Gonyleptidae, 4 . Trogulidae, 5. Nemastomidae, 6 . Ischyropsalidae, 7 . Phalangiidae. (Drawings

not to scale.) (After various authors.)

134 H A R V E S T - S P I D E R S

T h e s ize o f t h e b o d y va r i e s f r o m a b o u t 1 t o 2 0 m m i n l e n g t h , b u t

t h e m a j o r i t y a r e b e t w e e n 5 a n d 1 0 m m long .

T h e O p i l i o n e s a re d i v i d e d i n t o t h r e e s u b - o r d e r s , o f w h i c h t h e

C y p h o p h t h a l m i i s t h e m o s t p r i m i t i v e . I t c o m p r i s e s s o m e for ty

m i t e - l i k e spec ies v a r y i n g in l e n g t h b e t w e e n 1 a n d 3 m m , w i t h

s h o r t legs a n d r e p u g n a t o r i a l g l a n d s o p e n i n g a t t h e e n d s o f la te ra l

p r o s o m a t i c t u b e r c l e s . T h e gen i t a l i a a r e n o t c o v e r e d b y a n o p e r ­

c u l u m b u t t h e b o d y i s p r o t e c t e d b y a s h i e l d r e s u l t i n g f r o m t h e

fus ion o f t h e c e p h a l o t h o r a x a n d t h e a b d o m i n a l t e rg i t e s , e x c e p t i n g

t h e last . T h e a b d o m i n a l s t e r n i t e s a r e a lso fused i n a s imi l a r m a n n e r

a n d eyes a r e o f ten a b s e n t .

T h e C y p h o p h t h a l m i h a v e a v e r y d i s c o n t i n u o u s d i s t r i b u t i o n ,

spec ies o c c u r r i n g i n Cor s i ca , D a l m a t i a , c e n t r a l F r a n c e , p a r t s o f

t r o p i c a l Afr ica , C e y l o n , J a p a n , t h e E a s t I n d i e s a n d t h e U n i t e d

S t a t e s o f F l o r i d a a n d O r e g o n . T h e y a r e g e n e r a l l y t o b e f o u n d i n

h u m i d s i t u a t i o n s u n d e r m o r e o r less d e e p l y b u r i e d s t o n e s . T h e

g e n u s Siro is r e p r e s e n t e d in F r a n c e by S. rubens, a spec i e s first d i s ­

c o v e r e d by L a t r e i l l e a t B r i v e a n d long m i s t a k e n for a m i t e u n t i l

E . S i m o n e s t a b l i s h e d i ts t r u e n a t u r e . Siro duricorius i s k n o w n f ro m

t h e caves of C a r n i o l a in Y u g o s l a v i a a n d t h e r e l a t ed Parasiro cor-

sicus f r o m t h e n e i g h b o u r h o o d o f P o r t o V e c c h i o i n C o r s i c a . T h e

g e n u s Stylocellus o c c u r s in t h e E a s t I n d i e s , Ogivea a n d Paragovia

i n E q u a t o r i a l Afr ica a n d Purcellia o n t h e C a p e o f G o o d H o p e ,

w h e r e t h e g e n u s Speleosiro i s r e p r e s e n t e d by a s ing le t r o g l o d y t i c

spec ies .

T h e s e c o n d s u b - o r d e r , t h e L a n i a t o r e s , i s m o r e i m p o r t a n t t h a n

t h e p r e c e d i n g o n e a n d s o m e 1,500 spec ies h a v e s o far b e e n d e ­

sc r ibed , p r i n c i p a l l y f r o m s o u t h e r n l a t i t u d e s . T h e y a r e c h a r a c t e r ­

ised b y g r e a t d e v e l o p m e n t o f t h e p e d i p a l p s w h i c h a re a r m e d w i t h

s t o u t s p i n e s a n d s t r o n g c laws a n d a re u s e d a s r a p t a t o r y o r g a n s for

t h e c a p t u r e o f p r e y . T h e L a n i a t o r e s h a v e a n a l m o s t exc lus ive ly

t rop ica l d i s t r i b u t i o n , o n e fami ly , t h e P h a l a n g o d i d a e , h a v i n g a few

r e p r e s e n t a t i v e s i n E u r o p e (Scotolemon s p p . ) a n d i n N o r t h A m e r i c a

(Phalangodes s p p . ) . T h e s e a re t r o g l o d y t e s i n h a b i t i n g , a m o n g s t

o t h e r s , t h e M a m m o t h C a v e i n K e n t u c k y . I n a d d i t i o n , severa l

g e n e r a o c c u r i n t h e t r o p i c s o f t h e O l d W o r l d , A u s t r a l i a , t h e Pacific

i s l ands a n d m o s t o f S o u t h A m e r i c a . T h e r e m a i n i n g famil ies o f

L a n i a t o r e s a re en t i r e ly t rop ica l : t h e O n c o p o d i d a e a r e f o u n d i n

H A R V E S T - S P I D E R S 135

I n d i a , t h e A s s a m i i d a e i n I n d i a , a n d o t h e r p a r t s o f As ia a n d Afr ica

e x c l u d i n g M a d a g a s c a r , t h e C o s m e t i d a e i n t h e s o u t h e r n U n i t e d

S t a t e s a n d t h e T r i a e o n y c h i d a e i n M a d a g a s c a r , A u s t r a l i a a n d

A m e r i c a . T h e l a rges t fami ly i s t h e G o n y l e p t i d a e w h i c h i s a l m o s t

en t i r e ly conf ined t o S o u t h A m e r i c a w h e r e spec ies l ive i n d a m p

fores ts u n d e r s t o n e s a n d fal len t r e e s . T h e y h a v e p a r t i c u l a r l y l a rge ,

de fens ive s p i n e s on t h e last p a i r o f legs .

T h e m o s t i m p o r t a n t s u b - o r d e r o f t h e O p i l i o n e s i s t h e P a l p a -

to re s , t o w h i c h all t h e Br i t i sh spec ies b e l o n g . F o u r famil ies a re

k n o w n , o f w h i c h t h e T r o g u l i d a e a r e c o n s i d e r e d t o b e t h e m o s t

p r i m i t i v e . T h e s e a r e s lugg i sh , s h o r t - l e g g e d , g r o u n d - l i v i n g spec ies

t o b e f o u n d a m o n g g ras s r o o t s , m o s s a n d e v e n m u d i n c h a l k y d i s ­

t r i c t s o f E u r o p e , As ia M i n o r , N o r t h Afr ica a n d N o r t h A m e r i c a .

T h e fore e d g e o f t h e p r o s o m a f o r m s a b i f u r c a t e d h o o d c o v e r i n g t h e

m o u t h p a r t s , t h e r e i s n o o c u l a r t u b e r c l e a n d t h e b o d y i s d a r k

c o l o u r e d a n d h a b i t u a l l y c o v e r e d w i t h pa r t i c l e s o f d i r t a n d e a r t h

w h i c h r e n d e r t h e a n i m a l s e x t r e m e l y difficult t o see . T h e N e m a s -

t o m i d a e a re also sma l l , s h o r t - l e g g e d , da rk , g r o u n d - l i v i n g f o r m s

u sua l l y f o u n d a m o n g m o s s a n d d e a d leaves w h i l e t h e I s c h y r o p s a l -

idae a re a sma l l fami ly l i m i t e d to c e n t r a l E u r o p e , w h e r e t h e y live in

d a m p m o s s i n w o o d s , m o u n t a i n t o r r e n t s a n d t h e caves o f t h e P y r e ­

n e e s . T h e l a rges t fami ly i s t h e P h a l a n g i i d a e w h i c h i n c l u d e s all t h e

w e l l - k n o w n l o n g - l e g g e d h a r v e s t m e n o f E u r o p e , N o r t h Afr ica a n d .

N o r t h A m e r i c a . T h e s e a n i m a l s h a v e typ ica l ly r o u n d e d b o d i e s , t h e

pa lpa l t a r s u s i s l o n g e r t h a n t h e t ib ia a n d i ts c l aw i s wel l d e v e l o p e d .

T h e y a re t o b e f o u n d a m o n g l i t t e r a n d fal len leaves o n t h e g r o u n d ,

o n t h e t r u n k s o f t r e e s a n d i n v e g e t a t i o n ( T o d d , 1949) .

T h e d i s t r i b u t i o n o f h a r v e s t - s p i d e r s i n t h e B r i t i s h I s les h a s b e e n

d e s c r i b e d b y B r i s t o w e (1949) a n d S a n k e y ( 1 9 4 9 b ) , w h i l e t h e E u r o ­

p e a n f o r m s h a v e b e e n s t u d i e d b y S t i p p e r b e r g e r (1928) .

General behaviour T h e n a m e O p i l i o m e a n s , i n L a t i n , a ' s h e p h e r d ' a n d m a y refer t o

t h e fact t h a t i n s o m e c o u n t r i e s s h e p h e r d s w a l k a b o u t o n s t i l t s , t h e

b e t t e r t o c o u n t t h e i r f locks. I n o u r o w n l a n d h a r v e s t m e n w e r e

k n o w n a s ' s h e p h e r d s p i d e r s ' f ou r c e n t u r i e s ago , b u t T . M u f f e t t

(1634) in h i s Theatre of Insects 1 e x p l a i n e d t h i s by s ay ing ' t h e

1 Insectorum sive minimorum animalium theatrum. London .

H A R V E S T - S P I D E R S

E n g l i s h call i t S h e p h e r d e i t h e r b e c a u s e i t i s p l ea sed w i t h t h e C o m ­

p a n y o f S h e e p o r b e c a u s e S h e p h e r d s t h i n k t h o s e fields t h a t a re full

of t h e m to be e o o d w h o l e s o m e S h e e p - p a s t u r e . . . ' H o o k e (1658)

in h i s Micrographia gave t h e a l t e r n a t i v e n a m e s ' s h e p h e r d o r ca r t e r

s p i d e r ' a n d B r i s t o w e (1949) q u o t e s a n o ld E s s e x s u p e r s t i t i o n t h a t

i t was u n l u c k y p u r p o s e l y to kill a h a r v e s t m a n b e c a u s e of t h e belief

t h a t t h e s e c r e a t u r e s h e l p e d f a r m e r s w i t h t h e s c y t h e , r ake a n d sickle

w h i c h t h e y w e r e a l l eged t o pos se s s . I n F r a n c e t h e y a re k n o w n a s

faucheurs ( r e ape r s ) b e c a u s e t h e y g ive t h e a p p e a r a n c e of r e a p i n g as

t h e v walk , w h i l e t h e G e r m a n Weber-knechte m a y refer t o t h e j e r k y

m o v e m e n t s m a d e b y t h e legs o f t h e s e a n i m a l s after t h e y h a v e

b e c o m e d e t a c h e d f rom t h e b o d i e s o f t h e i r o w n e r s .

O n l v t w o spec ies , Phalangium opilio a n d Leiobunum rotundum,

are a t all c o n s p i c u o u s in o u r fields a n d a re m o s t n o t i c e a b l e a t t h e

h a r v e s t season , w h e n t h e y r e a c h matur i ty- . C o n s e q u e n t l y t h e s e ,

p a r t i c u l a r l y P . opilio, a re p r o b a b l y r e s p o n s i b l e for t h e n a m e

' h a r v e s t m e n ' . B r i s t o w e (1949) be l i eves t h a t 'Phalangium" w h i c h i s

o f e i g h t e e n t h c e n t u r y o r ig in , i s d e r i v e d f r o m t h e G r e e k ' p h a l a n x '

a n d t h a t t h e h a r v e s t - s p i d e r w a s l i k e n e d to a f o r m i d a b l e so ld i e r in a

p h a l a n x b e c a u s e i t w a s c o n f u s e d w i t h t h e v e r y p o i s o n o u s ' M a l -

m i g n a t t e ' , Latrodectus 13-guttatus, 2, r e la t ive of t h e n o t o r i o u s

' b l a c k - w i d o w ' s p i d e r w h i c h occas iona l ly b i t e s r e a p e r s in t h e fields o f

s o u t h e r n E u r o p e . O n t h e o t h e r h a n d , S a n k e y ( 1 9 4 9 b ) ha s s u g g e s t e d

t h a t t h e n a m e m a y be d e r i v e d f r o m phalange, a h e a d o r t oe seg­

m e n t , for l o n g l i m b s a re o n e o f t h e m o s t c o n s p i c u o u s f ea tu res o f

m o s t h a r v e s t - s p i d e r s .

T h e b io logy o f t h e L a n i a t o r e s , so c o m m o n in t r op i ca l r e g i o n s , i s

p rac t i ca l ly u n k n o w n b e y o n d t h e fact t h a t t h e y lead r e t i r i n g l ives i n

d a m p fores ts b e n e a t h b a r k , fal len t r ees a n d m o s s , a n d occas iona l ly i n

caves . I n N e w Z e a l a n d t h e h a r v e s t m e n o f t h e s u b - o r d e r L a n i a t o r e s

are a lways f o u n d in fo res t ed c o u n t r y o r in a reas w h i c h h a v e in

r e c e n t t i m e s b e e n fo res ted b u t w h e r e t h e b u s h ha s b e e n felled a n d

c lea red , l eav ing d e c a y i n g logs a n d sma l l p o c k e t s o f fores t w h i c h

p r o v i d e a f a v o u r a b l e h a b i t a t . T h e g rea t major i ty o f spec ies r e q u i r e

a h i g h a n d e v e n re la t ive h u m i d i t y . T h e y a re n o c t u r n a l a n d a re t o be

f o u n d d u r i n g t h e d a y s h e l t e r i n g b e n e a t h logs a n d s t ones , i n t h e

d e b r i s on t h e fores t floor, in m o s s g r o w i n g in s imi la r s i t u a t i o n s o r

o n t h e t r u n k s a n d b r a n c h e s o f t r ees i n t h e w e t t e r a r eas . T h e leaf-

H A R V E S T - S P I D E R S 157

m o u l d f a u n a cons i s t s m a i n l y o f t h e s m a l l e r spec ies o f N u n i a a n d

spec ies of Pristobunus. T h e spec ies of Synthetonychia a re r o u n d

on ly in l e a f - m o u l d a n d m o s s , w h i l e Muscicola pitta a n d Algidia

viridata a p p e a r t o be r e s t r i c t e d to m o s s a n d a re d i s t i n g u i s h e d by

t he i r s t r i k i n g g r e e n c o l o r a t i o n . N o a l t i t u d i n a l s p e c i a t i o n has b e e n

o b s e r v e d : on ly a few spec ies h a v e b e e n f o u n d a b o v e b u s h - l i n e a n d

t h e n o n l y i n sma l l n u m b e r s i n s u b - a l p i n e s c r u b . T h e y a re m o r e

n u m e r o u s n e a r sea level a n d p r o g r e s s i v e l y d i m i n i s h i n n u m b e r a t

h i g h e r a l t i t u d e s . Ve ry few a re e n c o u n t e r e d a b o v e 2 .500 ft. a n d on ly

P a l p a t o r e s a re f o u n d u n d e r a l p i n e c o n d i t i o n s ( F o r s t e r . 1954) . T h e

C y p h o p h t h a l m i a r e r a r e a n d e q u a l l y o b s c u r e , l iv ing like m i t e s

u n d e r s t ones , e tc . i n d a m p p laces , a n d a re u s u a l l y t o b e f o u n d on ly

after r a i n ha s fal len. T h e o n l y s u b - o r d e r w h o s e b i o l o g y i s k n o w n a t

all a d e q u a t e l y i s t h e P a l p a t o r e s . t h a n k s la rge ly to t h e w o r k o f

B r i t i s h n a t u r a l i s t s .

T h e T r o g u l i d a e a n d N e m a s t o m i d a e a re i n h a b i t a n t s o f t h e su r ­

face layers of t h e soil a n d a p p e a r to r e q u i r e a b a l a n c e d m i c r o c l i m a t e

a s t h e y a re p a r t i c u l a r l y s u s c e p t i b l e t o de s i cca t i on . T h e first n a m e d

fami ly i s c o n r i n e d to cha lky d i s t r i c t s w h e r e t h e y r ind t h e snai ls on

w h i c h t h e y feed, b u t m e m b e r s o f b o t h famil ies avoid t h e l igh t a n d

c rawl s lowly i n t o cove r i f e x p o s e d . V i b r a t i o n s of t h e soil u sua l l y

i n d u c e a d e a t h - f e i g n i n g reflex. T h e Br i t i sh spec ies Tropdus r n -

carinatus a n d Anelasmocephalus cambridgei a re r a r e f o r m s r o u n d on ly

by careful s e a r c h i n g in s o u t h e r n c o u n t i e s , b u t Nemastoma lugubre

a n d N . chrysomelas a re q u i t e c o m m o n a n d w i d e l y d i s t r i b u t e d .

' T h e s t u d y of h a r v e s t m e n i s a s t u d y of legs , ' w r o t e Savon* 1938)

a n d legs a re i n d e e d a f ea tu r e t h a t i s b o u n d to i m p r e s s a n y o n e o b -

s e r v i n g t h e P h a l a n g i i d a e . A l t h o u g h a u t o t o m y i s f r e q u e n t l y p r a c t i s e d

as an e s c a p e r eac t ion , no r e g e n e r a t i o n o f t h e l i m b s o c c u r s in

h a r v e s t m e n . A m i n i m u m of four legs, p r o v i d e d o n e or t h e s e c o n d

pa i r r e m a i n s , e n a b l e s m o s t spec ies to l ead a m o r e o r less n o r m a l

life, b u t i f b o t h of t h e s e c o n d pa i r a re lost d e a t h s o o n fo l lows.

T h e s e s e c o n d legs s e e m t o b e u s e d for tac t i le p u r p o s e s a n d pos s ib ly

for sme l l r e c e p t i o n a n d t h e s e n s o r y ha i r s on t h e first legs m a y also

se rve t h e l a t t e r p u r p o s e . I t i s i n t e r e s t i n g t o n o t e t h a t t h e l ong -

legged P h a l a n g i i d a e possess t w o sma l l sp i rac les on t h e t ib ia o f e a c h

leg i n a d d i t i o n t o t h e u s u a l sp i rac les w h i c h o p e n n e a r t h e coxae

of t h e f o u r t h pa i r of legs ( S a n k e y , 194°>b).

1 3 8 H A R V E S T - S P I D E R S

L i k e o t h e r A r a c h n i d s , h a r v e s t m e n careful ly c lean t h e i r l i m b s . A

leg i s h e l d i n t h e che l i ce rae w h i c h o p e n a n d s h u t a s t h e l o n g s e g ­

m e n t s a re p u l l e d t h r o u g h t h e m . B y t h e t i m e t h e t a r s u s i s r e a c h e d ,

t h e leg i s b e n t a l m o s t i n t o a c i rc le , a n d finally s h o o t s o u t l ike an

u n b e n t s p r i n g . T h e p e d i p a l p s a r e c l e a n e d i n t h e s a m e w a y a n d t h e

che l i ce rae a re w a s h e d w h i l e d r i n k i n g . A few spec ies a re ab le to

s t r i d u l a t e b u t t h e s o u n d i s p r o b a b l y t o o fa in t t o b e a u d i b l e t o t h e

h u m a n ear .

T o t h e l y r i fo rm o r g a n s — b u t t o n - s h a p e d sl i ts f o u n d s ing ly o r

t o g e t h e r i n a l y r e - s h a p e d g r o u p — h a v e b e e n a t t r i b u t e d t h e func t i on

o f sme l l . T h e y o c c u r espec ia l ly o n t h e f i r s t s e g m e n t s o f t h e che l i ­

ce rae a n d on t h e coxae o f t h e legs . E a c h i s s u p p l i e d w i t h a n e r v e

a n d t h e y m a y wel l b e p r o p r i o c e p t o r s a n a l a g o u s t o t h e c h o r d o t o n a l

sens i l lae o f i n sec t s w h i c h se rve to d e t e c t s t r a i n s a n d s t resses i n t h e

i n t e g u m e n t . H a r v e s t m e n r e s p o n d t o t o u c h a n d c h e m i c a l s t imu l i ,

a n d b u n c h t o g e t h e r i n cap t iv i t y . T h e i r eyes a re s i m p l e a n d p r o b ­

ably s e rve m a i n l y for d i s t i n g u i s h i n g l igh t f r o m d a r k n e s s . I t i s

d o u b t f u l i f t h e r e i s m u c h f o r m - v i s i o n in a n y o f t h e O p i l i o n e s b u t

s o m e p e r c e p t i o n o f m o v e m e n t m a y o c c u r . A l t h o u g h h a r v e s t -

s p i d e r s a re s u s c e p t i b l e t o c h a n g e s o f t e m p e r a t u r e a n d h u m i d i t y ,

t h e o r g a n s w h i c h s e rve t h e s e f u n c t i o n s a re n o t ye t k n o w n . T o d d

(1949) ha s w o r k e d o u t t h e t e m p e r a t u r e a n d h u m i d i t y p r e f e r e n c e s

for s o m e B r i t i s h spec ies a n d f o u n d a s t r o n g c o r r e l a t i o n b e t w e e n t h e

h u m i d i t y p r e f e r e n c e o f t h e spec ies t e s t e d i n t h e l a b o r a t o r y a n d

t h e i r s t ra t i f ica t ion i n oak w o o d l a n d . A t t h e s a m e t i m e i t w a s n o t e d

t h a t t h o s e spec ies w i t h t h e h i g h e s t t e m p e r a t u r e p r e f e r e n c e a p ­

p e a r e d to h a v e a s o u t h e r n d i s t r i b u t i o n o r to l ive in d r i e r o r w a r m e r

h a b i t a t s t h a n o t h e r s .

B r i t i sh h a r v e s t - s p i d e r s c a n b e d i v i d e d i n t o v a r i o u s g r o u p s

a c c o r d i n g t o t h e i r ve r t i ca l d i s t r i b u t i o n . T h u s t h e spec ies w h i c h

usua l ly l ive o n t h e g r o u n d u n d e r s t o n e s , logs a n d i n m o s s o r p l a n t

d e b r i s i n c l u d e t h o s e w i t h s h o r t legs a n d sma l l eyes s u c h as Trogulus

tricarinatus, Anelasmocephalus cambridgei, Nemastoma lugubre,

N. chrysomelas, Homalenotus quadridentatus, Oligolophus meadii a n d

Opilio saxatilis. T h e s e c o n d g r o u p i n c l u d e s spec ies w h i c h live

m a i n l y a m o n g s t l o w v e g e t a t i o n ( t h e f i e l d layer ) o f g rass a n d o t h e r

h e r b a c e o u s p l a n t s , b u t w h o s e y o u n g s tages o c c u r o n t h e g r o u n d ,

s u c h as Nelima silvatica, Leiobunum blackwalli, L. rotundum, Mito-

H A R V E S T - S P I D E R S 139

pus morio, Oligolophus tridens, Lacinius ephippiatus, Platybunus

triangularis, Megabunus diadema a n d Phalangium opilio. F i n a l l y

c e r t a i n spec ies t e n d t o l ive a s a d u l t s a b o v e t h e field l ayer on b u s h e s ,

t r ees , wa l l s a n d fences w h i l e t h e i r y o u n g s t ages a r e f o u n d n e a r e r

t h e g r o u n d . T h e s e i n c l u d e Oligolophus agrestis O. hansenii, Odiellus

spinosus a n d Opilio parietinus, b u t t h e r e is s o m e o v e r l a p b e t w e e n all

t h r e e g r o u p s a n d m o s t spec i e s m i g r a t e u p w a r d s a s t h e y m a t u r e .

T h i s a p p e a r s t o b e a s soc ia t ed w i t h t h e n e e d for b i g g e r p r e y , m o r e

space t o m o v e in , m a t i n g a n d p r o b a b l y dif ferent t e m p e r a t u r e a n d

m o i s t u r e r e q u i r e m e n t s ( S a n k e y , 1949b ) . I n a d d i t i o n , T o d d (1949)

ha s s h o w n t h a t m a n y spec ies o f h a r v e s t m e n a r e m o s t ac t ive a t

n i g h t w h e n t h e y s h o w a t e n d e n c y t o m i g r a t e u p w a r d s o n t o t r e e s

w h e r e t h e a i r i s d a m p e r . T h i s ac t iv i ty i s c o r r e l a t e d w i t h t h e d e ­

c rease i n l igh t i n t ens i t y , i nc r ea se i n r e l a t i ve h u m i d i t y a n d dec rea se

i n t e m p e r a t u r e t h a t o c c u r s af ter d a r k . T h u s i n W y t h a m W o o d s ,

s o m e 4 1 / 2 m i l e s n o r t h - w e s t of O x f o r d , Leiobunum rotundum h u n t s

on t h e u n d e r s i d e of Mercuralis perennis leaves d u r i n g t h e d a y b u t

passes t h e n i g h t o n t h e t r u n k s o f t r e e s .

A s imi l a r ve r t i ca l m i g r a t i o n w a s f o u n d to o c c u r in Oligolophus

tridens, a n d m a n y o t h e r spec ies s h o w a ve r t i ca l m i g r a t i o n d u r i n g

t h e i r life h i s to r i e s , a s a l r e a d y m e n t i o n e d . A t t h e s a m e t i m e t h e r e i s

u sua l l y a m i c r o h a b i t a t s e p a r a t i o n i n s p a c e a n d t i m e , o r b o t h , b e ­

t w e e n a l l ied spec ies of t h e s a m e g e n u s . L. rotundum a n d L. black-

walli r e s e m b l e e a c h o t h e r v e r y c losely b u t d u r i n g t h e i r life h i s to r i e s

t h e r e i s n o h a b i t a t o v e r l a p i n t i m e u n t i l t h e y b o t h a p p e a r o n t r e e

t r u n k s at t h e age of six m o n t h s . L. rotundum h a t c h e s a b o u t a

m o n t h in a d v a n c e of L . blackwalli a n d r e t a i n s t h i s l ead as i t a s c e n d s

f ro m o n e p l a n t l ayer to t h e n e x t . L . blackwalli i s n e v e r a b u n d a n t

a n d i s f o u n d on t h e l o w e r p a r t s o f t h e t r e e t r u n k s w h i l e L . rotundum

i s m u c h m o r e p l en t i fu l a n d i s u s u a l l y t o b e s een u p t o s e v e n feet

a b o v e g r o u n d level . S imi l a r l y Oligolophus tridens is a d o m i n a n t

f ie ld- layer f o r m w h i l e t h e less a b u n d a n t O. agrestis a n d O. hansenii

are f o u n d p r e d o m i n a n t l y o n t r e e t r u n k s a n d a m o n g s t t h e b r a n c h e s .

F o o d and feeding habits

H a r v e s t - s p i d e r s a re p r i m a r i l y c a r n i v o r o u s a n d u s u a l l y feed o n

f resh o r r e c e n t l y d e a d a n i m a l t i s sues , b u t t h e y wil l also ea t a va r i ed

a s s o r t m e n t of m a t t e r s u c h as b r e a d , fat, t h e gil ls of Chanterelle a n d

140 H A R V E S T - S P I D E R S

o t h e r fung i , s e e d s a n d e v e n c h e w pe l l e t s o f m i s c e l l a n e o u s v e g e ­

t a b l e m a t t e r w h i c h t h e y h a v e c a r r i e d t o a s u i t a b l e f e e d i n g g r o u n d

s u c h a s t h e t o p o f a leaf. T h e y h a v e b e e n r e c o r d e d s c a v e n g i n g on

b i r d d r o p p i n g s a n d d e a d a n i m a l m a t e r i a l s u c h a s w o r m s , m i l l i ­

p e d e s , c e n t i p e d e s , a n t s , s p i d e r s , flies, b e e t l e s a n d v e r t e b r a t e s : i n ­

d e e d i t s e e m s t h a t l i t t le o r g a n i c m a t e r i a l c o m e s a m i s s t o t h e s e

o m n i v o r o u s c r e a t u r e s ( S a n k e y , 1949a) . M o r e o f ten h o w e v e r t h e y

a re s e e n t o p r e y o n w o o d l i c e , m i l l i p e d e s , c e n t i p e d e s , f a l se - scor ­

p i o n s , s p i d e r s , m i t e s a n d a w i d e v a r i e t y of i n sec t s . A n u m b e r of

spec ies , s u c h as Mitopus morio, a r e h a b i t u a l l y c a n n i b a l i s t i c w h i l e

t h e T r o g u l i d a e feed on sna i l s s u c h as Cepaea a n d Oxychilus s p p .

a n d a r e m a i n l y f o u n d i n t h e c h a l k y d i s t r i c t s w h e r e t h e s e a r e m o s t

n u m e r o u s . T h e I s c h y r o p s a l i d a e also f eed o n G a s t e r o p o d m o l l u s c s

a n d h a v e e x t r a l o n g che l i ce rae w i t h w h i c h t h e p r e y i s d r a w n f r o m

its she l l . W h e n t h e sna i l i s c o m p l e t e l y r e t r a c t e d t h e h a r v e s t - s p i d e r

s o m e t i m e s b r e a k s off p i eces o f t h e she l l u n t i l i t c a n r e a c h t h e b o d y

o f t h e a n i m a l . T h e c a v e r n i c o l o u s Scotolemon s p p . a r e p a r t i c u l a r l y

fe roc ious a n d h u n t o t h e r a r t h r o p o d s , p a r t i c u l a r l y bee t l e s , w h i c h

they d e v o u r i n g r e a t n u m b e r s . T h e s ens i t i ve s e c o n d legs a re o f

p r i m e i m p o r t a n c e i n t h e r e c o g n i t i o n o f p r e y .

W h e n ea t i ng , t h e che l i ce r ae , p e d i p a l p s a n d legs m a y all b e

b r o u g h t i n t o u s e . L e g s a n d p a l p s h e l p i n s u b d u i n g l iv ing p r e y a n d

t h e p i n c e r s o f t h e che l i ce rae s e r v e t o t e a r i t t o b i t s . S o m e t i m e s t w o

o r m o r e P h a l a n g i d s m a y b e s e e n p u l l i n g a n d t e a r i n g a t t h e s a m e

m o r s e l o f food . W a t e r i s o f spec ia l i m p o r t a n c e in t h e e c o n o m y of

h a r v e s t - s p i d e r s a n d m o s t spec ies d o n o t s u r v i v e for l o n g w i t h o u t

it. T h e y m a y fast for a f o r t n i g h t o r m o r e w i t h o u t a p p a r e n t d i s c o m ­

fort b u t m a n y wil l d i e in a c o u p l e of d a y s i f u n a b l e to d r i n k . Af te r

r a in m a n y spec ies , b o t h d i u r n a l a n d n o c t u r n a l , m a y b e f o u n d

a b r o a d , b u t d u r i n g p e r i o d s o f d r o u g h t a l m o s t all wi l l avo id d i r ec t

l igh t a n d forage o n l y a t t w i l i g h t o r ea r ly i n t h e m o r n i n g ( B i s h o p ,

1949b) . A c c o r d i n g to S a v o r y (1938) a v e r y t h i r s t y h a r v e s t m a n i s

stiff a n d t o r p i d b u t i f p l a c e d on t h e su r face o f t h e w a t e r r e m a i n s

t h e r e s u c k i n g u p t h e l i q u i d l ike b l o t t i n g p a p e r .

Enemies A d u l t h a r v e s t - s p i d e r s s e e m t o h a v e few e n e m i e s a n d m o s t o f

t he i r difficulties in life a r e p r o b a b l y of a phys i ca l n a t u r e s u c h as

H A R V E S T - S P I D E R S 141

c h a n g e s o f t e m p e r a t u r e a n d h u m i d i t y : b u t a c c o r d i n g t o o n e s choo l

o f t h o u g h t t h e r e m u s t b e s o m e b io log ica l d e n s i t y - d e p e n d e n t fac tor

to k e e p t h e i r n u m b e r s in check . F o r i f a p a r t i c u l a r c o m p o n e n t o f

t h e e n v i r o n m e n t i s to r e g u l a t e t h e p o p u l a t i o n d e n s i t y o f a spec ies ,

i t m u s t be ab l e to d e s t r o y a g r e a t e r f r ac t ion o f t h e p o p u l a t i o n o f t h a t

spec ies w h e n t h e d e n s i t y i s h i g h t h a n w h e n i t i s low. I f d e s t r u c t i o n

w e r e m e r e l y p r o p o r t i o n a l t o p o p u l a t i o n d e n s i t y , t h e fac tor c a u s i n g

i t w o u l d n o t be a r e g u l a t o r y o n e . P a r a s i t e s a n d p r e d a t o r s a r e e x ­

a m p l e s o f t h e first c a t e g o r y ( d e n s i t y - d e p e n d e n t fac to rs ) , c l i ­

m a t i c c o n d i t i o n s o f t h e s e c o n d . O t h e r w r i t e r s s u g g e s t t h a t n a t u r a l

c o n t r o l i s a c h i e v e d chiefly b y c l i m a t i c a n d e d a p h i c fac tors a n d t h a t

i t i s u n n e c e s s a r y to i n v o k e d e n s i t y - d e p e n d e n t fac to rs t o exp l a in

e i t h e r t h e m a x i m u m o r t h e m i n i m u m n u m b e r o c c u r r i n g i n a

n a t u r a l p o p u l a t i o n . P e r h a p s t h e t r u t h m a y lie s o m e w h e r e b e t w e e n

t h e s e e x t r e m e s . 1

T h e fo l lowing p r e d a t o r s h a v e b e e n r e c o r d e d : fish ( w h e n h a r v e s t -

m e n h a v e b e e n c a u g h t b y t h e s u d d e n f lood ing o f s t r e a m s ) , f rogs ,

t o a d s , l i za rds , b i r d s , s h r e w s , b a d g e r s , foxes a n d o t h e r m a m m a l s ,

c e n t i p e d e s , s p i d e r s , p r e d a c e o u s flies, bee t l e s , e a r w i g s , d ragonf l i es ,

b u g s a n d o t h e r i n sec t s , a s wel l a s c a n n i b a l i s t i c O p i l i o n e s ( S a n k e y ,

1949a) . H o w e v e r , t h e g r o u n d - l i v i n g f o r m s a r e e x c e e d i n g l y i n c o n ­

s p i c u o u s a n d p r o b a b l y s e l d o m f o u n d b y t h e i r p o t e n t i a l e n e m i e s ,

wh i l s t t h e l o n g - l e g g e d spec i e s g e n e r a l l y h a v e c r y p t i c co lo ra t i on

a n d c a n o f t en s t r i d e o u t o f h a r m ' s w a y . I f c a u g h t t h e y m a y e scape

b y a u t o t o m i s i n g a l i m b . T h e leg b r e a k s a t t h e a r t i c u l a t i o n b e t w e e n

t h e coxa a n d t r o c h a n t e r a n d t h e r e i s n o b l e e d i n g . T h e d e t a c h e d

p o r t i o n m a y m a k e s p o n t a n e o u s r h y t h m i c a l m o v e m e n t s w h i c h p e r ­

sist for a n h o u r o r m o r e a n d s e r v e t o d i s t r a c t t h e p r e d a t o r ' s a t t e n ­

t i on f r o m i ts p r e y . L o s t a p p e n d a g e s a r e n o t r e g e n e r a t e d h o w e v e r ,

a n d h a r v e s t - s p i d e r s a p p e a r t o lack t h e ab i l i ty t o r i d t h e m s e l v e s o f

d a m a g e d m e m b e r s b u t c o n t i n u e t o d r a g a c r i p p l e d leg u n t i l i t

s evers itself. I t i s i n t e r e s t i n g t o n o t e h e r e t h a t a u t o t o m y does n o t

a p p e a r t o o c c u r i n t h e T r o g u l i d a e .

S h o u l d a h a r v e s t m a n c o m e to g r i p s w i t h an agg re s so r a fluid i s

e x t r u d e d f r o m i ts r e p u g n a t o r i a l g l a n d s t h a t i s d i s tas te fu l t o m o s t

i n v e r t e b r a t e p r e d a t o r s . T h u s few s p i d e r s wi l l s u s t a i n a n a t t ack o n 1 I have recently discussed these points; 1957, Entomologist, 9 0 ,

195-203. See also; M I L N E , A. (1957) Canad. Ent. 8 9 , 193-213 .

142 H A R V E S T - S P I D E R S

a d u l t h a r v e s t m e n : u s u a l l y t h e y r e t r e a t af ter o n e b i t e a n d w i p e t h e i r

m o u t h s on a leaf. I n no B r i t i s h spec ies i s t h e o d o u r d i s c e r n i b l e t o

m a n : t h e f luid i s co lour l e s s a n d d o e s n o t a p p e a r t o h a v e a n y m a r k e d

f lavour , b u t v a r i o u s G o n y l e p t i d a e in Braz i l p r o d u c e a s t r o n g ,

n a u s e a t i n g o d o u r i f h a n d l e d , a n d in a d d i t i o n c a n de l ive r a s h a r p

p i n c h b y f i rmly d r a w i n g t h e i r h i n d f e m o r a t o g e t h e r b e h i n d t h e m .

O d o r i f e r o u s g l a n d s a r e f o u n d in b o t h sexes o f all spec ie s o f h a r v e s t -

s p i d e r a n d i n t h e i r n a t u r e a r e v e r y s i m i l a r t o t h o s e o f m i l l i p e d e s .

As a l r e a d y m e n t i o n e d , t h e r e i s a s ing le p a i r o f g l a n d s w h i c h o p e n s

a t t h e m a r g i n o f t h e c e p h a l o t h o r a x a b o v e t h e coxa o f t h e s e c o n d

leg. I n t h e l a rge r S o u t h A f r i c a n L a n i a t o r e s s u c h a s Larifugella

natalensis, t h e o p e n i n g i s p r o t e c t e d a n d p a r t l y c o v e r e d by a l a rge

f l a t t ened t u b e r c l e o r p r o c e s s o f t h e coxa . I n s o m e spec ies t h e g l a n d ­

u l a r s e c r e t i o n c a n be d i s c h a r g e d in t h e f o r m of a f ine j e t to a d i s ­

t a n c e o f m o r e t h a n a n i n c h f rom t h e a n i m a l ( L a w r e n c e , 1937) , b u t

i n m o s t i t m e r e l y f l o w s f r o m t h e g l a n d o p e n i n g . T h e c o l o u r o f t h e

s e c r e t i o n in t h e L a n i a t o r e s i s b r i g h t y e l l o w o r r e d d i s h b r o w n : i t i s

h i g h l y vo la t i l e w i t h a n ac r i d s m e l l a n d m a y c a u s e a s m a r t i n g

s e n s a t i o n in t h e eyes i f a d r o p i s b r o u g h t t o o c lose to t h e m .

T h e i r r e p u g n a t o r i a l f l u id m a y be r e s p o n s i b l e for t h e fact t h a t i f a

n u m b e r o f p h a l a n g i d s a re con f ined in a l i m i t e d s p a c e t h e y s e e m to

b e a n a e s t h e t i s e d o r n a r c o t i s e d b y e a c h o t h e r a n d r e m a i n for a l o n g

p e r i o d i n a s t a t e o f i n sens ib i l i t y . W h e n t h r o w n o u t u p o n t h e floor

o f a cage t h e y p r o m p t l y r e c o v e r a n d r u n a b o u t n o r m a l l y ( S a v o r y ,

1938) . T h e s a m e p h e n o m e n o n h a s b e e n o b s e r v e d b y B i s h o p

( 1 9 4 9 b ) : t h e s p e c i m e n s lie in a t a n g l e d m a s s o f legs a n d b o d i e s ,

a p p a r e n t l y w i t h o u t life, b u t w h e n d i s t u r b e d b y s h a k i n g t h e y r e ­

cove r a n d a s s u m e t h e i r n o r m a l ac t iv i t i e s .

T h e p a r a s i t e s o f O p i l i o n e s i n c l u d e n e m a t o d e w o r m s a n d g r e -

g a r i n e s , w h i l e severa l spec ies h a v e b e e n f o u n d w i t h la rva l m i t e s

s u c h as Erythraeus phalangio ides , Belaustium nemorum, Leptus s p p .

a n d o t h e r T h r o m b i d i i d a e w h i c h a re a c o n s p i c u o u s b r i g h t r e d co lou r ,

a t t a c h e d t o t h e m . P h o r e t i c f a l s e - sco rp ions a r e occas iona l ly t o b e

s een c l i ng ing t o t h e i r legs . A c c o r d i n g t o F o r s t e r (1954) t h e N e w

Z e a l a n d L a n i a t o r e s a re n o t a t t a c k e d b y s p i d e r s b u t i n fe s t a t ion b y

n e m a t o d e s a n d C h a l c i d w a s p s ha s b e e n n o t e d . S p e c i m e n s a re of ten

heav i ly in fes ted w i t h m i t e s w h i c h c l ing t o i n t e r s e g m e n t a l m e m ­

b r a n e s o f a b d o m e n a n d a p p e n d a g e s .

H A R V E S T - S P I D E R S 143

Mating habits M a t i n g in h a r v e s t - s p i d e r s i s a s casua l a s e a t i n g o r d r i n k i n g .

M a t u r e m a l e s a n d f emales t h a t e n c o u n t e r o n e a n o t h e r i n t h e f i e l d

o r d i n a r i l y m a t e briefly, s e p a r a t e a n d c o n t i n u e t h e i r w a n d e r i n g s . A

s h o r t t i m e la te r t h e y m a y m a t e aga in w i t h o n e a n o t h e r o r w i t h

di f ferent i n d i v i d u a l s . T h e neces s i t y for f r e q u e n t m a t i n g s m a y p e r ­

h a p s be c o r r e l a t e d w i t h t h e fact t h a t t h e eggs m a t u r e a few a t a

t i m e a n d a re d e p o s i t e d a t i n t e r v a l s t h r o u g h o u t , a n d i n m o s t

Br i t i sh spec i e s , t o w a r d s t h e e n d o f s u m m e r . S e c o n d a r y sexua l

d i f ferences a r e v e r y s l igh t . N o t r u e c o u r t s h i p h a s b e e n o b s e r v e d i n

O p i l i o n e s , b u t s o m e c u r i o u s b e h a v i o u r s o m e t i m e s o c c u r s i n Mito-

pus morio, o n e of t h e d o m i n a n t A r a c h n i d s in I c e l a n d ( C l o u d s l e y -

T h o m p s o n , 1948a, b ) . T h i s spec ies i s p a r t i c u l a r l y e v i d e n t o n s u n n y

d a y s . T h e m a l e , r e c o g n i s a b l e b y h i s s m a l l e r b o d y , l o n g e r legs a n d

p a l e r co lou r , r u n s t o w a r d s a m o v i n g f ema le a n d t akes up a p o s i t i o n

w i t h h i s b o d y j u s t a b o v e a n d legs s t r a d d l i n g h e r s . T h e t w o r u n i n

th is p o s i t i o n for severa l i n c h e s be fo r e s t o p p i n g . T h e m a l e t h e n

m o v e s f o r w a r d s l igh t ly so t h a t h i s b o d y i s n o w in f ron t o f t h a t o f

t h e f ema le a n d t u r n s a b o u t t o face h e r . H i s l o n g e x t e r n a l gen i ta l i a

a re n o w t h r u s t f o r w a r d a n d m a t i n g t akes p l ace . I n t h e m a j o r i t y o f

spec ies , h o w e v e r , i t i s p r o b a b l e t h a t c o p u l a t i o n t akes p l ace a t n i g h t .

F o r s t e r (1954) h a s o b s e r v e d m a t i n g i n t h e N e w Z e a l a n d L a n i a ­

t o r e s of b o t h Nuncia a n d Algidia s p p . C o p u l a t i o n i s d i r e c t w i t h

l i t t le p r e n u p t i a l b e h a v i o u r . T h e m a l e a p p r o a c h e s t h e f emale

r ap id ly , t o u c h i n g h e r w i t h t h e t a r s i o f t h e s e c o n d p a i r o f legs .

W h e n face t o face h e c lasps h e r p e d i p a l p s w i t h h i s o w n . B o t h

b o d i e s a r e t h e n ra i sed , b r i n g i n g t h e gen i t a l o p e n i n g s i n l ine . T h e

l o n g p e n i s o f t h e m a l e i s t h e n e x s e r t e d a n d p l a c e d d i r ec t l y i n t o t h e

gen i t a l o p e n i n g o f t h e f ema le : i n n o case o b s e r v e d h a s t h e f emale

e x s e r t e d h e r o v i p o s i t o r t o r ece ive t h e p e n i s .

In Leiobunum calcar, a c o m m o n , w i d e l y d i s t r i b u t e d spec ies of

P a l p a t o r e s i n N o r t h A m e r i c a , t h e m a l e s a re easi ly r e c o g n i s e d b y

t h e p r e s e n c e on t h e f e m u r o f t h e p e d i p a l p o f a l a rge , v e n t r o - l a t e r a l

s p u r . T h e pa te l l a i s s h o r t , s t r o n g l y a r c h e d a b o v e a n d c u r v e d v e n -

t ra l ly a n d i ts swo l l en b a s e i s a r m e d w i t h s h o r t d a r k d e n t i c l e s .

Because o f t h e s h o r t n e s s o f t h e pa t e l l a t h e s p u r o n t h e f e m u r m a y

b e a p p o s e d t o t h e s w o l l e n b a s e o f t h e t i b i a t o f o r m a n efficient

g r a s p i n g o r g a n . W h e n a m a l e e n c o u n t e r s a f ema le he r u s h e s a t h e r

144 H A R V E S T - S P I D E R S

w i t h o u t p r e l i m i n a r y c o u r t s h i p , a n d g r a s p s h e r f i rmly, h o l d i n g t h e

t r o c h a n t e r s o f h e r f i r s t legs w i t h t h e s p u r o n h i s f e m u r w h i l e

c o p u l a t i o n t akes p l a c e ( B i s h o p , 1949a) .

I n t h e s h o r t - l e g g e d T r o g u l i d a e t h e m a l e h a n g s b e n e a t h t h e

f emale c l a s p i n g h e r w i t h h i s legs , w h o s e c l aws g r i p t h e r o u g h s u r ­

face o n h e r b a c k s o t h a t t h e v e n t r a l su r faces o f t h e t w o a r e o p p o s e d

( P a b s t , 1953) .

I t ha s of ten b e e n r e p o r t e d t h a t a t t h e b r e e d i n g s e a s o n m a l e

h a r v e s t - s p i d e r s f i g h t ' b l o o d l e s s b a t t l e s ' w i t h o n e a n o t h e r , b u t

B r i s t o w e ( 1 9 4 1 ) * h a s s u g g e s t e d t h a t t h e e x p l a n a t i o n o f t h e s e f i g h t s

ha s a s i ts bas i s s exua l e x c i t e m e n t a n d m i s t a k e n i d e n t i t y . T h e m a l e ' s

c h e m o - t a c t i c s e n s e i s s t i m u l a t e d n o t o n l y by a f ema le b u t a lso by a

m a l e o f i ts o w n k i n d a s i s s h o w n b y t h e e x t r u s i o n o f t h e p e n i s .

Reproduction and life cycle F e m a l e h a r v e s t - s p i d e r s h a v e v e r y l o n g o v i p o s i t o r s a n d gene ra l l y

lay t h e i r eggs i n c rev ices i n t h e soil , u n d e r s t o n e s , w o o d a n d i n

o t h e r m o i s t p l ace s . A m o n g t h e N e w Z e a l a n d P a l p a t o r e s m a t i n g

u sua l l y t akes p l a c e i n O c t o b e r a n d N o v e m b e r a n d eggs a r e la id

b e t w e e n la te O c t o b e r a n d D e c e m b e r . N o eggs a p p e a r t o b e la id i n

t h e a u t u m n for o v e r - w i n t e r i n g a s i s t h e case i n s o m e B r i t i s h P a l ­

p a t o r e s . In Hendea myersi a n d o t h e r T r i a e o n y c h i d a e t h e e g g s a re

d e p o s i t e d i n sma l l g r o u p s n u m b e r i n g f r o m o n e t o f i v e a m o n g leaf-

m o u l d o r m o r e c o m m o n l y i n r o t t i n g w o o d , a n d t h e s e r ece ive n o

f u r t h e r a t t e n t i o n . F r o m 2 0 t o 6 0 eggs m a y b e la id i n t h i s w a y

d u r i n g t w o w e e k s . T h e spec ies o f Soerensella, by c o n t r a s t , select

t h e u n d e r su r face of a log or occas iona l ly a s p a c e b e n e a t h a loose

f i t t ing r o c k for o v i p o s i t i o n . A s m a l l g r o u p of eggs , f r o m 10 to 20 ,

i s la id a n d t h i s i s t h e n g u a r d e d by t h e f ema le . At i n t e rva l s o f a few

days o r a w e e k f u r t h e r eggs a re d e p o s i t e d so t h a t in s o m e cases egg

m a s s e s o f s o m e 6 0 t o 100 eggs m a y b e f o u n d , s o m e o f w h i c h a re

h a t c h i n g , w h i l e o t h e r s a r e f o u n d in all s t ages o f d e v e l o p m e n t , o f ten

i n c l u d i n g n e w l y la id eggs . I t i s p r o b a b l e t h a t h a t c h i n g n o r m a l l y

t akes a b o u t 2 0 d a y s ( F o r s t e r , 1954) .

In Phalangium opilio a m o n g t h e P a l p a t o r e s t h e f i r s t ov ipos i t i on

u sua l l y t akes p l ace a b o u t 1 8 d a y s af ter t h e f i n a l m o u l t , t h e s e c o n d

2 to 22 d a y s l a t e r a n d a t h i r d in a n o t h e r week . V i r g i n f emales c a n lay

eggs , b u t d o n o t u s u a l l y d o s o ( G u e u t a l , 1944) . T h e e g g s a re

H A R V E S T - S P I D E R S 145

u s u a l l y w h i t e , d e v o i d o f s c u l p t u r i n g a n d a d h e r e loosely t o g e t h e r .

T h e i r n u m b e r va r i e s f r o m o v e r 2 0 0 in Odiellus spinosus a c c o r d i n g

to S a n k e y ( 1 9 4 9 b ) a n d 275 in Platybunus pinetorum ( S t i p p e r b e r g e r ,

1928) to 4 0 0 to 6 0 0 in Phalangium opilio a c c o r d i n g to G u e u t a l

(1944) . H o l m (1947) f o u n d t h a t Opilioparietinus l a id f r o m 2 0 t o 6 0

eggs a t 20° C , a n d t h a t t h e r e w a s n o f u r t h e r d e v e l o p m e n t af ter a n

ea r ly b l a s t o d e r m s t age u n l e s s t h e eggs w e r e t r a n s f e r r e d to a re f r ig ­

e r a t o r , w h e r e t h e y w e r e k e p t a t 6° C for t w o w e e k s a n d t h e n , for a

f u r t h e r w e e k , a t - 6° C. In Leiobunum blackwalli, h o w e v e r , t h e

p e r c e n t a g e o f eggs h a t c h i n g w a s n o t s ign i f ican t ly h i g h e r af ter co ld

t r e a t m e n t a c c o r d i n g t o T o d d (1949) .

A fa in t m o t t l i n g i n d i c a t e s t h e o n s e t o f d e v e l o p m e n t ; t h e eyes

a p p e a r a t o n e p o l e a n d j u s t be fo r e h a t c h i n g t h e b o d y s e g m e n t s a n d

l i m b s c a n be s e e n n e a t l y t u c k e d a w a y i n s i d e t h e egg . H a t c h i n g i s a

q u i c k p r o c e s s , t h e y o u n g b r e a k i n g t h e egg m e m b r a n e b y m e a n s o f

a p o w e r f u l e g g - t o o t h i n f r o n t o f t h e o c u l a r t u b e r c l e . E u r o p e a n P a l ­

p a t o r e s a r e a b o u t 1 m m i n l e n g t h o n e m e r g e n c e . T h e n e w l y

h a t c h e d y o u n g r e s e m b l e t h e a d u l t s i n g e n e r a l , b u t a r e d i s t i n g u i s h e d

by t h e a b s e n c e o f a n u m b e r o f d e t a i l e d c h a r a c t e r s w h i c h a r e g r a d ­

ua l ly a s s u m e d w i t h e a c h m o u l t . T h e f i r s t o f t h e s e o c c u r s a l m o s t

i m m e d i a t e l y af ter ec los ion a n d i s fo l lowed by s ix o r s e v e n o t h e r s a t

i n t e r v a l s o f a b o u t t e n d a y s e x t e n d i n g o v e r a p e r i o d o f six to n i n e

m o n t h s . T h e y o u n g a r e a t f i r s t s o f t - b o d i e d a n d s l u g g i s h i n t h e i r

m o v e m e n t s b u t t h e r e i s a p r o g r e s s i v e h a r d e n i n g o f t h e i n t e g u m e n t

w i t h e a c h e c d y s i s . I n t h o s e L a n i a t o r e s a n d P a l p a t o r e s w h i c h h a v e

n u m e r o u s t a r sa l s e g m e n t s i n t h e m a t u r e f o r m s , t h e n u m b e r i s far

f ewer i n t h e y o u n g s t ages a n d i n c r e a s e s a s t h e y g r o w o l d e r .

W h e r e k n o w n , t h e s o f t - s k i n n e d , de l i ca te eggs o f t h e T r o g u l i d a e

a r e la id in t h e she l l s o f sna i l s i n w h i c h t h e y a r e sea led by a p r o ­

t e c t i v e m e m b r a n e s e c r e t e d b y t h e o v i p o s i t o r o f t h e f ema le . T h e

n u m b e r va r i e s f r o m o n e t o e i g h t i n e a c h b a t c h , b u t a s m a n y a s 2 5

eggs m a y b e la id b y a s ing le f ema le d u r i n g t h e yea r . M a x i m u m

ac t iv i ty t akes p l ace i n t h e s p r i n g a n d a u t u m n b u t eggs a r e p r o d u c e d

d u r i n g e v e r y m o n t h e x c e p t D e c e m b e r a n d J a n u a r y . T h e d u r a t i o n

o f o n t o g e n y d e p e n d s u p o n t h e s e a s o n a t w h i c h t h e eggs a r e laid,

a n d d e v e l o p m e n t i s s l o w b e t w e e n O c t o b e r a n d M a r c h , c o m i n g

a l m o s t t o a s t ands t i l l b e t w e e n N o v e m b e r a n d F e b r u a r y , b u t i n t h e

s u m m e r m o n t h s i t las ts f i v e t o e i g h t w e e k s . P o s t - e m b r y o n i c d e v e l -

K S.S.C.M.

146 H A R V E S T - S P I D E R S

o p m e n t i s c o m p l e t e d af ter a c o n s t a n t n u m b e r o f e c d y s e s o f w h i c h

t h e first aga in t akes p l ace i m m e d i a t e l y after h a t c h i n g . In Anelas-

mocephalus cambridgei a n d t h e Trogulus s p p . t h e r e a r e five a n d six

m o u l t s r e spec t ive ly . T h e a n i m a l s d o n o t m o u l t af ter r e a c h i n g

m a t u r i t y w h i c h in A . cambridgei i s r e a c h e d in o n e to t w o m o n t h s

a n d t akes four t o five m o n t h s i n Trogulus s p p . , a l t h o u g h t h e a d u l t s

m a y c o n t i n u e t o l ive for a n o t h e r t w o y e a r s o r m o r e ( P a b s t , 1953) .

T h r e e t y p e s o f life cyc le c a n b e r e c o g n i s e d i n t h e B r i t i s h O p i ­

l iones . T h e T r o g u l i d a e a n d N e m a s t o m i d a e , w h i c h l ive i n s h e l t e r e d

h a b i t a t s , c a n b e f o u n d b o t h a s y o u n g a n d a d u l t s t h r o u g h o u t t h e

yea r . T h e n t h e r e a re t h e spec ies t h a t p a s s t h e w i n t e r a s eggs a n d

m a t u r e a t t h e e n d o f t h e fo l lowing s u m m e r , s u c h a s Oligolophus

a n d Odiellus s p p . F i n a l l y a few, s u c h as Platybunus triangularis a n d

Megabunus diadema, m a t u r e in ea r ly s u m m e r a n d lay eggs f r o m

w h i c h h a t c h y o u n g t h a t s p e n d t h e fo l lowing w i n t e r i n a n i m m a t u r e

s t age ( S a n k e y , 1949b ; T o d d , 1949) .

B I B L I O G R A P H Y

Identification

FORSTER, R. R. (1954) T h e N e w Zealand Harves tmen (sub-order Lania­tores). Canterbury Mus. Bull., No . 2, 1-329.

KASTNER , A. (1928) Spinnentiere oder Arachnoidea I I I . Opiliones in D A H L , F. Tierw. Deuts., 8, 1-51.

PICKARD-CAMBRIDGE , O. (1890) Monograph of the British Phalangidea or harvestmen. Proc. Dorset Field Club., 1 1 , 163-216.

ROEWER, C. F. (1923) Die Weberknechte der Erde, Jena (with several supplements) .

SAVORY, T. H. (1948) Synopses of the British Fauna. No. 1. Opiliones (Arachnida) or Harvestmen. 2ND Ed . London: Linn. Soc.

SIMON , E. (1879) Les Arachnides de France, Paris, 7, 116-332. T O D D , V. (1948) Key to the determination of the British harvestmen

(Arachnida, Opiliones). Ent. Mon. Mag., 8 4 , 109-13.

Biology

BISHOP , S. C. (1949a) T h e function of the spur on the femur of the palpus of the male Leiobunum calcar (Wood) (Arachnida: Phalangida). Ent. NewsPhilad., 6 0 , 1 0 - 1 1 .

(1949b) T h e Phalangida (Opiliones) of N e w York. Proc. Rochester Acad. Sci., 9 ,159-235.

BRISTOWE, W. S. (1949) T h e distribution of harvestmen (Phalangida) in Great Britain and Ireland, with notes on their names, enemies and food. J. Anim. Ecol. 1 8 . 1 0 0 - 1 4 .

H A R V E S T - S P I D E R S 147

CLOUDSLEY-THOMPSON , J . L. (1948a) Notes on Arachnida, 4 . Courtship behaviour of the harvester Mitopus morio. Ann. Mag. Nat. Hist., (11), 1 4 , 8 0 9 - 1 0 .

(1948b) Observations on the ecology of Arachnids in Nor th-wes t Iceland. Ibid., (12), 1, 437-47 .

GUEUTAL , J. (1944) La ponte chez un Opilion: Phalangium opilio L inne . Rev. fr. Ent. Paris, 1 1 , 6 -9 .

KASTNER, A. (1931) Biologische Beobachtungen an Phalangiiden. Zool. Anz., 9 5 , 293-302.

LAWRENCE, R. F. (1937) T h e odoriferous glands of some South African harvest-spiders. Trans. R. Soc. S. Africa, 2 5 , 333-42.

H O L M , A. (1947) On the development of OpilioparietinusDeg. Zool. Bidr. Uppsala, 2 5 , 4 0 9 - 2 2 .

PABST , W. (1953) Z u r Biologie der mit teleuropaischen Trogul iden . Zool. J. (Syst.), 8 2 , 1 - 4 6 .

ROTERS, M. (1944) Observations on British Harves tmen. J. Qnek. Micr. Club., (4), 2, 23 -5 .

SANKEY , J. H. P. (1949a) Observations on food, enemies and parasites of British harvest-spiders (Arachnida, Opiliones). Ent. Mon. Mag., 8 5 , 246-7.

(1949b) British harvest-spiders. Essex Nat., 2 8 , 1 8 1 - 9 1 . SAVORY, T. H. (1938) Notes on the biology of harvestmen. J. Quek.

Micr. Club., (4), 1, 89-94. (1949) Notes on the biology of Arachnida. Ibid., (4), 3 , 1 8 - 2 4 .

STIPPERBERGER, H. (1928) Biologie und Verbrei tung der Opilioniden Nord-Ti ro l s . Arb. Zool. Inst. Univ. Innsbruck, 3 , 1 2 - 7 9 .

T O D D , V. (1949) T h e habits and ecology of the British harvestmen (Arachnida, Opiliones), wi th special reference to those of the Oxford district. J. Anim. Ecol., 1 8 , 209-16.

C H A P T E R X

S P I D E R S

Classification and distribution W i t h o u t d o u b t s p i d e r s a r e t h e b e s t k n o w n a n d i n m a n y w a y s t h e

m o s t i n t e r e s t i n g o f all t h e A r a c h n i d a . T h e d ive r s i t y o f t h e i r w e b s

a n d t h e v a r i o u s a n d i n t r i c a t e m e t h o d s u s e d i n t h e i r c o n s t r u c t i o n

h a v e a lways a t t r a c t e d a t t e n t i o n . I n d e e d , m a n y p e o p l e s e e m t o

n o t i c e o n l y t h o s e spec ies t h a t c a p t u r e t h e i r p r e y i n w e b s s u c h a s

F I G . 32. Examples of spider families: 1. Liphistiidae, 2. T h e r a -phosidae, 3. Gnaphosidae, 4. Sparassidae, 5. Thomis idae , 6 .Sal-ticidae, 7 . Lycosidae, 8 . Agelenidae, 9 . Ther idi idae, 1 0 . Argio-pidae, 1 1 . Linyphiidae. (Drawings not to scale.) (After various

authors and original.) 1 4 8

S P I D E R S 149

t h e m u c h m a l i g n e d , l o n g - l e g g e d h o u s e s p i d e r s (Tegenaria s p p . )

w h i c h s p i n c o b w e b s i n t h e c o r n e r s o f r o o m s a n d o u t h o u s e s ; a n d

t h e g a r d e n s p i d e r s (Araneus s p p . ) w h o s e d e w - s p a n g l e d o r b w e b s

g l i s t en ing i n t h e s u n l i g h t l e n d t h e i r b e a u t y t o t h e a u t u m n m o r n i n g .

Al l s p i d e r s s p i n silk, b u t b y n o m e a n s all o f t h e m l ive s e d e n t a r y

l ives in w e b s : i f t h e y d id , a l a rge a m o u n t o f p o t e n t i a l food in t h e

f o r m o f i n sec t s w o u l d n o t b e e x p l o i t e d . I n fact t h e m o r e p r i m i t i v e

spec ies t e n d t o u s e silk o n l y for b u i l d i n g t h e i r r e t r e a t s a n d for

w e a v i n g t h e c o c o o n s i n w h i c h t h e y lay t h e i r eggs . I n d e e d , i t h a s

b e e n s u g g e s t e d t h a t p r e d a t i o n b y p r i m i t i v e h u n t i n g s p i d e r s u p o n

ea r ly w i n g l e s s in sec t s m a y h a v e b e e n o n e o f t h e m a i n fac tors t h a t

e n g e n d e r e d t h e e v o l u t i o n o f i n s e c t w i n g s . W h e n t h e i r p r e y t ook t o

t h e a i r t o e s c a p e , s p i d e r s e v o l v e d aer ia l w e b s a s a m e a n s o f t r a p p i n g

it in f l ight .

T h e A r a n e a e o r s p i d e r s r e s e m b l e t h e w h i p - s c o r p i o n s i n h a v i n g

t h e c e p h a l o t h o r a x ( p r o s o m a ) a n d a b d o m e n ( o p i s t h o s o m a ) s e p a r ­

a t e d b y a w a i s t f o r m e d b y t h e c o n s t r i c t i o n o f t h e p r e g e n i t a l s o m i t e ;

i n h a v i n g t h e a b d o m e n i n p r i m i t i v e f o r m s c o m p o s e d o f e l even seg ­

m e n t s , i n t h e p r e s e n c e o f t w o p a i r s o f l u n g - b o o k s o p e n i n g b e h i n d

t h e s t e r n i t e s o f t h e first a n d s e c o n d a b d o m i n a l s e g m e n t s ; a n d i n

h a v i n g m e d i a n a n d la te ra l eyes i n t h e c a r a p a c e . T h e y differ f r o m

t h e m i n t h a t t h e a p p e n d a g e s o f t h e t h i r d a n d f o u r t h a b d o m i n a l

s o m i t e s h a v e b e e n r e t a i n e d a s t h e so -ca l l ed s p i n n i n g m a m m i l l a e

for t h e m a n i p u l a t i o n o f silk s e c r e t e d b y c o m p l i c a t e d g l a n d s i n t h e

a b d o m e n ; i n t h e p r e s e n c e o f a p o i s o n g l a n d i n t h e m a n d i b l e s o r

che l i ce rae , t h e s e c o n d s e g m e n t o f w h i c h f o r m s a s h a r p , p i e r c i n g

fang w i t h a s ing le orifice a t t h e t i p for t h e exi t o f t h e p o i s o n ; in t h e

s i m p l e leg- l ike n o n - p r e h e n s i l e p a l p i ; a n d t h e c o n v e r s i o n o f t h e

t e r m i n a l s e g m e n t o f t h e p a l p o f t h e m a l e i n t o a s p e r m - c a r r i e r .

A l t h o u g h t h e o r d e r i s a h o m o g e n e o u s o n e , t h e p h y l o g e n e t i c a n d

s y s t e m a t i c p r o b l e m s i n v o l v e d i n d i s t i n g u i s h i n g t h e v a r i o u s famil ies

a re of ten c o m p l e x a n d seve ra l d i f ferent c lass i f ica tory s c h e m e s h a v e

b e e n p r o p o s e d (e .g . B r i s t o w e , 1938; P e t r u n k e v i t c h , 1933 , 1939,

e t c . ) . T h r e e s u b - o r d e r s a r e n o w g e n e r a l l y r e c o g n i s e d . T h e first,

L i p h i s t i o m o r p h a , i s c h a r a c t e r i s e d b y t h e fact t h a t t h e a b d o m e n

has r e t a i n e d i ts p r i m i t i v e s e g m e n t a t i o n , b e i n g p r o v i d e d w i t h e l even

t e rga l p l a t e s a n d o t h e r a tav is t i c q u a l i t i e s . T h e s p i d e r s o f t h i s s u b ­

o r d e r b e l o n g i n g t o t h e fami ly L i p h i s t i i d a e , o f w h i c h t h e b e s t

150 S P I D E R S

k n o w n g e n u s i s Liphistius, a r e r e s t r i c t e d to B u r m a , t h e M a l a y

P e n i n s u l a a n d n e i g h b o u r i n g c o u n t r i e s . S e v e r a l o f t h e spec ies s u c h

as L. desultor r e a c h a fair s ize b u t v e r y l i t t le is k n o w n of t h e i r

h a b i t s . S o m e live exc lus ive ly i n caves ; all i n b u r r o w s i n t h e g r o u n d .

I n t h e s u b - o r d e r M y g a l o m o r p h a , w h i c h i n c l u d e s t h e so -ca l l ed

' b i r d - e a t i n g ' s p i d e r s o f t h e t r o p i c s , t h e a r t i c u l a t i o n o f t h e m a n d ­

ib les w i t h t h e p r o s o m a i s ve r t i ca l s o t h a t t h e y p ro j ec t f o r w a r d , t h e

fang o r s e c o n d s e g m e n t c los ing s t r a i g h t b a c k w a r d o r n e a r l y s o .

T h e s p i d e r s o f t h i s g r o u p a r e con f ined t o t e m p e r a t e a n d t r o p i c a l

r e g i o n s o f t h e w o r l d w h e r e t h e y a r e r e p r e s e n t e d b y l a rge n u m b e r s

o f g e n e r a a n d spec ies b e l o n g i n g t o seve ra l fami l ies . T h e b e s t

k n o w n o f t h e s e a re t h e T h e r a p h o s i d a e , o f ten e r r o n e o u s l y s p o k e n

o f a s ' T a r a n t u l a s ' , w h i c h i n c l u d e t h e l a rges t spec ies k n o w n , t h e

C t e n i z i d a e o r t r a p - d o o r s p i d e r s w h i c h a r e f a m o u s for t h e p e r f e c ­

t ion o f t h e i r b u r r o w s , a n d t h e A t y p i d a e w h i c h i n c l u d e t h e p u r s e -

w e b s p i d e r Atypus affinisy t h e sole B r i t i s h r e p r e s e n t a t i v e of t h e s u b ­

o r d e r . T h i s , o n e o f o u r l a rges t spec ies , h a s a s h i n i n g r e d d i s h b lack

c o l o u r a n d i s p r o v i d e d w i t h e n o r m o u s che l i ce rae . I n t h e s t e a m i n g

j u n g l e s of S o u t h A m e r i c a live t h e l a rges t s p i d e r s of all . A m a l e

Theraphosa s p . f r o m F r e n c h G u i a n a m a y m e a s u r e t h r e e i n c h e s i n

l e n g t h w i t h a leg s p a n e x c e e d i n g t e n i n c h e s , w h i l e a n e n o r m o u s

f emale Lasiodora s p . f r o m Braz i l i s r e c o r d e d as h a v i n g a b o d y 3 1 / 2

i n c h e s l o n g a n d a w e i g h t of a l m o s t 3 oz . ( G e r t s c h , 1949) .*

B r i s t o w e (1947) r e l a t e s t h a t t h e h e r o o f M i l a n i s c l a i m e d t o h a v e

s l a in a m o n s t r o u s s p i d e r w h i c h h a d b e e n l a p p i n g u p t h e l a m p oil

o f t h e C a t h e d r a l C h u r c h i n 1 7 5 1 . 'Af te r d e a t h , w e a r e to ld , i t

w e i g h e d 4 l b . o r s o m e w h a t m o r e t h a n a l a rge P e k i n e s e ! A n o t h e r ,

w i t h s imi l a r o i l - d r i n k i n g h a b i t s , m a d e i ts h o m e i n S t . E u s t a c e ' s

C h u r c h i n P a r i s , a n d I s u s p e c t t h e s e x t o n w a s u n d e r g r a v e s u s ­

p i c ion o f b o r r o w i n g t h e oil h i m s e l f u n t i l h e r e p o r t e d see ing " a

s p i d e r o f e n o r m o u s d i m e n s i o n s c o m e d o w n t h e c h a i n b y w h i c h t h e

l a m p w a s s u s p e n d e d , d r i n k u p t h e oil , a n d w h e n g o r g e d t o sa t ie ty

s lowly r e t r a c e i t s s t e p s " . ' T h e l a rges t B r i t i s h h o u s e s p i d e r , Tegen­

aria parietina, h a s a b o d y l e n g t h of a b o u t 3 / 4 i n c h a n d a leg s p a n of

a b o u t f i ve i n c h e s . I t h a s b e e n r e c o r d e d t h a t , i n 1936, a p o l i c e m a n

o n p o i n t d u t y a t L a m b e t h B r i d g e h e l d u p t h e L o n d o n traffic for

s o m e m i n u t e s t o a l low a n o u t s i z e e x a m p l e t o c ross t h e r o a d i n

s a f e t y — w h i c h i t d id , m u c h t o t h e d e l i g h t o f p a s s e r s - b y . T h e r e i s

S P I D E R S 151

a n o b s c u r e l e g e n d t h a t C a r d i n a l W o l s e y , w h o s i m p l y c o u l d n o t

a b i d e s p i d e r s , h a d a p a r t i c u l a r a v e r s i o n to t h i s spec ies w h i c h w a s

all t oo p len t i fu l a t H a m p t o n C o u r t a n d i s sti l l p o p u l a r l y k n o w n a s

t h e ' c a r d i n a l s p i d e r ' .

T h e t h i r d s u b - o r d e r , A r a n e o m o r p h a , i n c l u d e s t h e m o s t spec i a l ­

i sed s p i d e r s a n d c o m p r i s e s t h e m a j o r i t y o f l iv ing spec ies w h i c h

exh ib i t a g r e a t e r r a n g e i n s t r u c t u r a l v a r i a t i o n a n d in h a b i t s t h a n

a n y o t h e r o r d e r o f A r a c h n i d a e x c e p t , p e r h a p s , t h e A c a r i . I n t h e

e l a b o r a t i o n o f c o m p l e x i n s t i n c t s a n d h a b i t s t h e y a r e u n e x c e l l e d .

T h e p l a n e o f a r t i c u l a t i o n o f t h e che l i c e r ae t o t h e c e p h a l o t h o r a x i s

h o r i z o n t a l s o t h a t t h e m a n d i b l e s p o i n t d o w n w a r d , t h e f angs c los ing

o b l i q u e l y i n w a r d . T h e s e s p i d e r s a re classified i n fami l ies a c c o r d i n g

t o s t r u c t u r a l c h a r a c t e r s w h i c h a r e o f ten c o r r e l a t e d w i t h t h e

m e t h o d s e m p l o y e d i n t h e c a p t u r e o f p r e y . T h u s t h e D i c t y n i d a e

a n d U l o b o r i d a e coa t t h e i r m e s h e d w e b s w i t h a b l u i s h , s t i cky s h e e t

o f f loccu len t silk p r o d u c e d by a f l a t s p i n n i n g o r g a n or ' c r i b e l l u m '

ly ing c lose i n f ron t o f t h e u s u a l s ix s p i n n e r e t s . T h e c r i b e l l u m m a y

b e l i kened t o t h e fused s p i n n i n g f i e l d s o f t w o s p i n n e r e t s ly ing

n e a r l y f l a t aga ins t t h e v e n t r a l su r f ace o f t h e a b d o m e n a n d i s a lways

a c c o m p a n i e d b y a n acces so ry c o m b o f h a i r s ca l led t h e ' ca la -

m i s t r u m ' u p o n t h e m e t a t a r s i o f t h e h i n d legs . T h e s p i d e r s p i n s its

c o m p o s i t e h a c k l e d b a n d b y r u b b i n g t h e c a l a m i s t r u m b a c k a n d

fo r th ove r t h e c r i b e l l u m , d r a w i n g o u t t w o r i b a n d s t h a t a r e a t t a c h e d

t o t w o l ines o f n o r m a l silk c o m i n g a t t h e s a m e t i m e f r o m t h e

s p i n n e r e t s . T h e O o n o p i d a e , D y s d e r i d a e a n d S c y t o d i d a e a re s ix -

eyed n o c t u r n a l h u n t i n g s p i d e r s . A l t h o u g h t h e n u m b e r o f eyes i s

n o t s u c h a f u n d a m e n t a l c h a r a c t e r as w a s o n c e t h o u g h t , i t i s st i l l a

c o n v e n i e n t d i a g n o s t i c f ea tu re .

T h e m e m b e r s o f t h e G n a p h o s i d a e a n d C l u b i o n i d a e a r e m o s t l y

n o c t u r n a l spec i e s t h a t m o v e s t ea l th i ly a s t h e y feel for t h e i r p r e y

w i t h f ron t legs o u t s t r e t c h e d . T h e G n a p h o s i d a e a r e g r o u n d s p i d e r s

o f s o m b r e co lo r a t i on w i t h few c o n t r a s t i n g m a r k i n g s , t h e du l l g r eys ,

b r o w n s a n d b l acks d e r i v i n g f r o m a c o v e r i n g o f s h o r t ha i r s t h a t

g ives t h e m a ve lve ty a p p e a r a n c e . M o r e f l a t t e n e d t h a n t h e C l u b i o n ­

idae , t h e y differ f r o m t h e l a t t e r i n h a v i n g t h e a n t e r i o r la te ra l

s p i n n e r e t s w i d e l y s e p a r a t e d . T h e A n y p h a e n i d a e a n d s o m e C l u b ­

i o n i d a e l ive o n p l a n t s , h a v e w e l l - d e v e l o p e d c l aw tu f t s a n d a r e g o o d

c l i m b e r s . M o s t l y w h i t i s h o r b r o w n i s h i n co lou r , t h e y dwe l l i n f l a t

152 S P I D E R S

t u b u l a r n e s t s o p e n a t b o t h e n d s , i n ro l l ed leaves o r u n d e r b a r k .

S o m e also l ive a m o n g v e g e t a b l e d e b r i s a n d n e s t u n d e r s t o n e s . T h e

C l u b i o n i d a e t h a t h a b i t u a l l y l ive o n t h e soil e x h i b i t far m o r e

d ive r s i ty i n s ize, a p p e a r a n c e a n d c o l o r a t i o n t h a n d o t h e c o n s e r v a ­

t ive p l a n t - d w e l l i n g f o r m s . M a n y s m a l l e r spec ies s u c h a s t h e Br i t i sh

Phrurolithus festivus a r e m y r m e c o p h i l o u s a n d m i m i c a n t s .

C r a b s p i d e r s o r T h o m i s i d a e a r e s e d e n t a r y a n i m a l s t h a t w a i t o n

t h e g r o u n d o r i n f l o w e r s a n d v e g e t a t i o n for p a s s i n g in sec t s w h i c h

a re se i zed b y t h e p o w e r f u l o u t s t r e t c h e d legs: t h e y f r e q u e n t l y

posses s m a r k e d l y c r y p t i c ( concea l i ng ) c o l o r a t i o n . T h e E n g l i s h

n a m e for t h i s fami ly d e r i v e s f r o m t h e i r h a b i t o f r u n n i n g s i d e w a y s

l ike c r a b s . T h e Sa l t i c idae o r j u m p i n g s p i d e r s a r e sma l l , r a t h e r

s q u a t a n i m a l s w i t h b r o a d s q u a r e h e a d s , e x t r e m e l y l a rge eyes a n d

s h o r t , s t o u t legs . T h e y h a v e v e r y k e e n s igh t a n d s ta lk t h e i r p r e y

f rom afar . T h i s i s o n e o f t h e l a rges t s p i d e r fami l ies a n d i n c l u d e s

severa l t h o u s a n d spec ies w h i c h a r e f o u n d m a i n l y i n t r o p i c a l

c o u n t r i e s w h e r e t h e y a l m o s t r iva l t h e i n sec t s i n t h e b r i l l i ance o f

t h e i r h u e s . O n l y t h i r t y - t w o s p e c i e s a r e o n t h e B r i t i s h l ist a n d m o s t

o f t h e s e a r e r a r e a n d u n l i k e l y t o b e f o u n d , e x c e p t b y t h e m o s t

e n e r g e t i c co l l ec to r . O u r c o m m o n e s t spec ies i s t h e l i t t le ' z e b r a

s p i d e r ' , Salticus scenicus, so n a m e d b e c a u s e i t is c o n s p i c u o u s l y

m a r k e d w i t h b l a c k a n d w h i t e s t r i p e s . T h o u g h less b r i l l i an t ly

c o l o u r e d t h a n s o m e o f i ts exo t i c r e l a t ives , i t i s an a t t r a c t i ve c r e a t u r e

of ten t o b e s een w a l k i n g o n wa l l s a n d fences i n t h e s u n s h i n e .

W o l f s p i d e r s o f t h e fami ly L y c o s i d a e h a v e l o n g e r b o d i e s a n d

l i m b s a n d m o d e r a t e l y l a rge eyes a n d o v e r c o m e t h e i r p r e y b y s h e e r

s t r e n g t h . L i k e t h e r e l a t e d P i s a u r i d a e , t h e y a r e essen t ia l ly g r o u n d -

l iv ing f o r m s a n d t h e m a j o r i t y o f t h e m h u n t i n t h e o p e n b y day .

T w o o t h e r fami l ies o f h u n t i n g s p i d e r s , t h e O x y o p i d a e a n d t h e

l a t e r i g r a d e S p a r a s s i d a e , c o n t a i n spec ies w h i c h a re u s u a l l y f o u n d i n

low h e r b a g e w h e n c e t h e y l eap d o w n o n t o t h e i r u n s u s p e c t i n g p r e y .

T h e y a r e r e p r e s e n t e d in t h e B r i t i s h f a u n a by Oxyopes hetero-

phthalmus a n d Micrommata virescens, r e spec t ive ly , a n d a r e m o r e

n u m e r o u s i n t h e w a r m e r r e g i o n s o f t h e w o r l d w h e r e t h e g i an t

c r a b s p i d e r , Heteropoda venatoria, is w i d e l y d i s t r i b u t e d .

T h e r e m a i n i n g fami l ies a r e all w e b - b u i l d e r s , t h e A g e l e n i d a e

c o n s t r u c t i n g f u n n e l - s h a p e d c o b w e b s c o n s i s t i n g of a t r i a n g u l a r

shee t w i t h i ts a p e x ro l l ed i n t o a t u b e in w h i c h t h e s p i d e r wa i t s for

S P I D E R S 153

i t s p r e y . T h e t h r e a d s o f w h i c h t h e w e b i s c o n s t r u c t e d a r e n o t

a d h e s i v e , b u t a t a n g l e d m a s s o f scaf fo ld ing a b o v e t r i p s p a s s i n g

insec t s w h i c h fall o n t o t h e s h e e t . Before t h e y h a v e t i m e t o r ecove r ,

t h e o w n e r o f t h e w e b h a s d a r t e d f r o m i ts t u b e a n d g a t h e r e d t h e m

in .

T h e c o m b - f o o t e d s p i d e r s o f t h e fami ly T h e r i d i i d a e a r e for t h e

m o s t p a r t t h i ckse t , s e d e n t a r y t y p e s t h a t h a n g u p s i d e d o w n f r o m

t h e i r i r r e g u l a r m a z e - l i k e w e b s . M o s t a r e s m a l l s p i d e r s s u s p e n d i n g

t h e i r s n a r e s o n p l a n t s w i t h l ines s o fine t h a t t h e y a r e o f t en u n ­

n o t i c e d , o r h i d i n g t h e m i n b u r r o w s o r f issures i n t h e soil a n d u n d e r

l i t te r .

T h e t w o - d i m e n s i o n a l o r b w e b o f t h e A r g i o p i d a e i s t h e c r o w n i n g

a c h i e v e m e n t of t h e aer ia l s p i d e r s : i t i s t h e las t s t age in a se r ies t h a t

h a s r e s u l t e d i n a c i r c u l a r d e s i g n . F i n a l l y , t h e L i n y p h i i d a e b u i l d

a h o r i z o n t a l p l a t f o r m u p o n w h i c h d r o p f l y i n g a n d j u m p i n g insec t s ,

u sua l l y af ter b e i n g h a l t e d in m i d - a i r by a s u p e r s t r u c t u r e o f c r i s s ­

c ros sed l ines g u y e d t o a d j a c e n t v e g e t a t i o n . T h e s p i d e r c l ings u p ­

s ide d o w n b e n e a t h it , r u n s o v e r t h e s u r f a c e w i t h s u r p r i s i n g

r a p i d i t y a n d p u l l s i t s p r e y t h r o u g h t h e w e b b i n g . A s e c o n d s h e e t i s

o f ten p r e s e n t b e n e a t h t h e h a n g i n g s p i d e r a n d p r o b a b l y s e rves a s a

b a r r i e r t o a t t a ck f r o m b e l o w . I n n u m b e r s o f i n d i v i d u a l s , g e n e r a

a n d spec ies t h e L i n y p h i i d a e far e x c e e d t h e to t a l o f a n y o t h e r

family o f s p i d e r s i n t h e t e m p e r a t e z o n e s w h e r e t h e y a r e t h e d o m i ­

n a n t aer ia l t y p e s . T h e m a j o r i t y o f t h e s e s p i d e r s a r e s m a l l , e v e n

m i n u t e , a n d t h e y o c c u r i n vas t , l i t t le n o t i c e d n u m b e r s u n d e r soil

d e b r i s . M o s t o f t h e m a re r e d d i s h o r b l a c k c r e a t u r e s w i t h s o m e w h a t

e l o n g a t e d b o d i e s a n d legs set w i t h fine s p i n e s , b u t t h e r e a re

n o t a b l e e x c e p t i o n s . T h e p r e s e n c e o f a s t r i d u l a t i n g file on t h e s ide

o f t h e che l i c e r ae a n d a s c r a p i n g s p i n e on t h e f e m u r o f t h e p e d i p a l p

se rves t o d i f fe ren t ia te t h e m f r o m t h e o r b w e a v e r s .

T h e s p i d e r f a u n a o f t h e B r i t i s h I s les c o m p r i s e s s o m e 2 4 famil ies

w i t h o v e r 570 spec ies , n e a r l y ha l f o f w h i c h a r e L i n y p h i i d a e . T h e

p o p u l a t i o n i n l a te s u m m e r h a s b e e n c o n s e r v a t i v e l y e s t i m a t e d b y

B r i s t o w e ( 1 9 3 9 ) * a t s o m e 2 1 / 4 m i l l i o n s p e r a c r e . H e h a s ca l cu l a t ed

t h a t i f all t h e s p i d e r s f r o m an ac re o f l a n d w e r e t o c o m b i n e t o b u i l d

o n e c o n t i n u o u s t h r e a d , t h e y w o u l d p r o d u c e a s t r a n d in a s ing le

d a y ' s s p i n n i n g t h a t w o u l d j u s t a b o u t c i rc le t h e w o r l d a t t h e

e q u a t o r : af ter t e n d a y s i t w o u l d b e l o n g e n o u g h t o r e a c h t h e m o o n .

154 S P I D E R S

T h e w e i g h t o f i n sec t s d e s t r o y e d e a c h y e a r b y s p i d e r s i n E n g l a n d

a n d W a l e s m u s t wel l e x c e e d t h e to ta l w e i g h t o f t h e h u m a n

p o p u l a t i o n !

General behaviour S p i d e r s a re s een i n d i f ferent l igh t s b y d i f ferent p e o p l e , b u t t h e

s u p e r s t i t i o n s r e g a r d i n g t h e m , i n b o t h p r i m i t i v e a n d civi l ised

c o u n t r i e s , a r e e x t r e m e l y n u m e r o u s . B r i s t o w e (1945) , w h o has

w r i t t e n a n i n t e r e s t i n g r e v i e w o f s p i d e r fo lklore , c o n c l u d e s t h a t o n

the w h o l e t h e y a re v e n e r a t e d a n d for a n u m b e r o f r e a s o n s . T h e s e

i n c l u d e a d m i r a t i o n for t h e s p i d e r s ' skill a s s p i n n e r s o f silk,

a d m i r a t i o n for t h e i r w i s d o m a n d c u n n i n g , fear o f t h e i r v e n o m o u s

a n d s in i s t e r qua l i t i e s , a s soc ia t ion o f s p i d e r s w i t h re l ig ious b e l i e f s —

in p a r t i c u l a r , t h a t i n s p i d e r s r e s i d e t h e sp i r i t s o f t h e d e a d — b e l i e f

i n t h e i r ab i l i ty t o fore te l l a n d in f luence t h e w e a t h e r , i n t h e i r m e d i ­

c ina l p r o p e r t i e s , a n d i n t h e k n o w l e d g e o f t h e p a r t t h e y p l ay i n

d e s t r o y i n g insec t s .

N o t all o f t h e s e h a v e g i v e n r ise t o s u p e r s t i t i o n s , b u t t h e first

f ou r in p a r t i c u l a r p r o v i d e t h e r a w m a t e r i a l s for folk ta les as a r e su l t

o f w h i c h t h e s p i d e r ' s p o w e r for g o o d a n d evil h a s b e c o m e t r a d i ­

t i ona l t h r o u g h o u t a l a rge p a r t o f t h e w o r l d . In p a r t i c u l a r t h e r e i s a

w i d e s p r e a d l e g e n d o f a fugi t ive w h o e s c a p e d h i s p u r s u e r s b e c a u s e

a s p i d e r b u i l t a w e b ac ross t h e m o u t h o f h i s h i d i n g p l ace so t h a t

t h e y t h o u g h t h e c o u l d n o t p o s s i b l y b e c o n c e a l e d t h e r e i n . A m o n g

o t h e r s t h i s s t o r y h a s b e e n t o l d o f t h e I n f a n t C h r i s t , w h o w a s t h u s

saved f rom H e r o d , D a v i d , w h o e s c a p e d f r o m t h e w r a t h o f Sau l ,

M o h a m m e d f r o m t h e C o r e i s h i t e s , a n d Y o r i t o m o , a twe l f t h -

c e n t u r y J a p a n e s e h e r o , w h o h i d i n a h o l l o w t r e e a n d w a s s aved b y

a s p i d e r i n s imi l a r f a sh ion . A n o t h e r a n d m o r e f a m o u s m y t h i s t h e

a n c i e n t G r e e k s t o r y o f A r a c h n e , w h o , a l t h o u g h d e p r i v e d o f h e r

h u m a n f o r m b y A t h e n e ( M i n e r v a ) for d a r i n g t o c h a l l e n g e t h e G o d ­

dess o f W i s d o m to a s p i n n i n g c o n t e s t , w a s n e v e r t h e l e s s left w i t h

h e r skill a s a s p i n n e r . T h i s s t o r y i s p r o b a b l y t h e o r ig in o f m a n y

s u p e r s t i t i o n s w h i c h h a v e s u r v i v e d i n E u r o p e a n c o u n t r i e s a l t h o u g h

t h e m y t h i tself h a s b e e n f o r g o t t e n . T h u s t h e r e i s a w i d e s p r e a d

bel ief t h a t a s p i d e r f o u n d r u n n i n g o v e r o n e ' s c lo the s h a s c o m e to

s p i n n e w o n e s : as a n a t u r a l c o n s e q u e n c e of t h i s i t i s u n l u c k y to kill

a s p i d e r . W h e t h e r t h e t e r m ' m o n e y s p i d e r ' s h o u l d b e a p p l i e d t o

S P I D E R S 155

sma l l scar le t m i t e s o r t h e sma l l s h i n y - b o d i e d b l ack L i n y p h i i d

s p i d e r s , b o t h o f w h i c h a r e n o t i n f r e q u e n t l y f o u n d r u n n i n g ove r

o n e ' s c l o t h e s o n s u n n y days , i s u n c e r t a i n . A s t h e m i t e s d o n o t s p i n

silk, h o w e v e r , a n d t h e L i n y p h i i d s a re r e s p o n s i b l e for t h e s i lver

s h e e t s o f g o s s a m e r w h i c h c loak o u r f i e l d s i n a u t u m n i t i s a p p r o ­

p r i a t e t h a t t h e y a n d n o t t h e m i t e s , s h o u l d b e a w a r d e d t h e t i t le .

( F o r a n u m b e r o f R e d I n d i a n s u p e r s t i t i o n s a n d m y t h s , see

G e r t s c h , 1949*) .

A m o n g t h e m a n y r e m a r k a b l e t r a i t s o f s p i d e r s , n o n e h a s exc i t ed

g r e a t e r i n t e r e s t n o r p r o d u c e d m o r e f an ta s t i c s p e c u l a t i o n t h a n t h a t

o f ' b a l l o o n i n g ' . T h e a n c i e n t s w e r e fami l ia r w i t h s o m e o f t h e

p h e n o m e n a a t t e n d i n g t h e f l i g h t o f s p i d e r s , for A r i s t o t l e be l i eved

t h a t s p i d e r s c o u l d s h o o t o u t t h e i r t h r e a d s , a n d P l i n y w r o t e : ' I n t h e

y e a r t h a t L . P a u l u s a n d C . M a r c e l l u s w e r e c o n s u l s , i t r a i n e d w o o l . '

O f t e n d u r i n g t h e la te s u m m e r a n d a u t u m n m o n t h s o n q u i e t , h a z y

days , t h e a i r i s f i l l e d w i t h s h i n i n g s t r a n d s a n d t h r e a d s o f g o s s a m e r ,

t h e silk p r o d u c e d b y t h e s p i d e r s t h a t h a v e a t t e m p t e d t o f l y a n d

fai led. S o m e t i m e s o n e sees a f i e ld o r m e a d o w c a r p e t e d w i t h silk

a n d a h o s t o f l i t t le s p i d e r l i n g s s p r e a d i n g t h e i r l ines in va in a t t e m p t s

t o f l y . O n t h e o t h e r h a n d m a n y a r e s u c c e s s f u l — D a r w i n , i n 1839,

r e c o r d e d t h e a r r iva l on H . M . S . Beagle o f ' vas t n u m b e r s o f a sma l l

s p i d e r , a b o u t o n e - t e n t h o f an i n c h in l e n g t h , a n d o f a d u s k y r e d

c o l o u r ' w h e n t h e s h i p w a s s ix ty m i l e s f r o m t h e coas t o f S o u t h

A m e r i c a — a n d b a l l o o n i n g i s w i t h o u t d o u b t a n i m p o r t a n t fac to r i n

t h e d i s t r i b u t i o n o f m a n y spec i e s all o v e r t h e w o r l d . N o r i s i t c o n ­

f i n e d t o a n y p a r t i c u l a r s ea son . I n B r i t a i n , a e r o n a u t i c d i s p e r s a l o f

i m m a t u r e s p i d e r s t akes p l ace m a i n l y i n s u m m e r , o f a d u l t L i n y ­

p h i i d a e chiefly d u r i n g t h e c o l d e r m o n t h s w h e n t e m p e r a t u r e i s t h e

m o s t i m p o r t a n t m i c r o - c l i m a t i c fac tor , a n d b a l l o o n i n g i s i n h i b i t e d

d u r i n g u n f a v o u r a b l e w e a t h e r (Duffey , 1956) .

T h e p r o s a i c t r a n s l a t e ' g o s s a m e r ' a s ' goose s u m m e r ' i n r e f e r e n c e

to t h e fanciful r e s e m b l a n c e o f t h e fragi le ske ins o f si lk to t h e d o w n

o f geese w h i c h t h e t h r i f t y h o u s e w i f e c ause s t o f l y w h e n s h e r e n o ­

va te s h e r f e a the r b e d s a n d p i l lows ; b u t g o s s a m e r t r a n s l a t e d a s

' G o d ' s s u m m e r ' re fe rs t o t h e l e g e n d t h a t t h i s g o s s a m e r ' is t h e

r e m n a n t o f O u r L a d y ' s w i n d i n g s h e e t w h i c h fell a w a y i n t h e s e

l igh tes t f r a g m e n t s a s s h e w a s a s s u m e d i n t o h e a v e n ' ( B i s h o p ,

1945) .

156 S P I D E R S

FIG. 33. Ballooning by young spiders.

S o o n a t a n g l e o f w e b s s p r i n g s u p , c r o s s i n g in all d i r e c t i o n s a n d

c o v e r i n g t h e v e g e t a t i o n . W h e n t h e y o u n g s p i d e r h a s r e a c h e d t h e

s u m m i t o f t h e n e a r e s t p r o m o n t o r y — a w e e d , a b u s h o r a f e n c e — i t

t u r n s t o face t h e w i n d , e x t e n d s i t s legs s o t h a t i t a p p e a r s t o b e

s t a n d i n g o n t i p t o e a n d le ts a i r c u r r e n t s c a r r y t h e si lk f r o m its

s p i n n e r e t s . W h e n t h e f r i c t ion o f t h e c u r r e n t s aga in s t t h e t h r e a d s

e x e r t s sufficient p u l l , t h e s p i d e r l o o s e n s i ts h o l d a n d u s u a l l y sails

away : a t t h e t a k e off, a t least , i t i s d r a g g e d b a c k w a r d s . S o m e t i m e s ,

af ter take-off, t h e s p i d e r c l i m b s r a p i d l y t o t h e m i d d l e o f i ts t h r e a d ,

w h i c h t h e n s w e e p s f o r w a r d a n d b e c o m e s d o u b l e d . L e s s f r e q u e n t l y

t h e s p i d e r m a k e s a f o r w a r d s t a r t . T h i s m e t h o d i s e m p l o y e d b y

sma l l s p i d e r s w h i c h m a k e a w e a k a t t a c h m e n t t o a s u p p o r t a n d

a l low t h e m s e l v e s t o b e b l o w n o u t w a r d a n d u p w a r d u n t i l t h e

t h r e a d s n a p s n e a r i ts h o l d ( B r a e n d e g a a r d , 1938) .

T h e m o d e s o f life a n d t h e h a b i t a t s o f s p i d e r s a re m o s t va r i ed :

s o m e a re w a n d e r e r s t h r o u g h o u t t h e i r l ives, o t h e r s a r e a l m o s t

e n t i r e l y s e d e n t a r y ; s o m e l ive i n s u n n y , a i ry p l ace s , o t h e r s a re

f o u n d i n o b s c u r e c a v e r n s w h e r e t h e l igh t n e v e r p e n e t r a t e s . A

M u c h o f t h e a d v e n t u r e a n d r i sk i n t h e life o f t h e s p i d e r i s

c r o w d e d i n t o t h e first f ew d a y s o f f r e e d o m w h e n t h e y o u n g s p i d e r -

l ings , h a v i n g first left t h e i r e g g sac , c l i m b o v e r t h e s t e m s o f p l a n t s

a n d u p t h e leaves o f g ra s ses , s t r i n g i n g t h e i r t h r e a d s a s t h e y go .

S P I D E R S 157

n u m b e r o f spec i e s i n h a b i t d e s e r t r e g i o n s , o t h e r s a r e a q u a t i c o r

s e m i - m a r i n e . I n d e e d , t h e r e a r e few p a r t s o f t h e w o r l d w h e r e

s p i d e r s do n o t t h r i v e . A n u m b e r o f g e n e r a l i s a t i o n s can , h o w e v e r ,

b e m a d e . S o m e s p i d e r s s u c h a s t h e M y g a l o m o r p h a , Sa l t i c i dae a n d

S p a r a s s i d a e f lour i sh i n t h e t r o p i c s a n d d i m i n i s h p r o g r e s s i v e l y t o ­

w a r d s t h e coo le r r e g i o n s ; t h e G n a p h o s i d a e , D y s d e r i d a e , A g e l e n i -

d a e a n d v a r i o u s c r i be l l a t e fami l i es t h r i v e m o s t success fu l ly i n t h e

w a r m e r t e m p e r a t e o r s u b - t r o p i c a l a r ea s , while* o t h e r s , i n c l u d i n g

t h e L y c o s i d a e a n d p a r t i c u l a r l y t h e L i n y p h i i d a e , r e a c h t h e i r g r e a t ­

es t d o m i n a n c e i n t h e a r c t i c o r s u b - a r c t i c r e g i o n s . E v e n i n s u c h a

sma l l a rea a s t h a t c o v e r e d b y t h e B r i t i s h I s l e s t h e r e a r e m a r k e d

d i f ferences b e t w e e n t h e s p i d e r s f o u n d i n t h e n o r t h a n d s o u t h ,

d i f ferences w h i c h d e m o n s t r a t e t h e s a m e t r e n d a s t h a t o u t l i n e d

a b o v e . S c o t l a n d lacks M y g a l o m o r p h a , O x y o p i d a e , P h o l c i d a e ,

S c y t o d i d a e , S p a r a s s i d a e e t c . , w h i l s t t h e L i n y p h i i d a e a n d Sa l t i c idae

r e p r e s e n t 5 0 % a n d 4 % o f i t s f a u n a r e spec t i ve ly , c o m p a r e d w i t h

4 2 % a n d 6 % for E n g l a n d ( B r i s t o w e , 1939 ) .*

S o m e p l a n t s h a r b o u r m o r e s p i d e r s t h a n o t h e r s . F o r e x a m p l e , t h e

f auna o f b r a c k e n , b l u e b e l l s , m i n t , l au re l , w i l l o w a n d b e e c h i s far

less r i c h t h a n t h a t o f g ra s s , h e a t h e r , g o r s e , ho l ly , y e w , con i fe r s a n d

oak. I t m a y b e t h a t t h e s c e n t s o f c e r t a i n p l a n t s a r e a v o i d e d , b u t t h e

d e n s i t y o f t h e fol iage i s a lso an i m p o r t a n t f ac to r as i t affects t h e

h u m i d i t y o f t h e e n v i r o n m e n t . A g a i n , t h e a b u n d a n c e o f i n s e c t life,

l iv ing o n , o r c o m i n g t o d i f ferent p l a n t s a lso affects t h e n u m b e r o f

s p i d e r s t h a t c a n l ive t h e r e . B r i s t o w e ( 1 9 3 9 ) * h a s c o n s i d e r e d i n

de ta i l t h e s p i d e r f a u n a o f s a n d h i l l s , m a r s h e s , m o u n t a i n s , caves ,

m i n e s a n d ce l la rs , h o u s e s , t o w n s , s e w a g e w o r k s , a n t s ' a n d t e r m i t e s '

n e s t s , b e e h i v e s , b i r d s ' a n d m a m m a l s ' n e s t s , a n d o t h e r s p i d e r s '

w e b s .

A n u m b e r o f a u t h o r s h a v e s t r e s s e d t h e i m p o r t a n c e o f m o i s t u r e

o n t h e d i s t r i b u t i o n o f s p i d e r s , a n d N e m e n z (1954) h a s d i s c u s s e d i t s

phys io log ica l s igni f icance . T h e confl ic t b e t w e e n t h e i n c o m p a t i b l e

r e q u i r e m e n t s o f r e s p i r a t o r y e x c h a n g e a n d t h e p r e v e n t i o n o f w a t e r -

loss h a s r e c e n t l y b e e n d e m o n s t r a t e d b y t h e w r i t e r b y a c o m p a r i s o n

of t w o c o m m o n B r i t i s h spec ie s , Amaurobius ferox a n d A. similis*

b o t h of w h i c h h a v e a c u t i c u l a r w a x - l a y e r w i t h a c r i t i ca l t e m p e r a t u r e

a t a b o u t 30° C , a b o v e w h i c h t h e y q u i c k l y lose w a t e r b y e v a p o r a t i o n

i n d r y air . A t l o w e r t e m p e r a t u r e s , h o w e v e r , t h e r a t e o f w a t e r - l o s s

158 S P I D E R S

in A. ferox is a l m o s t d o u b l e t h a t of A. similis. A. similis ' t i r e s ' v e r y

r a p i d l y w h e n fo rced t o r u n a t full s p e e d w i t h o u t s t o p p i n g a n d i s

a l m o s t a lways o v e r c o m e i n f i g h t s b e t w e e n e v e n l y m a t c h e d i n d i ­

v i d u a l s o f t h e t w o spec ie s . B o t h spec ies c a n r u n for l o n g p e r i o d s

w h e n s u p p l i e d w i t h o x y g e n a n d i t i s s u g g e s t e d t h a t t h e g r e a t e r

s t a m i n a of A. ferox d e p e n d s u p o n a p r o p o r t i o n a t e l y l a rge r r e s p i r a ­

t o ry su r face a c q u i r e d a t t h e e x p e n s e o f g r e a t e r d e p e n d e n c e u p o n

e n v i r o n m e n t a l h u m i d i t y ( C l o u d s l e y - T h o m p s o n , 1957) .

I n Br i t a in , a n d i n fact i n t h e w h o l e o f t h e n o r t h e r n h e m i s p h e r e ,

t h e r e i s o n l y o n e s p i d e r t h a t i s t r u l y a q u a t i c . T h i s i s t h e w e l l - k n o w n

Argyroneta aquatica, o n e of o u r l a rges t spec ies a n d s o m e w h a t ex­

c e p t i o n a l i n t h a t t h e m a l e i s b i g g e r t h a n i ts m a t e . I t s w i m s u n d e r

w a t e r c l o t h e d in a b u b b l e o f a i r t h a t s h i n e s l ike qu icks i lve r , a n d

c o n s t r u c t s a r e t r e a t in t h e f o r m of a d i v i n g be l l of silk f i l led w i t h air

w h i c h i s c a r r i e d d o w n i n b u b b l e s f r o m t h e su r f ace . T h e r e a re ,

h o w e v e r , severa l o t h e r spec ies w h i c h l ive, l ike f i s h e r m e n , b y a n d

o n t h e w a t e r . A l t h o u g h m o s t wol f s p i d e r s f r e q u e n t d r y a n d s t o n y

p laces a n d a re p a r t i c u l a r l y n u m e r o u s i n s p r i n g a n d ea r ly s u m m e r ,

t h e m e m b e r s o f t h e g e n u s Pirata a r e s e m i - a q u a t i c , l iv ing a t t h e

m a r g i n s o f r ive r s a n d p o n d s , a n d a re ab le t o r u n o n t h e su r f ace o f

t h e w a t e r . P . piscatorius s p i n s a s i lken t u b e in m o s s a t t h e w a t e r ' s

e d g e a n d will r u n b e n e a t h t h e w a t e r i f i t i s a l a r m e d . A s t h e i n c o m ­

i n g t i de c r e e p s ove r t h e m u d flats, Lycosa purbeckensis, an i n h a b i ­

t a n t o f sal t m a r s h e s , t o u c h e s t h e w a t e r ' l ike a b a t h e r fee l ing t h e

t e m p e r a t u r e w i t h h i s t oe be fo r e t a k i n g t h e p l u n g e ' , a n d t h e n

de l i be ra t e ly w a l k s d o w n t h e s t e m o f a s e d g e o r o t h e r h a l o p h y t i c

p l an t , t a k i n g w i t h i t a b u b b l e o f a i r c a u g h t by m e a n s o f t h e ha i r s on

i ts b o d y ( B r i s t o w e , 1923) . V a r i o u s T h e r i d i i d a e , s u c h as Oedo-

thorax fuscus a n d spec ies of Desis ( A g e l e n i d a e ) f r o m t h e s h o r e s of

t h e I n d i a n ocean , also l ive u n d e r s e m i - m a r i n e c o n d i t i o n s .

To e s c a p e c a p t u r e , t h e l a rge Dolomedes fimbriatus ( P i s a u r i d a e )

will r u n d o w n a p l a n t s t e m b e n e a t h t h e su r face o f t h e w a t e r . T h i s

spec ies , w h i c h l ives i n s w a m p s a n d d i t c h e s , i s s o m e t i m e s cal led t h e

' r a f t - s p i d e r ' on a c c o u n t of a p o p u l a r fallacy t h a t i t m a k e s a raft of

fallen leaves on w h i c h t o f l oa t d o w n s t r e a m . S o m e o f i ts fo re ign

r e l a t ions c a t c h t a d p o l e s a n d e v e n sma l l f i s h e s t o ea t . N o o b v i o u s

fea tu res i n d i c a t e t h a t t h e P i s a u r i d a e a re s p i d e r s o f t h e w a t e r , b u t

t h e y c a n r u n on t h e su r face w i t h a g r a c e a l m o s t e q u a l l i n g t h a t o f a

S P I D E R S 159

w a t e r - s k a t e r a n d c a n r e m a i n s u b m e r g e d for l o n g p e r i o d s i f

neces sa ry .

T o s u m m a r i s e , a q u a t i c s p i d e r s a r e k n o w n f r o m severa l famil ies

i n c l u d i n g t h e A g e l e n i d a e , L y c o s i d a e , P i s a u r i d a e , A r g i o p i d a e ,

C l u b i o n i d a e , L i n y p h i i d a e , Sa l t i c idae a n d T h o m i s i d a e . T h e ex­

t e n t t o w h i c h t h e y l ive b e n e a t h t h e su r f ace va r i e s a n d s o m e can

wa lk a b o u t c o m f o r t a b l y w i t h a b u b b l e o f air s u r r o u n d i n g t h e i r

b o d i e s wh i l s t o t h e r s re ly o n f ind ing s o m e c r a n n y c o n t a i n i n g ai r o r

enc lose t h e m s e l v e s a n d a s u p p l y of air in a s i lken cell . T h e sub jec t

ha s b e e n r e v i e w e d b y B r i s t o w e ( 1 9 3 0 b ) .

T h e m a j o r i t y o f s p i d e r s l ive on t h e su r face o f t h e soil , s o m e in

b u r r o w s , o t h e r s s h e l t e r i n g u n d e r s t o n e s , logs o r b e n e a t h t h e d e b r i s

o f fal len leaves in fo res t s . M o s t o f t h e T h e r a p h o s i d a e c h o o s e a n y

k i n d o f r e t r ea t , l iv ing u n d e r s t o n e s o r r u b b i s h o n t h e g r o u n d a n d

in c racks in t r e e s . S o m e d ig a s i m p l e cell w h i c h t h e y l ine w i t h a

s l ight w e b o f silk. F o r t h e m o s t p a r t t h e y a r e ac t ive f o r m s a n d

w a n d e r a b o u t a t n i g h t i n s e a r c h o f p r e y . T h e m o s t pe r fec t ly c o n ­

s t r u c t e d b u r r o w s a re t h o s e o f t h e C t e n i z i d a e , w h i c h d ig w i t h t h e

a id of a c o m b - l i k e r ake of l a rge s p i n e s on t h e m a r g i n s of t h e i r

che l i ce rae . T h e wal l s o f t h e t u b e i n w h i c h t h e s p i d e r l ives a re l ined

w i t h a w a t e r p r o o f c o a t i n g of e a r t h a n d sal iva to w h i c h a layer of

silk i s a p p l i e d : a s t h e s p i d e r g r o w s , i t en l a rge s i ts b u r r o w , t h e

e n t r a n c e to w h i c h i s c losed w i t h a t r a p - d o o r . T h e first d e s c r i p t i o n

o f t h i s i n t e r e s t i n g dev ice w a s g i v e n by P a t r i c k B r o w n in h i s Civil

and Natural History of Jamaica, L o n d o n (1756) . S e v e n y e a r s la ter

t h e careful o b s e r v a t i o n s o f t h e A b b e S a u v a g e s o n t h e ne s t s o f

Nemesia caementaria, w h i c h he d i s c o v e r e d n e a r M o n t p e l l i e r , w e r e

p u b l i s h e d . A l t h o u g h t r a p - d o o r s p i d e r ne s t s a t t r a c t e d p o p u l a r

a t t e n t i o n the rea f t e r , i t w a s n o t u n t i l M o g g r i d g e (1873) p u b l i s h e d

h is s t u d i e s o n t h e h a b i t s o f t h e s e a n i m a l s t h a t a n y c o m p r e h e n s i v e

t r e a t m e n t w a s a c c o r d e d t h e m .

M o g g r i d g e w a s ab le t o d i s t i n g u i s h four t y p e s o f n e s t a m o n g t h e

spec ies he s t u d i e d . T h e first w a s a s i m p l e cy l ind r i ca l t u b e w i t h a

t h i ck ' co rk d o o r ' , t h e s e c o n d h a d a t h i n 'wafe r d o o r ' , t h e t h i r d a

t h i n o u t e r d o o r w i t h a s e c o n d d o o r p a r t o f t h e w a y d o w n , w h i l e t h e

f o u r t h w a s t h e m o s t c o m p l i c a t e d : a t u b e c a p p e d o n t h e o u t s i d e b y

a t h i n d o o r a n d h a v i n g an o b l i q u e s i d e t u n n e l a t t h e e n t r a n c e t o

w h i c h w a s a n o t h e r t r a p - d o o r . S i n c e t h e n severa l o t h e r t y p e s o f

1 6 0 S P I D E R S

nes t h a v e b e e n d i s c o v e r e d in dif ferent p a r t s o f t h e w o r l d , s o m e o f

t h e m o f e v e n m o r e c o m p l i c a t e d des ign .

T h e m a j o r i t y o f h u n t i n g s p i d e r s l ive i n s i lken cells u n d e r s t o n e s ,

b a r k o r fal len logs . S o m e o f t h e s m a l l e r spec ies s e e m t o b e a b s o l u t e

w a n d e r e r s a n d h a v e n o h o m e a t all , s p e n d i n g t h e n i g h t u n d e r a n y

s u i t a b l e r o c k o r s t o n e t h a t t h e y c o m e ac ross , w h i l s t t h e l a rge r

k i n d s l ive p e r m a n e n t l y i n b u r r o w s f rom w h i c h t h e y n e v e r g o far.

FIG. 3 4 . T r apdoo r spider and burrow. (After Moggridge, 1 8 7 3 . )

H a b i t s v a r y c o n s i d e r a b l y . O n e h a n d s o m e l y m a r k e d wolf s p i d e r ,

Arctosa perita, m a k e s i ts silk l i ned b u r r o w s in d u n e s of f i rm s a n d

a n d o n h e a t h l a n d w h e r e t h e v e g e t a t i o n h a s b e e n b u r n e d a w a y .

W h e n a l a r m e d i t wi l l se ize w i t h i ts che l i ce rae t h e r i m o f t h e silk

t h a t l ines i ts b u r r o w , a n d p u l l i t ac ross t h e e n t r a n c e l ike a c u r t a i n .

T h e n r a p i d l y t u r n i n g r o u n d i t c loses t h e last c h i n k w i t h a few

S P I D E R S 1 6 1

s w e e p i n g s t r o k e s o f i ts s p i n n e r e t s ( B r i s t o w e , 1954) . S o m e t i m e s

severa l of t h e s e s p i d e r s l ive q u i t e c lose t o g e t h e r in a co lony .

W e b - b u i l d i n g s p i d e r s u s u a l l y c o n s t r u c t a r e t r e a t a m o n g s t t h e

v e g e t a t i o n f r o m w h i c h t h e i r s n a r e i s s u s p e n d e d . V i b r a t i o n s o f a

s i g n a l - t h r e a d c o n n e c t i n g t h e i r s h e l t e r w i t h t h e w e b e n a b l e t h e m

i n s t a n t l y t o d e t e c t t h e s t r u g g l e s o f a n y in sec t t h a t h a s b e e n c a u g h t .

S o m e spec ies a re p e c u l i a r i n t h a t t h e y s h o w a t e n d e n c y t o w a r d s

social h a b i t s . T h i s i s a p p a r e n t a m o n g a n u m b e r o f c r ibe l l a t e

fami l ies a n d an A u s t r a l i a n spec i e s Amaurobius socialis f r o m t h e

J e n o l a n C a v e s c o n s t r u c t s e n o r m o u s c o m m u n a l a n d d e n s e l y f ab r i ­

c a t e d w e b s m e a s u r i n g as m u c h as 12 feet in l e n g t h a n d 4 feet in

w i d t h , w h i c h a r e i n h a b i t e d b y a l a rge n u m b e r o f i n d i v i d u a l s . I n

a s imi l a r w a y c o m m u n a l w e b s c o n s t r u c t e d by Theridion socialis a n d

Uloborus republicanus h a v e b e e n d e s c r i b e d .

T h e s p i d e r ' s w e b i s u n i q u e a m o n g a n i m a l p r o d u c t i o n s i n t h a t ,

( save o n e c o n s t r u c t e d by a c a d d i s l a rva) i t i s t h e on ly t r a p b u i l t by

a n a n i m a l . T h e w e b i s s o efficient for o b t a i n i n g food t h a t i ts o w n e r

s e l d o m m a k e s u s e o f a n y s e n s e save t h a t w h i c h t h e ac t i on o f t h e

w e b d e m a n d s , a n d t h e l ives o f w e b - b u i l d i n g spec ies a r e a l m o s t

e n t i r e l y g o v e r n e d b y r e s p o n s e s t o t ac t i l e a n d v i b r a t o r y s t i m u l i

s u p p l e m e n t e d b y t h e d e v e l o p m e n t o f t h e m u s c u l a r s e n s e . T h e

m e t h o d s o f c o n s t r u c t i o n o f t h e v a r i o u s t y p e s o f w e b h a v e a t t r a c t e d

a g r e a t dea l o f a t t e n t i o n , in p a r t i c u l a r f r o m M a c C o o k ( 1 8 8 9 - 9 4 ) ,

P e t e r s ( 1 9 3 3 , e t c . ) , T i l q u i n (1942) a n d W i e h l e . T o r e v i e w all t h i s

w o r k w o u l d b e b e y o n d t h e s c o p e o f t h e p r e s e n t v o l u m e , b u t

f o r t u n a t e l y m u c h o f i t h a s b e e n s u m m a r i s e d r e c e n t l y b y S a v o r y

(1952) , f r o m w h o s e b o o k f u r t h e r de ta i l s c a n b e o b t a i n e d . B r i s t o w e

(1930) h a s s u g g e s t e d t h a t t h e o r ig in o f w e b s lies i n t h e u s e o f silk

a s a c o v e r i n g for s p i d e r s ' eggs w h i c h w e r e t h e n g u a r d e d by t h e

m o t h e r a n d f r o m w h i c h r a n d o m t h r e a d s r a d i a t e d b u t S a v o r y t h i n k s

t h a t t h e y h a v e r e s u l t e d f r o m a n a c c u m u l a t i o n o f d r a g l ines , laid

d o w n b y a n c e s t r a l h u n t i n g s p i d e r s w h e n t h e i r p r e y w a s c a p t u r e d

a n d w h i c h la te r gave t h e s p i d e r s w a r n i n g o f o t h e r in sec t s p a s s i n g b y .

T h e typ ica l p r o c e d u r e i n t h e c o n s t r u c t i o n o f a n o r b w e b i s t h e

c o n s t r u c t i o n of a f r a m e fo l lowed by t h a t of t h e r ad i i . A few sp i ra l s

a r o u n d t h e c e n t r e h o l d t h e rad i i i n p l ace w h i l e t h e s p i d e r t r ave l s

o u t w a r d s s p i n n i n g a w i d e l y s p a c e d t e m p o r a r y sp i ra l . F i n a l l y t h e

s p i n n i n g o f v i sc id sp i ra l s s t a r t s a t t h e o u t s i d e a n d w o r k s i n w a r d s

L S.S.C.M.

162 S P I D E R S

w i t h t h e s i m u l t a n e o u s d e s t r u c t i o n o f t h e t e m p o r a r y sp i ra l a s i t i s

r e a c h e d . M a n y o r b w e a v e r s r e n e w t h e i r w e b s , o t h e r t h a n t h e

f r a m e w o r k , dai ly , b u t r e n e w a l m a y b e p o s t p o n e d i f t h e s p i d e r s a re

wel l fed o r t h e w e a t h e r u n s u i t a b l e .

T h e chief e c o n o m i c u s e o f s p i d e r s ' silk lies i n t h e c o n s t r u c t i o n o f

fine g r a t i c u l e s for op t i c a l i n s t r u m e n t s . C o b w e b s w e r e u s e d yea r s

ago a s d r e s s i n g s for w o u n d s to s t a u n c h t h e flow o f b l o o d , for w h i c h

t h e y w e r e e x t r e m e l y effective. M o u l d s s u c h as Penicillium w e r e

s o m e t i m e s a d d e d , p e r h a p s f o r e s h a d o w i n g t h e p r e s e n t - d a y u s e o f

pen ic i l l in a n d o t h e r a n t i b i o t i c s . W h e n severa l s h e e t - w e b s a re

s u p e r i m p o s e d t h e y f o r m a fine t r a n s p a r e n t silk fabr ic on w h i c h

de l ica te a n d beau t i fu l p i c t u r e s w e r e p a i n t e d ea r ly i n t h e n i n e t e e n t h

c e n t u r y b y a n I n n s b r u c k fami ly n a m e d B u r g m a n . T h e y a re

' e x q u i s i t e e x a m p l e s o f a n a r t t h a t n o w r a n k s a s sca rce ly m o r e t h a n

a c u r i o s i t y ' .

F o o d and feeding habits

T h e food of s p i d e r s i n c l u d e s a v a r i e t y of in sec t s , w o o d l i c e ,

m y r i a p o d s , f a l s e - sco rp ions , h a r v e s t - s p i d e r s a n d o t h e r A r a c h n i d a .

B r i s t o w e (1941) ,* w h o h a s d i s c u s s e d t h e sub j ec t a t s o m e l e n g t h ,

ha s s h o w n t h a t t h e p o t e n t i a l food s u p p l y o f d i f ferent spec ies va r i e s

w i t h i n w i d e l imi t s . A h u n g r y s p i d e r i s l iable to a c c e p t an in sec t

w h i c h i t wi l l re ject w h e n fully fed, t h e r e b y i n d i c a t i n g t h a t i ts d i s ­

t a s t e i s r e l a t ive a n d n o t a b s o l u t e . By t h e i r m o d e o f life, t h e i r

h u n t i n g m e t h o d s a n d t h e n a t u r e o f t h e i r s n a r e s , d i f ferent spec ies o f

s p i d e r s b e c o m e a d a p t e d w i t h i n w i d e l imi t s t o t h e c a p t u r e o f

p a r t i c u l a r i n sec t s a n d m a y refuse t y p e s t o w h i c h t h e y a r e u n ­

a c c u s t o m e d . T h u s a l t h o u g h Amaurobius s p p . m a y i n v e s t i g a t e w i t h

the i r legs a w o o d l o u s e t h r o w n i n t o t h e i r w e b s , t h e y n e a r l y a lways

r e t r e a t w i t h o u t h a r m i n g it . U n l i k e Segestria senoculata, w h i c h wil l

a t t ack a b l a d e o f g ra s s d r a w n ac ross i ts w e b , a n d n o r m a l l y ea t s

wood l i ce , A. ferox a n d A. similis wi l l r e s p o n d o n l y to t h e v i b r a t i o n s

of a t u n i n g fork, a n d wil l a t t ack a w o o d l o u s e if a v i b r a t i n g t u n i n g

fork i s p l a c e d o n t h e w e b j u s t b e s i d e i t ( C l o u d s l e y - T h o m p s o n ,

1956) .

Atypus affinis, t h e sole B r i t i s h r e p r e s e n t a t i v e of t h e s u b - o r d e r

M y g a l o m o r p h a , b u r r o w s in t h e soil , b u t i n s t e a d o f m a k i n g a t r a p ­

doo r , i t c o n t i n u e s t h e silk l i n ing of i ts b u r r o w a b o v e t h e g r o u n d as a

S P I D E R S 163

c losed t u b e . W h e n in sec t s c r a w l o n t h i s , t h e s p i d e r se izes t h e m

f r o m w i t h i n a n d p u l l s t h e m t h r o u g h t h e silk. T h e c losed p u r s e -

w e b o f t h i s s p e c i e s c lea r ly r e s t r i c t s i ts d i e t t o c r a w l i n g insec t s ,

w o r m s a n d w o o d l i c e , w h e r e a s t h e o r b w e b s o f t h e A r g i o p i d a e

a r e a d a p t e d to t h e c a p t u r e o f i n sec t s in fl ight. A para l le l a m o n g s t

h u n t i n g s p i d e r s is a f forded by Dysdera erythrina or Drassodes

lapidosus, w h i c h h u n t m a i n l y u n d e r s t o n e s o r a t t h e r o o t s o f h e r ­

b a g e a t n i g h t , w h i l s t t h e f lower - l iv ing h a b i t of Misumena vatia a n d

Thomisius onustus b r i n g t h e m i n t o c o n t a c t w i t h w i n g e d insec t s .

P r o t e c t i v e f l avours h a v e b e e n evo lved b y m a n y i n v e r t e b r a t e s

w h i c h t e n d t o r e n d e r t h e m d i s t a s t e fu l t o s p i d e r s . A t least s o m e

spec i e s avo id e a r w i g s , s tonef l ies , c a d d i s f l i e s , m o t h s , bee t l e s , b u g s ,

a n t s a n d o t h e r H y m e n o p t e r a , h a r v e s t - s p i d e r s , m i t e s , w o o d l i c e a n d

m i l l i p e d e s , a n d m a n y o f t h e s e h a v e d e v e l o p e d w a r n i n g m o v e m e n t s

s ince n e i t h e r a p o s e m a t i c n o r p r o t e c t i v e c o l o r a t i o n a r e o f a n y avai l

aga ins t s p i d e r s t h a t r e s p o n d t o t ac t i l e r a t h e r t h a n v i sua l s t i m u l i .

A l t h o u g h i n v e r t e b r a t e a n i m a l s , p a r t i c u l a r l y A r t h r o p o d a , f o r m

t h e b u l k o f t h e d ie t o f s p i d e r s , t h e r e a re a n u m b e r o f r e c o r d s o f

v e r t e b r a t e s b e i n g e a t e n . A s a l r e a d y m e n t i o n e d s o m e s e m i - a q u a t i c

L y c o s i d a e a n d P i s a u r i d a e m a y c a t c h fishes, w h i l e a m p h i b i a , l i za rds ,

y o u n g snakes , b i r d s a n d sma l l m a m m a l s n o t i n f r e q u e n t l y f o r m t h e

p r e y o f l a rge r s p i d e r s , e spec ia l ly t h e T h e r a p h o s i d a e . T h e s u b j e c t

h a s b e e n r e v i e w e d b y M i l l o t ( 1943 ) , t o w h o m t h e r e a d e r i s r e f e r r e d

for f u r t h e r de t a i l s .

S p i d e r s a re a d a p t e d t o v a r i o u s h a b i t a t s w i t h i n w h i c h s o m e

a t t ack l a rge i n s e c t s , o t h e r s c a p t u r e s m a l l e r k i n d s : s o m e s p i d e r s

a t t ack d i u r n a l i n sec t s , o t h e r s h u n t b y n i g h t ; s o m e spec ia l i se i n

c r a w l i n g in sec t s , o t h e r s i n t h o s e t h a t f l y . B r i s t o w e ( 1 9 4 1 ) * d i scusses

t h e m e a n s e m p l o y e d for t h e c a p t u r e o f p r e y a n d o n t h i s bas i s

d iv ide s t h e v a r i o u s fami l ies i n t o h u n t i n g s p i d e r s , t u b e b u i l d e r s ,

s h e e t - w e b b u i l d e r s , b u i l d e r s o f scaffolding w e b s , m e s h e d w e b s a n d

o r b w e b s .

S o m e h u n t i n g s p i d e r s seek t h e i r p r e y b y day , t r u s t i n g t o t h e i r

g o o d s igh t , w h i l e o t h e r s a r e ac t ive a t n i g h t a n d d e p e n d m a i n l y o n

t h e s ense o f t o u c h . J u m p i n g s p i d e r s (Sa l t i c idae ) h a v e t h e k e e n e s t

s igh t o f all a n d s ta lk t h e i r p r e y f r o m afar. O u r c o m m o n e s t spec ies ,

Salticus scenicus, p r o v i d e s a c o n v e n i e n t e x a m p l e of t h e g r o u p .

E q u a l l y a t h o m e on a p e r p e n d i c u l a r su r face o r on t h e u n d e r s i d e o f a

164 S P I D E R S

h o r i z o n t a l b e a m , i t i s ab l e to m a i n t a i n i ts p o s i t i o n by m e a n s o f an

a d h e s i v e tu f t o f ha i r s , t h e ' s c o p u l a ' , on e a c h o f i ts feet . As i t m o v e s ,

t h e z e b r a s p i d e r t ra i l s b e h i n d i t an e x c e e d i n g l y fine t h r e a d o f silk

w h i c h i s a t t a c h e d a t f r e q u e n t i n t e rva l s like a c l i m b i n g r o p e , so t h a t

i n t h e e v e n t o f a s l ip t h e s p i d e r d o e s n o t fall t o t h e g r o u n d . T h e

spec ies h a s a c u r i o u s w a y of e x p l o r i n g t h e su r face ove r w h i c h i t i s

w o r k i n g b y success ive s h o r t r u n s a l t e r n a t i n g w i t h p e r i o d s o f

a b s o l u t e s t i l lness . I t wi l l o f ten p a t i e n t l y s e a r c h a l a rge a rea be fo r e

i t c a t c h e s s igh t o f an insec t , w h e n i t c a n be seen to t u r n i ts h e a d so

a s t o b r i n g i ts fou r l a rge a n t e r i o r eyes t o b e a r u p o n t h e q u a r r y . T h e

four p o s t e r i o r eyes a r e s m a l l e r a n d less i m p o r t a n t . F o r a t i m e i t

r e m a i n s m o t i o n l e s s , t h e n b e g i n s t o e d g e s t ea l th i ly n e a r e r u n t i l i t i s

c lose e n o u g h for a s u d d e n s p r i n g . T h e f ron t p a i r o f legs i s u s e d for

se iz ing t h e p r e y a n d t h e r e m a i n i n g p a i r s for j u m p i n g . H o w e v e r ,

t h e j u m p i s n o t a lways success fu l : of ten t h e insec t sees i ts pe r i l a t

t h e last m o m e n t a n d flies away , a n d t h e s p i d e r h a s t o b e g i n all o v e r

aga in . I n c o n t r a s t , t h e wol f s p i d e r s ( L y c o s i d a e ) c a p t u r e t h e i r

p r e y b y s h e e r s t r e n g t h a n d s p e e d .

T h e t yp i ca l c r a b s p i d e r s ( T h o m i s i d a e ) a r e s e l d o m s e e n b y t h e

o r d i n a r y o b s e r v e r , for t h e i r h a b i t s a r e r e t i r i n g a n d m a n y o f t h e m

a re r a t h e r s m a l l . T h e y w a i t m o t i o n l e s s for p a s s i n g i n sec t s w h i c h

a re se ized b y t h e p o w e r f u l o u t s t r e t c h e d legs , a n d h a v i n g b u r i e d

t h e i r j a w s i n t h e h e a d o r t h o r a x o f t h e p r e y , t h e y d r a w t h e i r l i m b s

b a c k w a r d s o u t o f d a n g e r o f t h e v i c t i m ' s b i t e o r s t i ng . S o m e spec ies

h o w e v e r a re t r u e r o v e r s h u n t i n g b y d a y a n d p a s s i n g t h e n i g h t

w h e r e v e r t h e y h a p p e n t o f i n d t h e m s e l v e s . T h o s e t h a t lie i n wa i t

of ten s h o w a r e m a r k a b l e d e g r e e o f r e s e m b l a n c e to t h e c o l o u r o f

t h e i r b a c k g r o u n d . O n e E a s t I n d i a n spec i e s s p i n s a w h i t e p a t c h o f

silk on t h e u p p e r su r f ace of a leaf. L y i n g on t h i s , i t looks exac t ly

like t h e d r o p p i n g o f s o m e b i r d , a n d s u c h d r o p p i n g s s e e m t o b e

p a r t i c u l a r l y a t t r a c t i v e t o bu t t e r f l i e s ! N o d o u b t , h o w e v e r , p r e d a t i o n

b y b i r d s h a s b e e n a n e v e n m o r e i m p o r t a n t f ac to r i n n a t u r a l

se lec t ion . T h e O x y o p i d a e , s o m e t i m e s ca l led l y n x s p i d e r s , a re

h a n d s o m e h u n t i n g s p i d e r s t h a t h a v e b e c o m e spec ia l i sed for life o n

p l a n t s . T h e y c a n r u n o v e r v e g e t a t i o n w i t h g r e a t agi l i ty a n d leap

f r o m s t e m to s t e m w i t h a p r e c i s i o n s u r p a s s e d o n l y by t h a t o f t r u e

j u m p i n g s p i d e r s . T h e o n l y Br i t i sh e x a m p l e o f t h i s fami ly i s t h e

r a r e Oxyopes heterophthalmus.

S P I D E R S 1 6 5

T h e r e m a i n i n g fami l ies s u c h a s t h e T h e r a p h o s i d a e , D y s d e r i d a e ,

O o n o p i d a e , G n a p h o s i d a e a n d C l u b i o n i d a e c o n t a i n m o s t l y s h o r t ­

s i g h t e d n o c t u r n a l h u n t e r s t h a t d e p e n d u p o n t h e s e n s e o f t o u c h a n d

g r a p p l e w i t h a n y s u i t a b l e in sec t t h e y c o m e ac ross i n t h e i r w a n d e r ­

ings . Harpactea hombergi, a sma l l g r e y spec ies c o m m o n u n d e r ba rk ,

h o l d s i ts v i c t i m s w i t h i ts t a r sa l c laws , w h i l e t h e la rge a n d f o r m i d ­

ab le Dysdera crocota a n d D. erythrina, easi ly r e c o g n i s e d by t h e i r

r e d c e p h a l o t h o r a x a n d y e l l o w a b d o m e n , feed m o s t l y u p o n w o o d l i c e

a n d l u n g e f o r w a r d s o q u i c k l y t h a t few e s c a p e . T h e i r che l i ce rae a re

espec ia l ly a d a p t e d for d e a l i n g w i t h t h i s p r e y ; t h e y a r e excep t iona l l y

la rge a n d p o w e r f u l , a n d b y t i l t i ng t h e p r o s o m a s i d e w a y s o n e fang

FIG. 3 5 . Dysdera sp. eating a woodlouse. (After Bristowe, 1 9 5 4 . )

i s i n t r u d e d b e n e a t h t h e w o o d l o u s e a n d t h e o t h e r a b o v e it . Scoto-

phaeus blackwalli is a m o u s e - c o l o u r e d h o u s e s p i d e r t h a t o f t en falls

in to b a t h s a n d s inks a n d t h e n c a n n o t c l i m b o u t . L i k e m a n y o t h e r

G n a p h o s i d a e a n d C l u b i o n i d a e , i t re l ies u p o n i ts s p e e d for t h e

c a p t u r e of i ts p r e y , w h i l e t h e fe roc ious Drassodes lapidosus, f re­

q u e n t l y f o u n d u n d e r b a r k a n d s t o n e s , i m m o b i l i s e s i ts p r e y b y

s w a t h i n g i t in b a n d s of silk.

P e r h a p s t h e m o s t i n t e r e s t i n g m e t h o d e m p l o y e d i n t h e c a p t u r e

of insec t s is t h a t of t h e r a r e Scytodes thoracica. T h i s s l o w - m o v i n g

ye l low c o l o u r e d spec ies s q u i r t s p o i s o n o u s g u m f r o m its j a w s

wh i l s t on t h e m o v e af ter t h e m a n n e r o f a c r u i s e r t a n k s p r a y i n g

166 S P I D E R S

in fan t ry w i t h m a c h i n e - g u n f i r e . T h e p r e y i s s t u c k f i r m l y t o t h e

g r o u n d w h i l e t h e s p i d e r a d v a n c e s a n d ea t s i t a t l e i sure .

T h e v a r i o u s u s e s o f silk e m p l o y e d b y s p i d e r s i n t h e c a p t u r e o f

p r e y h a v e a l r eady b e e n m e n t i o n e d . T h e C t e n i z i d a e d a r t f r o m t h e i r

t u b e s a n d c a p t u r e in sec t s p a s s i n g n e a r t h e t r a p - d o o r w h i l e t h e

A t y p i d a e s t r ike t h r o u g h t h e i r p u r s e - w e b s a t a n y sma l l a n i m a l

FIG . 36. Scytodes thoracica binding its prey with gum which it squirts from the fangs. (From Cloudsley-Thompson, 1953.)

c r a w l i n g o v e r t h e e x p o s e d p a r t . Segestria senoculata a n d o t h e r

m e m b e r s o f t h e g e n u s m a k e t h e i r t u b e s i n c rev ices o f wal ls a n d

rock faces. T h e r i m o f t h e o p e n e n t r a n c e i s s t r e t c h e d o u t w a r d s

b y half a d o z e n o r m o r e l o n g s t o u t s t r a i g h t t h r e a d s . W h e n a n

insec t o r w o o d l o u s e t o u c h e s o n e o f t h e s e t h e s p i d e r d a r t s f o r th t o

seize a n d r e t i r e w i t h it . A s imi l a r m e t h o d i s e m p l o y e d by t h e

F i l i s t a t i dae , s u c h as t h e w e l l - k n o w n M e d i t e r r a n e a n spec i e s Fili-

stata insidiatrix.

S h e e t - w e b s a re b u i l t b y severa l fami l ies , a n d i n B r i t a i n b y s o m e

of t h e A g e l e n i d a e , L i n y p h i i d a e a n d Pholcus phalangioides ( P h o l -

c idae ) . I n t h e f i r s t fami ly t h e s p i d e r s r u n i n a n e rec t p o s i t i o n o n t h e

u p p e r sur face o f t h e shee t , b u t i n t h e o t h e r t w o t h e y a re s u s p e n d e d

i n a n i n v e r t e d pos i t i on f r o m t h e l ower su r face . Scaffo ld ing w e b s

are cha rac t e r i s t i c of t h e T h e r i d i i d a e . In Stearodea bipunctata, for

e x a m p l e , a shee t o f w i d e m e s h e s i s k e p t t a u t f r om a b o v e a n d b e l o w

b y a n u m b e r o f t h r e a d s e x t e n d i n g ver t i ca l ly t o t h e g r o u n d . T h e s e

h a v e v isc id d r o p l e t s for p a r t o f t h e i r l e n g t h a n d b r e a k off easily

S P I D E R S 167

FIG. 37. Diagrammatic stages in the spinning of an orb-web. (After Savory, 1952.)

F ina l ly , t yp ica l o r b w e b s a r e m a d e b y t h e T e t r a g n a t h i d a e a n d

A r g i o p i d a e . D u r i n g t h e d a y t i m e t h e g a r d e n s p i d e r Araneus dia-

dematus gene ra l l y a b a n d o n s t h e h u b o f i ts w e b a n d re s t s in its

r e t r e a t n e a r b y , b u t t o w a r d s e v e n i n g i t u s u a l l y c o m e s t o t h e c e n t r e

a n d r e m a i n s t h e r e u n t i l ea r ly m o r n i n g w h e n i t c o n s t r u c t s a n e w

w e b . P e t e r s (1933) h a s s h o w n t h a t t h e p r e y i s dea l t w i t h b y m e a n s

of a ser ies of c h a i n reflexes. T h e s t r u g g l e s of a v i c t i m in t h e w e b

a re t h e s t i m u l u s for a l o n g b i t e a n d t h e t a s t e e x p e r i e n c e d s t i m u ­

lates t h e e n s h r o u d i n g o f t h e p r e y . T h e silk b a n d s p r o v i d e a tac t i le

s t i m u l u s for t h e reflex o f t h e s h o r t b i t e , w h i c h in t u r n p r o d u c e s a

s t i m u l u s for t h e c a r r y i n g reflex: smal l insec t s a re ca r r i ed t o t h e h u b

a t t h e i r p o i n t o f a t t a c h m e n t . A s t h e y a r e d r a w n v e r y t a u t , a n

insec t w h i c h b l u n d e r s i n t o o n e n o t on ly b r e a k s t h e a t t a c h m e n t b u t

m a y b e l if ted i n t o t h e a i r w h e r e its s t r u g g l e s b r i n g i t i n t o c o n t a c t

w i t h o t h e r v i sc id t h r e a d s . T h e m e s h e d w e b s o f t h e D i c t y n i d a e a n d

s o m e U l o b o r i d a e w i t h t h e i r t yp ica l c a l a m i s t r a t e d t h r e a d s h a v e

a l r eady b e e n m e n t i o n e d . T h e s e t h r e a d s e n t a n g l e t h e legs o f i n ­

sec ts ve ry s e c u r e l y a n d e n a b l e t h e s p i d e r s t o c a p t u r e p r e y of ten

m u c h l a rge r t h a n t h e m s e l v e s .

168 S P I D E R S

of t h e w e b in t h e che l i ce rae , w h i l e h e a v i e r p r e y a re ca r r i ed on a

t h r e a d f r o m t h e s p i n n e r e t s a n d s u p p o r t e d by a h i n d leg. W h e n a

lifeless i n e d i b l e ob jec t t o u c h e s t h e w e b i t i s u s u a l l y c u t o u t a n d

a l lowed to fall t o t h e g r o u n d , a s a re f o r m i d a b l e a n d d a n g e r o u s

insec t s s u c h a s w a s p s a n d bee s , w h e r e a s su i t ab l e p r e y i s b i t t e n a n d

t h e n w r a p p e d u p . T h e b e h a v i o u r w h i c h fol lows t h e b i t i n g o f a

d i s tas te fu l insec t i s s u r p r i s i n g : t h e s p i d e r m a k e s i ts way , s o m e t i m e s

c lums i ly as i f in d i s t r e s s , to t h e e d g e of i ts w e b w h e r e i t ge t s r id of

t h e d is tas te fu l l i qu id b y p r e s s i n g i ts m o u t h t o t h e g r o u n d o r

w i p i n g it on a leaf.

T h e s e br ie f d e s c r i p t i o n s o f t h e m e t h o d s e m p l o y e d b y s p i d e r s

for t h e c a p t u r e o f p r e y b y n o m e a n s e x h a u s t t h e list o f i n g e n i o u s

m e t h o d s t h a t h a v e a r i s en i n t h e c o u r s e o f e v o l u t i o n . T h e w a t e r

s p i d e r Argyroneta aquatica no l onge r u s e s i ts w e b to e n t r a p i ts

p r e y , b u t h u n t s for smal l a q u a t i c c r e a t u r e s w h i c h a re e a t e n o n d r y

l a n d or in i ts be l l , w h i l e a S o u t h Af r i can s p i d e r b u i l d s a sma l l s n a r e

r e s e m b l i n g a p o s t a g e s t a m p i n s ize a n d s h a p e . T h e c o r n e r s a r e

h e l d b y t h e s p i d e r ' s l o n g legs . W h e n a n in sec t a p p r o a c h e s , t h e w e b

i s s t r e t c h e d to n e a r l y five t i m e s i ts n o r m a l s ize a n d h u r l e d ove r t h e

p r e y . T h e r e can b e few d e v e l o p m e n t s m o r e r e m a r k a b l e h o w e v e r

t h a n t h a t o f c e r t a i n A r g i o p i d a e i n A u s t r a l i a a n d S o u t h Afr ica

(Dicrostichus magnificus a n d Cladomelea akermani) w h i c h e m e r g e

a t n igh t fa l l a n d w h i r l a t h r e a d w e i g h t e d w i t h a g u m m y g l o b u l e

u n t i l t h i s s t r ikes s o m e p a s s i n g in sec t w h i c h i s t h e n h a u l e d in .

Enemies S o far o n l y o n e s ide o f t h e p i c t u r e h a s b e e n c o n s i d e r e d . I n

a d d i t i o n to t h e vas t n u m b e r s ki l led as a r e s u l t o f u n f a v o u r a b l e

c l ima t i c c o n d i t i o n s , s p i d e r s a r e b e s e t w i t h e n e m i e s t h r o u g h o u t

t h e i r l ives. T h e in fan t m o r t a l i t y r a t e i n p a r t i c u l a r i s i m m e n s e .

B a b y s p i d e r s d o n o t feed u n t i l t h e y h a v e d i g e s t e d all t h e yolk w i t h

w h i c h t h e eggs f rom w h i c h t h e y h a t c h e d w e r e s u p p l i e d , b u t af ter

t h e i r first m o u l t t h e l i t t le s p i d e r l i n g s d e v e l o p t h e i r typ ica l c a n n i ­

ba l i s t ic t e n d e n c i e s a n d m a n y a re ea ten b y t h e i r o w n k in . A s

W a r b u r t o n (1912) w r o t e : ' T h e case o f t h e s u r v i v o r o f t h e Nancy

Bell i n t h e B a b Ba l lads w o u l d be e x c e e d i n g l y c o m m o n p l a c e in t h e

a r a n e i d w o r l d . ' I n a d d i t i o n t o t h e n u m b e r s d e v o u r e d b y o t h e r

s p i d e r s , b o t h o f t h e i r o w n as wel l a s o f o t h e r spec ies , s p i d e r s a n d

S P I D E R S 169

the i r eggs a re e a t e n by h o s t s o f d i f ferent k i n d s o f a n i m a l s . In t h i s

c o u n t r y t h e m o s t i m p o r t a n t o f t h e s e a re p r o b a b l y t o a d s a n d frogs ,

s t a r l ings a n d o t h e r i n s e c t i v o r o u s b i r d s , s h r e w s , w a s p s a n d c e n t i ­

p e d e s . I n v e r t e b r a t e e n e m i e s a re v e r y m u c h m o r e n u m e r o u s a n d

p r o b a b l y d e s t r o y l a rge r n u m b e r s o f s p i d e r s t h a n d o v e r t e b r a t e s ,

b u t s p i d e r s e n t e r la rge ly i n t o t h e d ie t o f s m a l l e r b i r d s , b e i n g fed

especia l ly t o t h e n e s t l i n g s . M o r e o v e r , m a n y spec ies o f b i r d s u s e

s p i d e r s ' egg c o c o o n s t o l ine t h e i r ne s t s .

Social w a s p s of ten kill s p i d e r s to feed t h e i r l a rvae , a n d t h e r e a re

t w o B r i t i s h famil ies o f so l i t a ry d i g g e r w a s p s , t h e P o m p i l i d a e a n d

T r y p o x y l i n i d a e , w h i c h h u n t s p i d e r s . T h e s p i d e r s a r e p a r a l y s e d b y

s t ings , o f ten i n t h e p r i n c i p a l n e r v e gang l i a a n d a r e t h e n d r a g g e d t o

p r e v i o u s l y p r e p a r e d cells o r b u r r o w s . Af t e r t h i s t h e w a s p lays a n

egg o n e a c h ca rcass a n d o t h e r p a r a l y s e d s p i d e r s a r e a d d e d be fo re

che b u r r o w i s sea led u p . T h e s e m u s t p r o v i d e e n o u g h food for t h e

wasp g r u b , w h e n i t h a t c h e s , t o last t h r o u g h o u t t h e w h o l e o f its

larval d e v e l o p m e n t , for t h e m o t h e r w a s p n e v e r sees h e r o f f spr ing .

F a b r e , H i n g s t o n a n d o t h e r n a t u r a l i s t s h a v e w r i t t e n g r a p h i c a c ­

c o u n t s o f t h e h a b i t s o f s p i d e r - h u n t i n g w a s p s . Al l k i n d s o f s p i d e r s

a re a t t a c k e d , a l t h o u g h wol f s p i d e r s a r e p e r h a p s t h e m o s t f r e q u e n t

v i c t i m s o f t h e P o m p i l i d a e , a n d i n t h e t r o p i c s e v e n l a rge T h e r a -

p h o s i d a e fall p r e y to t h e s e t e r r i b l e foes. T h e first a c t i on o f o n e o f

t h e s e w a s p s w h e n i t a t t acks a s p i d e r i s to r e m o v e t h e l a t t e r f r o m its

e n v i r o n m e n t , for a g a r d e n s p i d e r i s m u c h m o r e v u l n e r a b l e w h e n

t o r n a w a y f r o m i ts w e b a n d a b u r r o w i n g s p i d e r d r a g g e d i n t o t h e

o p e n i s n e a r l y de fence less . I t h a s b e e n o b s e r v e d , h o w e v e r , t h a t

s p i d e r s a p p e a r c o m p l e t e l y ' p a n i c - s t r i c k e n ' w h e n c o n f r o n t e d b y a

fossorial w a s p . T h e i r i m m e d i a t e r e a c t i o n s e e m s t o b e t o flee, a n d

t h e y d o n o t t r y t o d e f e n d t h e m s e l v e s e v e n w h e n c o r n e r e d .

T h e p a r a s i t e s o f s p i d e r s i n c l u d e P r o t o z o a a n d N e m a t o d a , b u t

t h e r e a re few r e c o r d s i n t h e l i t e r a t u r e . Inf in i te ly m o r e i m p o r t a n t ,

especia l ly in t r op i ca l c l i m a t e s , a r e ' p a r a s i t o i d s ' o r l e tha l pa ra s i t e s ,

p a r t i c u l a r l y o f t h e fami ly I c h n e u m o n i d a e . T h e s e in sec t s p r o b a b l y

p a r a l y s e a s p i d e r by m e a n s o f t h e i r s t i n g be fo re l ay ing an egg on i ts

back . A l t h o u g h t h e m o s t f r e q u e n t v i c t i m s o f s p i d e r pa ra s i t e s a r e

w e b - s p i n n e r s , severa l d i f ferent k i n d s o f h u n t i n g s p i d e r h a v e also

b e e n f o u n d w i t h eggs o r l a rvae o n t h e i r b a c k s . T h e s e la rvae e v e n ­

tua l ly cause t h e d e a t h o f t h e i r v i c t i m by f eed ing on t h e c o n t e n t s o f

170 S P I D E R S

t h e a b d o m e n . B y s o m e e x t r a o r d i n a r y i n s t i n c t t h e v i ta l o r g a n s a r e

n o t e a t e n u n t i l last so t h a t t h e s p i d e r d o e s n o t d ie u n t i l t h e insec t i s

r e a d y t o e m e r g e f r o m t h e n o w e m p t y sk in o f i ts h o s t . T h e A c r o -

c e r i d a e ( D i p t e r a ) a re a f ami ly of flies w h i c h h a v e evo lved s imi la r

pa ra s i t i c h a b i t s a n d m e m b e r s o f severa l o t h e r fly famil ies as wel l a s

t h e P i m p l i n a e a n d C r y p t i n a e ( H y m e n o p t e r a ) a r e pa r a s i t i c o n t h e

eggs o f s p i d e r s . A p p a r e n t l y c r y p t i c c o l o r a t i o n a n d o t h e r p r o t e c t i v e

dev ices a r e o f l i t t le avail aga in s t t h e s e c r e a t u r e s , b u t e v e n so ,

I c h n e u m o n s a n d o t h e r p a r a s i t o i d s a re p r o b a b l y a far less i m p o r t a n t

fac tor i n c o n t r o l l i n g t h e n u m b e r s o f s p i d e r s t h a n t h e y a re i n c o n ­

t ro l l i ng in sec t p o p u l a t i o n .

W i t h so m a n y t e r r i b l e foes i t i s n o t s u r p r i s i n g to f ind t h a t s p i d e r s

h a v e evo lved all k i n d s o f p r o t e c t i v e dev ices , i n c l u d i n g p r i ck ly

sp ine s , u n p l e a s a n t f lavour a n d scen t : s o m e e v e n eject u n p l e a s a n t

f luids t h a t d e t e r p r e d a t o r s . Scytodes thoracica s q u i r t s g u m f r o m its

fangs for de fens ive p u r p o s e s a s wel l a s w h e n i t i s h u n t i n g . M a n y

h u n t i n g s p i d e r s b u i l d s i lken p r o t e c t i v e cells i n w h i c h t h e y r e s t

w h e n n o t in s e a r c h of p r e y . Scotophaeus blackwalli h a s evo lved t h e

h a b i t o f r e t r e a t i n g w i t h a b d o m e n ra i sed , t r a i l i ng b e h i n d i t a r i b b o n

of silk t h a t s e rves as a p r o t e c t i o n aga ins t a t t ack f r o m t h e r e a r .

M a n y s p i d e r s ach i eve c o n c e a l m e n t b y m e a n s o f c r y p t i c co lo ra t ion ,

c losely r e s e m b l i n g t h e i r n a t u r a l b a c k g r o u n d , w h e t h e r t h i s i s a

c o l o u r e d f lower, a leaf, l i chen , s a n d o r b a r k . T h e c r a b s p i d e r s p r o ­

v i d e n u m e r o u s fine e x a m p l e s o f s u c h camouf l age . S o m e t i m e s t h e

o u t l i n e of t h e s p i d e r i s c a m o u f l a g e d by m e a n s of a ' d a z z l e -

p a t t e r n ' , as in t h e case of Salticus scenicus w h o s e i r r e g u l a r p a t c h e s

o f c o n t r a s t e d c o l o u r s t e n d t o d r a w t h e a t t e n t i o n o f t h e o b s e r v e r

f r o m t h e s h a p e t h a t b e a r s t h e m . E g g cases t o o a re f r e q u e n t l y c o n ­

cea led w i t h t w i g s a n d p ieces o f leaf. P o i s o n o u s a n d p o w e r f u l

spec ies m a y s h o w c o n s p i c u o u s co lo ra t i ons , w h i l e all k i n d s o f

p o i s o n o u s a n d d is tas te fu l i n sec t s s u c h a s a n t s , w a s p s , b u g s , bee t l e s

a n d e v e n s c o r p i o n s a r e effectively m i m i c k e d b y v a r i o u s s p i d e r s

(Br i s towe , 1941) .*

F o r e x a m p l e , a m o n g s t t h e A r g i o p i d a e s o m e spec ies o f t h e g e n u s

Cyclosa r e s e m b l e sma l l sna i l s w h i c h , on a c c o u n t o f t h e h a r d n e s s o f

t h e i r she l l s , w o u l d b e e a t e n b y few b i r d s a n d w o u l d ce r t a in ly

b e n e g l e c t e d b o t h b y P o m p i l i d a e a n d I c h n e u m o n i d a e , t h e p r i n c i ­

p a l e n e m i e s o f s p i d e r s . O n e s u c h spec ies h a s b e e n r e c o r d e d f r o m

S P I D E R S 171

C e y l o n , a n o t h e r f r o m N o r t h A m e r i c a . T h e la t te r , w h e n c l i ng ing

to t h e u n d e r s i d e o f a leaf w i t h i ts legs d r a w n u p , i s a l m o s t an exac t

c o p y in c o l o u r a n d s h a p e of a sma l l snai l w h i c h i s a b u n d a n t in

s imi la r s i t u a t i o n s i n t h e s a m e local i ty d u r i n g t h e w a r m m o n t h s o f

t h e yea r . T h e r e s e m b l a n c e i s e n h a n c e d b y t h e c o m p l e t e i m m o ­

bi l i ty t h e s p i d e r m a i n t a i n s w h e n t o r n f r o m i ts h o l d o r w h e n t h e

p l a n t i s r u d e l y s h a k e n .

A p a r t f r o m bee t l e s , t h e in sec t s m o s t f r e q u e n t l y m i m i c k e d b y

s p i d e r s a r e a n t s a n d s o n u m e r o u s a n d pe r f ec t a r e t h e i n s t a n c e s t h a t

all o t h e r e x a m p l e s o f m i m i c r y a m o n g s t s p i d e r s fall i n t o i n s i g n i ­

f icance b e s i d e t h e m . A c o n s t r i c t i o n on e a c h s ide o f t h e s p i d e r ' s

c a r a p a c e d i v i d e s i t i n t o an a n t e r i o r p a r t r e s e m b l i n g t h e h e a d , a

n a r r o w i n t e r m e d i a t e p a r t r e p r e s e n t i n g t h e n e c k a n d a p o s t e r i o r

p a r t r e p r e s e n t i n g t h e t h o r a x o f t h e insec t . I n m a n y cases t h e

a p p e a r a n c e o f s l e n d e r n e s s a b o u t t h e n e c k i s a u g m e n t e d by a s t r i p

o f w h i t e ha i r s o n e a c h s ide o f t h e c o n s t r i c t i o n , w h i c h h a s t h e

op t i ca l effect o f c u t t i n g o u t a n e x t r a p i e c e o f t h e i n t e g u m e n t . T h e

wa i s t o f t h e a n t i s r e p r o d u c e d b y t h e c o n v e r s i o n o f t h e e n d o f t h e

c a r a p a c e a n d of ten o f t h e a n t e r i o r e n d o f t h e a b d o m e n i n t o a

n a r r o w s ta lk . I n s o m e cases t h e a b d o m e n i s i tself sha l l owly c o n ­

s t r i c t e d a n d e v e n t h e a b d o m i n a l s e g m e n t s o f t h e in sec t m a y b e

r e p r e s e n t e d b y t r a n s v e r s e b a n d s o f h a i r s . T h e legs a r e a lways

s l e n d e r , l ike t h o s e o f an an t , a n d o n e o f t h e a n t e r i o r p a i r s i s h e l d

up in f ron t o f t h e h e a d as a s u b s t i t u t e for a n t e n n a e . F ina l l y , i t h a s

b e e n f o u n d t h a t t h e s p i d e r s c a r r y d e c e p t i o n t o t h e e x t e n t o f c o p y ­

ing t h e m a n n e r s a n d ga i t o f t h e i n sec t s (Pocock , 1909) . A s m i g h t

b e e x p e c t e d , a n t - m i m i c r y i s o f m u c h c o m m o n e r o c c u r r e n c e

a m o n g s t g r o u n d - l i v i n g spec ies o f s p i d e r s t h a n i t i s a m o n g s t t h e

s e d e n t a r y w e b s p i n n e r s , b u t i n s t a n c e s a r e n o t u n k n o w n a m o n g s t

t h e l a t t e r . S u c h m i m i c r y r e p r e s e n t s a w o n d e r f u l e x a m p l e o f c o n ­

v e r g e n t e v o l u t i o n a m o n g s t s p i d e r s b e l o n g i n g t o t h e fami l ies

Sa l t i c idae , G n a p h o s i d a e , C l u b i o n i d a e , T h o m i s i d a e , T h e r i d i i d a e ,

A r g i o p i d a e e t c . As i n all cases o f Ba t e s i an m i m i c r y , t h e m i m i c s

exis t i n sma l l n u m b e r s c o m p a r e d w i t h t h e i r m o d e l s .

L i k e s c o r p i o n s a n d Sol i fugae , m a n y o f t h e l a rge r s p i d e r s c a n

s t r i d u l a t e , p r o b a b l y a s a w a r n i n g to e n e m i e s . In t h e case o f s m a l l e r

spec ies i n w h i c h s o u n d - p r o d u c i n g o r g a n s a re conf ined t o t h e

ma l e s , t h e i r f u n c t i o n i s p r o b a b l y t h a t o f c o u r t s h i p . C h r y s a n t h u s

172 S P I D E R S

(1953) h a s r e v i e w e d t h e s u b j e c t o f h e a r i n g a n d s t r i d u l a t i o n i n

s p i d e r s . H e c o n c l u d e s t h a t v i b r a t i o n s o f t h e a i r a re p e r c e i v e d , s o

s p i d e r s m u s t posses s a real facu l ty of h e a r i n g .

I n c o n c l u s i o n , i t s h o u l d be r e m e m b e r e d t h a t o f t h e e n e m i e s o f

s p i d e r s , m a n i s i n t h e f i r s t r a n k n o t o n l y o n a c c o u n t o f t h e n u m b e r s

d e s t r o y e d b y insec t i c ides a n d i n a g r i c u l t u r e , b u t also for t h e n u m ­

b e r s e a t e n b y p r i m i t i v e p e o p l e s i n all p a r t s o f t h e w o r l d . I n S i a m

for e x a m p l e t h e L a o s ea t t w o dif ferent t y p e s , t h e g i a n t o r b w e b b e d

Nephila s p p . a n d t h e la rge h a i r y M y g a l o m o r p h a . T h e f o r m e r a re

k n o w n b y a S i a m e s e n a m e t h a t m e a n s ' t h e g o l d e n o n e ' . W h e n

roas t ed a n d d i p p e d i n salt t h e a b d o m e n , w h i c h i s t h e on ly p a r t

e a t en , h a s a f lavour o f r a w p o t a t o a n d l e t t u c e m i x e d . M y g a l o ­

m o r p h a a re e v e n m o r e h i g h l y p r i z e d : t h e i r che l i ce rae a re p u l l e d

o u t a n d t h e s p i d e r s a re r o a s t e d o n s t icks w h i c h r e m o v e s t h e ha i r ,

a n d t h e n e a t e n w i t h sal t . I n c i d e n t a l l y t h e h a i r s o f t h e s e M y g a l o -

m o r p h s p i d e r s can cause v e r y g r e a t d i s c o m f o r t , a n d i f t h e face i s

t o u c h e d after s t r o k i n g o n e o f t h e s e c r e a t u r e s , s igh t m a y e v e n b e

e n d a n g e r e d . O n t h e o t h e r h a n d t h e b i t e s o f g i a n t b i r d - e a t i n g

M y g a l o m o r p h a a re u sua l l y n o t s e r i o u s . F a r m o r e d a n g e r o u s a re

s o m e o f t h e C t e n i z i d a e , a n d t h e s p i d e r s o f t h e g e n u s Latrodectus

s u c h as L . mactans, t h e n o t o r i o u s ' b l ack w i d o w ' of N o r t h A m e r i c a ,

w h o s e b i t e causes a g o n i s i n g p a i n t h a t d e v e l o p s a n d s p r e a d s w i t h i n

a q u a r t e r o f an h o u r . T h i s i s o f ten a c c o m p a n i e d by p ro fuse swea t i ng ,

difficulty i n b r e a t h i n g , v o m i t i n g , p r o s t r a t i o n , c o n v u l s i o n s a n d n u m ­

e r o u s o t h e r effects. D r o p for d r o p t h e p o i s o n i s sa id t o b e m o r e

v i r u l e n t t h a n t h a t o f t h e r a t t l e snake , b u t t h e a m o u n t in jec ted b y t h e

s p i d e r i s sma l l a n d va r i ab l e : d e a t h h a s o c c u r r e d in a b o u t 5 % of k n o w n

cases o f b i t e s , b u t t h i s f igu re i s p r o b a b l y m i s l e a d i n g a s m a n y cases

are n e v e r r e c o r d e d o r d i a g n o s e d ( T h o r p a n d W o o d s o n , 1945) . T h e

food o f t h e ' b l ack w i d o w ' i n c l u d e s ve ry t o u g h a n d r e s i s t a n t bee t l e s

a n d i t h a s b e e n s u g g e s t e d t h a t t h e v i r u l e n t tox ic i ty o f i t s v e n o m

m a y b e c o r r e l a t e d w i t h t h e t o u g h n a t u r e o f its p r e y .

Mating habits S p i d e r s a re n e a r l y a lways on t h e offensive a n d a re r e a d y to kill

a n d eat m o s t a n i m a l s o f s u i t a b l e size t h a t c o m e w i t h i n r a n g e . T h e y

a re i n v e t e r a t e c a n n i b a l s , so i t i s o b v i o u s t h a t m a t i n g m u s t be a

h a z a r d o u s u n d e r t a k i n g f r a u g h t w i t h real d a n g e r , p a r t i c u l a r l y t o t h e

S P I D E R S 173

m a l e w h o i s u s u a l l y s m a l l e r a n d w e a k e r t h a n h i s i n t e n d e d m a t e .

I n d e e d , h e wil l a l m o s t c e r t a i n l y b e d e v o u r e d u n l e s s h e s u c c e e d s i n

a l l ay ing t e m p o r a r i l y t h e c a r n i v o r o u s i n s t i n c t s o f t h e female , a n d

th i s h e m u s t d o be fo r e h e v e n t u r e s w i t h i n r e a c h o f h e r r a p a c i o u s

j a w s . B r i s t o w e ( 1 9 4 1 , * e tc . ) h a s e m p h a s i s e d t h a t i t i s o f t h e u t m o s t

i m p o r t a n c e t o t h e m a l e t o e s t ab l i sh h i s i d e n t i t y s o t h a t h e i s n o t

t r e a t e d l ike a n insec t v i c t i m , a n d t h e r e a f t e r c o u r t s h i p m u s t p r o ­

ceed u n t i l t h e f ema le h a s b e e n s t i m u l a t e d t o a s t a t e i n w h i c h h e r

sexua l i n s t i n c t s h a v e b e e n a r o u s e d s o t h a t s h e wil l p e r m i t m a t i n g t o

take p l ace . C o n s e q u e n t l y , w h i c h e v e r o f t h e s enses i s t h e o n e o n

w h i c h t h e spec ies chiefly re l ies for t h e c a p t u r e o f i ts p r e y , i s t h e

sense m o s t e m p l o y e d i n c o u r t s h i p . M a l e j u m p i n g s p i d e r s a n d

wolf s p i d e r s m a k e u s e o f v i sua l s igns , s h o r t - s i g h t e d a n d n o c t u r n a l

spec ies o f c o n t a c t s t i m u l i , w e b s p i n n e r s u s e d i s t i n c t i v e t w e a k s a n d

v i b r a t i o n s o f t h e t h r e a d s o f t h e s n a r e , a n d s o on .

T h e m a t i n g p r o c e d u r e o f s p i d e r s i s q u i t e u n i q u e , for w h e n t h e

m a l e r e a c h e s m a t u r i t y he w e a v e s a sma l l p a d of silk on w h i c h a

d r o p o f s p e r m i s d e p o s i t e d a n d t h i s i s s u c k e d u p b y t h e spec ia l ly

mod i f i ed ' p e d i p a l p s ' o r h a n d s w h i c h i n d u e c o u r s e a r e i n s e r t e d

i n to t h e v a g i n a o f t h e f e m a l e . E a c h spec ies h a s a p a l p w i t h i ts o w n

d i s t i nc t i ve s h a p e , a d i a g n o s t i c c h a r a c t e r e s sen t i a l for a c c u r a t e

iden t i f ica t ion .

C o u r t s h i p i s a s u b j e c t o f g r e a t i n t e r e s t a n d i m p o r t a n c e a n d t h e

l i t e r a tu r e o n t h e s u b j e c t i s i m m e n s e .

In T h e r a p h o s i d s p i d e r s s u c h as Dugesiella hentzi, w h e n a r e s t ­

lessly w a n d e r i n g m a l e h a p p e n s t o t o u c h w i t h h i s legs s o m e p a r t o f

t h e b o d y o r leg o f a f emale , he a t o n c e s t o p s s h o r t a n d b e g i n s to

s t r ike i t s i m u l t a n e o u s l y a n d v io l en t ly w i t h h i s a n t e r i o r a n d s o m e ­

t i m e s w i t h all f o u r f ron t feet . T h i s c o n t i n u o u s b e a t i n g w i t h t h e

f ront legs u p o n t h e b o d y o r legs o f t h e f emale c o n s t i t u t e s t h e f i r s t

s t ep i n c o u r t s h i p . A t f i r s t t h e f ema le a s s u m e s a n a t t i t u d e o f de fence ,

b u t af ter a w h i l e s h e r i ses h i g h on h e r h i n d legs w h i l e still h o l d i n g

u p h e r f ron t legs . F i n a l l y s h e o p e n s h e r fangs a n d t h e m a l e c a t c h e s

t h e m w i t h t h e h o o k s o n h i s f ron t legs . H e n o w forc ib ly p u s h e s b a c k

t h e c e p h a l o t h o r a x o f t h e f ema le , a t t h e s a m e t i m e d r u m m i n g o n

h e r s t e r n u m w i t h t h e pa te l l a s o f h i s p e d i p a l p s . M a t i n g las ts o n l y a

m i n u t e o r t w o , af ter w h i c h t h e t w o sexes p a r t , t h e f ema le m a k i n g

n o a t t e m p t t o a t t ack ( P e t r u n k e v i t c h , 1911) .

174 S P I D E R S

W h e n t h e m a l e Atypus affinis f inds t h e t u b e of a female , he

d r u m s u p o n i t w i t h h i s p a l p s a n d p r e s u m a b l y i s ab le t o a sce r t a in

by t h e r e a c t i o n s o f t h e i n m a t e w h e t h e r he i s w e l c o m e . Af te r a

w h i l e h e c u t s o p e n t h e t u b e a n d e n t e r s ; t h e r e n t i s a f t e r w a r d s

r e p a i r e d b y t h e f emale . M a t i n g o c c u r s d e e p i n t h e t u b e a n d t h e

m a l e i s be l i eved t o live i n t h e b u r r o w for m a n y m o n t h s be fo re h i s

m a t e e v e n t u a l l y ea ts h i m .

A m o n g s t s h o r t - s i g h t e d h u n t i n g s p i d e r s t h e m a l e ' s c h e m o t a c t i c

sense o f ten w a r n s h i m of t h e p r e s e n c e o f a f ema le in t h e v ic in i ty .

H e m o v e s w i t h c a u t i o n a n d i n s o m e spec ies v i b r a t e s h i s legs .

Drassodes s p p . t a k e pos se s s ion of t h e i r f emales be fo r e t h e s e h a v e

a t t a i n e d m a t u r i t y o r full s t r e n g t h . S o m e , s u c h as Pachygnatha s p p .

avoid in ju ry b y se iz ing t h e che l i ce rae o f t h e females a n d h o l d i n g

t h e s e w i t h t h e a id o f spec ia l a d a p t a t i o n s , w h i l e o t h e r s s p a r w i t h

t h e i r m a t e s a n d re ly o n t h e i r o u t s t r e t c h e d legs a n d t h e i r agi l i ty t o

avo id i n j u r y f r o m a n y in i t ia l a t t ack r e s u l t i n g f r o m t h e first c o n t a c t .

T h e n o c t u r n a l Dysdera crocota h a s a p l a c i d tac t i le c o u r t s h i p w h i c h

a p p a r e n t l y c a n b e i n i t i a t ed b y e i t h e r sex. O n e s p i d e r a p p r o a c h e s

t h e o t h e r , q u i v e r i n g a n d g e s t i c u l a t i n g w i t h f ron t legs h e l d aloft .

D u r i n g c o p u l a t i o n t h e p a l p s a re i n s e r t e d s i m u l t a n e o u s l y a n d t h e

t w o s p i d e r s s t r o k e a n d ca ress each o t h e r w i t h t h e i r fore legs .

S o m e o f t h e s e d e n t a r y s p i d e r s w i t h in fe r io r eyes igh t s h o w few o f

t h e p r e l i m i n a r y ac t iv i t ies iden t i f i ab le a s t r u e c o u r t s h i p . E v e n

t h o u g h t h e eyes o f s o m e o f t h e T h o m i s i d a e a r e fairly l a rge , t h e

s p i d e r s m a k e l i t t le u s e o f s igh t i n c o u r t i n g . W h e n a m a l e d i s c o v e r s

a f emale o f h i s spec ies he i m m e d i a t e l y c l i m b s u p o n h e r b a c k o r

seizes a n a p p e n d a g e w i t h h i s che l i ce rae . H e i s m o r e agi le a n d c a n

t ick le a n d ca ress h e r b o d y u n t i l h e i s ab le t o a c c o m p l i s h h i s p u r ­

p o s e . T h e m a l e Xysticus s p . p r o t e c t s h i m s e l f i n m a t i n g b y f a s t en ­

i n g h i s m a t e t o t h e g r o u n d w i t h a few s i lken t h r e a d s (Br i s towe ,

1922 , e t c . ) , w h i l e in Pisaura mirabilis ( P i s a u r i d a e ) he c a t c h e s a n d

w r a p s a n insec t i n silk be fo r e a p p r o a c h i n g t h e f emale a n d h a n d s i t

t o h e r a s a p r e l i m i n a r y t o m a t i n g . T h i s b e h a v i o u r i s u n i q u e i n

s p i d e r s b u t h a s a para l le l a m o n g s t E m p i d flies.

T h e v i sua l d i sp l ays o f t h e L y c o s i d a e a n d Sa l t i c idae h a v e b e e n

s t u d i e d especia l ly b y B r i s t o w e a n d L o c k e t ( B r i s t o w e , 1929, 1 9 4 1 , *

e tc . ) , a n d m o r e r e c e n t l y C r a n e (1948 , 1949 , e tc . ) h a s m a d e de ta i l ed

ana lyses o f t h e b e h a v i o u r o f v a r i o u s t r op i ca l Sa l t i c idae s u c h a s

S P I D E R S 175

Corythalia s p p . I n m o s t wol f s p i d e r s t h e p e d i p a l p s a n d f ron t legs

a r e p r o v i d e d w i t h a n o r n a m e n t a t i o n o f h a i r t h a t c o n t r a s t s s h a r p l y

w i t h t h e r e s t o f t h e b o d y . T h e m a l e s t a n d s be fo re t h e f ema le w a v ­

i n g t h e s e s i m u l t a n e o u s l y o r a l t e rna t e ly in a k i n d o f s e m a p h o r e

c o u r t s h i p . O n e spec ies f o u n d o n S t a t e n I s l a n d , A r g e n t i n a , m a k e s a

c u r i o u s p u r r i n g no i se a t m a t i n g t i m e b y d r u m m i n g o n d e a d leaves

w i t h i ts p a l p s . I t i s p r o b a b l e t h a t i n t h i s case t h e female a p p r e c i a t e s

t h e v i b r a t i o n s a t s o m e d i s t a n c e . E v e n m o r e d r a m a t i c a r e t h e c o u r t ­

i n g d a n c e s o f m a l e j u m p i n g s p i d e r s . I n t h e t r o p i c a l spec ies Hasarius

adansoni f o u n d in m a n y h o t h o u s e s in Br i t a in , t h e m a l e i s a h a n d ­

s o m e , s q u a t , g lossy b l ack a n d b r o w n s p i d e r w i t h c o n s p i c u o u s

w h i t e m a r k i n g s o n t h e p e d i p a l p s , a b d o m e n a n d dis ta l l i m b seg­

m e n t s . D u r i n g c o u r t s h i p h e a d v a n c e s s lowly i n z ig - zag fash ion ,

w a v i n g h i s p a l p s u p a n d d o w n . W h e n t h e f emale , w h o i s a s o m b r e

F I G . 38. Hasarius adansoni) the male in courting att i tude. (From Cloudsley-Thompson, 1953.)

b r o w n co lour , t u r n s t o w a r d s h i m h e s t o p s a n d r e m a i n s m o t i o n l e s s

w i t h h i s l a rge fore legs h e l d h o r i z o n t a l l y a b o v e t h e g r o u n d . T h e n h e

m o v e s f o r w a r d aga in . A s h e n e a r s t h e f emale h e m a y j u m p r a p i d l y

s i d e w a y s o r b a c k w a r d s . A g a i n a n d aga in t h i s d i sp l ay c o n t i n u e s

u n t i l a t las t he i s p e r m i t t e d t o i n s e r t first o n e a n d t h e n t h e o t h e r o f

h is p e d i p a l p s , a n d c o p u l a t i o n t akes p lace , t h e p a l p s b e i n g i n s e r t e d

a l t e rna t e ly ( C l o u d s l e y - T h o m p s o n , 1949) .

M o c k , b l o o d l e s s b a t t l e s n o t i n f r e q u e n t l y o c c u r b e t w e e n r ival

m a l e j u m p i n g s p i d e r s . B r i s t o w e (1929) be l i eves t h e s e t o r e su l t f r o m

176 S P I D E R S

m i s t a k e n i d e n t i t y , o n e m a l e b e i n g s t i m u l a t e d sexua l ly b y a n o t h e r

o f t h e s a m e spec ies , b u t C r a n e (1948) r e g a r d s t h e m a s t h r e a t d i s ­

p l a y s a n d s h e h a s s h o w n t h a t i n Corythalia s p p . s u c h b e h a v i o u r i s

d i s t i nc t f r o m c o u r t s h i p . T h e f r inged , i r i d e s c e n t legs a re a lways

u s e d i n t h r e a t d i sp lays , b u t a re n e v e r e m p l o y e d i n c o u r t s h i p .

A m o n g w e b - b u i l d e r s c o u r t s h i p u s u a l l y cons i s t s o f t h e m a l e

t e l e g r a p h i n g to t h e f ema le o c c u p a n t o f a w e b by t w e a k i n g t h e

t h r e a d s as he a p p r o a c h e s , b u t in la te r s t ages a tac t i le s t r o k i n g of t h e

b o d y p r e c e d e s co i t ion . T h i s r o u t i n e m a y c o n s t i t u t e a t ac t i l e d i s ­

p l ay a l m o s t e q u a l i n i n t e r e s t t o t h e v i sua l d i sp l ays o f t h e l o n g ­

s i g h t e d h u n t i n g s p i d e r s .

I n e tho log ica l t e r m i n o l o g y , t h e f u n c t i o n o f c o u r t s h i p i s t o p r o ­

v ide r e l ease r s t i m u l i for t h e m a t i n g i n s t i n c t w h i c h a t t h e s a m e t i m e

b lock h u n g e r d r i v e s . T h e c o n c e p t o f r e c o g n i t i o n m a y n o t i n fact b e

neces sa ry .

P o l y g a m y i s t h e c u s t o m a m o n g s p i d e r s a n d i t i s i n d e e d w i se for

t h e m a l e t o r e t r e a t has t i ly i m m e d i a t e l y c o p u l a t i o n i s f i n i shed . I t i s

p r o b a b l e t h a t t h e m a l e Atypus affinis i s n o t g iven a n y o p p o r t u n i t y

t o e s c a p e f r o m t h e f e m a l e ' s lair , b u t t h e r e i s n o e v i d e n c e t h a t t h e

w i d o w wil l re fuse a d m i t t a n c e to a s u c c e s s i o n o f h u s b a n d s . In c o n ­

t r a s t i t s e e m s p r o b a b l e t h a t Amaurobius ferox f ema le s m a t e on ly

o n c e . O c c a s i o n a l l y t h e sexes a p p e a r t o l ive t o g e t h e r peacefu l ly , b u t

e x p e r i m e n t h a s s h o w n t h a t in t h e case of Meta segmentata t h i s

a p p a r e n t fa i th fu lness i s f i c t i o n a l a n d m a l e s m a y vis i t t h e w e b o f

m o r e t h a n o n e f emale . I n t h i s spec ies t h e m a l e s o f ten kil l o n e

a n o t h e r . S i n c e c o u r t s h i p i s d e f e r r e d u n t i l t h e f emale i s e n g a g e d in

t r u s s i n g a v i c t i m or e a t i n g a m e a l , i t i s n o t u n c o m m o n to see i t

t a k i n g p l ace o v e r t h e d e a d b o d y o f a v a n q u i s h e d r ival ( B r i s t o w e ,

1941) .*

Life history S p i d e r s lay t h e i r eggs i n r e t r e a t s a n d c o c o o n s w h i c h t h e y c o n ­

s t r u c t o f silk a n d of ten m o u n t g u a r d ove r t h e m u n t i l t h e y o u n g

have h a t c h e d . T h e r a p h o s i d a e p r e p a r e g r e a t f labby egg p u r s e s i n

t h e i r b u r r o w s a n d g u a r d t h e m a s s iduous ly , w h i l e t h e de l i ca te

s i lken sacs o f t h e t r a p - d o o r s p i d e r s o f ten h a n g f r o m t h e s ide o f t h e

t u b e . W o l f s p i d e r s ( L y c o s i d a e ) c a r r y t h e i r g l o b u l a r c o c o o n s

a t t a c h e d t o t h e i r s p i n n e r e t s w h e r e v e r t h e y go , a n d af ter h a t c h i n g

S P I D E R S 177

t h e y o u n g c l i m b o n t h e i r m o t h e r ' s b a c k w h e r e t h e y r e m a i n for

severa l d a y s . I n t h e P i s a u r i d a e t h e m o t h e r s p i d e r ca r r i e s h e r c o c o o n

u n d e r h e r s t e r n u m : w h e n t h e y o u n g a re r e a d y t o e m e r g e s h e fixes

i t t o t h e e n d o f a b r a n c h a n d m o u n t s g u a r d ove r it , w h i l e t h e f emale

Pholcus phalangioides g l u e s h e r few e g g s t o g e t h e r l igh t ly a n d ca r r i e s

t h e m a s s i n h e r c h e l i c e r a e . S o m e o f t h e m o s t e l a b o r a t e c o c o o n s a r e

s p u n b y w e b - b u i l d i n g s p i d e r s : t h e sac m a y h a n g f r o m t h e w e b o r

m a y b e fixed t o t h e v e g e t a t i o n n e a r b y .

T h e u s e o f silk t o p r o t e c t t h e eggs w a s p r o b a b l y e v o l v e d ea r ly i n

t h e h i s t o r y o f s p i d e r s a n d m a n y r e f i n e m e n t s h a v e s ince b e e n a d d e d .

T h e c o v e r i n g i s o f t en t o u g h e n e d a n d t h i c k e n e d w i t h severa l l ayers

o f silk a n d m a y b e p l a s t e r e d w i t h l aye r s o f m u d o r e m b e l l i s h e d

w i t h b i t s o f w o o d , leaves a n d o t h e r d e b r i s w h i c h r e n d e r i t i n ­

c o n s p i c u o u s . S o m e s p i d e r s s p i n a se r ies o f egg - sacs w h i c h a r e left

s ing ly h e r e a n d t h e r e , t h u s m i n i m i s i n g t h e r isk o f t h e w h o l e b r o o d

b e i n g pa ra s i t i s ed .

T h e n u m b e r o f eggs la id b y d i f ferent spec i e s va r i e s e n o r m o u s l y .

Theraphosa blondi, t h e l a rges t of all s p i d e r s , is sa id to lay as m a n y

a s 3 ,000 a n d t h e l a rge r o r b - w e a v e r s a n d P i s a u r i d a e m a y p r o d u c e

m o r e t h a n 2 ,000 . W h i l e t h e t i n y Oonops pulcher lays o n l y t w o , t h e

m a j o r i t y o f s p i d e r s p r o b a b l y lay a b o u t 100 eggs , a n d t h o s e p r o d u c ­

i n g m o r e t h a n o n e c o c o o n u s u a l l y lay f ewer eggs i n e a c h . T h e

l a rge r spec i e s t e n d t o lay m o r e eggs t h a n t h e s m a l l e r spec i e s . N o t

o n l y i s t h e r e a n o b v i o u s p h y s i c a l r e l a t i o n s h i p , b u t t h e r e m a y b e a n

ecologica l c o n n e c t i o n b e t w e e n size a n d egg n u m b e r , for b i g s p i d e r s

usua l ly t a k e l o n g e r t o r e a c h m a t u r i t y t h a n t h e s m a l l e r k i n d s .

T h e n u m b e r o f eggs la id i s c lear ly r e l a t e d t o t h e s ize o f t h e

m o t h e r s p i d e r w h e r e d i f ferent spec ies o f t h e s a m e fami ly a r e c o n ­

c e r n e d . P e t e r s e n (1950) , in a d i s c u s s i o n of t h e s igni f icance of t h i s

r e l a t i o n s h i p in t h e e v o l u t i o n of s ize in v a r i o u s spec ies of Lycosa,

c o n c l u d e s t h a t s ince l a rge r s p i d e r s lay m o r e eggs a n d t h e s ize o f t h e

m o t h e r i s to a c e r t a i n e x t e n t i n h e r i t e d , t h e r e m u s t be a se lec t ion

t o w a r d s l a rge r size w h i c h i n n a t u r e i s p r o b a b l y b a l a n c e d b y

efficient c o u n t e r s e l ec t ion . A s imi l a r r e l a t i o n s h i p h a s also b e e n

s h o w n to exis t in Amaurobius ferox a n d A. similis by C l o u d s l e y -

T h o m p s o n (1956) . In A . ferox, a b o u t t h r e e w e e k s e l apse in t h e

s u m m e r af ter egg l ay ing be fo r e t h e y o u n g b e g i n t o leave t h e i r

c o c o o n a n d t h e m o t h e r r e m a i n s i n t h e b r e e d i n g n e s t u n t i l t h e y

M S.S.C.M.

178 S P I D E R S

h a v e d i s p e r s e d . S o m e t i m e s s h e d ies a n d t h e n t h e s p i d e r l i n g s

a p p e a r t o feed o n h e r b o d y be fo r e t h e y leave t h e nes t . I n th i s

spec ies t h e life cyc le o c c u p i e s t w o o r m o r e y e a r s . S p i d e r l i n g s

h a t c h i n g i n t h e s u m m e r r e a c h m a t u r i t y i n t h e a u t u m n o f t h e

fo l lowing y e a r a n d lay t h e i r eggs w h e n t h e y a r e t w o y e a r s o ld .

T h e y m a y live for a n o t h e r s e a s o n o r e v e n l onge r . Af t e r h a t c h i n g , a

p e r i o d o f s o m e d a y s m a y e l apse be fo r e t h e s p i d e r l i n g s sca t t e r ,

d u r i n g w h i c h , a s w e h a v e seen , t h e y ea t l i t t le o r n o t h i n g . B r i s t o w e

(1947) s t a t e s t h a t t h e m o t h e r Theridion sisyphium f eeds h e r y o u n g

f r o m h e r m o u t h . W h i l s t s h e h a n g s d o w n w a r d s , t h e b a b i e s j o s t l e

o n e a n o t h e r t o r e a c h t h e d r o p s o f f luid s h e r e g u r g i t a t e s for t h e i r

benef i t , b u t t h i s m u s t b e af ter t h e first ecdys i s . F o r severa l d a y s t h e

p r o c e d u r e c o n t i n u e s a n d t h e n for s o m e w e e k s a f t e r w a r d s m o t h e r

a n d y o u n g feed s i m u l t a n e o u s l y o n t h e in sec t s s h e c a t c h e s .

T h e n u m b e r o f m o u l t s n e c e s s a r y t o a t t a i n m a t u r i t y va r i e s w i d e l y

i n s p i d e r s . I t h a s b e e n s h o w n t h a t i n m o s t spec i e s , s ize i s t h e d e t e r ­

m i n i n g fac tor : sma l l s p i d e r s m o u l t f o u r o r f i v e t i m e s , t h o s e o f

m e d i u m s ize s e v e n o r e i g h t t i m e s w h i l e s o m e o f t h e T h e r a p h i s o d a e

m a y m o u l t m o r e t h a n t w e n t y t i m e s . E v e n w i t h i n t h e s a m e spec ies

t h e r e i s v a r i a t i o n i n t h e n u m b e r o f e c d y s e s . F o r e x a m p l e , i n

Dolomedes plantarius t h e f ema le m a y m o u l t as few as n i n e or as

m a n y a s t h i r t e e n t i m e s , t h e n u m b e r b e i n g c o r r e l a t e d w i t h s ize a n d

n o u r i s h m e n t .

M o s t s p i d e r s t h a t i n h a b i t t h e t e m p e r a t e z o n e s l ive o n l y o n e yea r ,

b u t t h e m o r e p r i m i t i v e spec i e s t e n d t o l ive l o n g e r . I n t h e m a j o r i t y

o f spec ies t h e life cyc le va r i e s f r o m e igh t m o n t h s t o fou r y e a r s , a n d

t h e r e c o r d for l o n g e v i t y i s h e l d by a T h e r a p h o s i d , Eurypelma s p . ,

w h i c h l ived for t w e n t y y e a r s . T h e m a l e s m a t u r e i n e i g h t o r n i n e

yea r s , a n d u s u a l l y d i e a few m o n t h s la te r .

T h e d i s p e r s a l o f y o u n g s p i d e r s o f m a n y spec i e s i s a c h i e v e d b y

' b a l l o o n i n g ' , a l r e a d y m e n t i o n e d . T h o s e t h a t s u r v i v e t h e r i g o u r s o f

t h e s e p e r i l o u s j o u r n e y s a n d l a n d in a s u i t a b l e e n v i r o n m e n t b e g i n a

life of to i l a n d s l a u g h t e r , of sacrif ice a n d p a r e n t a l ca re w h i c h , for a

sma l l p r o p o r t i o n o f f o r t u n a t e i n d i v i d u a l s , m a y c u l m i n a t e i n t h e

p r o d u c t i o n o f ye t a n o t h e r b a t c h o f b a b y s p i d e r l i n g s .

S P I D E R S

B I B L I O G R A P H Y Identification

BLACKWALL, J. (1861) A History of the Spiders of Great Britain and Ireland 1. London .

(1864) Ibid., 2. BOSENBERG, W. (1901-3) Die Spinnen Deutschlands . Zoologica Stuttgart,

1 4 , 1 - 4 6 5 . BRISTOWE, W. S. (1938) T h e classification of spiders. Proc. Zool. Soc.

Lond., B 1 0 8 , 285-322. BRYANT , E. B. (1940) Cuban spiders in the M u s e u m of Comparative

Zoology. Bull. Mus. Comp. Zool, 8 6 , 249-532. CHECKERING, A. M. (1946) T h e Salticidae (spiders) of Panama. Ibid.,97,

1-248. D A H L , M. (1926) Spinnentiere oder Arachnoidea, 1 : Springspinnen

(Salticidae). Tierw. Deuts, 3 , 1 - 5 5 . (Various other families have been treated subsequently by different authors

u n d e r the general editorship of F. D A H L ) . H O L M , A. (1947) Svensk Spendelfauna Araneae Fam. 8-10. Stockholm. KASTON , B. J. (1948) Spiders of Connecticut . State Geol. Nat. Hist. Surv.

Hartford, 7 0 , 1 - 8 7 4 . LOCKET, G. H. and MILLIDGE , A. F. (1951) British Spiders, 1. London.

(1953) Idem., 2. LOHMANDER , H. (1942) Sudschwedische Spinnen, 1. Gnaphosidae. Medd.

Goteborgs Mus. Zool, 9 8 , 1-163. PETRUNKEVITCH, A. (1933) An inquiry into the natural classification of

spiders, based on a s tudy of their internal anatomy. Trans. Conn. Acad. Arts Sci., 3 1 , 299-389.

et al. (1939) Catalogue of American spiders, Par t 1. Ibid., 3 3 , 133-338.

PICKARD-CAMBRIDGE , O. (1879) The Spiders of Dorset, Part I. Sherbourne. (1881) Ibid., Par t 2.

SIMON , E. (1892-1903) Histoire naturelle des Araignees, 2me ed. Paris. (1914-1937) Arachnides de France, 6 , 1 - 1 2 9 8 .

TULLGREN , A. (1944) Svensk Spindelfauna Araneae, Fam. 1-4. Stockholm. (1946) Ibid., Fam. 5-7.

WIEHLE , H. (1953) Spinnentiere oder Arachnoidea (Araneae) IX. Tierw. Deuts., 4 2 , 1 - 1 5 0 .

Biology

BISHOP , S. C. (1945) Our Lady ' s threads. Trans. Conn. Acad. Arts Sci., 3 6 , 91 -7 .

BRAENDEGAARD, J. (1938) Aeronautic spiders in the Arctic. Medd. om Gronland, 1 1 9 , (5), 1-9.

(1946) T h e spiders (Araneina) of East Greenland. Ibid., 121, (15), 1-128.

180 S P I D E R S

BRISTOWE, W. S. (1922) Spiders found in the neighbourhood of Oxshott Proc. S. Lond. Ent. Soc, 1 9 2 2 , 1 - 1 1 .

—— (1923) A British semi-marine spider. Ann. Mag. Nat. Hist., (9), 1 2 , 154-6.

(1928) Facts and fallacies about spiders. Proc. S. Lond. Ent. Nat. Hist. .Soc, 1 9 2 8 - 9 , 1 2 - 2 3 .

(1929) T h e mating habits of spiders with special reference to the problems surrounding sex dimorphism. Proc. Zool. Soc. Lond., 1 9 2 9 , 309-58.

(1930a) Notes on the biology of spiders. 1. T h e evolution of spiders ' snares. Ann. Mag. Nat. Hist. (10), 6, 334-42.

(1930b) Notes on the biology of spiders, 11.—Aquatic spiders. Ibid., (10), 6, 343-7.

(1932) Insects and other invertebrates for human consumption in Siam. Trans. Ent. Soc. Lond., 8 0 , 387-404.

(1945) Spider superstit ions and folklore. Trans. Conn. Acad. Arts Sci., 3 6 , 53-90.

(1947) A Book of Spiders. London . (1954) T h e chelicerae of spiders. Endeavour, 1 3 , 42-9 .

CLOUDSLEY-THOMPSON , J . L. (1949) Notes on Arachnida, 11. Mat ing habits of Hasarius adansoni Sav. Ent. Mon. Mag., 8 5 , 261-2.

(1953) T h e biology of hunt ing spiders. Discovery, 1 4 , 286-9. (1956) T h e life histories of the British cribellate spiders of the genus

Ciniflo Bl. (Dictynidae). Ann. Mag. Nat. Hist., (12), 8, 787-94. (1957) Studies in diurnal rhy thms, V. Nocturnal ecology and water

relations of the British cribellate spiders of the genus Ciniflo B\.J. Linn.

Soc. (Zool), 4 3 , 1 3 4 - 5 2 .

CRANE , J. (1948) Comparative biology of Salticid spiders at Rancho Grande , Venezuela. Part 1. Systematics and life histories in Corythalia. Zoologica, 3 3 , 1-38.

(1949) Idem. Par t IV. An analysis of display. Ibid., 3 4 , 1 5 9 - 2 1 4 . CHRYSANTHUS , F. (1953) Hearing and stridulation in spiders. Tijdscr. Ent.,

9 6 , 57-83 .

DUFFEY , E. (1956) Aerial dispersal in a known spider population. J. Anim Ecol, 2 5 , 85-114.

MACCOOK , H. C. (1889-94) American Spiders and their Spinningwork, 1 - 3 , Philadelphia.

MILLOT , J. (1943) Les araign6es mangeuses de vertebres. Bull. Soc. zool. Fr., 6 8 , 1 0 - 1 6 .

MOGGRIDGE , J. T. (1873) Harvesting Ants and Trap-door Spiders. London. (1874) Ibid. Supplement .

NEMENZ , H. (1954) Ober den Wasserhoushalt einiger Spinnen, mit besonderer Beriicksichtigung der Transpira t ion. Ost. Zool. Zeits., 5, 123-58.

NIELSEN , E. (1932) The Biology of Spiders, 1, 2. Copenhagen.

S P I D E R S 181

PECKHAM, G. W. and PECKHAM, E. G. (1889) Observations on sexual selection in spiders of the family Attidae. Occ. Pap. Nat. Hist. Soc. Wisc, 1 , 1 - 6 0 .

PETERS, H. (1933) Weitere Untersuchungen uber die Fanghandlung der Kreuzspinne. Z. vergl. Physiol., 1 9 , 47-67 .

PETERSEN, N. (1950) T h e relation between size of mothe r and n u m b e r of young in some spiders and its significance for the evolution of size. Experientia, 6, 96 -8 .

PETRUNKEVITCH, A. (1911) Sense of sight, courtship and mat ing in Dugesiella hentzi (Gerard) , a Theraphos id spider from Texas . Zool. Jahrb. (Syst.), 3 1 , 355-76.

POCOCK, R. I. (1909) Mimicry in spiders. J. Linn. Soc. (Zool), 3 0 , 256-70. SAVORY, T. H. (1952) The Spider's Web. London . THOMAS , M. (1953) Vie et Moeurs des Araignees. Paris. T H O R P , R. W. and WOODSON , W. D. (1945) Black Widow: America's most

Poisonous Spider. Chapel Hill. T I L Q U I N , A. (1942) La Toile geometrique des Araignees. Paris. WARBURTON , C. (1912) Spiders. Cambridge.

[Note: A complete list of spider li terature up to 1939, systematically classified by subject, will be found in the first volume of: P. BONNET (1945) Bibliographia Araneorum. Toulouse.]

C H A P T E R X I

M I T E S A N D T I C K S

O N ACCOUNT o f t h e i r e c o n o m i c a n d m e d i c a l i m p o r t a n c e t h e o r d e r

Acar i w h i c h c o m p r i s e s t h e m i t e s a n d t i cks h a s a t t r a c t e d m o r e

a t t e n t i o n t h a n all t h e o t h e r A r a c h n i d a p u t t o g e t h e r . B e c a u s e o f

t h e i r vas t n u m b e r s , sma l l s ize a n d t h e e n o r m o u s t a x o n o m i c diffi­

cu l t i es i nvo lved , t h e i r s t u d y i s v e r y m u c h a m a t t e r for t h e spec ia l -

FIG. 3 9 . Examples of various kinds of mites: 1. Notostigmata, 2. Dermanyssidae, 3 . Halarachnidae, 4 . Ixodid tick, 5 . Argasid tick, 6 . Demodicidae, 7 . Bdellidae, 8 . Halacaridae, 9 . Hydrach-nidae, 1 0 Thrombidi idae , 1 1 . Tyroglyphidae, 1 2 . Sarcoptidae,

1 3 . Oribatei, 1 4 . Eriophyidae. (From various sources.) 1 8 2

M I T E S A N D T I C K S 183

ist , a n d i n t h i s c h a p t e r o n l y t h e b r i e fes t o u t l i n e o f t h e b io logy o f t h e

g r o u p wil l b e a t t e m p t e d .

Classification and distribution T h e A c a r i d o n o t r e p r e s e n t a n a t u r a l g r o u p , b u t c o m p r i s e

severa l h e t e r o g e n e o u s a n d d i s t i n c t p h y l o g e n e t i c l ines . T h e y a r e

m o s t l y o f s m a l l s ize a n d p o s s e s s four , s ix o r e i g h t legs : u s u a l l y t h e

la rva l s t ages h a v e t h r e e p a i r s , t h e n y m p h a l a n d a d u l t f ou r p a i r s o f

l i m b s . T h e s h a p e o f t h e b o d y va r i e s c o n s i d e r a b l y a n d m a y b e

e l o n g a t e d a n d w o r m - l i k e , s h o r t , r o u n d e d , e l l ip t ica l o r s p h e r i c a l .

T h e m o r e p r i m i t i v e f o r m s s h o w t r a c e s o f s e g m e n t a t i o n w h i c h d i s ­

a p p e a r c o m p l e t e l y i n t h e m o r e a d v a n c e d g r o u p s . S ix s u b - o r d e r s

a re r e c o g n i s e d b y A n d r e (in G r a s s e , 1949)* a n d t h e s e a r e s e p a r a t e d

la rge ly a c c o r d i n g t o t h e p o s i t i o n o f t h e sp i r ac le s . T h e N o t o s t i g -

m a t a i s a s m a l l g r o u p o f p r i m i t i v e m i t e s i n w h i c h t h e s e g m e n t a t i o n

o f t h e b o d y i s m a n i f e s t . T h e m e t a p o d o s o m a cons i s t s o f t w o

s o m i t e s , t h e o p i s t h o s o m a o f n i n e . T h e s e a n i m a l s r e s e m b l e h a r v e s t -

s p i d e r s i n g e n e r a l f o r m b u t a r e b r i g h t l y c o l o u r e d a n d e x h i b i t a

c o m b i n a t i o n o f go ld , b l u e a n d v io le t h u e s u n k n o w n e l s e w h e r e i n

t h e o r d e r . T h e y a r e all r e f e r r e d to a s ing le g e n u s Opilioacarus, t h e

spec ies o f w h i c h a r e f o u n d f ree - l iv ing u n d e r s t o n e s a n d a r e w i d e l y

d i s t r i b u t e d i n E u r o p e , N o r t h Afr ica a n d S o u t h A m e r i c a .

T h e s u b - o r d e r H o l o t h y r o i d e a aga in c o n t a i n s b u t a s ing le g e n u s

o f w i d e d i s t r i b u t i o n f o u n d i n t h e Seyche l l e s , M a u r i t i u s , A u s t r a l i a ,

N e w G u i n e a a n d C e y l o n . A few spec i e s of Holothyrus f o u n d in

P a p u a a r e o f i n t e r e s t b e c a u s e t h e i r s ize , w h i c h m a y r e a c h 7 m m

m a k e s t h e m t h e l a rges t o f all t h e m i t e s , o t h e r t h a n t i cks . T h e i r

s e g m e n t a t i o n i s h i d d e n by a s t r o n g l y c h i t i n i s e d p l a t e w h i c h cove r s

t h e u p p e r su r f ace o f t h e b o d y . T h e N o t o s t i g m a t a a n d H o l o t h y ­

r o i d e a a r e b o t h i n c l u d e d i n t h e s u b - o r d e r O n y c h o p a l p i d a b y

B a k e r a n d W h a r t o n (1952) .

T h e t h i r d s u b - o r d e r , t h e P a r a s i t i f o r m e s , c o n t a i n s a vas t a s s e m ­

b l a g e o f g e n e r a a n d spec ies b o t h f ree - l iv ing a n d p a r a s i t i c o n o t h e r

a n i m a l s a n d p l a n t s . T h e y fall i n t o t w o d i s t i n c t g r o u p s , t h e M e s o ­

s t i g m a t a c o n t a i n i n g t h e s u p e r - f a m i l i e s G a m a s i d e s a n d U r o p o d i n a

a n d t h e I x o d o i d e a o r t i cks , w h i c h i n t u r n a re s u b d i v i d e d i n t o t h r e e

s u p e r - f a m i l i e s , t h e I x o d e i , t h e Nu t t a l l i e l l e i a n d t h e A r g a s i d e s .

F r o m t h e p o i n t o f v i e w o f t h e b io log i s t t h e M e s o s t i g m a t a a r e t h e

184 M I T E S A N D T I C K S

m o r e i n t e r e s t i n g , s i nce t h e r a n g e o f h a b i t a t a n d m o d e o f life i s

m o r e v a r i e d . T h e g r o u p s e e m s t o h a v e b e c o m e a d a p t e d t o d i f ferent

h a b i t a t s w i t h l i t t le r e s u l t i n g c h a n g e i n f u n d a m e n t a l s t r u c t u r e .

T h e t i cks a r e t h e m o s t f ami l i a r o f t h e m i t e s , n o t o n l y o n a c c o u n t

o f t h e i r l a rge s ize, b u t b e c a u s e t h e y a r e o f m e d i c a l a n d v e t e r i n a r y

i m p o r t a n c e . T h e m a j o r i t y o f spec ies a r e i n c l u d e d i n t h e family

I x o d i d a e i n w h i c h a s c u t u m o r sh ie ld i s a lways p r e s e n t . T h e sexes

a re d i s t i nc t : t h e m a l e s feed l i t t le o r n o t a t all, b u t t h e females a n d

i m m a t u r e s t ages i m b i b e l a rge q u a n t i t i e s o f b l o o d s o t h a t t h e s c u t u m

b e c o m e s a m e r e p a t c h o n t h e a n t e r i o r p o r t i o n o f t h e i r g r e a t l y d i s ­

t e n d e d b o d i e s . T h e y t a k e severa l d a y s t o g o r g e t h e m s e l v e s , a n d

e a c h s t a g e feeds o n l y o n c e .

T h e A r g a s i d a e , o n t h e o t h e r h a n d , a r e t i cks w i t h l e a t h e r y i n t e ­

g u m e n t , n o p o r t i o n b e i n g spec ia l ly c h i t i n i s e d t o f o r m a s c u t u m .

W h e n g o r g e d t h e r e i s no e x t r a v a g a n t i n c r e a s e i n s ize a s i n f ema le

I x o d i d a e .

T h e f o u r t h s u b - o r d e r i s t h e T h r o m b i d i f o r m e s o r T r o m b i d i -

f o r m e s w h i c h i n c l u d e s a v e r y d i v e r s e g r o u p o f m i t e s p r o b a b l y

d e r i v e d f r o m m o r e t h a n o n e a n c e s t r a l t y p e . A c o n s i d e r a b l e d e g r e e

o f s e g m e n t a t i o n i s r e t a i n e d in m a n y spec ies o f t h e s u p e r - f a m i l y

T a r s o n e m i n i w h i c h c o n t a i n s a n u m b e r o f i n sec t p a r a s i t e s . T h e

s u p e r - f a m i l y P r o s t i g m a t a c o m p r i s e s a g r o u p k n o w n a s t h e E l e u -

t h e r e n g o n a in w h i c h a re f o u n d a n u m b e r o f p l a n t - f e e d i n g fami l ies ,

o f w h i c h t h e m o s t i m p o r t a n t e c o n o m i c a l l y a r e t h e ' r e d - s p i d e r '

m i t e s o r T e t r a n y c h i d a e , t h e u n i v e r s a l fo l l i c le -mi tes Demodex s p p . ,

t h e fami l ia r Bde l l i dae o r ' s n o u t - m i t e s ' a n d t h e sal t w a t e r H a l a -

ca r idae .

T h e P a r a s i t e n g o n a i s t h e g r o u p o f t h e T h r o m b i d i f o r m e s w h i c h

c o n t a i n s t h e f resh w a t e r m i t e s , s o m e t i m e s k n o w n a s H y d r a c a r i n a .

T h e s e b e l o n g t o a l a rge n u m b e r o f fami l ies s u c h a s t h e H y d r a -

c h n i d a e , L i m n o c h a r i d a e , E y l a i d a e , L i m n e s i i d a e a n d A r r e n u r i d a e ,

e tc . T h e y a r e r e l a t ed t o t h e i r r i t a t i n g h a r v e s t - m i t e s , c h i g g e r s o r

T h r o m b i d i i d a e w h i c h a r e b e c o m i n g i n c r e a s i n g l y i m p o r t a n t m e d i ­

cally a s t h e y h a v e b e e n s h o w n t o t r a n s m i t m a n y f o r m s o f s c r u b -

t y p h u s ( A u d y a n d H a r r i s o n , 1951) .

T h e fifth s u b - o r d e r , t h e S a r c o p t i f o r m e s , i s p r o b a b l y t h e m o s t

spec ia l i sed a n d e x t e r n a l s e g m e n t a t i o n i s r e d u c e d to a m i n i m u m . I t

c o n t a i n s t w o la rge a n d success fu l g r o u p s : t h e A c a r i d i a e w h i c h i n -

M I T E S A N D T I C K S 185

e l u d e s t h e c h e e s e - m i t e s a n d o t h e r T y r o g l y p h i d a e w h i c h a r e o f ten

p e s t s of s t o r e d p r o d u c t s , as wel l as t h e i t c h - m i t e Sarcoptes scabei.

a n d t h e O r i b a t e i o r b e e t l e - m i t e s . G e n e r a l l y s p e a k i n g , t h e A c a r i d i a e

a re soft a n d t h e O r i b a t e i m o r e o r less a r m o u r e d , b u t e x c e p t i o n s

o c c u r i n b o t h g r o u p s .

F ina l ly , t h e T e t r a p o d i l i o r E r i o p h y i d m i t e s a r e a n a b e r r a n t s u b ­

o r d e r o f t h e A c a r i a s t h e y p o s s e s s o n l y t h e f ron t t w o p a i r s o f legs:

t h e t w o p o s t e r i o r p a i r s a r e l ack ing o r r e d u c e d t o fine h a i r s . T h e s e

i n c l u d e t h e g a l l - m i t e s a n d o t h e r p l a n t p a r a s i t e s , all o f w h i c h h a v e

e l o n g a t e d , w o r m - l i k e b o d i e s i n w h i c h t h e o r ig ina l s e g m e n t a t i o n i s

i n d i s t i n g u i s h a b l e , for t h e r i n g - l i k e a p p e a r a n c e o f t h e p o s t e r i o r p a r t

o f t h e b o d y i s o n l y an e p i d e r m a l f e a t u r e . A g e n e r a l c h a r a c t e r i s t i c i s

t h e p o s s e s s i o n o f t w o l o n g s i n u o u s se tae a r i s ing f r o m t h e p o s t e r i o r

p a r t o f t h e b o d y .

T h e A c a r i a r e w i d e l y d i s t r i b u t e d all o v e r t h e w o r l d f r o m t h e

n o r t h o f G r e e n l a n d t o t h e a n t a r c t i c . T e r r e s t r i a l f o r m s o c c u r f r o m

sea level t o t h e m o u n t a i n t o p s , w h i l e m a r i n e a n d f resh w a t e r spec i e s

a re n o t u n c o m m o n . T h e d i s t r i b u t i o n o f p a r a s i t e s a n d c o m m e n s a l s

i s i n t i m a t e l y r e l a t e d w i t h t h a t o f t h e i r h o s t s , b u t e v e n f ree - l iv ing

m i t e s s h o w m a r k e d d e g r e e s o f a d a p t a t i o n t o e n v i r o n m e n t s far

r e m o v e d f r o m t h e i r o r ig ina l b i o t o p e .

General behaviour M i t e s a r e f o u n d e v e r y w h e r e : m a n y a r e p r e s e n t i n d a m p soil a n d

m o s s i n s h a d y p l aces , w h e r e t h e y l ive o n s m a l l fung i , o t h e r s l ive o n

p l a n t s , s u c k i n g t h e s a p a n d s o m e t i m e s c a u s i n g ga l l - l ike t u m o u r s ,

w h i l e st i l l m o r e a r e t h e p r e d a t o r s o r p a r a s i t e s o f i n sec t s , v e r t e ­

b r a t e s a n d o t h e r a n i m a l s . W h e r e a s i n sec t s a r e n u m e r i c a l l y t h e

l e a d i n g g r o u p o f a n i m a l s i n h a b i t i n g a r a b l e soi ls , i n fo res t s t h e i r

p l ace i s t a k e n b y t h e A c a r i w h i c h , i n h u m u s a r e easi ly t h e m o s t

a b u n d a n t i n v e r t e b r a t e s . I t h a s b e e n s h o w n t h a t t h e y c o n s t i t u t e

2 - 3 % o f t h e to t a l w e i g h t o f t h e i n v e r t e b r a t e f a u n a i n D a n i s h b e e c h

w o o d s a n d 5 - 7 % i n s p r u c e w o o d s . T h i s d i f ference , d u e t o vas t

n u m b e r s o f O r i b a t i d m i t e s w h i c h a r e p r ac t i ca l l y l i m i t e d t o h u m u s ,

a p p e a r s t o be a c o n s t a n t o n e .

M a n y m i t e s a r e c a v e r n i c o l o u s , o t h e r s a r e m y r m e c o p h i l o u s : o f

t h e s e s o m e a r e s c a v e n g e r s , o t h e r s ea t t h e a n t s ' food a n d sti l l m o r e

feed o n t h e a n t s t h e m s e l v e s .

186 M I T E S A N D T I C K S

T h e N o t o s t i g m a t a a r e s ec re t ive a n d l ive u n d e r s t o n e s a n d o t h e r

d e b r i s . C h i t i n o u s r e m a i n s o f a r t h r o p o d s h a v e b e e n f o u n d i n t h e i r

g u t s a n d i t i s p r o b a b l e t h a t t h e y a r e p r e d a t o r y , b u t s o few s p e c i ­

m e n s h a v e b e e n co l l ec ted t h a t l i t t le i s y e t k n o w n o f t h e i r b io logy .

T h e h a b i t s a n d life h i s to r i e s o f t h e H o l o t h y r o i d e a t oo a re v i r tua l ly

u n k n o w n . M a n y o f t h e M e s o s t i g m a t a l ive o n p l a n t s a n d p r e y o n

sma l l i n sec t s a n d o t h e r m i t e s . A g r e a t m a n y o f t h e g e n e r a o f

G a m a s i d e s a n d U r o p o d i n a a r e f o u n d i n d a m p p laces , i n m a n u r e

h e a p s a n d a m o n g s t m o s s a n d d a m p leaves , t h e G a m a s i d e s p r e y i n g

o n s m a l l e r c r e a t u r e s . T h e U r o p o d i n a , w h i c h a re s l o w m o v i n g a n d

s lugg i sh , feed o n fungi a n d v e g e t a b l e m a t t e r . T h e m e m b e r s o f t h e

P a r a s i t i d a e , for e x a m p l e , a re f o u n d typ i ca l l y in a c c u m u l a t i o n s o f

o r g a n i c m a t e r i a l s u c h a s r o t t i n g logs a n d l i t te r . O t h e r fami l ies

h o w e v e r , s u c h a s t h e L a e l a p t i d a e , a r e u s u a l l y p a r a s i t i c o n v e r t e ­

b r a t e s a n d to a lesser e x t e n t on i n v e r t e b r a t e s . I n d e e d , t h i s fami ly

i n c l u d e s t h e m o s t c o m m o n e c t o p a r a s i t e s o f m a m m a l s , w h i l e t h e

H a l a r a c h n i d a e l ive i n t h e a i r pa s sages o f m a m m a l s , o n e g e n u s

o c c u r r i n g exc lus ive ly in t h e r e s p i r a t o r y p a s s a g e s o f seals o f t h e

fami ly P h o c i d a e , a n o t h e r p a r a s i t i s i n g t h e o t h e r P i n n i p e d i a .

T i c k s a re c o m p a r a t i v e l y l a rge , l e a t h e r y a n i m a l s w h i c h a re all

pa ra s i t i c o n v e r t e b r a t e s . E v e n t h e larval f o r m s o r ' s eed t i cks ' a r e

v is ib le to t h e n a k e d eye a n d a fully g o r g e d f ema le m a y a t t a i n a

l e n g t h o f ha l f a n i n c h . T h e I x o d i d a e a re o f g r e a t e c o n o m i c a n d m e d i ­

cal i m p o r t a n c e . H e a v y in fe s t a t ion b y t h e s e c r e a t u r e s c a n cause

a n a e m i a i n d o m e s t i c a n i m a l s , a n d t h e y c a r r y severa l n o x i o u s d i s ­

eases t o m a n a n d o t h e r v e r t e b r a t e s . T h u s R o c k y M o u n t a i n s p o t t e d

fever a n d T e x a s fever o f ca t t l e i n A m e r i c a a r e t r a n s m i t t e d b y

Dermacentor andersoni a n d Boophilus annulatus r e spec t ive ly , w h i l e

m a n i s i n fec t ed w i t h R o c k y M o u n t a i n fever , K e n y a t y p h u s , Q

fever a n d T u l a r e m i a b y t h e b i t e s o f v a r i o u s t i cks . T i c k pa ra ly s i s o f

m a n a n d a n i m a l s i s b e l i e v e d t o b e d u e t o t o x i n s s e c r e t e d i n t h e

sal iva o f t h e t i cks . T h o u g h m o r e f r e q u e n t l y o b s e r v e d i n t i ck-

in fes ted a n i m a l s , a n u m b e r o f h u m a n cases h a v e b e e n r e p o r t e d i n

t h e U n i t e d S t a t e s , C a n a d a a n d A u s t r a l i a . T h e a s c e n d i n g pa ra lys i s

i s c a u s e d by a r a p i d l y e n g o r g i n g f ema le t i ck a t t a c h e d to t h e b a s e o f

t h e h e a d w h e r e t h e h a i r m a y h i d e i ts p r e s e n c e for a l o n g p e r i o d .

C o m p l e t e r e c o v e r y fol lows w i t h i n a d a y or t w o of r e m o v a l o f t h e

o f fending pa ra s i t e , b u t d e a t h m a y o c c u r i f t h e pa ra lys i s h a s r e a c h e d

M I T E S A N D T I C K S 187

t h e r e s p i r a t o r y c e n t r e s o f t h e h u m a n o r a n i m a l v i c t i m be fo re t h e

t ick h a s d r o p p e d off o r b e e n r e m o v e d .

T h e ill effects o f t i cks o n t h e i r h o s t s h a v e b e e n r e c o g n i s e d s ince

200 B.C. w h e n M . P o r c i u s C a t o r e f e r r e d t o t r e a t m e n t s w h e r e b y

' t h e r e wi l l b e n o so re s a n d t h e w o o l wi l l b e m o r e p l en t i fu l a n d i n

b e t t e r c o n d i t i o n a n d t h e t i cks ( r ic in i ) wi l l n o t b e t r o u b l e s o m e ' .

Ea r l i e r , A r i s t o t l e in h i s f a m o u s Historia Animalium m a d e s o m e

o b s e r v a t i o n s o n t h e eco logy o f t h e s e e c t o p a r a s i t e s a n d s t a t e d t h a t

t h e ' t ick i s g e n e r a t e d f r o m c o u c h g r a s s ' . H e w a s also a w a r e o f t h e

h a r m t h a t t h e y c a u s e d . D e s p i t e t h e ea r ly r ea l i s a t ion o f t h e fact t h a t

t i cks a r e e c t o p a r a s i t i c o n m a m m a l s , i t w a s n o t u n t i l t h e la te n i n e ­

t e e n t h c e n t u r y t h a t t h e i r ro le i n t h e t r a n s m i s s i o n o f d i sease w a s

first s u s p e c t e d .

T h e c o m m o n s h e e p t i ck i s Ixodes reduvius, f o u n d a lso on ca t t l e

a n d h o r s e s . I t s d i s t r i b u t i o n i n B r i t a i n h a s b e e n s h o w n t o b e i n ­

f luenced b y super f ic ia l soil d e p o s i t s . W h e r e g o o d p a s t u r e o c c u r s

a l o n g s i d e ' i s l a n d s ' o f d a m p g r o u n d , d i s c r e p a n c i e s i n t h e d i s t r i b u ­

t i o n o f t h e t i cks a r e n o t e d . S u c h ' i s l a n d s ' m a y h a r b o u r t i cks w h i l e

t h e r e s t o f t h e p a s t u r e i s free, a n d w h e n ca t t l e m o v e i n t o t h e s e

' i s l a n d s ' t h e y a r e in fes t ed ( A r t h u r , 1952) . M i l n e (1945) h a s s h o w n

t h a t t h e d u r a t i o n o f t h e h u m i d i t y level d u r i n g d a y l i g h t i n c o n j u n c ­

t i o n w i t h t h e t e m p e r a t u r e m a y d e c i d e t h e a m o u n t a n d e x t e n t o f

ac t iv i ty o f t h e s e a n i m a l s i n s u m m e r .

D u r i n g r e c e n t y e a r s c o n s i d e r a b l e a t t e n t i o n h a s b e e n d e v o t e d t o

t h e p h y s i o l o g y a n d b e h a v i o u r o f t i cks . F o r e x a m p l e , L e e s (1947)

ha s s h o w n t h a t t h e y o w e t h e i r r e s i s t a n c e t o d e s i c c a t i o n p r i m a r i l y t o

a super f ic ia l l aye r o f w a x in t h e i n t e g u m e n t : af ter e x p o s u r e to i n ­

c r e a s i n g t e m p e r a t u r e s , w a t e r - l o s s i n c r e a s e s a b r u p t l y a t a c e r t a i n

' c r i t ica l t e m p e r a t u r e ' a s i n i n sec t s . S p e c i e s h a v i n g h i g h e r cr i t ica l

t e m p e r a t u r e s a r e m o r e r e s i s t a n t t o d e s i c c a t i o n a t t e m p e r a t u r e s

w i t h i n t h e b io log ica l r a n g e . A b r o a d c o r r e l a t i o n i s p o s s i b l e b e t w e e n

t h e s e p o w e r s o f r e s i s t a n c e a n d t h e n a t u r a l c h o i c e o f h a b i t a t : A r g a -

s idae infes t d r y , d u s t y s i t u a t i o n s , w h e r e a s I x o d i d a e o c c u p y a w i d e r

va r i e ty o f ecologica l n i c h e s . U n f e d t i cks a r e ab l e t o t a k e u p w a t e r

r a p i d l y t h r o u g h t h e w a x - l a y e r w h e n e x p o s e d t o h i g h h u m i d i t y .

T h i s w a t e r u p t a k e i s d e p e n d e n t o n t h e s e c r e t o r y ac t iv i t i es o f t h e

e p i d e r m a l cells a n d i s c o m p l e t e l y i n h i b i t e d by a b r a s i o n of o n l y a

p a r t o f t h e to t a l cu t i c l e su r face w h i c h s u g g e s t s t h a t t h e cells a re

188 M I T E S A N D T I C K S

func t i ona l l y i n t e r c o n n e c t e d . R e s i s t a n c e t o d e s i c c a t i o n a t low

h u m i d i t i e s i s a c h i e v e d by a d u a l m e c h a n i s m : ac t ive s e c r e t i o n a n d

t h e p h y s i c a l r e t e n t i o n o f w a t e r b y t h e w a x - l a y e r .

T h e u n f e d s h e e p t i ck w h e n a t r es t a d o p t s e i t h e r a q u e s t i n g a t t i ­

t u d e w i t h t h e fore legs e x t e n d e d , o r a n a t t i t u d e o f r e p o s e w i t h t h e

legs fo lded . T h e t i cks r e s p o n d t o g rav i ty , h u m i d i t y , t e m p e r a t u r e ,

sme l l , l i gh t a n d t ac t i l e s t i m u l i . T h e y c l i m b u p w a r d s t o w a r d s t h e

t i p s o f t h e leaves o f t h e g ra s s i n w h i c h t h e y l ive u n t i l t h e y b e c o m e

d e s i c c a t e d w h e n t h e y b e c o m e ac t ive a n d m o v e d o w n w a r d s aga in t o

t h e m o i s t a i r n e a r t h e g r o u n d w h e r e t h e y r e c o v e r t h e i r w a t e r

b a l a n c e b y ac t ive s e c r e t i o n t h r o u g h t h e cu t i c l e : t h e n t h e y c l i m b

u p w a r d s aga in . I f a s u i t a b l e h o s t h a p p e n s t o p a s s t h e y a r e a t t r a c t e d

b y t h e m o i s t u r e a n d s c e n t o f i ts b o d y , a n d t h e v i b r a t i o n s c a u s e d b y

i ts m o v e m e n t s , a n d r e s p o n d b y ac t ive q u e s t i n g . A f t e r f eed ing , t h e

e n g o r g e d t i cks d r o p t o t h e g r o u n d a n d a r e t h e n s t r o n g l y p h o t o -

n e g a t i v e ( L e e s , 1948) .

T h e m a i n s t i m u l u s g o v e r n i n g t h e a s c e n t o f g r a s s b l a d e s b y

l a rvae of t h e A u s t r a l i a n ca t t l e t ick , Boophilus microplus, is pos i t i ve

p h o t o t a x i s t o m o d e r a t e l igh t i n t ens i t i e s : t h e t i cks s h e l t e r f r o m

d i r e c t s u n l i g h t . I n t h e f i e l d t h e y a r e f o u n d t o b e m o r e e x p o s e d i n

t h e ea r ly m o r n i n g w h e n t h e y a r e o f t en a t t h e t o p s o f g r a s s s ta lks .

T h e s t r o n g e s t q u e s t i n g b e h a v i o u r o c c u r s i n r e s p o n s e t o o d o u r s ,

b u t v i b r a t i o n , a i r c u r r e n t s , i n t e r r u p t e d i l l u m i n a t i o n , w a r m t h a n d

m o i s t u r e all p l a y a p a r t i n t h e r e a c t i o n s to t h e h o s t ( W i l k i n s o n ,

1953) .

A r g a s i d t i cks a r e a lso o f c o n s i d e r a b l e e c o n o m i c a n d m e d i c a l

i m p o r t a n c e . T h e y o c c u r o n a w i d e v a r i e t y o f h o s t s i n c l u d i n g r e p ­

t i les , b i r d s a n d m a m m a l s a n d i n h a b i t s s o m e w h a t r e s e m b l e b e d

b u g s . As a r u l e t h e y a r e n o c t u r n a l , f e ed ing m o d e r a t e l y a n d a t f re ­

q u e n t i n t e r v a l s . W h e n fas t ing t h e y a r e flat a n d r e a d i l y c r e e p i n t o

n a r r o w c rev ices . Argas persicus is n o t o n l y a t r o u b l e s o m e d o m e s t i c

p e s t i n s o m e p l aces b u t i t a lso infes t s p o u l t r y all o v e r t h e w o r l d ,

c a u s i n g m u c h d a m a g e b y i ts b i t e s a n d s o m e t i m e s t r a n s m i t t i n g a

s p i r o c h a e t e d i sease . C a t t l e a r e s u s c e p t i b l e t o t h e s p i n o s e ea r t ick

a n d r e l a p s i n g fever i s c o n v e y e d to h u m a n s by t h e n o t o r i o u s Or-

nithodorus moubata.

T h e T h r o m b i d i f o r m e s s h o w a g r e a t d ive r s i t y o f f o r m , life

h i s t o r y a n d b e h a v i o u r a n d b u t a few se l ec t ed e x a m p l e s c a n b e

M I T E S A N D T I C K S 189

m e n t i o n e d . M a n y o f t h e T a r s o n e m i n i a r e pa r a s i t i c o n o t h e r

A r t h r o p o d a a l t h o u g h t h e s u p e r - f a m i l y a lso c o n t a i n s s o m e w e l l -

k n o w n p l a n t p e s t s . T h e fami ly S c u t a c a r i d a e a r e m i n u t e , b i z a r r e

c r e a t u r e s f o u n d i n m o s s a n d soil t h r o u g h o u t t h e w o r l d , a s wel l a s

on a n t s a n d o t h e r i n sec t s . O n e spec ies , Acarapis woodi, infes ts

t h e t r a c h e a l t u b e s o f b e e s c a u s i n g t h e fatal ' I s l e o f W i g h t d i sease '

f o u n d t h r o u g h o u t E u r o p e . T h e m i t e s c a u s e i n j u r y b y i m b i b i n g

t h e h o s t s ' b o d y f l u i d s , a n d b y m e c h a n i c a l l y b l o c k i n g t h e i r t r a c h e a e .

T h e b e h a v i o u r of t h e r e d - l e g g e d e a r t h m i t e Halotydeus destructor

( fami ly E u p o d i d a e ) h a s b e e n i n v e s t i g a t e d e x p e r i m e n t a l l y b y S o l o ­

m o n (1937) i n A u s t r a l i a . T h e d r y s e a s o n i s b r i d g e d ove r b y r e s t i n g

eggs p r o d u c e d i n O c t o b e r . T h e s e eggs a re la id i n g r e a t n u m b e r s o n

t h e su r f ace soil , u n d e r c l o d s o f e a r t h o r s t i cks a n d a r e h i g h l y

r e s i s t a n t t o h e a t , d r o u g h t o r d e s i c c a t i n g w i n d s : m o i s t u r e a n d s u n ­

s h i n e a r e n e c e s s a r y for t h e m t o h a t c h . T h e a d u l t i s a s o f t - b o d i e d

m i t e w h o s e f ron t legs ac t a s s e n s o r y o r g a n s . I t l ives f r o m 25 t o 50

days , p r e f e r s l igh t , w e l l - d r a i n e d soi ls a n d i s k i l l ed b y h e a t a n d

d r o u g h t .

T h e T e t r a n y c h i d a e i n c l u d e t h e w e l l - k n o w n r e d - s p i d e r m i t e s ,

s u c h as Metatetranychus ulmi, w h i c h a r e p r o b a b l y t h e m o s t i m p o r ­

t a n t e c o n o m i c a l l y o f all t h e p l a n t f e e d i n g m i t e s . P o p u l a t i o n s m a y

b u i l d u p t o s u c h f an t a s t i c n u m b e r s i f u n c o n t r o l l e d t h a t t r e e s m a y

b e c o m p l e t e l y de fo l i a t ed a n d k i l l ed . T h e s e m i t e s a r e o f ten b r i g h t l y

c o l o u r e d a n d d o d a m a g e n o t o n l y b y s u c k i n g p l a n t j u i c e s b u t also

b y s p r e a d i n g v i r u s i n f ec t i ons .

T h e foll icle m i t e s , Demodex s p p . , a r e r e s p o n s i b l e for v a r i o u s

sk in d i seases i n m a n a n d a n i m a l s . U s u a l l y t h e g e n e r a l h e a l t h o f t h e

h o s t i s n o t affected, b u t n o d u l e s o r p u s t u l e s a re c a u s e d o n t h e sk in

w h i c h , i n t h e case o f ca t t l e p a r a s i t e s , m a y v a r y i n s ize f r o m t h e

h e a d o f a p i n to t h a t o f a h e n ' s egg . O n e spec i e s c ause s r e d m a n g e

in d o g s , w h i c h i s a c c o m p a n i e d by a foul a n d d i s g u s t i n g o d o u r .

T h e C h e y l e t i d a e , s u c h a s Syringophilus s p p . , a re o f t en f o u n d w i t h i n

t h e qu i l l s o f b i r d s a n d a r e c o r r e s p o n d i n g l y e l o n g a t e d , w h i l e o t h e r s

have s t o u t c l aws w i t h w h i c h t h e y c l ing t o t h e fur o f m a m m a l s . I t

i s p r o b a b l e t h a t t h e y feed o n t h e d e t r i t u s i n s i d e t h e q u i l l s a n d o n

t h e sk in . T h e m a j o r i t y o f t h e fami ly h o w e v e r a r e f r ee - l iv ing p r e ­

d a t o r s a n d h a v e a w o r l d - w i d e d i s t r i b u t i o n .

Bde l l id m i t e s a r e u s u a l l y t o b e f o u n d i n m o s s , l i chen , leaf m o u l d

190 M I T E S A N D T I C K S

a n d d e b r i s , w h e r e v e r t h e r e i s a n a b u n d a n c e o f sma l l i n sec t s a n d

o t h e r m i t e s . T h e y a re p r e d a c e o u s i n h a b i t a n d s o m e spec ies a r e

sa id t o c a p t u r e t h e i r p r e y by s q u i r t i n g on to t h e m a l i q u i d silk

w h i c h e n m e s h e s t h e i r a p p e n d a g e s w h i l e t h e m i t e s u c k s t h e i r b o d y

c o n t e n t s .

A few m i t e s a r e l i t to ra l a n d r u n a b o u t t h e s a n d b e t w e e n t i de s ,

w h i l e o t h e r s , t h e H a l a c a r i d a e , a r e d r e d g e d f r o m t h e sea. N e w e l l

(1947) r e c o r d s a to t a l o f 41 spec ies , s u b - s p e c i e s a n d va r i e t i e s f rom

N o r t h A m e r i c a a n d G r e e n l a n d a n d h a s s t u d i e d t h e i r eco logy . H e

f o u n d t h a t t h e f auna o f t h e s u b - t i d a l z o n e i s m o r e u n i f o r m t h a n

t h a t o f t h e i n t e r - t i d a l z o n e , espec ia l ly f r o m a qua l i t a t i ve s t a n d p o i n t .

T h e r e i s a w e l l - d e v e l o p e d s a n d f auna , a f auna b a s e d u p o n m o l l u s c s

a n d v a r i o u s a lg ico lous f a u n a s , w h i l e h a b i t a t s c h a r a c t e r i s e d b y l o w

sa l in i ty h a v e t h e i r o w n p e c u l i a r m i t e f a u n a c o n t a i n i n g b u t a sma l l

n u m b e r o f spec ies .

N u m e r o u s spec ies a re f o u n d s w i m m i n g i n f resh w a t e r . T h e s e

w a t e r m i t e s c o n s t i t u t e a far f r o m neg l ig ib l e p r o p o r t i o n o f t h e f auna

o f all n o r m a l a n d p e r m a n e n t w a t e r s . Bio logica l ly a n d ecologica l ly

t w o g r o u p s c a n b e d i s t i n g u i s h e d : t h e e u r y t h e r m i c f o r m s w h i c h l ive

m o s t l y i n s t a n d i n g w a t e r s n a t u r a l l y s u b j e c t t o w i d e v a r i a t i o n o f

t e m p e r a t u r e , a n d t h e s t e n o t h e r m i c f o r m s w h i c h dwe l l i n co ld

w a t e r s a n d a r e ab le t o e n d u r e o n l y s l igh t v a r i a t i o n s o f t e m p e r a t u r e .

T h e l a t t e r a re l a rge ly r e s t r i c t e d t o s p r i n g w a t e r s , s t r e a m s a n d o v e r ­

f lowings , b u t i n a d d i t i o n t o t h e t e m p e r a t u r e fac to r g o v e r n i n g t h e

c h o i c e of h a b i t a t , t h e r e is a lso a n e c e s s i t y for fas t - f lowing , r i ch ly

o x y g e n a t e d w a t e r . V i e t s (1940 , e tc . ) h a s s t u d i e d t h e d i s t r i b u t i o n o f

s o m e 2 1 9 spec ies i n E u r o p e a n d h a s d r a w n s o m e e x t r e m e l y i n t e r ­

e s t i n g c o n c l u s i o n s r e g a r d i n g t h e p r o b a b l e p r e -g l ac i a l f a u n a a n d t h e

p o s s i b l e r o u t e s a n d t i m e s o f m i g r a t i o n t h a t t o o k p l a c e af ter t h e ice

age . A b o u t 2 2 0 spec i e s a r e r e p r e s e n t e d i n t h e B r i t i s h f auna , a n d

t h e i r d i s t r i b u t i o n i s o f ten p e c u l i a r . T h e d i s p e r s a l o f m a n y o f t h e m

d e p e n d s u p o n t h e l a rvae a t t a c h i n g t h e m s e l v e s t o t h e b o d i e s o f

v a r i o u s a q u a t i c i n sec t s for t r a n s p o r t .

T h e T h r o m b i d i i d a e a r e e x t r e m e l y n u m e r o u s i n b o t h n u m b e r s a n d

k i n d s . T h e y a r e o f w o r l d - w i d e d i s t r i b u t i o n a n d h a v e b e e n f o u n d

o n eve ry l a n d m a s s e x c e p t t h o s e p e r m a n e n t l y c o v e r e d b y ice a n d

s n o w . T h e y a r e m o r e a b u n d a n t i n t h e t r o p i c s t h a n i n t e m p e r a t e

c l ima te s a n d c o n s t i t u t e a c o n s p i c u o u s p o r t i o n o f t h e m i t e f aunas

M I T E S A N D T I C K S 191

o f o c e a n i c i s l ands . On a d r y , s t o n y p a t h on a s u n n y d a y in t h i s

c o u n t r y , o n e o f ten f ind t h e a d u l t s o f s ca r l e t ve lve ty m i t e s Throm-

bidium s p . r u n n i n g a b o u t a n d f e e d i n g o n s m a l l i n sec t s a n d t h e i r

eggs , w h i l e o t h e r s a r e c o m m o n i n leaf l i t t e r a n d u n d e r b a r k .

M u c h a t t e n t i o n h a s r e c e n t l y b e e n d i r e c t e d t o w a r d t h e b io logy o f

t h e m i n u t e h e x a p o d m i t e s w h i c h for ages h a v e p l a g u e d m a n i n

v a r i o u s p a r t s o f t h e w o r l d , a n d w h i c h a r e k n o w n p o p u l a r l y a s

' h a r v e s t b u g s ' , ' h a r v e s t m i t e s ' , ' b e t e r o u g e ' , ' r o u g e t ' , ' c h i g g e r

m i t e s ' , e t c . G r e a t diff iculty i s u s u a l l y e x p e r i e n c e d i n o b t a i n i n g t h e

c o m p l e t e life h i s t o r y o f t h e s e m i t e s a s t h e l a rvae a l o n e a r e p a r a s i t e s .

J o n e s (1950a) h a s i n v e s t i g a t e d t h e s e n s o r y p h y s i o l o g y o f t h e h a r v e s t

m i t e Thrombicula autumnalis. T h e s e a n i m a l s a r e a t t r a c t e d to l igh t

a n d t o m o i s t a ir : t h e y a r e v e r y s ens i t i ve t o t o u c h b u t n o t t o t e m ­

p e r a t u r e a l t h o u g h a r a n g e e x t e n d i n g f r o m 15° to 26° C a p p e a r s to

be p r e f e r r e d . T h e g r e g a r i o u s h a b i t o f t h e m i t e s i s p r i m a r i l y a

r e s p o n s e t o t h e t o u c h o f e a c h o t h e r s b o d i e s . T h e food o f t h e h a r v e s t

m i t e , Thrombicula autumnalis, c o n s i s t s of t i s s u e , f luid a n d d i s ­

i n t e g r a t e d cel ls o f t h e m a l p i g h i a n l aye r pa r t i a l l y l iquef ied b y t h e

a c t i o n of i n j ec t ed sal iva, a c o n d i t i o n t y p i c a l of e x t r a - i n t e s t i n a l

d i g e s t i o n . T h e p h y s i c a l f ac to rs o f t h e sk in h a v e b e e n s h o w n t o

in f luence t h e c h o i c e o f h a b i t a t u p o n t h e h o s t . O n b i r d s t h e m i t e s

a p p e a r t o f a v o u r t h e a n a l a r e a a n d t h e l a t e ra l s u r f a c e o f t h e b o d y

b e t w e e n t h e w i n g a n d t h e t h i g h ; b u t o n m a n t h e f ac to r s w h i c h

in f luence t h e c h o i c e a r e m o r e v a r i e d , r e g i o n s w h e r e t h e sk in i s t h i n

a n d w h i c h p r o v i d e t h e w a r m t h a n d h u m i d i t y f a v o u r e d b y t h e

l a rvae b e i n g m o s t l ikely t o b e a t t a c k e d ( J o n e s , 1950b ) .

L i k e t h e T h r o m b i d i i d a e , t h e A c a r i d i a e a r e n o t a b l e for t h e e x t e n t

o f t h e i r d i s t r i b u t i o n . T h e y a r e f o u n d i n all t y p e s o f h a b i t a t f r o m

a r c t i c t u n d r a t o t r o p i c a l r a i n fores t a n d w h e r e v e r m a n i n h i s

w a n d e r i n g s h a s t a k e n m i t e s i n h i s food a n d p r o d u c e . O f t h e s p e c i e s

a t t a c k i n g s t o r e d food , Tyroglyphus farinae i s by far t h e m o s t

i m p o r t a n t . I t in fes t s all k i n d s o f f a r i n a c e o u s m a t e r i a l , n o t o n l y

e a t i n g t h e food b u t g i v i n g i t a c u r i o u s m u s t y s m e l l a n d t a s t e so t h a t

i t b e c o m e s unf i t for h u m a n c o n s u m p t i o n . N o t o n l y i s t h i s spec i e s

f o u n d i n w a r e h o u s e s , b u t i t a lso o c c u r s i n t h e n e s t s a n d fu r o f

sma l l r o d e n t s w h i c h ac t a s a n a t u r a l r e s e r v o i r o f t h e m i t e . G r a i n

w h i c h h a s b e c o m e a t t a c k e d b y weev i l s o r d a m a g e d m e c h a n i c a l l y

i s m a d e m o r e r e a d i l y access ib l e t o f lour m i t e s w h i c h a r e t h e n a b l e

192 M I T E S A N D T I C K S

t o p e n e t r a t e t h e p e r i c a r p a n d c o n s u m e t h e e m b r y o . G r a i n t h a t h a s

b e c o m e d a m a g e d b y w a t e r s e e p i n g i n t o t h e h o l d s o f s h i p s i s o f ten

a t t a c k e d b y a n o t h e r g r o u p o f m i t e s r e l a t e d t o t h e f o r m s t h a t a t t ack

f lower b u l b s , p a r t i c u l a r l y in b a d l y - d r a i n e d soil , w h i l e i f t h e g r a i n

b e c o m e s c o m p l e t e l y s a t u r a t e d i t m a y b e in fes ted w i t h v a r i o u s

o t h e r spec ies w h i c h c a n l ive c o m p l e t e l y i m m e r s e d i n w a t e r .

S c a b i e s of m a n i s a c o n d i t i o n p r o d u c e d by t h e i t c h - m i t e Sar-

coptes scabei w h i c h b u r r o w s in t h e sk in w h e r e i t lays i ts eggs , t h e

m i t e c a u s i n g i n t e n s e i t c h i n g a n d i r r i t a t i o n . I n a g g r a v a t e d cases , a n

e x t e n s i v e c r u s t i n g a n d s c a b b i n g r e s u l t s , p a r t i c u l a r l y o v e r t h e h a n d s

a n d a r m s .

O r i b a t i d m i t e s l ive i n m o s s , i n t h e h u m u s o f t h e fores t floor, i n

l i chens g r o w i n g ove r t r e e s t u m p s a n d t r e e s , free o n t w i g s a n d

leaves , i n d e c a y i n g w o o d a n d in t h e s p h a g n u m of m a r s h e s . A few

a r e s l igh t ly a q u a t i c a n d sti l l f ewer a re k n o w n t o i n h a b i t t h e sea.

T h e y a r e f o u n d e v e r y w h e r e t h a t p l a n t s d e c a y w i t h sufficient

m o i s t u r e a n d a r e p e n e t r a t e d b y funga l m y c e l i a ( W i l l m a n , 1931) .

A n u m b e r of spec i e s a r e i m p o r t a n t as v e c t o r s of t a p e - w o r m s of

s h e e p , e t c . A p p a r e n t l y t h e r e i s n o t a x o n o m i c u n i t o f m i t e s t h a t a r e

v e c t o r s ; t h e d e t e r m i n i n g fac to r i s w h i c h spec ies i s d o m i n a n t o n

p a s t u r e a n d l a rge e n o u g h t o b e ab l e t o s w a l l o w t h e eggs o f t h e

w o r m s . O n t h e w h o l e v e r y l i t t le i s k n o w n o f t h e h a b i t s o f t h e

O r i b a t e i a n d t h e r e i s m u c h s c o p e for f u r t h e r w o r k .

T h e c u r i o u s e x c r e s c e n c e s a n d a b n o r m a l g r o w t h s w h i c h o c c u r o n

t h e leaves a n d b u d s o f p l a n t s a r e f ami l i a r t o e v e r y o n e . V a r i o u s

c r e a t u r e s a r e r e s p o n s i b l e for t h e s e d e f o r m i t i e s , m a n y b e i n g t h e

w o r k o f i n sec t s , b u t o t h e r s a re d u e t o m i t e s o f t h e s u b - o r d e r

T e t r a p o d i l i . T h o u g h t h e gal ls c a u s e d b y t h e s e m i t e s a r e of ten

o u t w a r d l y s i m i l a r t o t h o s e o f i n sec t o r ig in , t h e y c a n a t o n c e b e

d i s t i n g u i s h e d on c lose e x a m i n a t i o n . M i t e - g a l l s c o n t a i n a s ing le

c h a m b e r c o m m u n i c a t i n g w i t h t h e e x t e r i o r b y a p o r e w h i c h i s

u s u a l l y g u a r d e d b y h a i r s . T h e m i t e s l ive g r e g a r i o u s l y w i t h i n ,

a p p a r e n t l y f e e d i n g u p o n t h e ha i r s w h i c h g r o w a b u n d a n t l y o n i ts

i n n e r su r face , w h e r e a s in i n sec t -ga l l s e a c h in sec t l a rva l ives in a

s e p a r a t e c losed c h a m b e r .

Food and feeding habits M i t e s l ive p r i n c i p a l l y u p o n f l u i d n u t r i m e n t , a l t h o u g h t h i s m a y

M I T E S A N D T I C K S 193

b e o b t a i n e d f r o m l iv ing a n i m a l s a n d p l a n t s o r f r o m d e c a y i n g

o r g a n i c m a t t e r . S o m e a r e e n t i r e l y p a r a s i t i c u p o n p l a n t s o r o t h e r

a n i m a l s , o t h e r s a t t a c h t h e m s e l v e s t o a n i m a l s i n t h e i r la rva l s t age

b u t a r e free w h e n a d u l t , w h i l e aga in o t h e r s l ive a n e n t i r e l y i n d e ­

p e n d e n t a n d p r e d a c e o u s life. I n t h e p r e d a t o r y f o r m s t h e m a n d i b l e s

a re c h e l a t e a n d m a s t i c a t o r y , b u t i n t h e p a r a s i t i c f o r m s t h e m o u t h

p a r t s a r e m o d i f i e d for s u c k i n g t h e b l o o d o r j u i c e s o f t h e h o s t . T h e

l a rges t a n d sma l l e s t e x a m p l e s o f t h e o r d e r a r e f o u n d a m o n g s t t h e

pa ras i t i c spec i e s .

T h e food a n d f e e d i n g h a b i t s o f m i t e s a r e c lose ly r e l a t e d t o t h e i r

g e n e r a l b e h a v i o u r a n d h a v e a l r e a d y b e e n d i s c u s s e d i n s o m e de ta i l .

S o m e spec ies o f m i t e s r a r e ly o c c u r free l iv ing b u t a r e f o u n d i n

a s soc ia t ion w i t h m a m m a l s : h e r e t h e y feed, n o t o n t h e hos t , b u t o n

o t h e r m i t e s a n d in sec t s l iv ing o n i t . I t c a n r e a d i l y b e i m a g i n e d t h a t

af ter a t i m e , i n s t e a d of l iv ing a b l a m e l e s s ex i s t ence , s o m e of t h e s e

f o u n d a n easy w a y t o o b t a i n food b y s u c k i n g t h e b l o o d o f t h e

a n i m a l o n w h i c h t h e y h a p p e n e d t o f ind t h e m s e l v e s , a n d t h u s

d e v e l o p e d t h e p a r a s i t i c h a b i t . I n t h i s w a y m a n y fami l i es h a v e

b e c o m e e c t o - p a r a s i t i c o n b i r d s a n d m a m m a l s .

T h e m a j o r i t y o f t h e m i t e - b o r n e d i seases o f m a n w e r e o r ig ina l ly

d i seases o f a n i m a l s c lose ly a s soc i a t ed w i t h h u m a n s , s u c h a s

d o m e s t i c r a t s a n d m i c e . A t p r e s e n t s o m e o f t h e s e d i seases , w h i c h

i n c l u d e d e r m a t i t i s , r i cke t t s ios i s , p l a g u e , v a r i o u s t y p h u s a n d o t h e r

fevers , p h t h i r i a s i s , s cab ies a n d g a s t r o - e n t e r i t i s , t e n d t o b e e n ­

c o u n t e r e d on ly in c e r t a i n local i t ies , b u t t h e r e i s a lways a r i sk t h a t

t h e y m a y b e s p r e a d e i t h e r b y t h e i r o r ig ina l a n i m a l h o s t s , o r b y

m a n , s o t h a t n e w foci o f t h e d i sease a r e c r e a t e d . T h i s i m p o r t a n t

sub jec t , s o m e w h a t b e y o n d t h e s c o p e o f t h e p r e s e n t v o l u m e , h a s

r e c e n t l y b e e n r e v i e w e d b y Z u m p t a n d G r a f (1950) t o w h o s e

p u b l i c a t i o n t h e r e a d e r i s r e f e r r e d .

H a l a c a r i d a e a r e e i t h e r p r e d a c e o u s , l i c h e n f eede r s o r a r e p a r a ­

si t ic ( N e w e l l , 1947) . T h e bas i s o f t h e b e h a v i o u r o f f resh w a t e r

m i t e s i s a r a n d o m l o c o m o t o r y ac t iv i ty in s e a r c h of food s u c h as

C r u s t a c e a a n d a q u a t i c i n sec t s w h i c h a re d e t e c t e d b y t o u c h . A

s i m p l e a c t i o n s y s t e m b a s e d o n t h e p r i n c i p l e o f t r i a l a n d e r r o r s e e m s

t o b e c o r r e l a t e d w i t h a s i m p l e m o d e o f life. T h e p r e d a t o r y h a b i t

is o f ten of e c o n o m i c i m p o r t a n c e a n d Cheyletus eruditus is t h e

c o m m o n e s t p r e d a t o r o f T y r o g l y p h i d m i t e s i n s t o r e d p r o d u c t s . N o t

N S.S.C.M.

M I T E S A N D T I C K S

i n f r e q u e n t l y m i t e s a re o f eco log ica l i m p o r t a n c e i n c o n t r o l l i n g t h e

n u m b e r s o f i n sec t s , s p i d e r s a n d o t h e r m i t e s b y e a t i n g t h e i r eggs .

Enemies T h e p r e d a t o r s o f m i t e s i n c l u d e a l a rge n u m b e r o f a r t h r o p o d s ,

i n c l u d i n g o t h e r m i t e s , i n sec t s , s p i d e r s a n d s o on , s o m e o f w h i c h

a p p e a r t o spec ia l i se i n a n a c a r i n e d ie t . T h u s spec ies o f C o n i o p -

t e r y g i d a e ( N e u r o p t e r a ) a p p e a r t o p r e y o n t h e f r u i t - t r e e r e d - s p i d e r

m i t e Metatetranychus ulmi b o t h in t h e la rva l a n d a d u l t s t ages . T h e

l a rvae p i e r c e t h e m i t e s w i t h t h e i r j a w s a n d s u c k o u t t h e c o n t e n t s ,

l eav ing d r y e m p t y sk in s . T h e m i t e eggs a r e a lso s u c k e d d r y , t h e i r

c o m p l e t e l y e m p t y she l l s a l o n e r e m a i n i n g . T h e a d u l t i n sec t s p i ck

u p m i t e s a n d d e v o u r t h e m , b i t e off t h e t o p ha lves o f t h e eggs a n d

r e m o v e t h e c o n t e n t s . W h e n h u n t i n g for food t h e y m o v e q u i c k l y

and a t r a n d o m o v e r a leaf, fee l ing t h e su r f ace w i t h t h e i r p a l p s .

O n t h e w h o l e , d e s p i t e t h i s , m i t e s t e n d t o b e a v o i d e d b y m a n y

p r e d a t o r s a n d t h e i r b r i l l i an t c o l o u r s m a y we l l be a f o r m o f w a r n i n g

co lo ra t i on . I t i s r a r e for s p i d e r s to kill o r ea t m i t e s . A c c o r d i n g to

B r i s t o w e ( 1 9 4 1 ) * t h i s i s i n p a r t d u e t o t h e i r s t r o n g c h i t i n o u s e x o -

ske l e tons , b u t i n t h e m a i n t o d i s t a s t e fu lnes s . T h e O r i b a t e i c o m e

in to t h e f o r m e r c a t e g o r y . T h e y m o v e v e r y s lowly a n d d r a w i n t h e i r

legs a t t h e first a l a r m . I n t h i s w a y t h e y e s c a p e t h e a t t e n t i o n o f m a n y

s p i d e r s a n d m o s t o f t h o s e t h a t d o a t t ack t h e m find i t i m p o s s i b l e t o

p i e r ce t h e i r s t r o n g a r m o u r . O f t h e r e m a i n d e r t h e m a j o r i t y a r e d i s ­

tas te fu l . O f t e n t h e y a r e r e j ec t ed af ter o n e t o u c h a n d a s p i d e r w h i c h

b i t e s a m i t e wi l l n o t i n f r e q u e n t l y r e t i r e t o w i p e i ts m o u t h o n t h e

g r o u n d . S o m e spec ies of Holothyrus p r o d u c e a s e c r e t i o n w h i c h is

p o i s o n o u s t o p o u l t r y .

T h e ed ib i l i t y o f w a t e r m i t e s h a s b e e n i n v e s t i g a t e d b y E l t o n

(1922) a n d C l o u d s l e y - T h o m p s o n (1947) w h o h a v e c o n c l u d e d t h a t

t h e b r i g h t c o l o u r s o f so m a n y spec ies m a y h a v e a s e m a t i c f u n c t i o n

a n d b e c o r r e l a t e d w i t h u n p a l a t a b i l i t y i f n o t d i s t a s t e fu lnes s t o p r e ­

d a t o r s . I t i s q u i t e p r o b a b l e t h a t t h e fact t h a t s o m a n y spec ies a r e

b r i g h t r e d i n c o l o u r a n d c o n s p i c u o u s aga in s t g r e e n v e g e t a t i o n , a s

t h e b e r r i e s o n hol ly , m a y b e t h e r e s u l t o f M u l l e r i a n m i m i c r y — t h e

spec ies t e n d i n g t o r e s e m b l e o n e a n o t h e r s o t h a t n u m e r i c a l losses

i nvo lved i n t e a c h i n g w o u l d - b e p r e d a t o r s t o a v o i d t h e m a r e re ­

d u c e d . T h e c o m m o n c o l o u r faci l i ta tes t h e i m m e d i a t e r e c o g n i t i o n

M I T E S A N D T I C K S 195

o f u n d e s i r a b l e p r e y . T h e p r e d a t o r s i n v e s t i g a t e d i n c l u d e d v a r i o u s

a q u a t i c i n sec t s a n d f ishes, m o s t o f w h i c h r e j ec t ed t h e w a t e r m i t e s ,

b u t s t i ck l ebacks a n d n e w t s a t e t h e m w i t h a lac r i ty . A s u r v e y o f t h e

l i t e r a t u r e r e g a r d i n g t h e s t o m a c h c o n t e n t s o f f ishes a n d i n v e r t e ­

b r a t e p r e d a t o r s h a s s h o w n t h a t w a t e r m i t e s a re s e l d o m e a t e n i n

n a t u r e ( C l o u d s l e y - T h o m p s o n , 1947) a n d m o r e r e c e n t l y i t h a s b e e n

s h o w n by e x p e r i m e n t t h a t n y m p h s of Aeschna grandis l e a r n to

avo id Hydrachna s p p .

T h e i n t e g u m e n t o f m a n y A c a r i i s p r o v i d e d w i t h g l a n d s w h i c h

m a y p r o d u c e d i s t a s t e fu l a n d p o i s o n o u s s e c r e t i o n s a n d t h e s e a re

p a r t i c u l a r l y e v i d e n t a m o n g t h e w a t e r m i t e s . I n a d d i t i o n , m o s t

m i t e s a r e c o v e r e d w i t h h a i r s a n d s e t ae . M a n y o f t h e s e a r e n o d o u b t

s e n s o r y , b u t o t h e r s s e r v e t o p r o t e c t t h e i r o w n e r s f r o m a t t a ck b y

p r e d a t o r s i n t h e s a m e m a n n e r t h a t t h e qu i l l s o f a p o r c u p i n e p r o ­

tec t i t . T h e s h a p e a n d f o r m o f t h e s e s e t ae a r e l eg ion .

I n c o n t r a s t t o m a n y o f t h e A c a r i , s o m e o f t h e t i cks d o n o t a p p e a r

t o b e d i s t a s t e fu l a n d m a y e v e n b e c o l o u r e d s o t h a t t h e y b l e n d

i n c o n s p i c u o u s l y w i t h t h e b o d y o f t h e i r h o s t . I n t h i s w a y t h e y m a y

n o t o n l y e s c a p e t h e a t t e n t i o n s o f t h e h o s t itself, b u t a lso o f t i ck -

b i r d s a n d o t h e r p o t e n t i a l p r e d a t o r s .

T h e e g g s of t h e t i ck Dermacentor andersoni c o n t a i n a t ox i c p r i n ­

c ip le a n d , w h e n i n o c u l a t e d i n q u a n t i t y i n t o e x p e r i m e n t a l a n i m a l s ,

m a y c a u s e d e a t h . I t i s n o t i m p o s s i b l e t h a t t h i s m a y h a v e b e e n

evo lved a s a d e t e r r e n t t o p o s s i b l e p r e d a t o r s . N o d o u b t f u r t h e r

w o r k w o u l d p r o d u c e e v i d e n c e t o s h o w t h a t t h e b r i g h t c o l o u r s o f s o

m a n y m i t e eggs a r e a f o r m o f w a r n i n g a d v e r t i s e m e n t , l ike t h e

c o l o u r s o f t h e i m m a t u r e a n d a d u l t s t ages .

Reproduction and life cycle N e a r l y all m i t e s lay eggs , a l t h o u g h a few of t h e O r i b a t e i a re

o v o v i v i p a r o u s . O c c a s i o n a l l y t h e m o t h e r m a y d ie a t a t i m e w h e n h e r

a b d o m e n c o n t a i n s a few r i p e eggs , a n d t h e s e a r e ab le t o c o m p l e t e

the i r d e v e l o p m e n t i n t e r n a l l y s o t h a t f u l l y - f o r m e d l a rvae e m e r g e

f rom t h e d e a d b o d y o f t h e i r p a r e n t . T h e y o u n g u n d e r g o m e t a ­

m o r p h o s i s v a r y i n g i n c o m p l e t e n e s s i n t h e d i f ferent g r o u p s . A l ­

t o g e t h e r five o r s ix s t ages c a n b e r e c o g n i s e d , b u t t h e y a r e s e l d o m ,

i f ever , all e x h i b i t e d in t h e d e v e l o p m e n t of a s ing le spec i e s . T h e

life h i s t o r y n o r m a l l y cons i s t s o f t h e egg w h i c h , i s s o m e cases i s

1 9 6 M I T E S A N D T I C K S

p a r t h e n o g e n e t i c , a n d h a t c h e s i n t o a s i x - l egged la rva . T h i s passes

t h r o u g h f r o m o n e t o t h r e e n y m p h a l f o r m s be fo r e b e c o m i n g a d u l t ,

e a c h s t age i n t h e life cyc le b e i n g p r e c e d e d by a r e s t i n g p e r i o d . In

m o s t m i t e s t h e l a rvae , e x c e p t for t h e a b s e n c e o f gen i t a l o p e n i n g s

a n d t h e p o s t e r i o r p a i r o f legs , s o m e w h a t r e s e m b l e a d u l t s . I n s o m e

P r o s t i g m a t a , h o w e v e r , t h e y a r e q u i t e d i f ferent a n d m e t a m o r p h o s e

i n t o a n y m p h w h i c h i s m o r e l ike t h e a d u l t i n f o r m . I n t h e a c c o u n t

g i v e n b e l o w a few typ i ca l e x a m p l e s of life h i s t o r i e s wil l be g iven .

FIG. 4 0 . Stages in the development of an Oribatid mite (Pelops sp.): 1 . egg, 2 . larva, 3 . nymph , 4 . adult. (After Michael, 1 8 8 4 . )

T h e life h i s t o r y a n d s e n s o r y b e h a v i o u r o f t h e M e s o s t i g m a t i d

s n a k e m i t e Ophionyssns natricis h a s r e c e n t l y b e e n i n v e s t i g a t e d by

C a m i n (1953) w h o f o u n d t h a t d e v e l o p m e n t o f t h e eggs t akes f r o m

28 to 98 h o u r s ; l a rvae 18 to 47 h o u r s , p r o t o n y m p h s 3 to 14 days ,

d e u t o n y m p h s 1 3 t o 2 6 h o u r s a n d a d u l t s 1 0 t o 3 2 d a y s w i t h i n t h e

r a n g e o f t e m p e r a t u r e s 20° t o 30° C , c o m m o n l y o c c u r r i n g i n s n a k e

cages i n zoos . T h e a d u l t f ema le m i t e , a f ter c o m p l e t i n g e n g o r g e ­

m e n t , c r awl s o u t f r o m u n d e r t h e sca le o f t h e h o s t , d r o p s f r o m t h e

s n a k e ' s b o d y a n d w a n d e r s a b o u t u n t i l i t f inds s o m e d a r k m o i s t

c r ev ice w h e r e o v i p o s i t i o n t akes p l a c e . T h e e m e r g i n g l a rvae r e m a i n

i n t h e m o i s t r e g i o n w h e r e t h e r e i s l i t t le r i sk o f d e s i c c a t i o n a n d t h e

p r o t o n y m p h s s t ay t h e r e t o o u n t i l t h e i r i n t e g u m e n t b e c o m e s

sc l e ro t i s ed a n d t h e d a n g e r o f d e a t h f r o m w a t e r - l o s s i s l e s sened .

T h e n t h e y w a n d e r a t r a n d o m u n t i l t h e y c o m e u p o n a s u i t a b l e hos t ,

b e c o m e c o n c e a l e d u n d e r a sca le a n d c o m m e n c e f eed ing . If, on t h e

M I T E S A N D T I C K S 197

o t h e r h a n d , a m i t e fails to m e e t w i t h a s u i t a b l e h o s t i t c l i m b s to t h e

t o p of s o m e ob jec t s u c h as a r ock or t h e t i p of a b r a n c h w h e r e i t

c o m e s t o r e s t w i t h o t h e r n y m p h s . I f a s n a k e h a p p e n s t o c r awl ove r

a c l u m p o f t h e s e r e s t i n g m i t e s , t h e y b e c o m e ac t ive a n d c l i m b o n t o

t h e s n a k e a n d c o n c e a l t h e m s e l v e s b e n e a t h i ts sca les . Af t e r f e ed ing

t o e n g o r g e m e n t , t h e p r o t o n y m p h s d r o p off a n d c r awl a b o u t u n t i l

t h e y f ind a d a r k , m o i s t c r ev ice . H e r e m a l e s a n d f emales s o m e t i m e s

p a i r off a n d r e m a i n p a i r e d u n t i l t h e y r e a c h m a t u r i t y . E c d y s i s

fo l lows s o o n af ter r e p l e t i o n a n d t h e n e w l y m o u l t e d d e u t o n y m p h s ,

a l t h o u g h ac t ive , u s u a l l y r e m a i n i n t h e h u m i d a rea u n t i l t h e n e x t

ecdys i s . T h e d e u t o n y m p h m a l e s a n d f ema les u s u a l l y p a i r i f t h i s

h a s n o t o c c u r r e d i n t h e p r e v i o u s s t age . Af t e r m o u l t i n g t o t h e a d u l t

s t age , t h e m i t e s r e m a i n i n t h e m o i s t c rev ices u n t i l t h e i r i n t e g u ­

m e n t h a s h a r d e n e d a n d t h e n b e g i n t o w a n d e r a b o u t u n t i l t h e y

c o m e i n c o n t a c t w i t h a s u i t a b l e h o s t , t o w h i c h t h e y r e s p o n d b y

t h e i r r e a c t i o n s t o g r av i ty , t e m p e r a t u r e a n d o d o u r . M a l e m i t e s wil l

c o p u l a t e af ter f e e d i n g b u t a r e n o t a t t r a c t e d b y r e p l e t e f emales .

T h e s e u n f e c u n d e d f ema les lay eggs w h i c h d e v e l o p p a r t h e n o -

gene t i ca l ly i n t o m a l e s . F e m a l e s n o r m a l l y lay f r o m 6 0 t o 8 0 eggs ,

f e ed ing t w o o r t h r e e t i m e s a t i n t e r v a l s o f o n e o r t w o w e e k s .

T h e b l o o d - s u c k i n g m i t e s o f t h e g e n u s Haemolaelaps a r e m a m m a l

a n d b i r d p a r a s i t e s a n d s e e m t o s h o w a p r e f e r e n c e for r o d e n t s . T h e y

a re p r o b a b l y o v o v i v i p a r o u s a n d g ive b i r t h t o t h e first n y m p h a l

f o r m . A s i n m o s t p a r a s i t i c m i t e s t h e m a l e s p r o b a b l y d o n o t feed o n

t h e b l o o d o f t h e h o s t , b u t h a e m o g l o b i n h a s b e e n d e m o n s t r a t e d i n

b o t h p r o t o - a n d d e u t o n y m p h s w h i c h leave t h e h o s t i m m e d i a t e l y

af ter f e e d i n g a n d m o u l t i n t h e nes t .

T i c k s a r e p a r a s i t i c d u r i n g t h e g r e a t e r p a r t o f t h e i r l ives, b u t all

leave t h e h o s t i n o r d e r t o d e p o s i t t h e i r eggs . T h e s e a r e laid o n t h e

g r o u n d i n e n o r m o u s n u m b e r s a n d h a t c h i n t o s i x - l egged l a rvae .

T h e y o u n g t i cks r e m a i n c l u s t e r e d t o g e t h e r for s eve ra l d a y s b u t

t h e n c l i m b t h e n e a r e s t b l a d e o f g r a s s a n d a w a i t t h e c o m i n g o f t h e i r

hos t . M a n y d ie i n t h e a t t e m p t , b u t s o m e s u c c e e d i n a t t a c h i n g t h e m ­

selves t o a p a s s i n g a n i m a l a n d p r o c e e d to g o r g e t h e m s e l v e s w i t h

b l o o d . Af t e r f e ed ing for a few d a y s t h e l a rvae d r o p off, seek a h i d i n g

p lace a n d m o u l t i n t o n y m p h s w h i c h b e h a v e i n m u c h t h e s a m e w a y .

T h e a d u l t s t age i s r e a c h e d af ter o n e m o r e m o u l t .

L e e s a n d B e a m e n t (1948) h a v e s h o w n t h a t ' t h e egg o f t h e s h e e p t ick

198 M I T E S A N D T I C K S

Ixodes reduvius i s w a t e r - p r o o f e d by an e x t e r n a l c o v e r i n g of w a x

w h i c h i s s e c r e t e d b y t h e f ema le af ter t h e she l l l ayers a r e c o m p l e t e .

T h i s w a x y c o v e r i n g i s f i r s t s m e a r e d o v e r t h e e g g a s i t pa s se s d o w n

t h e v a g i n a a n d a f u r t h e r l aye r o f l i po id i s a p p l i e d w h e n t h e egg

t o u c h e s G e n e ' s o r g a n , a g l a n d u l a r s t r u c t u r e t h a t i s e v e r t e d s h o r t l y

be fo r e o v i p o s i t i o n . In Ornithodorus moubata t h e w a x is a p p l i e d

sole ly b y G e n e ' s o r g a n : t h i s d i f ference m a y b e r e l a t e d t o t h e size

o f t h e egg w h i c h i s re la t ive ly s m a l l i n t h e I x o d o i d e a . T h e w a x i s

p r o b a b l y s e c r e t e d t h r o u g h p o r e c a n a l s d i s t r i b u t e d o v e r a n a r r o w

z o n e o f cu t i c l e b e t w e e n t h e h o r n s o f t h e o r g a n , a n d t h e c e m e n t

c o v e r i n g layer o f t h e e p i c u t i c l e d o e s n o t e x t e n d t o t h i s z o n e .

S e x u a l d i m o r p h i s m i s r a r e i n T h r o m b i d i f o r m m i t e s a l t h o u g h i t

d o e s o c c u r i n s o m e g e n e r a o f w a t e r m i t e s , s o m e t i m e s e v e n affect­

i n g t h e n y m p h s . I t i s also t o b e f o u n d i n t h e T a r s o n e m i n i a n d i n

t h e g e n u s Tenuipalpus o f t h e T e t r a n y c h i d a e a n d s o m e few o t h e r s .

I t i s t h e r e f o r e o f i n t e r e s t t h a t T u r k a n d P h i l l i p s (1946) f o u n d

r u d i m e n t a r y sexua l d i m o r p h i s m in t h e s lug m i t e Riccardoella

limacum ( fami ly E r e y n e t i d a e ) , a spec ies in w h i c h t h e a d u l t s t age is

d i s a p p e a r i n g . T h e f ema le d e u t o n y m p h p r o d u c e s t h e eggs w h i c h

a re c a p a b l e o f fe r t i l i sa t ion , b u t w h e t h e r t h e l a r g e r a d u l t f ema le also

lays eggs i s u n d e c i d e d . T h e eggs m a t u r e i n t h e i r o w n oocys t s a n d

s o m e a t leas t a r e fer t i l i sed i n t h e o v a r y . C o p u l a t i o n t akes p l ace o n

t h e h o s t a n d i s p r o b a b l y con f ined t o t h e ea r ly s u m m e r , t h e on ly

t i m e a t w h i c h a d u l t m a l e s a r e f o u n d . T h e eggs a r e c o m m o n l y la id i n

t h e m a n t l e cav i ty o f t h e hos t , b u t m a y s o m e t i m e s b e f o u n d e m ­

b e d d e d i n m u c u s o n t h e sk in . V i v i p a r i t y a n d o v i p a r i t y exis t s ide b y

s ide a n d s e e m i n g l y n o t all i n d i v i d u a l s r e t a i n an egg o f r e t a r d e d

d e v e l o p m e n t ove r t h e w i n t e r , w h i l e s o m e o v e r - w i n t e r i n g la rvae

r e m a i n i n t h e d r y sk in o f t h e f emale .

I n t h e Bde l l i dae t h e sexes a re v e r y s imi la r . T h e eggs a r e s l igh t ly

e l l ip t ica l a n d a r e c o v e r e d w i t h c lava te s p i n e s a n d p r o j e c t i o n s . T h e y

a re la id o n t h e soil , i n leaf m o u l d o r w h e r e v e r t h e m i t e h a p p e n s t o

b e a n d h a t c h i n t o a typ ica l s ix - l egged larva w h i c h d e v e l o p s t h r o u g h

t h r e e n y m p h a l s t ages t o t h e a d u l t .

T h e life cycles o f t h e r e d - s p i d e r m i t e s a r e c o m p a r a t i v e l y wel l

k n o w n . T h e w i n t e r i s p a s s e d a s eggs w h i c h a re d e p o s i t e d o n

b r a n c h e s a n d tw igs a n d a r e b r i g h t r e d i n co lou r . T h e y h a t c h i n

s p r i n g t o a la rva w h i c h passes t h r o u g h v a r i o u s n y m p h a l s tages t o

M I T E S A N D T I C K S 199

t h e a d u l t . D u r i n g c o p u l a t i o n t h e m a l e c r awl s u n d e r t h e female

f rom t h e r e a r a n d c lasps h i s f ron t legs a b o u t h e r a b d o m e n a n d h is

s e c o n d p a i r o f legs a b o u t h e r h i n d legs . H e t h e n c u r v e s t h e e n d o f

his a b d o m e n u p w a r d a n d f o r w a r d u n t i l i t m e e t s t h e e n d o f t h e

female ' s a b d o m e n . C o p u l a t i o n las ts f r o m t e n t o f i f t e e n m i n u t e s .

E g g s a re la id w i t h i n a d a y o r t w o d a y s o f e m e r g e n c e in h o t w e a t h e r :

t h e s e s u m m e r eggs d o n o t s h o w d i a p a u s e a n d h a t c h i n a b o u t e igh t

t o t e n days . T h e n u m b e r o f g e n e r a t i o n s i n a y e a r d e p e n d s o n

c l i m a t e a n d l a t i t u d e . O v e r - w i n t e r i n g , d i a p a u s i n g eggs a r e laid

t o w a r d s t h e a u t u m n , t h e i r p r o d u c t i o n b e i n g e n g e n d e r e d b y t h e

d e c r e a s i n g l e n g t h o f d a y l i g h t u n t i l co ld w e a t h e r kil ls t h e a d u l t

m i t e s o r causes t h e leaves on w h i c h t h e y a re f eed ing t o fall ( L e e s ,

1955) .

T h e c o n d i t i o n s o f t h e m i c r o - e n v i r o n m e n t u n d e r w h i c h m a n y

pa ras i t i c m i t e s c a n m u l t i p l y a re o f t en l i m i t e d . T h u s 12° to 14° C

r e p r e s e n t s t h e lowes t t e m p e r a t u r e a t w h i c h Liponyssus bacoti c a n

r e p r o d u c e a n d t h e n o n l y w i t h a g r e a t l e n g t h e n i n g o f t h e cyc l e a n d

a n i nc r ea se i n m o r t a l i t y , a n d m a n y o t h e r spec ies t h a t n o r m a l l y feed

o n t h e b o d y o f t h e i r h o s t w h e r e t h e y a re p r o t e c t e d f r o m t h e co ld

a re r e s t r i c t e d in a s imi l a r way .

M o s t o f t h e C h e y l e t i d a e a n d D e m o d i c i d a e d e v e l o p n o r m a l l y

f ro m egg, la rva l a n d n y m p h a l s t ages t o t h e a d u l t , b u t i n t h e w a t e r

m i t e s o n l y t h r e e s t ages a r e n o t e d s u b s e q u e n t l y t o t h e egg, v iz . t h e

larva, n y m p h a n d a d u l t o r p r o s o p o n , b e t w e e n e a c h o f w h i c h m e t a ­

m o r p h o s i s t akes p l a c e . T h e eggs a r e u s u a l l y r e d d i s h i n c o l o u r a n d

laid on a q u a t i c v e g e t a t i o n o r s t o n e s t o w h i c h t h e y a r e f i xed by a

m u c i l a g i n o u s c o v e r i n g . I n t h e g e n u s Hydrachna, t h e eggs a r e p l a c e d

in cavi t ies p i e r c e d in t h e s t e m s o f a q u a t i c p l a n t s for t h e i r r e c e p t i o n .

T h e la rva l a n d n y m p h a l s t ages a r e u s u a l l y pa r a s i t i c o n a q u a t i c

insec t s a n d a r e s e p a r a t e d b y r e s t i n g s t ages w h e n t h e c r e a t u r e s a re

c o n c e a l e d i n t h e axi ls o f leaves o r u n d e r s t o n e s . T h e a d u l t s a re free

l iv ing . F o r f u r t h e r de ta i l s , see S o a r a n d W i l l i a m s o n ( 1 9 2 5 , 1927,

1929) .

T h e life cyc le o f t h e A c a r i d i a e i s s imi l a r t o t h a t o f o t h e r m i t e s ,

p a s s i n g a s i t d o e s t h r o u g h t h a t o f egg , h e x a p o d la rva a n d t w o

n y m p h a l s t ages be fo r e b e c o m i n g a d u l t . I n s o m e cases , h o w e v e r ,

a n a d d i t i o n a l h e t e r o m o r p h i c s t a g e i s i n t r o d u c e d i n t o t h e life

h i s to ry b e t w e e n t h e t w o n y m p h a l s t ages . T h i s i s k n o w n a s t h e

200 M I T E S A N D T I C K S

hypopus a n d differs c o m p l e t e l y f r o m all t h e o t h e r s . I n s t e a d of

h a v i n g a f lexible cu t i c l e i t is we l l c h i t i n i s e d a n d d e v o i d of a m o u t h :

i t d o e s n o t a p p e a r t o b e f o r m e d a s t h e r e s u l t o f a d v e r s e c o n d i t i o n s

b u t ac ts as a m e a n s of d i s p e r s a l . By m e a n s of a v e n t r a l s u c k e r p l a t e

t h r o u g h w h i c h p r o j e c t a se r ies o f f i nge r - l i ke s u c k e r s , t h e h y p o p u s

a t t a c h e s itself to a p a s s i n g in sec t a n d i s c a r r i e d f r o m o n e p l ace to

a n o t h e r . A t t h e s a m e t i m e i t i s ab l e t o s u r v i v e d r i e r c o n d i t i o n s t h a n

t h e a d u l t .

I t h a s b e e n f o u n d t h a t a t e m p e r a t u r e o f 23° to 25° C i s t h e o p t i ­

m u m for r e a r i n g c u l t u r e s o f t h e f u r n i t u r e m i t e , Glycyphagus

domesticus a n d t e m p e r a t u r e a n d h u m i d i t y h a v e a m a r k e d effect on

t h e d e v e l o p m e n t o f t h e egg a n d h y p o p u s s t ages .

T h e life cyc le o f t h e f ea the r m i t e s , f ami ly D e r m o g l y p h i d a e , i s a s

fol lows: t h e r e a re t w o t y p e s of egg , a h a r d s h e l l e d a n d a t h i n she l l ed

o n e . T h e l a t t e r c o n t a i n l a rvae w h i l e sti l l w i t h i n t h e m o t h e r w h o

m a y b e e i t h e r v i v i p a r o u s o r o v o v i v i p a r o u s . T h e s i x - l egged la rva

h a t c h e s f rom t h e egg t o m o u l t t o t h e e i g h t - l e g g e d p r o t o n y m p h

w h i c h i n t u r n f o r m s t h e d e u t o n y m p h . W h e n m a t i n g t akes p l a c e t h e

m a l e a lways c o p u l a t e s w i t h t h e f ema le d e u t o n y m p h w h i c h la te r

m o u l t s t o t h e a d u l t s t age .

D e t a i l e d k n o w l e d g e o f t h e d e v e l o p m e n t o f t h e l a rvae a n d n y m p h

o f t h e O r i b a t i d m i t e s i s v i r t u a l l y n o n - e x i s t e n t , b u t S e n g b u s c h

(1954) h a s r e c e n t l y s u c c e e d e d i n t i m i n g t h e d e v e l o p m e n t o f t h r e e

A m e r i c a n spec ies o f Galumna f r o m egg to a d u l t . O v i p o s i t i o n m a y

o c c u r i n n a t u r e f r o m s p r i n g t o a u t u m n a n d i s p r o b a b l y c o r r e l a t e d

w i t h t e m p e r a t u r e w h i c h also affects t h e t i m e o f d e v e l o p m e n t . T h i s

ave rages 63 d a y s at 20° C in G. nervosus, b u t on ly 47 d a y s at 25° C.

F ina l ly , w e c o m e t o t h e s u b - o r d e r T e t r a p o d i l i . N o t u n t i l K e i f e r ' s

w o r k (1946) o n t h e a l t e r n a t i o n o f g e n e r a t i o n s o f t h e b u c k e y e r u s t

m i t e Oxypleurites aesculifoliae w a s t h e life cyc le of a n y of t h e

E r i o p h y i d a e fully u n d e r s t o o d . T h e d e u t o g y n e s b e c o m e ac t ive i n

la te w i n t e r a n d leave t h e i r h i b e r n a t i n g q u a r t e r s o n t w i g s . W h e n t h e

b u d s swel l i n F e b r u a r y t h e y p e n e t r a t e t h e o u t e r scales a n d feed o n

t h e g r e e n i n n e r t i s sue b e n e a t h . W i t h t h e d e v e l o p m e n t o f leaves ,

t h e y lay eggs w h i c h h a t c h i n t o n y m p h s p r o d u c i n g p r i m a r y m i t e s

o n t h e leaves . T h e s e s o o n p r o d u c e a d d i t i o n a l p r i m a r y m i t e s . I n

ear ly M a y n e w d e u t o g y n e s a p p e a r w h i c h w h e n fully fed t r ave l

d o w n t h e s t e m for six i n c h e s o r m o r e a n d t h e n c r a w l i n t o c rev ices

M I T E S A N D T I C K S 201

o f t h e p r e v i o u s s e a s o n ' s w o o d . T h e p r i m a r y m i t e s a r e conf ined t o

t h e leaves a n d p e r i s h w i t h t h e m b u t t h e d e u t o g y n e s , o n c e t h e y

h a v e a t t a i n e d a s u i t a b l e c rev ice , b e c o m e d o r m a n t d u r i n g la te

s u m m e r . W i n t e r r a i n s a n d frost t e n d t o b r e a k t h i s d i a p a u s e h o w ­

ever a n d t h e d e u t o g y n e s b e c o m e ac t ive aga in t h e fo l lowing s p r i n g .

T h e r e i s a h i g h m o r t a l i t y a m o n g s t t h e m , p r i n c i p a l l y b e c a u s e o f t h e

l imi t ed n u m b e r o f s u i t a b l e c rev ices .

B I B L I O G R A P H Y Identification

ANASTOS , G. (1950) T h e scutate ticks, or Ixodidae, of Indonesia. Ent. Amer. (N.S.) , 3 0 , 1 - 1 4 4 .

A U D Y , J . R. (ed.) (1954) Malaysian Parasites, I - X V . Stud. Inst. Med. Res. Malaya, N o . 26, 1-242.

BAKER, E. W. and WHARTON , G. W. (1952) An Introduction to Acarology. New York.

BEER, R. E. (1954) A revision of the Tarsonemidae of the Western H e m i ­sphere (Order Acarina). Univ. Kansas Sci. Bull., 3 6 , (2), 1091-1387.

COOLEY, R. A. and KOHLS , G. M. (1944) T h e Argasidae of Nor th America, Central America and Cuba. Amer. Midi. Nat. Monograph, N o . 1, 1-152.

(1945) T h e genus Ixodes in Nor th America. Bull. Nat. Inst. Health, N o . 184 ,1 -246 .

HAMMEN , L. VAN DER (1952) T h e Oribatei (Acari) of the Nether lands . Zool. Verh. Leiden, N o . 17, 1-139.

HOOGSTRAAL, H. (1956) African Ixodoidea 1, Ticks of the Sudan. Cairo. HUGHES , A. M. (1948) The Mites associated with stored Food Products.

London: Min. Agric. Fish. KEEGAN , H. L. (1951) T h e mites of the sub-family Haemogamasinae

(Acari: Laelaptidae). Proc. U.S. Nat. Mus. Wash., 1 0 1 , 203-68. MICHAEL , A. D. (1883) British Oribatei, 1, London .

(1887) Ibid., 2. (1901) British Tyroglyphidae, 1. London. (1903) Ibid., 2.

NUTTALL , G. and WARBURTON , C , COOPER, W. and ROBINSON , L . (1908)

Ticks. A Monograph of the Ixodoidea. Part 1, Argasidae. Cambridge. (1911) Ibid., Part 2, Ixodidae, the genus Ixodes. (1915) Ibid., Part 3, Ixodidae, the genus Haemaphysalis.

ROBINSON , L . E. (1926) Ibid., Part 4, Ixodidae, the genus Amblyomma. PRITCHARD, A. E. and BAKER, E. W. (1955) A Revision of the Spider Mite

Family Tetranychidae. San Francisco. SENEVET, G. (1937) Ixodoides Faune de France, No . 32, 1-100. Paris.

202 M I T E S A N D T I C K S

Biology

ARTHUR , D. R. (1951) T h e bionomics of Ixodes hexagonus Leach in Britain. Parasitology, 4 1 , 82-90.

(1952) Economic importance of ticks. Discovery, 1 3 , 379-83.

AUDY, J. R. and HARRISON, J. L. (1951) A review of investigations on mite typhus in Burma and Malaya, 1945-1950. Trans. R. Soc. Trop. Med. Hyg., 4 4 , 371-404.

CAMIN, J. H. (1953) Observations on the life history and sensory behav­iour of the snake mite, Ophionyssus natricis (Gervais) (Acarina: M a -cronyssidae). Spec. Publ. Chicago. Acad. Sci., No . 10, 1-75.

CLOUDSLEY-THOMPSON, J. L. (1947) T h e edibility of Hydracarina Naturalist, 1 9 4 7 , 1 1 6 - 1 8 .

ELTON , C. S. (1922) On the colours of water mites. Proc. Zool. Soc. Lond., 1 9 2 2 , 1 2 3 1 - 4 0 .

HUGHES , A. M. (1951) A general survey of the Acari (Arachnida). J.

Quek. Micr. Club, (4), 3, 247-60.

JONES, B. M. (1950a) T h e sensory physiology of the harvest mite Trom-

bicula autumnalis Shaw. J. Exp. Biol., 2 7 , 461-94. (1950b) T h e penetrat ion of the host tissue by the harvest mite,

Trombicula autumnalis Shaw. Parasitology, 4 0 , 247-60. KEIFER, H. H. (1946) A review of Nor th American economic Eriophyid

mites. J. Econ. Ent., 3 9 , 563-70. LEES, A. D. (1947) Transpira t ion and the structure of the epicuticle in

ticks. J. Exp. Biol., 2 3 , 379-410. (1948) T h e sensory physiology of the sheep tick, Ixodes ricinus L.

Ibid., 2 5 , 145-207. (1955) The Physiology of Diapause in Arthropods. Cambridge.

LEES, A. D. and BEAMENT, J. W. L. (1948) An egg-waxing organ in ticks. Quart. J. Micr. Sci., 8 9 , 291-332.

M I L N E , A. (1945) T h e ecology of the sheep tick, Ixodes ricinus L. T h e seasonal activity in Britain with particular reference to nor thern England. J. Exp. Biol, 3 6 , 1 4 2 - 5 2 .

SOAR, C. D. and WILLIAMSON, W. (1925) The British Hydracarina. 1. London.

(1927) Ibid.,2. (1929) Ibid., 3.

TOUMANOFF , C. (1944) Les Tiques (Ixodoidea) de ITndochine. Saigon. VIETS , K. (1955) Die Milben des Sufiwassers und des Meers, 1. Jena. VITZTHUM , G. H. (1940-43) Acarina in H. G. BRONN'S Klass. Ordn.

Tierreichs, 5, IV (5), 1-1011. WILLMAN , C. (1931) Moosmilben oder Oribatiden (Oribatei). Tierzv.

Deutsch., 2 2 , 79-200.

M I T E S A N D T I C K S 2 0 3

NEWELL , I . M. ( 1 9 4 7 ) A systematic and ecological s tudy of the Hala-caridae of eastern N o r t h America. Bull. Bingham Oceanogr. Coll., 1 0 , ( 3 ) , 1 - 2 3 2 .

SENGBUSCH , H. G. ( 1 9 5 4 ) Studies on the life history of three Oribatoid mites with observations on other species (Acarina, Oribatei). Ann. Ent. Soc. Amer., 4 7 , 6 4 6 - 6 7 .

SOLOMON , M. E. ( 1 9 3 7 ) Behaviour of the red-legged earthmite, Halo-tydeus destructor, in relation to environmental conditions. J. Anim. Ecol.,6, 3 4 0 - 6 1 .

TURK, F . A. and PHILLIPS , S -M. ( 1 9 4 6 ) A monograph of the slug mite

Riccardoella limacum (Schrank). Proc. Zool. Soc. Lond., 1 1 5 , 4 4 8 - 7 2 . VIETS , K. ( 1 9 4 0 ) Ausbreitungswege und nacheiszeitliche Verbrei tung der

Kalt wasser und S t romung liebenden Wassermilben in Europa. Arch. Hydrobiol., 3 7 , 2 7 8 - 3 1 9 .

WILKINSON, P . R. ( 1 9 5 3 ) Observations on the sensory physiology and behaviour of larvae of the cattle tick, Boophilus microplus, (Can.), (Ixodidae). Austr.J. Zool., 1, 3 4 5 - 5 6 .

WOODROFFE, G . E. and SOUTHGATE, B. J. ( 1 9 5 1 ) Birds ' nests as a source of

domestic pests. Proc. Zool. Soc. Lond., 1 2 1 , 5 5 - 6 2 . ZUMPT, F. and GRAF , H. ( 1 9 5 0 ) Medical importance of mites. S. Afr. J .

Clin. Sci., 1 , [ 1 9 6 - 2 1 2 .

E P I L O G U E

IN THE i n t r o d u c t i o n to t h i s v o l u m e t h e c o m p l e x i t y o f fac tors

i n f luenc ing t h e eco logy a n d d i s t r i b u t i o n o f a n i m a l s w a s i n d i c a t e d ,

a n d t h e i n t e r a c t i o n s w i t h t h e i r e n v i r o n m e n t s o f t h e spec ies m e n ­

t i o n e d h a v e b e e n s t r e s s e d t h r o u g h o u t . E c o l o g y c a n b e s t u d i e d

f rom t h e p o i n t o f v i e w o f t h e spec i e s ( a u t e c o l o g y ) o r f r o m t h a t o f

t h e p a r t i c u l a r h a b i t a t i n w h i c h n u m b e r s o f spec ies o c c u r ( s y n e c o -

logy) . T h e f o r m e r i s a s i m p l e r a p p r o a c h a n d m o r e s u i t e d t o t h e

ac t iv i t ies o f t h e i n d i v i d u a l n a t u r a l h i s t o r i a n : t h e l a t t e r u s u a l l y

invo lves t e a m w o r k . W h i c h e v e r i s a d o p t e d , h o w e v e r , t h e o t h e r

s h o u l d c o n s t a n t l y b e b o r n e i n m i n d o r e lse t h e p i c t u r e wil l b e c o m e

u n b a l a n c e d a n d d i s t o r t e d .

C o n s i d e r a b l e u n i f o r m i t y i s a p p a r e n t t h r o u g h o u t t h e g r o u p s t h a t

h a v e b e e n c o n s i d e r e d h e r e : t h i s i s n o t a l t o g e t h e r s u r p r i s i n g i n

m e m b e r s o f t h e s a m e p h y l u m . A r t h r o p o d s h a v e a n e x o s k e l e t o n

w h i c h , i n all c lasses , s e e m s to be bas ica l ly s imi l a r a l t h o u g h i t m a y

v a r y g r e a t l y i n c o m p l e x i t y . A n e x c e e d i n g l y t h i n o u t e r e p i c u t i c u l a r

layer o f ' c u t i c u l i n ' , a c o n d e n s e d l i p o - p r o t e i n t a n n e d w i t h q u i n -

ones , i s a lways p r e s e n t b u t o n l y i n i n sec t s a n d A r a c h n i d s d o e s t h i s

s u p p o r t t h e i m p e r v i o u s l aye r o f w a x t o w h i c h t h e i r s u c c e s s o n l a n d

is la rge ly d u e .

I t w o u l d be m i s t a k e n h o w e v e r t o r e g a r d t h e a b s e n c e o f a d i s c r e t e

c u t i c u l a r w a x layer a s a p r i m i t i v e c h a r a c t e r i s t i c , a l t h o u g h t h e f o r m s

t h a t lack o n e a re so r e s t r i c t e d in t h e i r cho i ce o f e n v i r o n m e n t t h a t

t h e y c a n n o t b e r e g a r d e d a s e n t i r e l y success fu l l a n d a n i m a l s . R a t h e r ,

i t s e e m s t h a t a p a r t i c u l a r m e t h o d h a s b e e n e x p l o i t e d for s u r v i v i n g

t h e c o n d i t i o n s o f life on l a n d . T h e p r i m i t i v e r e s p i r a t o r y o r g a n i s

t h e sk in , b u t spec ia l r e s p i r a t o r y s t r u c t u r e s h a v e b e e n evo lved i n a l l

b u t t h e sma l l e s t a n d s i m p l e s t o f t h e A r t h r o p o d a . I n i n sec t s a

s y s t e m o f m i n u t e a i r t u b e s o r ' t r a c h e a e ' l ead i n t o e v e n f i n e r

' t r a c h e o l e s ' t h a t c a r r y o x y g e n d i r ec t l y t o t h e t i s sues w h e r e m e t a ­

bo l ic p r o c e s s e s t a k e p lace , w h i l e t h e A r a c h n i d a posses s b o t h t u b u ­

lar t r a c h e a e a n d l u n g - b o o k s . S c o r p i o n s h a v e l u n g - b o o k s , w h i l e

204

E P I L O G U E 205

s p i d e r s a r e p a s s i n g t h r o u g h a p r i m i t i v e l u n g - b o o k s t age f ro m

w h i c h n o n e h a s y e t e m e r g e d . T w o p a i r s o f l u n g - b o o k s w i t h o u t

t r a c h e a e o c c u r i n t h e m o r e p r i m i t i v e fami l ies w h i l e m o s t o t h e r s

h a v e an a n t e r i o r p a i r o f l u n g - b o o k s a n d a p o s t e r i o r p a i r o f t r a c h e a e .

L u n g - b o o k s p r o v i d e a loca l i sed r e s p i r a t o r y a rea f r o m w h i c h

o x y g e n i s d i s t r i b u t e d b y t h e r e s p i r a t o r y p i g m e n t , h a e m o c y a n i n , i n

t h e b l o o d . I n s e c t s p o s s e s s n o r e s p i r a t o r y p i g m e n t s b e c a u s e all t h e i r

t i s sues a r e s u p p l i e d w i t h o x y g e n d i r e c t l y b y t h e t r a c h e o l e s .

T h e e n t r a n c e t o b o t h l u n g - b o o k s a n d t r a c h e a e i s g u a r d e d b y

sp i rac le s c losed b y m e a n s o f spec ia l m u s c l e s . I n t h i s w a y t h e

m i n i m u m q u a n t i t y o f a i r n e c e s s a r y for r e s p i r a t o r y p u r p o s e s i s

a l l o w e d t o c i r c u l a t e a n d c o n s e q u e n t l y w a t e r - l o s s i s m u c h r e d u c e d .

W h e n a n i n s e c t o r A r a c h n i d i s p l a c e d i n a n a t m o s p h e r e c o n t a i n i n g

a n a b n o r m a l l y h i g h p r o p o r t i o n o f c a r b o n d i o x i d e t h e sp i r ac l e s a re

k e p t o p e n t o t h e i r ful lest e x t e n t a n d t h e r a t e o f w a t e r - l o s s i n d r y

a i r i s t h e n c o n s i d e r a b l y i n c r e a s e d .

In all o r g a n i s m s g r o w t h t e n d s to be a cycl ical p r o c e s s , p e r i o d s o f

r e s t a l t e r n a t i n g w i t h ac t iv i ty . I n n o a n i m a l s , h o w e v e r , i s i t m o r e

m a r k e d t h a n i n t h e A r t h r o p o d a w h o s e d e v e l o p m e n t i s p u n c t u a t e d

by a se r ies of m o u l t s or e c d y s e s , e a c h of w h i c h i s p r e c e d e d by a

p e r i o d o f ac t ive g r o w t h a n d fo l lowed b y o n e o f a p p a r e n t i n ­

ac t iv i ty . Al l p a r t s o f t h e i n t e g u m e n t a r e m o u l t e d t o g e t h e r , i n d e ­

p e n d e n t l y o f n e r v e s u p p l y : t h e s t i m u l u s for t h i s i s h o r m o n i c i n

n a t u r e , m e t a m o r p h o s i s t o o b e i n g u n d e r h o r m o n e c o n t r o l .

D u r i n g m o u l t i n g t h e o ld e n d o c u t i c l e i s d i g e s t e d b y e n z y m e s i n

t h e m o u l t i n g f luid a n d w i t h d r a w n i n s o l u t i o n t h r o u g h t h e ' p o r e

c a n a l s ' . T h e s e a re n u m e r o u s f i n e t u b e s , s o m e t i m e s n u m b e r i n g ove r

a m i l l i o n p e r sq . c m o f su r face , w h i c h p e n e t r a t e t h e e x o - a n d

e n d o c u t i c l e . A n e w e p i c u t i c l e i s a lways la id d o w n b e n e a t h t h e o ld

o n e b e f o r e m o u l t i n g t akes p l ace , s o t h a t t h i s p r o c e s s i s a c c o m p a n i e d

by l i t t le loss o f w a t e r a n d a h i g h d e g r e e of e c o n o m y i s a c h i e v e d .

W o o d l i c e a n d m i l l i p e d e s a r e a l m o s t e n t i r e l y v e g e t a r i a n , w h i l e

c e n t i p e d e s a n d A r a c h n i d s , w i t h t h e e x c e p t i o n o f c e r t a i n m i t e s ,

a r e p r i m a r i l y c a r n i v o r o u s ; b u t d i f ferent spec ies o f i n sec t s s e e m t o

b e ab le t o t h r i v e o n a l m o s t a n y k i n d o f o r g a n i c m a t t e r c a p a b l e o f

s u p p o r t i n g m e t a b o l i s m . I n m o s t o f t h e s e a n i m a l s w a t e r c o n s e r ­

v a t i o n i s o f p r i m e i m p o r t a n c e ; insuff ic ient w a t e r i s o b t a i n e d w i t h

t h e food t o a l low for m u c h excess t o b e lost d u r i n g e x c r e t i o n .

206 E P I L O G U E

T h e f u n c t i o n o f e x c r e t i o n , l ike t h a t o f o s m o t i c r e g u l a t i o n , i s t h e

m a i n t e n a n c e o f a c o n s t a n t i n t e r n a l e n v i r o n m e n t w i t h i n t h e a n i m a l

b o d y . A n a q u a t i c a n i m a l s u r r o u n d e d b y a l a rge v o l u m e o f w a t e r

c a n e x c r e t e t ox i c n i t r o g e n o u s c o m p o u n d s w i t h i m p u n i t y , b u t t h e

neces s i t y for w a t e r e c o n o m y i n t e r r e s t r i a l f o r m s g e n e r a l l y r e q u i r e s

t h e e x c r e t i o n o f s o m e c o m p o u n d less p o i s o n o u s t h a n a m m o n i a .

W o o d l i c e a r e essen t ia l ly a m m o n o t e l i c s i nce o v e r half o f t h e i r

s o l u b l e n o n - p r o t e i n n i t r o g e n i s e x c r e t e d i n t h e f o r m o f a m m o n i a ,

b u t t h e r e t e n t i o n o f t h i s p r i m i t i v e c h a r a c t e r h a s b e e n a t t e n d e d b y

a g e n e r a l s u p p r e s s i o n o f n i t r o g e n o u s m e t a b o l i s m . In h i g h e r insec t s ,

a s i n m y r i a p o d s , b i r d s a n d r e p t i l e s , u r i c ac id i s t h e chief e x c r e t o r y

c o m p o u n d . T h i s s u b s t a n c e h a s i n t h e first p l a c e b e e n e v o l v e d i n

r e s p o n s e t o t h e c o n d i t i o n s o f e m b r y o n i c life. U r i c o t e l i c m e t a ­

b o l i s m i s c o r r e l a t e d w i t h t h e p o s s e s s i o n o f ' c l e ido ic ' eggs p r o v i d e d

w i t h w a t e r a n d e n c l o s e d in a c o m p a r a t i v e l y i m p e r m e a b l e she l l .

A m m o n i a i s t o x i c a s we h a v e s e e n a n d i s o n l y s u i t a b l e a s an

e x c r e t o r y c o m p o u n d for eggs d e v e l o p i n g i n w a t e r : i t c a n n o t b e

c o n v e r t e d t o u r e a a s t h i s w o u l d c a u s e u r e a m i a , a n d i n excess u p s e t

t h e o s m o t i c r e l a t i o n s h i p s o f t h e egg . H e n c e u r i c ac id , a n o n - t o x i c ,

h i g h l y i n s o l u b l e s u b s t a n c e , h a s b e e n evo lved w h i c h c a n a c c u m u l a t e

w i t h i n t h e egg w i t h o u t c a u s i n g a n y ill effects.

T h e chief e x c r e t o r y c o m p o u n d o f t h e A r a c h n i d a i s g u a n i n e

w h i c h , l ike u r i c ac id , i s v e r y i n s o l u b l e , b u t t h e p h y s i o l o g y o f its

e x c r e t i o n h a s n o t b e e n s t u d i e d i n t h e s a m e de ta i l .

T h r o u g h o u t t h e A r t h r o p o d a en t i r e ly m e c h a n i s t i c p a t t e r n s o f

b e h a v i o u r a r e f o u n d , i n v o l v i n g r ig id b u t c o m p a r a t i v e l y s i m p l e

r e s p o n s e s t o t h e s t i m u l i o f t h e e n v i r o n m e n t s i n w h i c h t h e y l ive.

I n d e e d i t w o u l d s e e m t h a t t h e t yp i ca l a r t h r o p o d a n n e r v o u s s y s t e m

i s c a p a b l e o n l y o f s t e r e o t y p e d reflex b e h a v i o u r p a t t e r n s a n d t h a t

t h i s p e r h a p s r e s t r i c t s t h e m n o less t h a n t h e i r r i g id i n t e g u m e n t !

N e v e r t h e l e s s , w i t h i n t h e l imi t s i m p o s e d b y t h e i r ba s i c m o r p h o ­

logy a n d p h y s i o l o g y , eve ry c o n c e i v a b l e t y p e o f m o d i f i c a t i o n a n d

spec ia l i sa t ion o c c u r s w i t h i n t h e A r t h r o p o d a a n d h e r e i n l ies t h e

g r ea t i n t e r e s t o f t h e s e a n i m a l s t o t h e s e r i o u s s t u d e n t o f n a t u r a l

h i s t o r y .

G E N E R A L B I B L I O G R A P H Y

I n a d d i t i o n t o t h e spec ia l b i b l i o g r a p h i e s t h a t fol low e a c h c h a p t e r ,

t h e fo l lowing m o r e g e n e r a l w o r k s wil l b e f o u n d t o b e use fu l .

Re fe r ences t o t h e m i n t h e t e x t h a v e b e e n m a r k e d b y a n as te r i sk .

BERLAND , L. (1932) Les Arachnides. Paris. BONNET , P. (1945) Bibliographia Araneorum, 1. Toulouse . BRISTOWE, W. S. (1939) The Comity of Spiders, 1. London .

(1941) Ibid. 2. BRUES, C. T . , MELANDER , A. L . and CARPENTER, F . M . (1954) Classifica­

tion of Insects. Keys to the living and extinct families of insects, and to the living families of other terrestrial Ar thropods . Bull. Mus. Comp. Zool,108,1-917.

COMSTOCK, J. H. (1940) (edited by W. J. GERTSCH). The Spider Book. (revised ed.). New York.

DONISTHORPE, H. St. J. K., (1927) The Guests of British Ants. London . EDNEY, E. B. (1957) The Water Relations of Terrestrial Arthropods,

Cambridge. GERTSCH, W. (1949) American Spiders. N e w York. GRASSE, P - P . (ed.) (1949) Traite de Zoologie Anatomie, Systematique,

Biologie, 6, Paris. HARMER, S. F. and SHIPLEY , A. E. (eds.) (1909) The Cambridge Natural

History, 4 , London .

KAESTNER, A. (1956) Lehrbuch der Speziellen Zoologie, 1 (13) ,485-658. Berlin.

KEVAN, D. K . M C E . (ed.) Soil Zoology. London .

K U H N E L T , W. (1950) Bodenbiologie. Wien . LAWRENCE , R. F. (1953) The Biology of the Cryptic Fauna of Forests. Cape

T o w n . PATTON , W. S. and EVANS , A. M. (1929) Insects, Ticks, Mites and Venomous

Animals of Medical and Veterinary Importance, 1. Liverpool. PHISALIX, M. (1922) Animaux venemeux et Venins, 1. Paris.

POCOCK, R. I. (1928) Guide to the Arachnida, Millipedes and Centipedes exhibited in the Department of Zoology, British Museum (Natural History). London .

SAVORY, T. H. (1928) The Biology of Spiders. London . (1935) The Arachnida. London .

SMART, J. and TAYLOR, G. (1953) Bibliography of Key Works for the Identification of the British Fauna and Flora, 2nd ed., London.

Zoological Record, London . (Published annually since 1865). 207

C L A S S I F I C A T O R Y I N D E X

IN THE fo l lowing s u m m a r y of classif icat ion a r e i n c l u d e d all spec ies ,

famil ies , s u b - o r d e r s , o r d e r s a n d classes m e n t i o n e d i n t h e t ex t .

T h u s , a l t h o u g h i t i s n o t a b s o l u t e l y c o m p r e h e n s i v e , r e f e r ence ha s

b e e n m a d e i n i t t o m o s t i f n o t all o f t h e m o r e i m p o r t a n t g r o u p s

k n o w n . R e f e r e n c e s t o text - f igs , a r e g i v e n i n h e a v y t y p e .

Phylum ARTHROPODA [Sub-phylum CRUSTACEA]

Class Malacostraca ORDER Isopoda (Chapter I)

Sub-order Oniscoidea Family Ligiidae 2

*Ligia spp. 9 *L. oceanica 3, 6, 9, 12,

PI. la,b L. baudiniana 6 L. exotica 6

* Ligidium hypnorum 3, PL la

L. longicaudatum 3 Family Trichoniscidae 2,

3 ,6 * Trichoniscus spp. 1,12 *T.pusillus XIII, 4, 10

T. commensalis 7 * Andr-oniscus dentiger

PL la Family Oniscidae 2

* Oniscus asellus 1,4,7, 8, 10, 11, PL la,b

*Halophiloscia spp. 9 *Philoscia muscorum 4,

6 ,13 , PL la *Platyarthrus spp . 1 *P. hoffmannseggi 7 ,10,

PL lb

Family Porcellionidae 2, 3

*Cylisticus convexus 3, 13

* Metoponorthus pruin-osus 3

*Porcellio scaber XII, XIII, 2-4, 10, 11, 13, PL la

*P. spinicornis 3 *P. dilatatus 13 *P. rathkei 3

P. demivirgo 4 Hemilepistus reaumuri

7, 8, 9, PL la Family Armadillidiidae

2 ,3 _ *Armadillidium spp. *A. vulgare XIII, 3,

8, 10, 13, PL la *A. nasatum 3

Family Eubelidae 1 Sphaerobathvtropa spp.

1

Class Diplopoda (Chapter II) Sub-class Chilognatha

ORDER Oniscomorpha

Family Glomeridae 1 5 , 17

12 4,

* British genera and species. 209 S . S . C . M .

210 C L A S S I F I C A T O R Y I N D E X

*Glomeris marginata 1 6 , 32 ,33 , 35

Family Sphaerotheriidae 17

ORDER Limacomorpha

Family Glomerides-midae 17

Family Zephroniodes-midae 17

ORDER Colobognatha

Family Pseudodesmidae 17

Family Platydesmidae 17 Family Siphonophoridae

17

Siphonophora spp. 17 Family Polyzoniidae 1 5 ,

17 *Polyzonium spp. 29 *P. germanicum 17, 20,

21 ORDER Ascospermophora

Family Chordeumidae 1 5 , 1 8

* Microchordeuma spp. 18 Family Brachychae-

teumidae 18 *Brachychaeteuma spp.

18 Family Craspedosomidae

1 5 , 1 8 *Craspedosoma razvlinsi

18 * Poly micr odon poly-

desmoides 18 ,34 Family Heterochor-

deumidae 18 ORDER Proterospermophora

Family Polydesmidae 1 5 , 1 8 , 2 9 , 3 2 , 3 3

*Polydesmius spp. 18, 30, 35

*P.angustus 1 8 , 3 2 , 3 3 , PI. IVfl

P. ricinus 29

Luminodesmus sequoia. 25

Habrodesmus sp. PI. 116 Family Mastigonodes-

midae 18 *Eumastigonodesmius

bond 18 Family Cryptodesmidae

1 5 , 1 8 Family Strongylosomidae

1 5 , 1 8 , 3 6

*Macrosternodesmus palicola 18

* Oxidus gracilis XII, 18, 20-4, 27, 28, 32, 34 ,35

*Ophiodesmus albonanus 18

Fontaria corrugata 21 Family Lysiopetalidae

18 Lysiopetalum spp. 19,

30 L.foetidissimum 29

ORDER Opisthospermophora

Family Stemmiulidae 19 Family Iulidae 1 5 , 19,

20, 25 *Iulus spp. 27,30,31,35 *TachypodoiuIus niger,

27, PI. *Schizophyllum sabido-

sum 21 * Cylindroiulus spp. 27

Cylindroiulus londinensis 27

*Paraiidus spp. 30 Pachyiulus spp. 31

Family Blaniulidae 1 5 , 19, 25

*Blaniulus guttidatus 20-26, PI. I l i a

*Proteroiidus fuscus 25 Family Spirostreptidae

19

C L A S S I F I C A T O R Y I N D E X 211

Spirostreptus spp. 19, PI. IVb

Gymnostreptus para-sitarius 31

Ophistreptus sp. 24 Family Spirobolidae 1 5 ,

1 9

Spirobolus spp. 31 Arctobolus marginatus

3 4 , 3 5

Rhinocricus lethifer 28 Sub-class Pselaphognatha

ORDER Penicillata

Family Polyxenidae 1 5 , 1 9 , 2 9

*Polyxenius spp. 19 *P. lagurus 1 9 , 2 5 , 3 5 ,

PI. lla Lophoproctus spp. 19

Class Chilopoda (Chapter I I I ) ORDER Geophilomorpha

Family Geophilidae 4 0 , 4 1 , 5 0

*Geophilus electricus 54 * G . carpophagus 5 4 *Necrophlaeophagus

longicornis 54 Pachymerium ferrugi-

neum 4 8 , 5 6 *Scolioplanes maritimus

4 8 , 4 9

*S. crassipes 54 Dignathodon spp. 48 Mixophilus indicus 49 Pectinunguis americanus

4 8

Family Himantari idae *Haplophilus subterra-

neus 42 Family Schendylidae

*Hydroschendyla sub-marina 4 8 - 5 0

Family Oryidae Orya barbarica 42 O. almohadensis 42

ORDER Scolopendromorpha

Family Cryptopidae 4 1 , 4 2 , 5 2 , 5 5

*Cryptops hortensis 4 3

*C. anomalans 43 *C. p a r i s i 4 3

Newportia spp. 43 Theatops spp. 43

Family Scolopendridae 4 1 , 4 2

Scolopendra spp. 4 3 , 5 6

S . morsitans 4 3 , 5 1 - 5 3 S. angulata 57 S. cingulata 4 3 , 5 1 , 5 2 ,

5 7 , PI. V i a , 6

S. clavipes 52 S. dalmatica 57 S . gigantea 4 3 , 5 0 S.heros 5 1 , 5 2 , 5 4 S. subspinipes 4 3 , 5 1 ,

5 2

S. viridis 5 1 , 52 Alipes spp. 43 Cormocephalus spp.

4 3

Ethmostigmus spp. 43 Rhysida afra 43

ORDER Craterostigmomorpha

Family Craterostigmidae 4 3

Craterostigmus spp. 43 ORDER Lithobiomorpha

Family Lithobiidae 4 1 , 4 4

* Lithobius spp. 4 4 , 46 * L . forficatus 4 4 , 4 7 ,

5 0 , 5 2 , 5 4 , 5 5 , 5 7 , 5 8 ,

PI. Vb *L. calcaratus 48 * L . variegatus 4 4

S . S . C M .

C L A S S I F I C A T O R Y I N D E X

*L.piceus 55 L.fasciatus 44 Bothropolys multidenta-

tus 47 Neolithobius voracior

47, 48 Family Henicopidae 44

*Lamyctesfulvicornis 44 Family Cermatobiidae

44 Cermatobius spp. 44

ORDER Scutigeromorpha

Family Scutigeridae 4 1 , 44, 46

Scutigera spp. 46-8 PL Ya

*S. coleoptrata 44, 47, 58

S. chtnifera 44 S. longicornis 44 S. forceps 54

Class Pauropoda (Chapter IV) Family Pauropodidae

*Pauropus spp. 6 1 , 62, 63

P. amicus 63 P. carolinensis 63

*P. huxleyi 63 P. silvaticus 63

Family Eurypauropodi-dae

Eurypauropus spp. 62 E. spinosus 63

Class Symphyla Family Scutigerellidae

64 *Scutigerella spp. 61

immaculata 65-7 , 6 8

Hanseniella agilis 67 H. hova 67 Family Scolopendrellidae

64

*Scolopendrella spp. 66 notacantha 65

[Class Arachnida] ORDER Scorpiones (Chapter V)

Family Buthidae 7 0 , 72, 83

Buthus occitanus 70, 72-4, 76, 78, 80, 82, 84

Androctonus australis 72-4, 76, 78, 80, 85, PI. V i l a , IXa

A. aeneas PL IXb Buthotus alticola 82,

84 Parabuthus capensis 74,

77 Isometrus maculatus 72 Centrums spp. 72 Centruroides vittatus 80 C. scidpturatus 80, 81 C. gertschi 80 Hadrurus spp. 74, 75 Tityus spp. 72 P. trinitatis 74

Family Diplocentridae 72

Family Scorpionidae 7 0 , 7 2 , 8 3 , 8 4

Scorpio spp. 74 .S. maurus 72-4 , 76 Opisthophthalmus lati-

manus 83 Palamnaeus spp. 73,

74 P. longimanus 73, 75,

76, 78, 84, 85 P. swammerdami 78 Pandinus spp. 73

Family Vejovidae 72 Family Chactidae 7 0 ,

72-4, 77, 83

C L A S S I F I C A T O R Y I N D E X

Euscorpius spp. 73 E. carpathicus 84 E. flavicaudis 84 E. germanus 72, 78, 84 E. italicus 73, 76, 80,

84, PI. V i l l a , b Family Bothriuridae 72,

83 ORDER Solifugae (Solpugida)

(Chapter VI) Family Rhagodidae 8 7 ,

88 ,94 Rhagodes spp. 88, 92,93

Family Karschiidae 89 Gylippus rickmersi 89

Family Ceromidae 88 Family Hexispodidae 8 7 ,

88 Chelypus spp. 88

Family Melanoblossiidae 89

Dinorhax spp. 88 Family Daesiidae 88

Gluvia dorsalis 89 Family Solpugidae 88

Solpuga caffra 92, 96, 97, PI. Xb

S. hostilis 94, 96, 97 S. lineata 90 S. sericea 90 Solpugyla globicornis 90

Family Galeodidae 8 7 , 88

Galeodes arabs 77, 88¬ 93 ,95

G. araneoides 88, 89, 92 G. caspius 96

Family Eremobatidae 8 7 , 88

Eremobates pallipes 90 E.formicaria 90 ,97

Family Ammotrechidae 8 7 , 88

Mummucia variegata 89

Pseudocleobis morsicans 89

ORDER Pseudoscorpiones (Chelo-nethi) (Chapter VI I )

Sub-order Ch thon i i nea Family Chthoniidae 99

*Chthonius spp. 101, 107, 108

*C. ischnocheles 101, 107,108,111

*C.halberti 101 Sub-order N e o b i s i i n e a

Family Neobisiidae 99 * Neobisium spp. 101,

108 *N. carpenteri 111 *N.maritimum 101,

107,111 *N. muscorum 101,107,

111 N.sylvaticum 101

*Roncus spp. 101,108 *R. lubricus 101

Microbisium femoratum 101

M. dumicola 101 Microcreagris cam­

bridgei 101 Gary pus beauvoisi 101,

102 G. minor 111

Sub-order Che l i f e r i nea Family Cheiridiidae 99

"Cheiridium museorum 101, 111

Family Cheliferidae 108, 110

*Chelifer spp. 101 *C. cancroides 101,

102 ,105 ,108 , 110-2 *Dactylochelifer latreillei

107-9 * Withius subruber 101

214 C L A S S I F I C A T O R Y I N D E X

Ellingsenius hendrickxi 1 0 6

Family Chernetidae 99 *Lamprochernes nodosus

103,108 *Pselapho cherries scor-

pioides 101 *Allochernes zvideri 101 A. italicus 101

*Toxochernes panzeri 101, 111, PI. XI I6

*Chernes spp. 101 *C. cimicoides 111,112 *Dendrochernes cyrneus

102 ,108 ,109 ,111 Cordylochernes scorpi-

oides 103 Sphenochernes schulzi

105

ORDER Palpigradi (Chapter V I I I )

Family Koeneniidae 1 1 4 Koenenia spelaea 115 K. draco 115 K. mirabilis 115, 116 K. pyrenaica 115 Prokoenenia wheeleri

116

ORDER Thelyphonida

Family Thelyphonidae 1 1 4

Thelyphonus spp. 117 T. caudatus 119, 121,

PI. Xlb T. linganus, 119 T.sepiaris 117,119-21 T. skimkewitchii 118—

20 Hypoctonus spp. 117 H.oatesi 119 Labochirus proboscideus

117,118

Mastigoproctus spp. 117

M. giganteus 117-19 Typopeltis spp. 117

ORDER Schizomida

Family Schizomidae 1 1 4 , 1 2 1

Schizomus spp. 122 S. crassicaudatus 122,

1 2 3

*S.latipes 123 S. vittatus 122 Stenochrus spp. 122 Trithy'reus spp. 122 T. paradenigensis 122

ORDER Phrynichida (Ambly-pygi)

Family Charontidae 124, 125

Charon grayi 1 2 4 , 1 2 7 Charinides bengalensis

125, 127, 128 Charinus milloti 124 Paracharon caecus 126

Family Tarantul idae 124,125

Phrynichus ceylonicus 126,127

Damon variegatus 126, 128

Z). medius 126 Masicodamon allanteus

126 ORDER Ricinulei

Family Ricinoididae 1 2 8 , 129

Ricinoides spp. 129 sjostedti 129

Cryptocellus spp. 129 C.dorotheae 129

ORDER Opiliones (Phalangidea) (Chapter IX)

C L A S S I F I C A T O R Y I N D E X

Sub-order C y p h o t h a l m i 1 3 3

Siro rubens 134 S. duricorius 134 Parasiro corsicus 134 Speleosiro sp. 134 Stylocellus spp. 134 Ogivea spp. 134 Paragovia spp. 134 Purcellia spp. 134

Sub-order Lan ia to res Family Phalangodidae

1 3 3

Phalangodes spp. 134 Scotolemon spp. 134,

140 Family Oncopodidae 134 Family Assamiidae 135 Family Cosmetidae 135 Family Triaeonychidae

135,144 Larifugella natalensis

142 Soerensella spp. 144 Nunciaspp. 137,143 Pristobunus spp. 137 Algidia spp. 143 A viridata 137 Muscicola picta 137 Hendea myersi 144

Family Gonyleptidae 1 3 3 , 135, 142

Family Synthetonychidae 137

Synthetonychia spp. 137 Sub-order Palpatores

Family Trogul idae 1 3 3 , 135 ,140 ,141 ,144

*Trogulus tricarinatus 137, 138, 146, PI. ^ X I I 6

*Anelasmocephalus cam­bridgei 137,138,146

Family Nemastomidae 133

215

ORDER Araneae (Chapter X) Sub-order L i p h i s t i o -

m o r p h a Family Liphistiidae 148,

149

*Nemastoma lugubre 137,138

*N. chrysomelas 137, 138, P1.XII6

Family Ischyropsalidae 133 , 1 4 0

Family Phalangiidae 1 3 3 "Homalenotus quadri-

dentatus 138 *Leiobunum rotundum

136,138,139 *L. blackwalli 138, 139,

145 L. calcar 143

*Nelima silvatica 138 *Mitopus morio 13 8,140,

143 * Oligolophus spp. 146 *0. agrestis 139 *0.meadii 138 *O. tridens 139 *O.hansenii 139 *Odiellus spp. 146 *0.spinosus 139,145 *Lacinius ephippiatus

139

*Megabunus diadema 139,146

*Platybunus triangularis 139,146

P.pinetorum 145 *Phalangium opilio 136,

139, 144,145 *Opilio parietinus 139,

145 *O. saxatilts 138

216 C L A S S I F I C A T O R Y I N D E X

Liphistius spp. 149 L. desultor 149

Sub-order M y g a l o -m o r p h a

Family Theraphosidae 148, 150, 157, 159, 163, 165, 169, 172,

P 1 . 1 7 6 X I I a Theraphosa sp. 150 T.blondi 177 Lasiodora sp. 150 Dugesiella hen tzi 173 Eurypelma sp. 178

Family Ctenizidae 150, 1 5 9 ,160 , 1 6 6 , 1 7 2

Nemesia caementaria 159

Family Atypidae 150, 166

*Atypus affinis 150, 162 ,174 ,176

Sub-order A r a n e o m o r p h a Family Filistatidae 166

Filistata insidiatrix 166 Family Dictynidae 151,

167 *Amaurobius spp. 162 *A. ferox, 157-8, 162,

176,177, P1.XIV6 *A. similis 157-8, 162,

177 A.socialis 161

Family Uloboridae 151, 167

Uloborus republicanus 161

Family Oonopidae 151, 165

* Oonops pidcher 177 Family Dysderidae 151,

157,165 *Dysdera spp. 165 *D.crocota 10 ,165,174 *D. erythrina 10, 163,

165

*Segestria senoculata 162,166

*Harpactea hombergi 165

Family Scytodidae 151, 157

*Scytodes thoracica 165. 166 , 170 , PI. XIV6

Family Pholcidae 157, 166

*Pholcus phalangioides 166,177

Family Gnaphosidae 148 ,151,157,165,171

*Drassodes spp. 174 *D.lapidosus 163,165 *Scotophaeus blackwalli

165,170 Family Clubionidae 151,

159,165,171 * Phrurolithus fes tivus

152 Family Anyphaenidae

151 Family Sparassidae 148,

152,157 Heteropoda venatoria

152 * Micromtnata virescens

152 Family Thomisidae 148,

152,159,164,171,174 * Thomisius onustus 163 * Misumena va tia 163 * Xysticus spp. 174

Family Salticidae 148, 152, 157, 159, 163, 171,174

*Salticus scenicus 152, 163,170

*Hasarius adansoni 175 Corythalia spp. 175,

176 Phidippus andax PI.

Xllla,b

C L A S S I F I C A T O R Y I N D E X 2 1 7

Family Oxyopidae 1 5 2 , 1 5 7 , 1 6 4

*Oxyopes heterophthal-mus 1 5 2 , 1 6 4

Family Lycosidae 148, 1 5 2 , 1 5 7 , 1 5 9 , 1 6 4 ,

1 7 4 , 1 7 6

*Lycosa spp. XII, 1 7 7 , PI. XlVa

*L. purbeckensis 1 5 8 *Arctosaperita 1 6 0 *Pirata spp. 1 5 8 *P. pisca tortus 1 5 8

Family Pisauridae 1 5 2 , 1 5 9 , 1 7 7

*Pisaura mirabilis 1 7 4 *Dolomedes fimbriatus

1 5 8

D. plantarius 1 7 8 Family Agelenidae 148,

1 5 2 , 1 5 7 , 1 5 9 , 1 6 6

*Argyroneta aquatica 1 5 8 , 1 6 8

* Tegenaria spp. 1 4 9 *T. atrica 10 *T. parietina 1 5 0

Desis spp. 1 5 8 Family Ther idi idae 148,

1 5 3 , 1 6 6 , 1 7 1

*Theridion sisyphium 1 7 8 T. socialis 1 6 1

*Stearodeabipunctata 1 6 6 *Oedothorax fuscus 1 5 8 La trodectus spp. 1 7 2 L. mactans 1 7 2 L. 13-guttatus 1 3 6

Family Tetragnathidae 1 6 7

*Pachygnatha spp. 1 7 4 Family Argiopidae 148,

1 6 7 , 1 7 0 , 1 7 1

*Argiope bruennichi PI. XVa

* A raneus spp. 1 4 9 *A. diadematus 1 0 , 1 6 7

*Metamenardi 10 *M. segmentata 1 7 6 *Cyclosa spp. 1 7 0

Nephila spp. 1 7 2 Dicrostichus magnificus

1 6 8

Cladomelea akermani 1 6 8

Family Linyphiidae 148, 1 5 3 - 7 , 1 5 9 , 1 6 6

ORDER Acari (Chapter XI ) Sub-order Notostigmata

Opiliocarus spp. 1 8 2 , 1 8 3 , 1 8 6

Sub-order Holothyroidea Holothyrus spp. 1 8 3 ,

1 8 6 , 1 9 4

Sub-order Parasitiformes (Mesostigmata)

Super-family Gamasides 1 8 3 , 1 8 6

Family Parasitidae 1 8 3 , 1 8 6

Family Dermanyssidae 182

Ophionyssus natricis 1 9 6

Liponyssus bacoti 1 9 9 Family Laelaptidae

3 0 , 1 8 6

Haemolaelaps spp. 1 9 7

Family Halarachnidae 182, 1 8 6

Super-family Uropodina 1 8 3 , 1 8 6 ,

(Ixodoidea) Super-family Ixodei ( Ixo­

didae) 182, 1 8 3 , 1 8 4 , 1 8 6 , 1 8 7

* Ixodes reduvius 1 8 7 , 1 9 8

C L A S S I F I C A T O R Y I N D E X

Amblyomma heb-raeum PL XVla

Boophilus microplus 188

B.annulatus 186 Dermacentor ander-

soni 186, 195 Rhipicephalus appen-

dicidatus PL XVb Super-family Nut ta l -

liellei 183 Super-family Argasides

(Argasidae) 182, 183, 184,187

Argas persicus 188 Ornithodorus mou-

bata 188,198 Sub-order Thrombidi-

formes Super-family Tarsone-

mini 184,189, 198

Family Scutacaridae 189

*Acarapis zvoodi 189 Super-family Prostig-

mata 184, 196 ELEUTHERENGONA

Family Eupodidae 189

Halotydeus destruc­tor 189

Family Ereynetidae 198

*Riccardoella limacum 198

Family Tetranychidac 184, 189,198, 199

*Metatetranychus ulmi 189,194

*Paratetranychas pilo-sus PL XVI6

* Tenuipalpus spp. 198 Family Demodicidae

182,199

*Demodex spp. 184, 189

Family Cheyletidae 189,199

* Ch eyle tus eruditus 193

*Syringophilus spp. 189

Family Bdellidae 182, 184, 189, 198

Family Halacaridae 182 ,190,193

PARASITENGONA

Family Hydrachnidae 182,184

*Hydrachna spp. 195, 199

Family Limnocharidae 184

Family Eylaidae 184 Family Limnesiidae

184 Family Arrenuridae

184 Family Thrombidi idae

(Trombidiidae) 182, 190

*Erythraeus phalan-gioides 142

*Belaustium nemorum 142

*Leptus spp. 142 FamilyThrombicul idae

(Trombiculidae) *Thrombidium {Trom-

bidium sp. 191 *Thrombicula (Trom-

biculd) spp . 191 *T. autumnalis 191

Sub-order Sarcoptiformes (Acaridiae)

Family Tyroglyphidae 185

*Tyroglyphus farinae 191

C L A S S I F I C A T O R Y I N D E 219

*Glycyphagus domes -ticus 200

Family Sarcoptidae 182

*Sarcoptes scabei 185, 192

Family Dermogly-phidae 200

(Oribatei) 182,185, 192, 194, 195, 200

Family Pelopidae 196 *Pelops sp. 196

Family Galumnidae 200

*Galumna spp. 200 *G. nervosus 200

Sub-order Tetrapodili Family Eriophyidae

182 ,185,192, 200 *Eriophyes ribis PI.

X V I la, b Oxypleurites aesculi-

foliae 200,201

G L O S S A R Y A N D I N D E X O F S C I E N T I F I C T E R M S

IN THE fo l lowing g lossary , r e f e r e n c e s to p a g e s on w h i c h scientif ic

t e r m s h a v e b e e n m o r e fully d e s c r i b e d a r e i n d i c a t e d b y h e a v y t y p e .

P a g e r e fe rences a r e n o t g i v e n w h e r e w o r d s a re i n c o n s t a n t u se .

W h e n a w o r d i s in g e n e r a l u s e in m o r e s enses t h a n o n e , i t i s e x ­

p l a i n e d b e l o w in r e l a t i on t o t h e s ense i n w h i c h i t i s u s e d i n t h e t ex t

o f t h e p r e s e n t v o l u m e , a n d w i t h r e f e rence t o t h e p a r t i c u l a r g r o u p s

of a n i m a l s c o n s i d e r e d .

Aktograph—apparatus for recording locomotory activity 24, 25 Anamorphosis—development involving transformation, characteristic

of millipedes, dur ing which additional segments appear at each moult or ecdysis. Cf. Epimorphosis (q.v.) 35, 57, 63

Apophysis—projecting outgrowth or process Aposematic coloration or sound—conspicuous warning or advertising

coloration or sound, found in or produced by distasteful, poisonous or otherwise formidable animals and their mimics. Cf. Cryptic (q.v.) 79, 8 0 , 1 6 3 , 1 7 0 , 1 9 4 - 5

Arolium—median tarsal lobe forming a pad or sucker beneath the claws of the leg of false-scorpions, etc. 103

Asparagine—amino-acid found in plant tissues and known to be strongly attractive to wireworms and other insects 27

Autotomy—reflex separation of par t of the body; self-amputation 50, 52, 137, 141

Basiconic sensillae—conical sense-organs found in Arthropoda 22, 23, 27,66

Batesian mimicry—imitation of the conspicuous appearance of a dis­tasteful, poisonous or otherwise formidable species by a harmless one 171

Berlese funnel—apparatus for extracting small animals from leaf litter and other debris which is placed in a horizontal sieve above a funnel. Heat from an electric light or a water-jacket dries the debris so that the fauna is driven downwards and eventually falls through the sieve and funnel into a bottle of preservative 102

Calamistrum—comb of short spines on the metatarsi of the fourth legs of some spiders 151, 167

220

I N D E X O F S C I E N T I F I C T E R M S 221

Carapace—covering of anterior upper surface in arthropods 71 Carina—lateral keel-like projection from the body segments of some

millipedes 18 Cavernicolous—cave-dwelling Cephalothorax—fore part of the body of an Arachnid, corresponding to

the head and thorax of an insect; more properly called the prosoma (q.v.) Chelate—pincer-like, as the claw of a lobster. T h e last segment of a limb

apposed to that preceding it so that the appendage is adapted for grasp­ing

Chelicerae—jaws of an Arachnid; carrying the poison fangs in spiders Chiggers—parasitic larvae of Thrombicu l id mites 184, 191 Chitin—nitrogenous polysaccharide forming the basic material of the

integument or cuticle in the Ar thropoda. Usually hardened by impreg­nation with calcium or sclerotin (q.v.)

Chiton—a mollusc that clings to rocks on the sea-shore 21 Chordotonal organs—integumental sensillae with auditory or pro-

preoceptive function 138 Chromatophore—colour pigment cell 6 Cleidoic egg—one containing enough water for development and en­

closed in a comparatively impermeable membrane or shell 206 Clavate—club-shaped Clypeus—narrow strip of prosoma between the eyes and bases of the

chelicerae in spiders Collum—first post-cephalic segment of myriapods 64 Commensal—an animal living in a loose association with another and

from which only one par tner derives benefit 30, 103, 185 Compound eye—eye composed of numerous visual elements, found in

many of the ar thropods 40 Coxa—first segment of the limb attaching it to the body Cribellum—sieve-like plate in front of the spinnerets in some spiders

151 ,157,161 Cryptic coloration—colour pattern making for inconspicuousness. Cf.

Aposematic (q.v.) 133,141, 152 ,163 ,170 Cucullus—mobile hood at front edge of carapace of Ricinulei 129 Cuticle;—hardened integument of arthropods

Dermal light sense—appreciation of light stimuli through the integu­ment 22

Deutogyne—secondary female Eriophyid mite differing from the p r imo-gyne or pr imary type and having no male counterpart 200, 201

Deutonymph—second nymphal stage following the larval instar of a mite or false-scorpion 112,197

Diapause—dormant state usually characterised by temporary failure of growth or reproduction, by reduced metabolism and often by enhanced resistance to climatic factors such as cold, heat or drought 199-201

2 2 2 I N D E X O F S C I E N T I F I C T E R M S

Digitigrade—walking on the toes or claws. Cf. Plantigrade (q.v.) 46 Distal—part of limb or segment farthest from the centre of the body

Ecdysis—moulting, casting of the outer skin in growth Endocuticle—inner layers of the integument 205 Endite—endopodite (q.v.) Endopodite—inner ramus of a primitively forked ar thropodan limb or

mouth part Endogenous rhythm—rhythm of activity that persists under constant

conditions 24 Epicuticle—thin outermost chitin-free layer of the integument or cuticle

xi, 205 Epigyne—external genitalia of the female Arachnid Epimorphosis—development characteristic of centipedes in which slow

growth takes place bu t the number of segments does not increase 57 Eurythermic—able to tolerate considerable variations in temperature .

Cf. Stenothermic (q.v.) 190 Exocuticle—outer layers of chitinous endocuticle beneath epicuticle (q.v.)

205

Femur—third segment of an Arachnid 's leg or palp Flagellum—a whip-like extension of the body, a l imb or antenna. In

false-scorpions, a structure composed of setae on the chelicerae

Galea—spinneret on movable finger in false-scorpions 104, 108 Genital operculum—chitinous plate covering reproductive opening Geotaxis—directed movement in response to the st imulus of gravity Gnathobase—projection from the coxa of a l imb used to crush food Gnathochilarium—mouth parts of millipedes composed of fused maxil­

lae 16 , 17 , 23 , 26 ,27 ,66 Gonopod—limb modified for sexual reproduction 19, 31, 37 Guanine—insoluble nitrogenous excretory compound characteristic of

Arachnids 206

Haemocyanin—respiratory pigment found in Crustacea and Arachnids in which the metallic element is copper and not iron as in haemoglobin 205

Hypopus—resistant, dispersal stage of some mites 199-200

Instar—larval, nymphal or other developmental stage of an ar thropod. Instars change at moul t ing and metamorphosis (q.v.)

Ion—electrically charged atom or group of atoms 25

Kinesis—non-directed locomotory response to a st imulus. Cf. Taxis (q.v.) Kinetic reaction—kinesis (q.v.)

I N D E X O F S C I E N T I F I C T E R M S 22

Labium—lower ' l ip ' or lower surface of mouth between the maxillae of an ar thropod

Labrum—upper ' l ip ' of an ar thropod 75, 107 Lacuna—space among the tissues serving in place of vessels for the cir­

culation of the blood 47 Lamella—one of an aggregate of thin plates which compose gills, lung-

books, e tc . Lamina—blade-like structure. On fingers of false-scorpion 100 Laterigrade—able to run sideways Luciferin—substance oxidised in the presence of luciferase to form oxy-

luciferin. T h e reaction is accompanied by the production of light 26 Luciferase—enzyme in the presence of which luciferin is oxidised and

light produced 26 Lyriform organ—lyre-shaped sensillae of harvest-spiders 138

Malleoli—organs of unknown function on the legs of the fourth pair in Solifugae, otherwise known as ' racquet organs ' 87

Mandibles—modified anterior l imbs of ar thropods forming jaws p r imi ­tively adapted for chewing. T h e chelicerae of Arachnids

Marsupium—brood pouch of woodlice 1, 12 Maxilla—one of the anterior appendages of insects and other ar thropods

so modified as to serve the purpose of mastication Maxillipede—poison claw or toxocognath of centipedes, literally 'jaw-

foot' 40, 50-4 Mesopeltidium—central port ion of carapace in Schizomida 121 Metapeltidium—posterior portion of carapace in Schizomida 121 Metachronal wave or rhythm—wave of rhythmic movement of similar

objects, such as cilia or the legs of a millipede in which each is slightly and equally out of phase wi th the next 20

Metamorphosis—ecdysis accompanied by a change in form from larva to nymph , or n y m p h to adult instar (q.v.)

Metapodosoma—posterior par t of prosoma of mites, bearing third and fourth pairs of legs 183

Metasoma—hind region of opisthosoma of scorpions, etc., forming a tail region 70 ,99

Metatarsus—penultimate segment of an Arachnid ' s leg Miillerian mimicry—imitation of the conspicuous or aposematic ap­

pearance of one distasteful animal by another, resulting in a reduction in the losses required to teach would-be predators to avoid this par­ticular appearance or colour pat tern and thus benefiting both species equally 194-5

Myrmecophilous—living in company with ants

Ocellus—simple type of eye, sometimes occurring in groups, but which, by itself, cannot provide form-vision 40, 44, 47, 138

224 I N D E X O F S C I E N T I F I C T E R M S

Ocular tubercle—prominence bearing the eyes in harvestmen and some spiders, etc. 132-3, 135, 145

Odoriferous glands—repugnatorial glands (q.v.) Ontogeny—origin and development of an individual living being as dis­

tinguished from phylogeny (q.v.) Operculum—exoskeletal plate forming a lid or cover. See genital oper­

culum Opisthosoma—posterior region of the body of Arachnids, often known

as the abdomen Ovoviviparous—retaining the eggs inside the body of the mother ,

although within the egg-membrane, until the embryos are fully de­veloped so that living young are produced

Osmosis—flow of water from a weaker to a stronger solution through a semi-permeable membrane 206

Palp—pedipalp (q.v.). Also tactile head appendage of insects, crus­taceans, myriapods, etc.

Papilla—a projection Parasitoids—parasitic insects which, like Ichneumon wasps, eventually

kill their host 11 ,169 Parthenogenesis—the development of unfertilised eggs Patella—short leg segment between femur and tibia Pectine—comb-like sense-organ on ventral surface of abdomen in scor­

pions 71 , 76-8 , PI. IXb, Xa Pedicle—the narrow 'waist ' of an Arachnid unit ing the prosoma and

opisthosoma Pedipalp—leg-like tactile organ in front of the legs of an Arachnid form­

ing claw of scorpions, reproductive organ of male spiders, etc. Penolic tanning—sclerotisation (q.v.) Phoresy—utilisation of another animal for transport 30, 101, 103,

142 Phototaxis—directed response in relation to the st imulus of light Phylogeny—evolutionary change in the ancestry of a living organism.

Cf. Ontogeny (q.v.) Planidium larva—active larva of parasitic Hymenoptera developing

from an egg laid away from the host. It is a migratory form adapted to seek out the latter 31

Plantigrade—walking on the sole of the foot or on a flat termination of the l imb and not on the toes or claws. Cf. Digitigrade (q.v.) 46

Pleopods—plate-like, respiratory endopodites of abdominal limbs of crustaceans 2 ,6

Pleurite—chitinous plate forming the side of a body segment Propeltidium—front portion of carapace in Schizomida 121-2 Proprioceptors—sense organs that detect the positions and movements

of different parts of their possessor 's body 138

I N D E X O F S C I E N T I F I C T E R M S 225

Prosoma—anterior region of the body of an Arachnid, sometimes called the cephalothorax (q.v.)

Prosopon—adult or imago stage in Hydracarina 199 Protonymph—first nymphal stage following the larval instar of a mite or

false-scorpion 105, 111, 112, 196, 200 Pseudo-tracheae—respiratory tubules in pleopods of woodlice 2, 6, 7 Pulvilli—lateral tarsal lobes forming suckers beneath the bases of the

claws in Phrynichida, etc. 125, 127 Pygidium—posterior part of the body forming a distinct division 117,

122,124,129

Racquet organs—malleoli (q.v.) Ram's-horn organ—extrusible reproductive organ of some male false-

scorpions 108,109-10 Reflex—simple, automatic and involuntary response to a st imulus Repugnatorial gland—gland secreting distasteful or unpleasant liquid

whose function is to deter aggressors

Sclerite—sclerotised or chitinous plate on the body of an ar thropod Sclerotin—product of sclerotisation (q.v.) Sclerotisation—chemical process analogous to the tanning of leather by

which a protein combines with a phenol or quinone to form sclerotin, a tough, resistant and somewhat impervious component of the ar thro-podan integument 20

Scopula—brush of hairs or setae at the end of the tarsus 164 Scutum—dorsal plate in ticks and some mites formed by a fusion of

tergites 184 Sensilla—arthropodan sense-organ Serrula—row of chitinous teeth as on the maxillae or chelicerae 100,

104,107-8 Seta—hair, bristle or spine, often sensory, on the body of an arthropod Somite—segment of the body Spermathecae—female organs in which are stored the spermatozoa

received from the male 110 Spermatophore—envelope or bag containing spermatozoa and secreted

by some male ar thropods 55, 83, 109-10 Spinneret—spinning organ at rear of body in spiders and on chelicerae of

false-scorpions 104-5, 149 ,161 ,176 Spiracle—respiratory aperture, the orifice of a tracheal tube 16, 40, 42,

44 ,137 ,183 ,205 Stabilimentum—narrow ribbon of silk on a spider 's web which helps to

camouflage the spider PL XVa Stadium—developmental stage Stenothermic—unable to tolerate wide variations in temperature . Cf.

Eurythermic (q.v.) 190

226 I N D E X O F S C I E N T I F I C T E R M S

Sternite—chitinous plate on the ventral side of a body segment Sternum—chitinous plate behind the labium, forming the unders ide of

the prosoma of an Arachnid Stink gland—repugnatorial gland (q.v.) Stridulation—sound production by the mechanical friction of one part

of the body against another; usually by means of a number of file-like ridges which rub against another set of ridges or a cluster of chitinous granules or pegs

Systole—contraction of the heart or arteries forcing the blood through the system 47

Tarsus—terminal segment of an ar thropodan limb which bears the claws Taxis—direct orientation in response to a st imulus. Cf. Kinesis (q.v.) Tergite—chitinous plate on the dorsal side of a body segment Thigmotaxis—directed response to the st imulus of contact 73 Tibia—segment of ar thropodan limb between patella and metatarsus

(q.v.) Toxocognath—maxillipede (q.v.) Tracheae—fine tubes carrying air from the spiracles and branching into

the tracheoles of most terrestrial ar thropods 16, 40, 44, 62, 189, 205 Tracheoles—fine tracheal capillaries which conduct air from the tracheae

to the tissues in most terrestrial ar thropods 205 Trichobothrium—very fine seta or hair usually believed to have an

auditory as well as tactile function 75, 112 Tritonymph—third nymphal stage following deu tonymph (q.v.) 112 Trochanter—the second, ring-like segment of an ar thropodan limb

Uric acid—insoluble excretory compound characteristic of insects 206 Uropod—terminal abdominal appendage of Crustacea 8

Vulva—external reproductive organ, especially the orifice or opening of that organ 31

I N D E X O F

Ballooning of spiders 156 Behaviour

centipedes 45-50 false-scorpions 102-5 harvest-spiders 135-9 millipedes 19-26 mites 185-92 Palpigradi 115 Pauropoda 62-3 Phrynichida 125-7 Ricinulei 129-30 Schizomida 122 scorpions 72-4 Solifugae 89-90 spiders 154-62 Symphyla 65-6 Thelyphonida 117-18 woodlice 5-9

Courtship false-scorpions 108-10 harvest-spiders 143 scorpions 81-3 spiders 172-6 Thelyphonida 120-1

Disease transmission by mites 184,189, 193 by ticks 184-8 ,193

Distribution centipedes 4 0 - 4 , 5 6 false-scorpions 99-102 harvest-spiders 132-5 millipedes 15-19 mites 183-92 Palpigradi 115 Pauropoda 61-2 Phrynichida 124-5

G E N E R A L T O P I C S

Ricinulei 129 Schizomida 121-2 scorpions 70-2 Solifugae 87-9 spiders 148-54 Symphyla 64-5 Thelyphonida 116-17 woodlice 1-5

Enemies centipedes 52-5 false-scorpions 108 harvest-spiders 140-2 millipedes 27-31 mites 194-5 Palpigradi 116 Pauropoda 63 scorpions 76-80 Solifugae 94-5 spiders 168-72 Symphyla 66-7 woodlice 10-12

Folklore centipedes 4 9 , 5 3 - 4 harvest-spiders 13 5-6 millipedes 31 spiders 150-1 , 154-5, 158, 162 woodlice 5

Food centipedes 50-2 false-scorpions 105-8 harvest-spiders 139-40 millipedes 26-7 mites 192-4 Palpigradi 115-16 Pauropoda 63 Phrynichida 126-7

22o I N D E X O F G E N E R A L T O P I C S

Schizomida 122-3 scorpions 74-6 Solifugae 90-4 spiders 162-8 Symphyla 66 Thelyphonida 118-20 woodlice 9-10

Gall formation by mites 185,192

Humid i ty responses centipedes 48 harvest-spiders 136, 138, 140 millipedes 20-5 mites 191,196-7 spiders 157-8 ticks 187-8 Thelyphonida 119 woodlice 5-6, 8

Luminescence centipedes 54 millipedes 25

Migration centipedes 23-4 , 29 millipedes 23-4 woodlice 23-4

Myrmecophi lous habits false-scorpions 101, 105-6 millipedes 25 mites 185 Schizomida 123 spiders 152 ,157 ,171 woodlice 7

Poison centipedes 52-5 false-scorpions 105-8 scorpions 80-1 Solifugae 91-2

spiders 172 Thelyphonida 120

Pseudoparasit ism by myriapods 26, 49-50

Reproduction and life-cycle centipedes 55-8 false-scorpions 110-12 harvest-spiders 143-6 millipedes 31-7 mites 195-201 Palpigradi 116 Pauropoda 63-4 Phrynichida 127-8 Ricinulei 130 Schizomida 123-4 scorpions 83-5 Solifugae 96-7 spiders 172-8 Symphyla 67-8 Thelyphonida 120-1 woodlice 12-14

Repugnatorial glands harvest-spiders 132 ,134 ,141-2 millipedes 17 -1 9 ,2 8 -9 Schizomida 123 Thelyphonida 119-20 woodlice 11

Silk production by false-scorpions 104-5

Stridulation centipedes 43, 52 scorpions 78-80 Solifugae 95 spiders 153, 171-2

Webs of spiders 148-9, 153, 161, 163 ,166 -8