Relatives

Echinoderms (phylum Echinodermata-"spiny skin") are one of the most numerous of marine phyla. Starfish, brittle stars, sea cucumbers, sand dollars, and sea urchins are important members of most ocean floor communities. Brittle stars and sea cucumbers are the most common animals on the deep abyssal plains of the ocean. As important as echinoderms are in today's marine realm, the living classes represent but a small remnant of their past diversity. Evolutionarily, echinoderms are important in yet another way. Among invertebrates echinoderms may be our closest relatives.