Spatangoida

Heart urchins Temporal range: Lower Cretaceous–recent PreЄ Є O S D C P T J K Pg N
Echinocardium cordatum
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Superorder:	Atelostomata
Order:	Spatangoida L. Agassiz, 1840
Suborders
Asterostomatina Hemiasterina Holasterina Micrasterina Toxasterina

The heart urchins or Spatangoida are an order of sea urchins.

Their body is a somewhat elongated oval in form, and is distinguished by the mouth being placed towards one end of the animal, and the anus towards the other. As a result, heart urchins, unlike most other sea urchins, are bilaterally symmetrical, and have a distinct anterior surface. The presence and position of the mouth and anus typically give members of this group the distinct "heart" shape from which they get their name.

Heart urchins have no feeding lantern, and often have petaloids sunk into grooves. They are a relatively diverse order, with a number of varying species.

Taxonomy

Order Spatangoida

• Suborder Asterostomatina
  • Family Asterostomatidae
• Suborder Hemiasterina
  • Family Aeropsidae
  • Family Hemiasteridae
  • Family Palaeostomatidae
  • Family Pericosmidae
  • Family Schizasteridae
• Suborder Holasterina
  • Family Calymnidae
  • Family Holasteridae
  • Family Pourtalesiidae
  • Family Urechinidae
• Suborder Micrasterina
  • Family Brissidae
  • Family Brissopsidae
  • Family Loveniidae
  • Family Spatangidae
• Suborder Toxasterina
  • Family Toxasteridae

See also

• Abatus agassizii

References

• Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 981. ISBN 0-03-056747-5. 
• National History Museum. "Spatangoida". http://www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/taxa/taxon.jsp?id=531. Retrieved 19th Dec 2009.