Spatangoida
Introduction 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 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 †Image:Brissus latecarinatus.jpg | ''Brissus latecarinatus'' (Brissidae)Image:Eupatagus mooreanus fossil heart urchin (Eocene; Florida, USA) 1 (16765728703).jpg|''Eupatagus mooreanus'' (Eupatagidae)Image:Echinocardium_cordatum.jpg|''Echinocardium cordatum'' (Loveniidae)Image:Phrissocystis.jpg|''Phrissocystis sp.'' (Macropneustidae)Image:Tiny maretia heart urchin (Maretia planulata).jpg | ''Maretia planulata'' (Maretiidae)Image:Spatangus purpureus.jpg|''Spatangus purpureus'' (Spatangidae)Image:Palhemiastercomanchei.jpg|Fossil of ''Palhemiaster comanchei'' (Hemiasteridae)Image:Oliver2012 fig5 Aeropsis rostrata (Wyville Thomson, 1877) with Kelliola symmetros (Jeffreys, 1876).png|''Aeropsis rostrata'' (Aeropsidae)Image:Micraster leskei MHNT Turonien Puys 76.jpg|Fossil of ''Micraster leskei'' (Micrasteridae)Image:Prymnaster investigatoris dPNG12 2718.JPG|''Prymnaster investigatoris'' (Schizasteridae)Image:Heteraster oblongus.3 - Cretacico inferior.JPG|Fossil of ''Heteraster oblongus'' (Toxasteridae)
See also * ''Abatus agassizii''* ''Meoma ventricosa''
References * *