echinoderms2009_1per-1

echinoderms2009_1per-1 -...

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Bilateria: Protostomes vs. Deuterostomes Protostomes: nelids arthropods annelids, arthropods, mollusks, lophophorates Deuterostomes: echinoderms, chordates Developmental differences distinguish the two groups Slide 1 (of 22)
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Coelom lined by an epithelium derived from mesoderm rgans formed inside a coelom can freely move grow and •Organs formed inside a coelom can freely move, grow, and develop independently of the body wall while fluid cushions and protects them from shocks. d to the evolution of nearly all large, complex animals led to the evolution of nearly all large, complex animals •All deuterostomes have a coelom •Some protostomes do not have a true coelom Slide 2 (of 22)
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Echinodermata •Ancient taxon, all marine Hemichordata •Very derived, unlike the ancestral deuterostomes •declining ~ 6000 extant species 5 classes 6000 extant species, 5 classes • 13K known extinct species 20 extinct classes, •Secondarily radially symmetrical as adults •Larvae and ancestors have primary bilateral symmetry •Arranged around a central oral aboral axis Slide 3 (of 22) •Some with secondary bilateral symmetry Fossil crinoid ~350 MYO
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5 classes Asteroidea t tf ih • Sea stars, starfishes • About 1500 extant species •Centra l disk from which the arms radiate • Arms broadly joined to central disk Ophiuroidea (Ophio = snake) •Br itt le stars (=serpent stars), basket stars • Arms sharply demarcated; long and snaky •~ 2000 extant species Echinoidea (Echin = spiny) • urchins, sand dollars, sea biscuits •~ 1000 extant species egular urchins are semi herical and radial Slide 5 (of 22) • Regular urchins are semi
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5 classes Holothuroidea (holothur = polyp) a cucumbers • Sea cucumbers •~ 900 extant species • Elongate on oral/aboral axis ± secondarily bilateral ing of branched tentacles around Ring of branched tentacles around the mouth •No spines, no arms • Flexible body wall •Sluggish, benthic gg Crinoidea (Crin = lily) •Sea lilies, feather stars •~ 600 extant species ich fossil record Slide 6 (of 22) Rich fossil record •Oral surface oriented upward • Branched arms encircle the mouth
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Body wall Epidermis •Monolayered ooa y eed • monoflagellated collar cells
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This note was uploaded on 10/22/2011 for the course ORGANIC CH 308 taught by Professor O connor during the Fall '09 term at Rutgers.

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echinoderms2009_1per-1 -...

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