Platyzoa

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

The Platyzoa (pronounced /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:

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.

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