Echinoderms

Echinoderms - ECHINODERMS Widevarietyofbodyplans

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ECHINODERMS
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Wide variety of body plans stalked crinoids, starfish, sea urchins, sand dollars, sea cucumbers,  and weird “sci-fi” stuff Not much range in size - few mm’s to 2 m Trophics – filter feeders, detritus feeders, grazers, predators, scavengers No plankton and few nekton – heavy skeleton Skeleton made of plates of single crystals of high Mg Calcite – sponge-like Plates = ossicles, partly endoskeletal, come apart after death Larvae bilaterally symmetrical, adults can be bilateral, pentameral,  radial None known to be fresh water or terrestrial, very few brackish – no  discrete respiratory, excretory, or osmoregulatory system All have water vascular system (hydraulic system filled with seawater)
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Water Vascular System Opens to environment at point covered by  Madreporite plate Connects to ampullae which are controlled by muscles to control tube feet Areas with openings for tube feet = ambulacral areas rest are interambulacral  areas
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Echinoderms and chordates are deuterostomes Tornaria larva – blastopore develops into anus, not mouth, Coelom develops from pockets in endoderm Means vertebrate and echinoderms closely related
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Phylum Echinodermata “stalked” Pelmatozoans     Class Crinoidea (Camb-R)      Class Paracrinoidea (O-S)
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Echinoderms - ECHINODERMS Widevarietyofbodyplans

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