Sea daisies (infraclass Concentricycloidea;
order
Order, ORDER or Orders may refer to:
* A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica
* Categorization, the process in which ideas and objects are recognized, differentiated, and understood
...
Peripodida) make up an unusual group of deep-sea taxa belonging to the phylum
Echinodermata
An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as larvae, ...
, with three
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
described in the genus ''Xyloplax''. Intestine and anus are absent.
Distribution
Sea daisies have been discovered in three localities, including deep-sea habitats off New Zealand, the Bahamas and most recently from the northern central Pacific. They have been collected primarily from sunken, deep-sea (1000+ meters) wood. Although known from only a handful of specimens initially, many specimens have now been collected from the Bahamas.
Classification
Since they were discovered in 1986, their position within the echinoderms has been debated. At first they were placed in a new class, Concentricycloidea, since it was unclear whether they might have affinities with asteroids or ophiuroids. The former view gained acceptance, and since 2006, they are currently considered a sister group to the Infraclass Neoasteroidea, which represents all post-Paleozoic asteroids within the Class
Asteroidea
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...
.
Class Asteroidea,
Infraclass Concentricycloidea,
Order Peripoda (or Peripodida),
Family Xyloplacidae
* Genus ''Xyloplax''
** ''
Xyloplax janetae
''Xyloplax janetae'' is a ''Xyloplax'' of the family Xyloplacidae. It lives on the surface of wood sunken to abyssal depths.
Morphology
''Xyloplax janetae'' is a flattened disk, from in diameter, and about thick. It has adambulacral spines whi ...
''
** ''
Xyloplax medusiformis''
** ''
Xyloplax turnerae''
References
Introduction to Xyloplax
{{Taxonbar, from=Q1078908
Peripodida