Name this phylum that also includes the class asteroidea—sea stars—with a name that comes from the Greek for "spiny skin".
One grouping under this phylum, distinguished by a concentrically arranged skeleton, lives on waterlogged wood and is called sea daisies. These animals possess snapping structures used to keep away small organisms, the pedicellaria, as well as an ambulacral system, used for respiration, locomotion, and defense, and based on water pressure. That water vascular system drives structures used for feeding and gas exchange, the tube feet. This phylum's members have imperfect radial symmetry of five parts, and include sea cucumbers, urchins, and sand dollars. Name this phylum that also includes the class asteroidea—sea stars—with a name that comes from the Greek for "spiny skin".
One grouping under this phylum, distinguished by a concentrically arranged skeleton, lives on waterlogged wood and is called sea daisies.
{echinodermata} [or {echinoderms}]