Except for the Acanthocephala, all these phyla share characteristics such as the structure of their jaws and pharynx. They belong among the Lophotrochozoa, and appear to be particularly close relatives of the Platyhelminthes.
Gnathifera also contains a fourth phylum, the Acanthocephala.
Acanthocephala are highly modified parasites that live in the intestine of vertebrates, thus their feeding biology is so different that their alimentary system, including pharynx and jaws, is totally reduced.
Both Gnathostomulida and Rotifera-Acanthocephala have earlier been difficult to place in the Animal Kingdom, so the gathering of the gnathiferan animals in one group has shed new light on the most basal splits in the Animal Kingdom.
Feeds |
Contact