what does echinoderm mean
echinoderm. n. 1. (Animals) any of the marine invertebrate animals constituting the phylum Echinodermata, characterized by tube feet, a calcite body-covering (test), and a five-part symmetrical body. The group includes the starfish, sea urchins, and sea cucumbers.ny of various invertebrate sea animals having a hard spiny outer covering, an internal skeleton, and a radially symmetrical body. Starfish, sea urchins, and sea cucumbers are echinoderms.