Sea daisy: Difference between revisions
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| genus = '''''Xyloplax''''' |
| genus = '''''Xyloplax''''' |
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| subdivision_ranks = Species |
| subdivision_ranks = Species |
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| subdivision = |
| subdivision = See text. |
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* ''X. medusiformis'' |
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* ''X. turneae'' |
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* ''X. janetae'' |
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}} |
}} |
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Sea daisies typically have two [[circumoral canal]]s and a single peripheral ring of tube feet (i.e., podia). Concentricyloids (commonly known as sea daisies) were supported as members of the asteroid lineage, although its exact relationship to other asteroids is likely to remain a contentious issue. |
Sea daisies typically have two [[circumoral canal]]s and a single peripheral ring of tube feet (i.e., podia). Concentricyloids (commonly known as sea daisies) were supported as members of the asteroid lineage, although its exact relationship to other asteroids is likely to remain a contentious issue. |
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==Distribution== |
==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, nearly 100 specimens have been collected from the Bahamas with decent numbers collected from the north central Pacific. |
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, nearly 100 specimens have been collected from the Bahamas with decent numbers collected from the north central Pacific. |
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==Classification== |
==Classification== |
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They were discovered in [[1986]] and their position within the echinoderms has been contentious, being placed at first in a new class, ''Concentricycloidea''. As of [[2006]], they are considered the sister branch to the Infraclass Neoasteroidea, which represents all post-Paleozoic asteroids (i.e., modern Asteroidea), within the Class Asteroidea. |
They were discovered in [[1986]] and their position within the echinoderms has been contentious, being placed at first in a new class, ''Concentricycloidea''. As of [[2006]], they are considered the sister branch to the Infraclass Neoasteroidea, which represents all post-Paleozoic asteroids (i.e., modern Asteroidea), within the Class Asteroidea. |
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Class Asteroidea |
Class Asteroidea, |
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Infraclass Concenricycloidea |
Infraclass Concenricycloidea, |
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Order Peripodida |
Order Peripodida, |
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Family [[Xyloplacidae]] |
Family [[Xyloplacidae]] |
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* Genus ''[[Xyloplax]]'' |
* Genus ''[[Xyloplax]]'' |
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** ''Xyloplax medusiformis'' |
** ''[[Xyloplax medusiformis]]'' |
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** ''Xyloplax turneae'' |
** ''[[Xyloplax turneae]]'' |
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** ''Xyloplax janetae'' |
** ''[[Xyloplax janetae]]'' |
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==References== |
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* [http://www.calacademy.org/research/izg/echinoderm/classify.htm] |
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* [http://www.nature.com/nature/journal/v321/n6073/abs/321862a0.html Nature]] |
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[[Category:Echinoderms]] |
[[Category:Echinoderms]] |
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Revision as of 14:32, 12 January 2007
| Sea daisies | |
|---|---|
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | |
| Order: | Peripoda Baker, Rowe & Clark, 1986
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| Family: | Xyloplacidae
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| Genus: | Xyloplax
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| Species | |
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See text. | |
Sea daisies (Infraclass Concentricycloidea; order Peripoda) make up an unusual group of deep-sea taxa belonging to the phylum Echinodermata, with three species described in the genus Xyloplax.
Characteristics
These species have disk-shaped flattened body and are less than 1 cm in diameter. They have a water-vascular system and are dotted with tube feet around the edge of the disk. They do not have arms, but five ambulacral areas. A gut is either reduced or absent, depending on the species. An oral opening is present, but it is unclear how these organisms derive their nutrition.
Sea daisies typically have two circumoral canals and a single peripheral ring of tube feet (i.e., podia). Concentricyloids (commonly known as sea daisies) were supported as members of the asteroid lineage, although its exact relationship to other asteroids is likely to remain a contentious issue.
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, nearly 100 specimens have been collected from the Bahamas with decent numbers collected from the north central Pacific.
Classification
They were discovered in 1986 and their position within the echinoderms has been contentious, being placed at first in a new class, Concentricycloidea. As of 2006, they are considered the sister branch to the Infraclass Neoasteroidea, which represents all post-Paleozoic asteroids (i.e., modern Asteroidea), within the Class Asteroidea.
Class Asteroidea, Infraclass Concenricycloidea, Order Peripodida, Family Xyloplacidae