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WCHS Zoology Chapter 16 Classification Phylum Echinodermata

Phylum Echinodermata the phylum of tripoblastic, coelomate animals whose members are pentaradially symmetrical as adults and possess a water-vascular system and an endoskeleton covered by epitheluium; Pedicellaria often present
Class Crinoidea free-living or attached by an aboral stalk of ossicles; flourished in the Paleozoic era; approximately 230 living species; Sea lilies, feather stars.
Class Asteroidea rays not sharply set off from central disk; ambulacral grooves with tube feet; suction disks on tube feet; pedicellariae present; Sea stars; about 1,500 species.
Class Ophiuroidea Arms sharply marked off from the central disk; tube feet without suction disk; Brittle stars; over 2,000 species.
Class Echinoidea globular or disk shaped; no rays; movable spines; skeleton (test) of closely fitting plates; Sea urchins, sand dollars; approximately 1,000 species.
Class Holothuroidea No rays; elongated along the oral-aboral axis; microscopic ossicles embedded in a muscular body wall; circumoral tentacles; Sea cucumbers; approximately 1,500 species.
Created by: dmoudy