Starfish or sea stars are echinoderms belonging to the class Asteroidea. The names "starfish" and "sea star" essentially refer to members of the Class Asteroidea. However, common usage frequently finds "starfish" and "sea star" also applied to ophiuroids which are correctly referred to as "brittle stars" or "basket stars".
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starfish (Asteroidea) Animals belonging to the echinoderms characterized by five arms extending from a central disk.