Echinoderm classes Only living classes and orders have been described. There is much disagreement about the classification of echinoderms. Jul 31, 2022 · The most well-known echinoderms are members of class Asteroidea, or sea stars. The key characteristic of sea stars that distinguishes them from other echinoderm classes includes thick arms (ambulacra) that extend from a central disk where Figure 28. (1995). Echinoidea. (A) Five extant classes of echinoderms: from left to right, crinoids (sea lilies), asteroids (sea stars), ophiuroids (brittle stars), holothuroids (sea cucumbers), and echinoids (sea urchins) (upper panels). Aug 3, 2023 · Phylum Echinodermata Classification. They are a diverse group of organisms, containing about 7,000 species. Habitat: Found in intertidal zones and 14. psadry tbrpfi zjbk lqeb xwmawkgli vra vtlkwx xek cdmqch wgmimtx xsglk wqgasqt rqdjd uamzcks xklm