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Holasteroida
Order of sea urchins From Wikipedia, the free encyclopedia
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Holasteroida is an order of irregular sea urchins.
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Characteristics
These irregular sea urchins are characterized by a particularly marked bilateral symmetry, including for the apical system, which is highly elongated. In some contemporary abyssal groups such as Pourtalesiidae, some species are even bottle-shaped. The mouth (peristome) does not contain an Aristotle's lantern. The anus (periproct) has migrated towards the periphery of the test. The plastron is never amphisternous.[1]
Echinosigra amphora (Pourtalesiidae)
This order seems to have appeared at the lower Cretaceous.[1]
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List of families
According to World Register of Marine Species :
- † Family Disasteridae Gras, 1848
- genus † Disaster L. Agassiz, 1835
- Family Hemipneustidae (Lambert, 1917) †
- genus Hemipneustes L. Agassiz, 1835 †
- genus Medjesia Jeffery, 1997 †
- genus Opisopneustes Gauthier, 1889 †
- genus Plesiohemipneustes Smith & Wright, 2003 †
- genus Toxopatagus Pomel, 1883 †
- Suborder Meridosternata (Lovén, 1883)
- Infraorder Cardiasterina †
- Family Cardiasteridae Lambert, 1917 †
- Family Stegasteridae Lambert, 1917f †
- Family Echinocorythidae Wright, 1857 †
- Family Holasteridae Pictet, 1857 †
- Genus Salvaster Saucède, Dudicourt & Courville, 2012 †
- Infraorder Urechinina
- Family Calymnidae Mortensen, 1907
- Family Carnarechinidae Mironov, 1993
- Family Corystusidae Foster & Philip, 1978
- Family Plexechinidae Mooi & David, 1996
- Family Pourtalesiidae A. Agassiz, 1881
- Family Urechinidae Duncan, 1889
- Infraorder Cardiasterina †
- Family Pseudholasteridae (Smith & Jeffery, 2000) †
- genus Eoholaster Solovjev, 1989 †
- genus Giraliaster Foster & Philip, 1978 †
- genus Pseudholaster Pomel, 1883 †
- genus Taphraster Pomel, 1883 †
- Family Stenonasteridae (Lambert, 1922) †
- genus Stenonaster Lambert, 1922 †
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References
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