Arbacioida are an order of sea urchins, consisting of a single extant family, the Arbaciidae. They are distinguished from other sea urchins by the presence of five separate plates around the anus. Unlike their close relatives, the Salenioida, all of the tubercles on their tests are of similar size.
Arbacioida are an order of sea urchins, consisting of a single extant family, the Arbaciidae. They are distinguished from other sea urchins by the presence of five separate plates around the anus. Unlike their close relatives, the Salenioida, all of the tubercles on their tests are of similar size.
This order includes about 50 species (roughly 24 extant) divided into 14 genera: Arbacia Gray, 1835 Arbaciella Mortensen, 1910 Arbia Cooke, 1948† Baueria Noetling, 1885† Codiopsis Agassiz, in Agassiz & Desor, 1846† Coelopleurus Agassiz, 1840a Cottaldia Desor, 1856 † Dialithocidaris Agassiz, 1898 Habrocidaris Agassiz & Clark, 1907b Hattopsis Podocidaris Agassiz, 1869 Pygmaeocidaris Döderlein, 1905 Sexpyga Shigei, 1975 Tetrapygus Agassiz, 1841b
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).