颚胃动物门（学名Gnathostomulida）是动物界的一个门。这类无体腔的动物体型很小，生活在浅海细砂间，一直未被发现，于1956年发现。目前已记录了18个属，大约有100种。

Gnathostomulids, or jaw worms, are a small phylum of nearly microscopic marine animals. They inhabit sand and mud beneath shallow coastal waters and can survive in relatively anoxic environments. They were first recognised and described in 1956.