Holasteroida is an order of irregular
sea urchin
Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
s.
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
Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
. The anus (periproct) has migrated towards the periphery of the test. The plastron is never amphisternous.
Maastrichtian
The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...
)
Image:Echinosigra amphora.jpg, '' Echinosigra amphora'' ( Pourtalesiidae)
This order seems to have appeared at the lower
Cretaceous.
List of families
According to
World Register of Marine Species
The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms.
Content
The content of the registry is edited and maintained by scientific speciali ...
:
* 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 †
* Sub-order
Meridosternata (Lovén, 1883)
** Infra-order
Cardiasterina †
*** Family
Cardiasteridae Lambert, 1917 †
*** Family
Stegasteridae Lambert, 1917f †
** Family
Echinocorythidae Wright, 1857 †
** Family
Holasteridae Pictet, 1857 †
*** Genus ''
Salvaster''
Saucède, Dudicourt & Courville, 2012 †
** Infra-order
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
* 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 †
References
Holasteroidaat the
Natural History Museum
A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more ...
*
{{echinoidea-stub