Protostomia (blastopore becomes the mouth; scizocoel)

Gastrotricha
 Xenotrichula velox

Cycliophora


Gnathifera


Gnathifera - Gnathostomulida


Gnathifera - Micrognathozoa


Gnathifera - Acanthocephala



Gnathifera - Rotifera


Gnathifera - Seisonidea