Xenoturbella is a genus of very simple bilaterians up to a few centimeters long. It contains a small number of marine benthic worm-like species.
Convolutidae is a family of acoels, belonging to the phylum Xenacoelomorpha. This family contains more than a third of all known acoel species.
Acoela, or the acoels, is an order of small and simple invertebrates in the subphylum Acoelomorpha of phylum Xenacoelomorpha, a deep branching bilaterian group of animals, which resemble flatworms. Historically they were treated as an order of turbellarian flatworms. About 400 species are known, but probably many more not yet described.
Actinoposthiidae is a family of acoels.
Childia is a genus of acoels in the family Mecynostomidae.
Diopisthoporus is a genus of acoels. It is the only genus in the monotypic family Diopisthoporidae
Hallangiidae is a family of Acoela. It contains 2 species in 2 genera.
Mecynostomidae is a family of acoels.
Nemertodermatidae is a family of wormlike animals in the phylum Acoelomorpha. They are similar to the flatworms of the phylum Platyhelminthes, and were traditionally classified as such.
Isodiametridae is a family of acoels.
Centrovarioplana tenuis is a species of Maricola triclad that is found in Antarctica. It is the only species known in the monotypic genus Centrovarioplana and the family Centrovarioplananidae.
Neppia is a genus of dugesiid triclad that is found in South America, Subantarctic region, Africa, Tasmania and New Zealand.
Pseudostomum is a genus of flatworms in the family Pseudostomidae.
Microstomum is a genus of flatworms in the family Microstomidae.
Meara is a genus of bilaterally symmetric, small aquatic worms in the phylum Acoelomorpha. This genus contains only one species, Meara stichopi, a parasite of the sea cucumber Parastichopus tremulus. It occurs in Norway and Sweden.
Multipeniata is a genus of flatworms in the order Prolecithophora. It is the only genus in the monotypic family Multipeniatidae.
Hallangia is a genus of acoels belonging to the family Hallangiidae.
Faerlea is a genus of acoels belonging to the family Isodiametridae.
Intoshia is a genus of worms belonging to the family Rhopaluridae.
Nemertoderma is a genus of acoelomorphs belonging to the family Nemertodermatidae.
