Sea daisies (infraclass Concentricycloidea; order Peripodida) make up an unusual group of deep-sea taxa belonging to the phylum Echinodermata, with three species described in the genus Xyloplax. Intestine and anus are absent.

Sea daisies
Xyloplax janetae
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Echinodermata
Class: Asteroidea
Infraclass: Concentricycloidea
Baker, Rowe & Clark, 1986
Order: Peripodida
Baker, Rowe & Clark, 1986
Family: Xyloplacidae
Baker, Rowe & Clark, 1986
Genus: Xyloplax
Baker, Rowe & Clark, 1986
Species

Xyloplax janetae
Xyloplax medusiformis
Xyloplax turnerae

Distribution

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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

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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.

Class Asteroidea, Infraclass Concentricycloidea, Order Peripoda (or Peripodida), Family Xyloplacidae

References

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