Scientific name Cidaroida Rank Order | ||
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Similar Cidaridae, Arbacioida, Eucidaris, Cidaris, Cassiduloida | ||
Cidaroida is an order of primitive sea urchins, the only living order of the subclass Perischoechinoidea. All other orders of this subclass, which were even more primitive than the living forms, became extinct during the Mesozoic.
Contents
Description
Their primary spines are much more widely separated than in other sea urchins, and they have no gills. Other primitive features include relatively simple plates in the test, and the ambulacral plates continuing as a series across the membrane that surrounds the mouth.
List of families
According to World Register of Marine Species:
References
Cidaroida Wikipedia(Text) CC BY-SA