Echinodermata
Echinoderms are a phylum of marine animals. The adults are recognized easily by their radial symmetry, and include such well known animals as sea stars, sea urchins, sand dollars, and sea cucumbers. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssa zone. The phylum contains about 70,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are also the largest phylum that has no freshwater or terrestrial representatives.