One pouch forms water vascular system. Covered by thin epithelium and endoskeletal elements. Gonads in multiples of 5.
Eggs cleave radially.
Direct development or ciliated larva. 6,000 species known. B Taxonomy of the Phylum. Antedon, Neometra, Cenocrinus. Astropecten, Luidia, Dermasterias, Ctenodiscus, Patiria, Henricia, Echinaster, Pteraster, Leptasterias, Heliaster Asterina, Solaster.