Clade for ECHINODERMATA
Phylum ECHINODERMATA (traits & tree after Ruppert & Barnes 1994 and Brusca & Brusca 1990 834)
==1================================= Crinoidea (sea lilies, feather stars) <<=E====| | ==3=========================== Asteroidea ('true' starfish) ==2===| | ==5===================== Ophiuroidea (brittle stars) ==4===| | ==7=============== Echinoidea (sea urchins) ==6===| ==8=============== Holothuroidea (sea cucumbers)
(** plesiomorphic- a primitive state, not unique to clade): b) endoskeleton of calcareous ossicles with unique perforated structure c) unique water vascular system with suckerless podia d) open ambulacral grooves e) mouth & anus on oral surface** f) sessile; attached to substratum with aboral surface (primitively) g) multiple gonads** Ý h) spherical sperm** Ý i) gill pores/slits absent in adults b) multiple arms bearing open ciliated grooves for suspension feeding c) podia lack suckers**, not used for locomotion d) use articulated cirri for locomotion (derived forms) b) oral surface becomes ventral c) anus becomes dorsal d) use podia (tube feet) for locomotion e) stone canal becomes ossifiedÝ b) open ambulacral grooves** c) podia possess suckers d) pedicellaria** (2 orders) |
b) arm ossicles like miniature 'vertebrae' c) anus absent in adult b) ambulacral grooves extend from oral to aboral pole c) aboral surface restricted to small region around anus d) podia possess suckers e) podia possess calcified discÝ f) podia possess secretory goblet & tuft cellsÝ g) esophagous has internal skeletonÝ b) test covered with articulated, moveable spines; spines quite large in some taxa c) pedicellaria** (all orders) d) secondary bilateral symmetry (some groups) e) elongate spermÝ b) fleshy body c) elongation of body along oral-aboral axis d) oral podia modified as tentacles e) secondary bilateral symmetry (some groups) f) single gonadÝ |
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Copyright © 2002 by A. Richard Palmer. All rights reserved.
(revised April 3, 2002)