Sea daisy

Sea daisies
Xyloplax janetae
Scientific classification
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

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. The intestine and anus are absent.

Distribution

Sea daisies have been discovered in three localities: deep‑sea habitats off New Zealand, the Bahamas, and the northern central Pacific. They have been collected primarily from sunken, deep‑sea (1,000+ meters) wood. Although known from only a handful of specimens initially, many specimens have now been collected from the Bahamas. In 2026, their known habitat was expanded to depths of up to 5,634 meters after being found to inhabit whale-falls in the Diamantia Zone in the southeastern Indian Ocean^[1].

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 have been considered a sister group to the Infraclass Neoasteroidea, which represents all post-Paleozoic asteroids within the Class Asteroidea.

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

• Genus Xyloplax
  • Xyloplax janetae
  • Xyloplax medusiformis
  • Xyloplax turnerae

References

• Introduction to Xyloplax
• Controversies in Xyloplax Classification
• Classification of the Extant Echinodermata Archived 2006-07-09 at the Wayback Machine
• Nature "A new class of Echinodermata from New Zealand"