An echinoderm /ɪˈkaɪnoʊdɜːrm/ is any member of the phylum Echinodermata /ɪˌkaɪnoʊˈdɜːrmətə/ (from Ancient Greek ἐχῖνος echīnos "hedgehog" and δέρμα derma "skin") of marine animals. The adults are recognizable by their (usually five-point) radial symmetry, and include starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone.The phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes (a superphylum), after the chordates (which include the vertebrates, such as birds, fishes, mammals, and reptiles). Echinoderms are the largest phylum that has no freshwater or terrestrial members.