Synonym: Rouphozoa
ZoologyThey have bilateral symmetry, so they have and up and down side and a front and backside; this makes the development of a head with senses possible.
They have 3 germ layers: endoderm, ectoderm and mesoderm; they triploblast.
Gnatifera: srmall, flat, unsegmented animals; protostome; no respiration system; no circulation system; flat body or parasitic lifestyle.
TaxonomyPlatyzoa is proposed by Thomas Cavalier-Smith in 1998. He included in
Platyzoa the phylum
Platyhelminthes, flatworms, and a new phylum, the Acanthognatha, several phyla of microscopic animals. More recently it has been described as the Rouphozoa and the
Gnathifera.
Rouphozoa, Platyhelminthes and Gastrotricha, are acoelomate.Gnathifera: have a pseudocoel; characteristic structure of their jaws and pharynx.
Gnathifera Gnathostomulida Micrognathozoa Chaetognatha Rotifera Seisonida
Acanthocephala Bdelloidea
Monogononta
Platytrochozoa
Rouphozoa, acoelomate
Platyhelminthes, flatworms
GastrotrichaGnathifera Syndermata
Rotifera, no flat, round
Seisonida
Acanthocephala, parasitic
Gnathostomulida Micrognathozoa Cycliophora