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24-1
Ph
ylu
m: C
ho
rdat
a
Characteristics and Adaptations
24-2
Plan Estructural Nombre Cordados viene de notocorda
En forma de barra, tejido semirigido encerrrado en una funda En la mayora de los casos, se extiende a lo largo del tubo
digestivo y el sistema nervioso Sirve principalmente para armar o tensar el cuerpo (rigidez) y
provee el andamiaje esqueletico para el acoplamiento de los msculos para la natacin.
5 caracteristicas de los cordados Medula nerviosa dorsal tubular Notocorda Hendiduras Faringeas Endostilo Cola Postanal
Five Chordate Hallmarks
4
Notochord Always found at some embryonic stage First part of the endoskeleton to appear in the
embryo Serves as an axis for muscle attachment Can bend without shortening and permits undulation In protochordates and jawless vertebrates,
Persists throughout life
5
Funda Elstica
Funda Fibrosa
Notocorda
Five Chordate Hallmarks
7
In vertebrates Series of cartilaginous or bony vertebrae form from
mesenchymal cells derived from blocks of mesodermal cells lateral to notochord
In most vertebrates Notochord displaced by vertebrae Remnants may persist between or within vertebrae
Five Chordate Hallmarks
8
Dorsal Tubular Nerve Cord
In most invertebrate phyla
Nerve cord is solid and ventral to alimentary canal
In chordates
Single, tubular cord is dorsal to alimentary canal
Anterior end enlarges to form the brain
Cord is produced in embryo by infolding of ectodermal cells on the dorsal side of body
Five Chordate Hallmarks
9
Pharyngeal Pouches and Slits Pharyngeal slits lead from pharyngeal cavity to the
outside Form by the inpocketing of the ectoderm and the
evagination of endoderm of pharynx In aquatic chordates
2 pockets break through to form pharyngeal slit
In amniotes Pockets may not break through and only grooves are formed
Five Chordate Hallmarks
10
In tetrapods Pharyngeal pouches give rise to a variety of structures,
including the Eustachian tube, middle ear cavity, tonsils and parathyroid glands
Perforated pharynx functions as filter-feeding apparatus in protochordates
Fishes added a capillary network with thin gas-permeable walls Led to evolution of gills
Five Chordate Hallmarks
11
Endostyle or Thyroid Gland
Recently, the endostyle was recognized as a shared chordate character
Endostyle or its derivative, the thyroid gland, found in all chordates
Some cells in endostyle secrete iodinated proteins homologous with the iodinated-hormone-secreting thyroid gland of adult lampreys and the remainder of vertebrates
Five Chordate Hallmarks
12
Postanal Tail
Postanal tail, plus musculature, provided motility for larval tunicates and Amphioxus to swim.
Efficiency increased in fishes but became smaller or vestigial in later lineages
24-13
Subphylum Urochordata: Tunicata
14
Cilia on gill bars of pharynx pull mucus into a sheet Particles trapped in sheet are worked into a rope and carried
back to the esophagus and stomach
Heart drives blood first in one direction, then in reverse Organisms also concentrate very rare elements, such as
vanadium, in dramatically high concentrations Nervous system has one nerve ganglion and a plexus of
nerves on dorsal side of pharynx
Subphylum Urochordata: Tunicata
15
Subneural gland samples incoming water and may have an endocrine function
Hermaphroditic with a single ovary and a single testes Fertilization is external Adult sea squirts
Retain 2 of the 5 chordate features: pharyngeal slits and endostyle
Tadpole larvae Have all 5 chordate characteristics
Larva does not feed, but swims awhile before attaching and developing into a sessile adult
16
Taxonomy
Subphylum: Urochordata (urocordado, tunicates, sea squirts, salps, ascidies)
Class: Appendicularia pelagic tunicates, apendiculria, oicopleura, oikopleura
Class: Ascidiacea ascidians, sessile tunicates, ascdia, ascidies, tuniqus sessiles
Class: Thaliacea pelagic tunicates, doliolum, salpa, taliceo
24-17
Sub
ph
ylu
m: U
roch
ord
ata
24-18
Plan Estructural (Ascidiacea)
Cordados 1-19
Cordados 1-20
21
Subphylum Urochordata: Tunicata
22
Form and Function of Appendicularian (Larvacea) Resemble the larval stages of other tunicates
Each builds a delicate hollow sphere of mucus interlaced with passages for water entry
Phytoplankton and bacteria trapped on a feeding filter inside sphere are drawn into mouth through a tube
When filters become clogged with wastes, they are left behind and a new sphere is built
Paedomorphic Sexually mature individuals that retain the larval body form
of ancestors
24-23
Sub
ph
ylu
m: U
roch
ord
ata
24-24
Sub
ph
ylu
m: U
roch
ord
ata
Appendicularians create a feeding current to filter food particles from the
surrounding water. The dotted arrows indicate the direction of the current
through the house.
Source: http://www.microscopy-
uk.org.uk/mag/indexmag.html?http://www.microscopy-
uk.org.uk/mag/artjan01/oiko.html
Cordados 1-25
24-26
Subphylum Urochordata: Tunicata
27
Form and Function of Thalacians Salps are pelagic with a lemon-shaped, transparent body
Pump water through body by muscular contraction rather than ciliary action
Alternate sexual and asexual generations
Increase in number rapidly with abundant food supply
24-28
Sub
ph
ylu
m: U
roch
ord
ata
24-29
Cyclosalpa affinis (Chamisso, 1819).
A, B, Solitary zooid, dorsal view; C, D,
Aggregate zooid; C, Right side view;
D, Left side view. A.S., atrial siphon;
Br, branchial septum;
B.S., buccal siphon;
Dt, dorsal turbercle;
End, endostyle;
G, ganglion;
i.m., intermediate muscle;
Int, Intestine;
I-VI, body muscles;
Pd., peduncle;
St, stolon.
Scale bars: A, B=6 mm, C, D=3mm.
Taxonomic Study of Genus Cyclosalpa
(Thaliacea: Salpida: Salpidae) from Korea
Sunwoo Kim , Jung-Hye Won , Chang-Bae Kim
Animal Systematics, Evolution and Diversity.
2012. Oct, 28(4): 261-268
DOI
: http://dx.doi.org/10.5635/ASED.2012.28.4.261
24-30
24-31
ESPECIES EN COLOMBIA ASCIDIAS
Phallusia nigra
Microcosmus spp.
Pyura
Cnemidocharpa
Polyclinum
Symplegma
Distaplia
Cordados 1-32
Taxonomy
24-33
Phylum: Chordata
Subphylum: Cephalochordata
Orden: Anfioxiformes
Familia: Branchiostomidae
Genero: Branchiostoma (21 spp) Epigonichthys (7 spp)
Trabajo para el ltimo 30% en una cartulina:
FICHA TAXONMICA DE LOS TAXONES ESTUDIADOS
Phylum: Cordados
Subphylum:
Superclase: ETC
Construirla grupo a grupo usando ITIS, de manera individual.
Cordados 1-34
24-35
Sub
ph
ylu
m: C
eph
alo
cho
rdat
a
Subphylum Cephalochordata
36
Diversity Lancelets
Slender, laterally flattened, translucent animals about 57 cm long
Live in sandy bottoms of coastal waters around the world
Originally bore the generic name Amphioxus, but by priority are now in the genus Branchiostoma Still referred to by general name, amphioxous
About 25 species of amphioxus are described 5 occur in North American coastal waters
Subphylum Cephalochordata
37
Food particles separated from mucus are passed into hepatic cecum where they are phagocytized
Filtered water leaves body by an atriopore Closed circulatory system is complex but lacks a heart
Blood is pumped by peristaltic contractions in ventral aorta, passes upward through branchial arteries in pharyngeal bars to paired dorsal aortas
Blood moves by microcirculation through tissues and returns to ventral aorta
Subfilo: Cefalocordado
24-38
Cordados 1-39
Subphylum Cephalochordata
40
Blood lacks erythrocytes and hemoglobin and mainly transports nutrients
Hollow nerve cord lies above the notochord Pairs of spinal nerve roots emerge at each trunk segment Sense organs are simple, including an unpaired ocellus
that functions as a photoreceptor Anterior nerve cord is not enlarged, yet is homologous to
vertebrate brain
Subphylum Cephalochordata
41
Reproduction Sexes are separate
Gametes are set free in the atrium and pass out through atriopore
Fertilization is external
Cleavage is holoblastic and a gastrula forms by invagination
Larvae soon hatch and gradually assume the shape of adults
Subphylum Cephalochordata
42
Basic Plan Amphioxus possesses features that suggest the
vertebrate plan Cecum is a diverticulum resembling the vertebrate
pancreas in secreting digestive enzymes Trunk muscles resemble vertebrate patterns Possess basic circulatory plan of more advanced
chordates Many zoologists consider amphioxus a living
descendant of ancestors that gave rise to both cephalochordates and vertebrates Would make them the living sister group of the vertebrates
ORIGIN OF THE PHYLUM CHORDATA Hypothesis and evidences
24-43
24-44
Origin
Hemichordata Echinodermata
LARVAE
24-45
Origin
Neoteny
the growth rate of body form is slowed so that the animal does not attain the ancestral
adult form
Progenesis
Precocious maturation of gonads in a larval (or
juvenile) body that then stops growing
Post -displacement
developmental process is delayed
relative to reproductive maturation
24-46
24-47
Origin
Origin
24-49
24-50
24-51
Cordados 1-52
Subfilo: Cefalocordado
24-53
Cordados 1-54
Corte transversal de un cefalocordado a nivel farngeo
24-55
Verde: Sistema nervioso, Rojo: Msculos, Violeta: Faringe, Fucsia: Gnadas, Puntos rojos: arteria subendostilar y aortas
dorsales
Observe la notocorda y la organizacin alternada de las barras farngeas con y sin celoma.