Arbacioida

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 Temporal range: Middle Jurassic–recent PreꞒ Ꞓ O S D C P T J K Pg N
Arbacia lixula
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Superorder:	Echinacea
Order:	Arbacioida Gregory, 1900
Family:	Arbaciidae Gray, 1855

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 Ali, 1992†
• Podocidaris Agassiz, 1869
• Pygmaeocidaris Döderlein, 1905
• Sexpyga Shigei, 1975
• Tetrapygus Agassiz, 1841b

References

• Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 980. ISBN 0-03-056747-5.
• National History Museum. "Arbacioida". Retrieved 19 Dec 2009.