Platyzoa

Platyzoa
Pseudobiceros bedfordi (Bedford's Flatworm)
Scientific classification
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
(unranked): Protostomia
Superphylum: Platyzoa
Cavalier-Smith, 1998
Phyla

The Platyzoa /ˌplætˈz.ə/ are a group of protostome animals proposed by Thomas Cavalier-Smith in 1998. Cavalier-Smith included in Platyzoa the Phylum Platyhelminthes or flatworms, and a new phylum, Acanthognatha, into which he gathered several previously described phyla of microscopic animals. Subsequent studies have supported Platyzoa as a clade,[1] a monophyletic group of organisms with a common ancestor, while differing on the phyla included and on relationships within Platyzoa.

Phyla

One current scheme places the following traditional phyla in Platyzoa:

Characteristics

None of the Platyzoa groups have a respiration or circulation system because of their small size, flat body or parasitic lifestyle. The Platyhelminthes and Gastrotricha are acoelomate. The other phyla have a pseudocoel, and share characteristics such as the structure of their jaws and pharynx, although these have been secondarily lost in the parasitic Acanthocephala. They form a monophyletic subgroup called the Gnathifera.

The name "Platyzoa" is used because most members are flat, though rotifers are not.[2]

Classification

The Platyzoa are close relatives of the Lophotrochozoa, and are sometimes included in that group. Together the two make up the Spiralia.

References

  1. Passamaneck Y, Halanych KM (July 2006). "Lophotrochozoan phylogeny assessed with LSU and SSU data: evidence of lophophorate polyphyly". Mol. Phylogenet. Evol. 40 (1): 20–8. doi:10.1016/j.ympev.2006.02.001. PMID 16556507.
  2. "Explanations.html". Retrieved 2009-06-28.
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