[2] They are parasitic worms that attach themselves to the intestinal wall of terrestrial vertebrates, including humans.

They are characterised by the body wall and the lemnisci (which are a bundle of sensory nerve fibers), which have nuclei that divide without spindle formation, or the appearance of chromosomes, or it has a few amoebae-like giant nuclei.

[clarification needed] Typically, there are eight separate cement glands in the male, which is one of the few ways to distinguish the dorsal and ventral sides of these organisms.

However, the lack of features such as an absence of a muscle plate, a midventral longitudinal muscle, lateral receptacle flexors, and an apical sensory organ when compared to the other three orders of class Archiacanthocephala indicate it is an early offshoot (basal).

The worms are also characterised by the body wall and the lemnisci (which are a bundle of sensory nerve fibers),[6] which have nuclei that divide without spindle formation or the appearance of chromosomes or it has a few amoebae-like giant nuclei.