The Echinacea are a superorder of
sea urchins. They are distinguished by the presence of a rigid
test
Test(s), testing, or TEST may refer to:
* Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities
Arts and entertainment
* ''Test'' (2013 film), an American film
* ''Test'' (2014 film), ...
, with ten buccal plates around the mouth, and solid spines. Unlike some other sea urchins, they also possess
gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...
s. The group is a large one, with species found worldwide.
Echinacea are part of
Animalia (kingdom),
Echinodermata
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...
(phylum),
Echinozoa
Echinozoa is a subphylum of free-living echinoderms in which the body is or originally was a modified globe with meridional symmetry. Echinozoans lack arms, brachioles, or other appendages, and do not at any time exhibit pinnate structure. Their t ...
(subphylum),
Echinoidea
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) ...
(class),
Euechinoidea
The subclass Euechinoidea includes almost all living species of sea urchin, and fossil forms going back as far as the Triassic.
Taxonomy
List of orders according to World Register of Marine Species :
* Infra-classis '' Acroechinoidea''
** O ...
(subclass),
Carinacea (infraclass).
Child taxa
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 specialis ...
:
* Order
Arbacioida (Gregory, 1900) -- 1 family and 2 fossiles
* Order
Camarodonta (Jackson, 1912)
** Infraorder
Echinidea (Kroh & Smith, 2010) -- 5 families
** Infraorder
Temnopleuridea (Kroh & Smith, 2010) -- 2 families and 2 fossiles
* Order
Stomopneustoida (Kroh & Smith, 2010) -- 2 families and 1 fossile
* Family
Glyphopneustidae Smith & Wright, 1993 †
Image:Arbacia lixula (oursin noir).JPG,
Image:Paracentrotus lividus profil.JPG,
Image:Black sea urchin (Temnopleurus toreumaticus).jpg,
Image:S. variolaris.jpg,
References
*
*
Extant Early Jurassic first appearances
{{echinoidea-stub