Members:
PlatyzoaZoologyThey 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.
Propriosepsis is the ability to perceive oneself and one’s body in space, where it is, where the limbs are, and how one moves in space.
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