English

A heart urchin, Spatangus purpureus

Noun

heart urchin ‎(plural heart urchins)

1. Any echinoderm of the class Spatangoida.
   • 1996, Marty Snyderman, Guide to Marine Life: Caribbean, Bahamas, Florida, page 129,

     Red heart urchins, like other heart urchins, are usually buried under the sand and are only seen on rare occasions.

   • 2003, Gunther J. Eble, Developmental Morphospaces and Evolution, James P. Crutchfield, Peter Schuster (editors), Evolutionary Dynamics, page 47,

     Spatangoids constitute a monophyletic group of heart urchins that appears in the early Cretaceous (145 M.Y. ago) and ranges to the Recent.

   • 2007, Marian Armstrong, Wildlife and Plants, Volume 16, 3rd Edition, page 967,

     The class of animals (Echinoidea) that sea urchins belong to includes sand dollars and heart urchins. Sand dollars are flat, while heart urchins are oval, covered in short spines with longer spines down their back.

Synonyms

• (any species of Spatangoida): spatangoid

See also

• sand dollar
• sea urchin