Spatangoida

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

Heart urchins Temporal range: Lower Cretaceous–recent PreꞒ Ꞓ O S D C P T J K Pg N
Spatangus purpureus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Subclass:	Euechinoidea
Infraclass:	Irregularia
Superorder:	Atelostomata
Order:	Spatangoida L. Agassiz, 1840
Suborders
Brissidina Micrasterina Paleopneustina

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

According to World Register of Marine Species :

• suborder Brissidina Stockley, Smith, Littlewood, Lessios & MacKenzie-Dodds, 2005
  • family Asterostomatidae Pictet, 1857
  • family Brissidae Gray, 1855
  • family Palaeotropidae Lambert, 1896
  • superfamily Spatangoidea Fischer, 1966
    • family Eupatagidae Lambert, 1905
    • family Eurypatagidae Kroh, 2007
    • family Loveniidae Lambert, 1905
    • family Macropneustidae Lambert, 1905
    • family Maretiidae Lambert, 1905
    • family Megapneustidae Fourtau, 1905 †
    • family Spatangidae Gray, 1825
• family Hemiasteridae H. L. Clark, 1917
• suborder Micrasterina Fischer, 1966
  • family Aeropsidae Lambert, 1896
  • family Micrasteridae Lambert, 1920a
• family Palaeostomatidae Lovén, 1868
• suborder Paleopneustina Markov & Solovjev, 2001
  • superfamily Paleopneustoidea A. Agassiz, 1904
    • family Paleopneustidae A. Agassiz, 1904
    • family Pericosmidae Lambert, 1905
  • family Prenasteridae Lambert, 1905
  • family Schizasteridae Lambert, 1905
• family Somaliasteridae Wagner & Durham, 1966a †
• family Toxasteridae Lambert, 1920a †

• 
  Brissus latecarinatus (Brissidae)
• 
  Eupatagus mooreanus (Eupatagidae)
• 
  Echinocardium cordatum (Loveniidae)
• 
  Phrissocystis sp. (Macropneustidae)
• 
  Maretia planulata (Maretiidae)
• 
  Spatangus purpureus (Spatangidae)
• 
  Fossil of Palhemiaster comanchei (Hemiasteridae)
• 
  Aeropsis rostrata (Aeropsidae)
• 
  Fossil of Micraster leskei (Micrasteridae)
• 
  Prymnaster investigatoris (Schizasteridae)
• 
  Fossil of Heteraster oblongus (Toxasteridae)

See also

• Abatus agassizii
• Meoma ventricosa

References

• Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 981. ISBN 0-03-056747-5.
• National History Museum. "Spatangoida". Retrieved 19 Dec 2009.