Phylum Arthropoda

Subphylum MyriapodaClasses Diplopoda & Chilopoda

Subpylum HexapodaClass Insecta

Subphylum Myriapoda• 1 pr antennae

• 1pr mandibles

• 2 or 1 pr maxillae

• uniramous appendages

SP Myriapoda, Class Chilopoda

Centipedes

• Scutigera coleoptrata

Cheliped Examples

Scolopendra castaneiceps

http://gprime.net/video.php/bateatingcentipede

SP Myriapoda, Class Diplopoda

Millipedes

• 4 thoracic segments– each has 1 pr legs

• 25-100 abdominal segments– each has 2 pr legs

• Larval stages have 1pr legs/segment

Diplopod Examples

SP Hexapoda, Class Insecta• 4 pr feeding appendages (mouthparts)• 6 pr walking legs• 2 pr flight appendages

– 2pr wings– 1pr wings + 1pr halteres– 1pr elytra + 1pr wings

• No appendages on abdomen• Tagmata:

– Head – 5-7 segments– Thorax – 3 segments– Abdomen – 8-11 segments

Class Insecta

Tagmata

Segmentation

Insect Anatomy

Head Appendages

labrum maxilla

mandible

labium

labial palp

maxillary palp

ocelliantenna

compound eye

Famous Mouth Parts

Insect Respiratory System

Excretory System – Malpighian Tubules

• Insects excrete nitrogenous waste in the form of uric acid (urate)

• Solid uric acid is formed in the rectum by the removal of H2O

Holometabolous Insects

Tobacco horn worm Larva of sphinx moth

Holometabolous Development

1-4 instars

Lepidopteran Lifecycle

Holometabolous Development• Dipteran larvae

Bot Fly Lifecycles

Coleopteran – Grub Larvae

Boll Weevil

Beneficial Coleopterans

Ladybird Beetle Life Stages

1st instar

3rd instar

pupaAdult

Aphid parasites

Hemimetabolous Development

Larvae

hemipteran

odonatanorthopteran

Beneficial Insects

• Ichneumon wasps lay eggs in body of beetle & lepidopteran larvae – many of which are plant pests

• The wasp larvae feed on the host, killing it in the process

Insect Behavior• Hymenopterans & Isopterans often show complex

social behavior– Termite colonies– Ant colonies– Bee hives– Hornets & wasps

• All have unique genetic/environmental sex determination mechanisms

Social Insects

MUTATIONS INREGULATORY GENES CAN GIVE THE PROTEINS NEWPROPERTIES: UBXACQUIRES THE ABILITY to REPRESSDISTAL-LESS in theINSECT CLADE

R. Galant and S. B. Carroll,2002. Nature 415:910.

Ronschaugen, M. et al.2002. Nature 415: 914.

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Arthropod Evolution

Arthropod Evolution

Mutation of the ultrabithorax

gene

Arthropod & Chordate EvoDevo

Arthropod Evolution• Paleozoic insect fossils – show ties to crustacean

morphology

3 pr of Biramous

appendages

Wing primordia arose from

thoracic gills

Present Mayfly Nymph