
Gigantorhynchus is a genus of Acanthocephala that parasitize marsupials, anteaters, and possibly baboons by attaching themselves to the intestines using their hook-covered proboscis. Their life cycle includes an egg stage found in host feces, a cystacanth (larval) stage in an intermediate host such as termites, and an adult stage where cystacanths mature in the intestines of the host. This genus is characterized by a cylindrical proboscis with a crown of robust hooks at the apex followed by numerous small hooks on the rest of the proboscis, a long body with pseudosegmentation, filiform lemnisci, and ellipsoid testes. The largest known specimen is the female G. ortizi with a length of around 240 millimetres (9.4 in) and a width of 2 millimetres (0.08 in). Genetic analysis on one species of Gigantorhynchus places it with the related genus Mediorhynchus in the family Gigantorhynchidae. Six species in this genus are distributed across Central and South America and possibly Zimbabwe. Infestation by a Gigantorhynchus species may cause partial obstructions of the intestines, severe lesions of the intestinal wall, and may lead to death.

Macracanthorhynchus, also known as the giant thorny-headed worm of swine, is a member of the Oligacanthorhynchidae which contains many species. One species, M. hirudinaceus, is a parasite which lives in the intestines of pigs and other suids, and very occasionally in humans or dogs. It causes enteritis, gastritis or peritonitis. Its life cycle includes beetles of the genus Melolontha as intermediate hosts. This species has many synonyms which include: Echinorhynchus gigas, Macracanthorhynchus gigas, Echinorhynchus hirundinacea, Gigantorhynchus hirundinaceus, Gigantorhynchus gigas, Hormorhynchus gigas, Taenia haeruca, and Taenia hirundinaceus The complete mitochondrial genome of M. hirudinaceus has been sequenced. The eggs have 4 membranes are 98 um long and have an elongation ratio of 1.85.

Moniliformidae is a family of parasitic spiny-headed worms. It is the only family in the Moniliformida order and contains three genera: Australiformis containing a single species, Moniliformis containing eighteen species and Promoniliformis containing a single species. Genetic analysis have determined that the clade is monophyletic despite being distributed globally. These worms primarily parasitize mammals, including humans in the case of Moniliformis moniliformis, and occasionally birds by attaching themselves into the intestinal wall using their hook-covered proboscis. The intermediate hosts are mostly cockroaches. The distinguishing features of this order among archiacanthocephalans is the presence of a cylindrical proboscis with long rows of hooks with posteriorly directed roots and proboscis retractor muscles that pierce both the posterior and ventral end or just posterior end of the receptacle. Infestation with Monoliformida species can cause moniliformiasis, an intestinal condition characterized as causing lesions, intestinal distension, perforated ulcers, enteritis, gastritis, crypt hypertrophy, goblet cell hyperplasia, and blockages.

Moniliformidae is a family of parasitic spiny-headed worms. It is the only family in the Moniliformida order and contains three genera: Australiformis containing a single species, Moniliformis containing eighteen species and Promoniliformis containing a single species. Genetic analysis have determined that the clade is monophyletic despite being distributed globally. These worms primarily parasitize mammals, including humans in the case of Moniliformis moniliformis, and occasionally birds by attaching themselves into the intestinal wall using their hook-covered proboscis. The intermediate hosts are mostly cockroaches. The distinguishing features of this order among archiacanthocephalans is the presence of a cylindrical proboscis with long rows of hooks with posteriorly directed roots and proboscis retractor muscles that pierce both the posterior and ventral end or just posterior end of the receptacle. Infestation with Monoliformida species can cause moniliformiasis, an intestinal condition characterized as causing lesions, intestinal distension, perforated ulcers, enteritis, gastritis, crypt hypertrophy, goblet cell hyperplasia, and blockages.

Moniliformis moniliformis is a parasite of the Acanthocephala phylum in the family Moniliformidae. The adult worms are usually found in intestines of rodents or carnivores such as cats and dogs. The species can also infest humans, though this is rare.

Oligacanthorhynchida is an order containing a single parasitic worm family, Oligacanthorhynchidae, that attach themselves to the intestinal wall of terrestrial vertebrates.

Oligacanthorhynchida is an order containing a single parasitic worm family, Oligacanthorhynchidae, that attach themselves to the intestinal wall of terrestrial vertebrates.

Pachysentis is a genus of Acanthocephala that parasitize carnivourous mammals by attaching themselves to the intestines using their hook-covered proboscis. Their life cycle includes an egg stage found in host feces, a cystacanth (larval) stage in an intermediate host such as the Egyptian cobra, and an adult stage where cystacanths mature in the intestines of the host. This genus appears identical to the closely related Oncicola apart from a greater number of hooks on the proboscis. The eleven species in this genus are distributed across Africa and the Americas.