Platyzoa

Taxobox
name = Platyzoa


image_width = 200px
image_caption = Bedford's Flatworm, "Pseudobiceros bedfordi"
regnum = Animalia
subregnum = Eumetazoa
unranked_phylum = Bilateria
superphylum = Platyzoa
superphylum_authority = Cavalier-Smith, 1998
subdivision_ranks = Phyla
subdivision =

* Platyhelminthes
* Gastrotricha
* "Gnathifera (unranked)"
** Rotifera
** Acanthocephala
** Gnathostomulida
** Micrognathozoa
** CycliophoraThe Platyzoa (pronEng|ˌplætɨˈzoʊə) 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, a monophyletic group of organisms with a common ancestor, while differing on the phyla included and on relationships within Platyzoa.

One current scheme places the following traditional phyla in Platyzoa:
* Platyhelminthes
* Gastrotricha
* Gnathifera
** Rotifera
** Acanthocephala
** Gnathostomulida
** Micrognathozoa
** Cycliophora

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

References

* [http://sn2000.taxonomy.nl/Taxonomicon/TaxonTree.aspx?id=126691 The Taxonomicon - Taxon: Infrakingdom Platyzoa Cavalier-Smith, 1998] - retrieved January 31 2006
* [http://www.paru.cas.cz/folia/pdf/2-01/Zrz.pdf The interrelationships of metazoan parasites: a review of phylum- and higher-level hypotheses from recent morphological and molecular phylogenetic analyses] - retrieved January 31 2006
* [http://taylorandfrancis.metapress.com/(karlsa55kkmi3nmox1xujfbv)/app/home/contribution.asp?referrer=parent&backto=issue,9,14;journal,32,42;linkingpublicationresults,1:102493,1 Triploblastic Relationships with Emphasis on the Acoelomates and the Position of Gnathostomulida, Cycliophora, Plathelminthes, and Chaetognatha: A Combined Approach of 18S rDNA Sequences and Morphology] - retrieved January 31 2006
* [http://www.blackwell-synergy.com/doi/abs/10.1111/j.1096-0031.2001.tb00116.x Myzostomida Are Not Annelids: Molecular and Morphological Support for a Clade of Animals with Anterior Sperm Flagella] - retrieved January 31 2006
* [http://www.botany.utoronto.ca/ResearchLabs/guttmanLab/Bot1700/Giribet_2002_MPE(24)345.pdf Current advances in the phylogenetic reconstruction of metazoan evolution. A new paradigm for the Cambrian explosion?] - retrieved January 31 2006