词条 | Spatangoida |
释义 |
| name = Heart urchins | image = Spatangus purpureus rob.jpg | image_width = 250px | image_caption = Spatangus purpureus | fossil range = {{Fossil_range|Lower Cretaceous|recent}} | regnum = Animalia | phylum = Echinodermata | classis = Echinoidea | superordo = Atelostomata | ordo = Spatangoida | ordo_authority = L. Agassiz, 1840 | subdivision_ranks = Suborders | subdivision =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. TaxonomyAccording to World Register of Marine Species :
See also
References
2 : Spatangoida|Extant Early Cretaceous first appearances |
随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识,基本涵盖了大多数领域的百科知识,是一部内容自由、开放的电子版国际百科全书。