Spatangoida

views updated May 09 2018

Spatangoida (heart urchins; subphylum Echinozoa, class Echinoidea) An order of irregular echinoids which have a compact apical system and a plastron in which the labrum is followed by a pair of large plates. Most spatangoids have narrow bands of densely ciliated spines, which can be recognized in fossils as areas of very small tubercles on denuded fascioles. The Spatangoida first appeared in the lowermost Cretaceous.

A Dictionary of Zoology MICHAEL ALLABY

heart urchins

views updated May 18 2018

heart urchins See ECHINOIDEA; SPATANGOIDA.

A Dictionary of Zoology MICHAEL ALLABY

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Heart urchins

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