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Deuterostome development

results form mesodermal out pocketing of the primitive gut, or enteron

Protostome development

results from the splitting of the mesoderm

Cell division in deuterostomes is (blank)


Cell division in protostomes is (blank)


Asteroidea characteristics

Sea stars, 5+ arms, ventral mouth, dorsal anus, tube feed, suckers

Ophiuroidea characteristics

Brittle stars, central disk, long flexible arms, tube feet without suckers

Echinoidea characteristics

sand dollars and sea urchins, unevenly spherical or disk-shaped, no arms, five rows of tube feet, Aristotle's lantern rings mouth

Holothuroidea characteristics

sea cucumbers, five rows of tube feet, modified tube feet as feeding tentacles, no spines, reduced skeleton

Crinoidea characteristics

sea lilies, sessile, feathered arms surrounding dorsal mouth

Why are there two invertebrate groups in phylum Chordata?

They exhibit a notochord, dorsal hollow nerve cord, pharyngeal gill slits, and a post anal tail. Intermediate characters.


lampreys, no jaw, larva resembles lancelet, cartilaginous skeleton, notochord is primary support, rudimentary vertebrae


sharks, skates, rays, jaws present, paired fins, mineralized skeleton, placoid scales


ray-finned fish, rayed fins, operculum, cycloid scales


coelacanths, lobed fins


lungfishes, lobed fins, lungs or lung derivatives


frogs, salamanders, legs


turtles, snakes, crocodiles, birds, amniotic egg, diapsid descent


mammals, milk, hair, synapsid descent

Adaptations of vertebrates to terrestrial life

cranium, vertebrae, skeleton, paired fins, muscular pharynx, jaws

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