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40 Cards in this Set

  • Front
  • Back
Mechanisms of evolution
high reproductive potential
competition for the declining resources
survival of the few- natural selection
homology
2 or more features that share a common ancestry
analogy
features with a similar function
radial symmetry
a boy is laid out equally from a central axis
frontal plane
divides a bilateral body into dorsal and ventral, where as a transverse plane divides into top and bottom
hydrostatic skeleton
a fluid-filled cavity enclosed by a membrane and muscular coat
3 groups of living chordates
vertebrates
cephalochordates
urochordates
coelom
fluid-filled internal body cavity
schizocoelom
solid mass of mesodermal cells split to form the body cavity within them
enterocoelom
mesoderm arises as outpocketings of the gut that pinch off to form body cavity (deuterostomes)
protostomes
blastopore = mouth
spiral cleavage
schizocoelic coelom
ectodermal skeleton
5 fundamental features of Chordates
notochord
dorsal hollow nerve cord
endostyle/thyroid gland
pharyngeal slits
post-anal tail
notochord
lies dorsal to coelom but beneath and parallel to the CNS mechanical propertes
can be flexed laterally side to side but cannot be collapsed
(core of cells and fluid encased in tough sheath)
endostyle
a glandular groove in the floor of the pharynx, involved in filler feeding
dorsal & tubular nerve cord
neural plate folds or rolls up and sinks inward from the surface as a tube to take up residence...just above the notochord
myomere
blocks of muscle & segmentation in chordates
protochordates
primitive chordates
sessile & burrowing
both dioceous and monoceous
hemichordate
burrowing forms and sessile forms
system: nephridium, pulsatile vesicle, muscle and connective tissue lining, probiscis duct, podousla w/specialized blood vessels
enteropheusta
acorn worms: marine animals
deep/shallow waters
3 regions : probiscis, collar, trunk
live in mucous lined burrows
glomerulus (hemichordates)
podousla w/specialized blood vessels
pulsatile vesicle (hemichordates)
contractile tissue, or heart vessicle
nephridium (hemichordates)
an excretory organ
pterobranchia
2 genera: sessile pterobranch
suspension feeding
live in secreted tubes
small and colonial
zooid
zooid
each individual contributes to the group
Hemichordate affinities to Echinoderms
marine
unsegmented
pentaradial symmetry
endoskeleton
water vascular system
no head/brain present
nervous system: radial nerves from central nerve ring
cephalochordates
ex: lancelets, amphioxus
pharyngeal slits, etc.
suspension feeding: oral hood, buccal cirri (prevent entrance of large particles), wheel organ, Hatscheks pit/groove
velum, atriopore
velum
partial diaphragm, short sensory tentacles
Hatscheks pit/groove
like vertebrate pituatary glands
cephalochordates: circulatory system
paired anterior and posterior cardinal veins + the hepatic vein = swollen sinus venosus --> the endostylar artery (ventral aorta) --> the visceral, skeletal, coelomic vessels
larval amphioxus
planktonic
assymetrical in head and pharyns
pharyngeal slits only on left side of the body
specialized notochord of amphoixus (cephalochordate)
notocord sheath
plates of slowly contracting muscles
cytoplasmic extensions of these plates synapse w/the dorsal nerve cord
fluid-filled spaces separate muscle cells
urochordata
5 chordate characteristics
suspension feeding
marine
tunic-flexible outer body cover
ex: ascidiacea (sea squirts)
Sea Squirts (Ascidiacea)
marine animals, brightly colored, solitary/colonial
adults are sessile, larvae planktonic
sensory vesicle: the ocellus and the otolith
neural crest: pigment cells
the CNS has 3 subdivisions
3 subdivisions of the CNS (Ascidiacea)
visceral ganglion
dorsal nerve cord
sensory vesice (ocellus and otolith)
adult solitary ascidian
tunic
atrium
branchial basket
viscera
incurrent and excurrent siphons
oral tentacles
the heart = single layer of muscle
Larvacea (appendicuularia)
monoecious
suspension feeding (gelatinous matrix)
protandrous (sperm and eggs, same gonad)
House building, reverse flow clears clogged filters
Thaliacea
free living, pelagic
derivative of the adult ascidian
Chordate Origin hypotheses
1. chordates from Annelids/ Arthropods (a/a on its back = basic chordate body)
2. chordates from echinoderms (both deuterostomes, share embryonic similarites)
prochordate to chordate
the dorsoventral inversion of chordates occured w/in the deuterostomes
dorso/ventral axis changed (reversed)
paedomorphisis
retention of some larval traits in the adult