Gigantorhynchus echinodiscus Species of the genus Moniliformis are usually pseudosegmented and have a cylindrical proboscis with longitudinal rows of hooks that have posteriorly directed roots.

Moniliformis species are further characterized by the presence of a simple, double-walled proboscis receptacle with the outer wall having spirally aligned muscle fibers, brain at posterior end of receptacle, and dorsal and ventral lacunar canals.

[7] The cerebral ganglion is in the mid to posterior region, and the lemnisci are long and flat and not bound to the body wall.

These worms also lack protonephridia and males have eight cement glands, each with a giant nucleus, which are used to temporarily close the posterior end of the female after copulation.

[12] M. acomysi was found infesting the Cairo spiny mouse (Acomys cahirinus) in South Sinai, Egypt.

[13] M. amini was found in the small intestine parasitising the olive grass mouse (Abrothrix olivaceus) in the Santa Cruz Province, Argentina.

[1][16] M. clarki commonly infects squirrels, chipmunks, deer mice, and gophers in North America.

Ten cotton-top tamarins (Saguinus oedipus) were infected at the St. Louis Zoo with at least one being killed by the parasite.

[17] Eggs of what is thought to be M. clarki due to the heavy population of common rodent hosts were discovered while examining human coprolite specimens gathered from Danger Cave in Utah.

[16] M. convolutus has been found infesting the large flying fox (Pteropus vampyrus) in Brazil.

[1] M. cryptosaudi is a cryptic species with M. saudi being morphologically identical, apart from the metal content of the hooks, but genetically distinct.

It has been found in the intestine infesting the long-eared Hedgehog (Hemiechinus auritus) near Baqubah, Iraq.

[2] M. echinosorexi has been found infesting the moonrat (Echinosorex gymnurus) in Malaysia but may also infect hedgehogs.

In the juvenile, the reproductive system is underdeveloped, with ovoid testes and occasionally lacking cement glands.

The female reproductive system measures 572 to 946 μm in total length but lacks vaginal muscles.

[22] M. moniliformis is a globally distributed parasite where the adult worms are usually found in intestines of rodents or carnivores such as cats and dogs but can on rare occasions infest humans.

After this time, the eggs are excreted with the feces, to be ingested yet again by another intermediate host and renew this cycle.

It is thought that this behavioral change holds an evolutionary advantage for the parasite by increasing its chances of getting to its definitive host.

[26] Another study concludes an increased vulnerability of infected Periplaneta americana due to increased phototaxis, more time spent moving (due to slower movement) and movement in response to light (uninfected cockroaches hesitated before moving).

[27] Cases of moniliformiasis, a form of acanthocephaliasis, caused by human infestation by M. moniliformis have been reported in the United States, Iran, Iraq, and Nigeria,[23] but human moniliformiasis is now rare as it requires consumption of raw infested beetles or cockroaches.

Calandruccio provided the first description of the clinical manifestations of moniliformiasis and similar accounts are found in the few case studies since; many of the patients described were asymptomatic.

When they showed symptoms, they normally experienced abdominal pain, diarrhea, dizziness, edema, and anorexia.

M. monoechinus was found infesting the Giant anteater (Myrmecophaga tridactyla) in South America.

[1] M. necromysi has been found infesting the hairy-tailed bolo mouse (Necromys lasiurus) in the cerrado in the state of Minas Gerais, Brazil.

Phylogenetic analyses using the partial mitochondrial cytochrome c oxidase subunit I gene and the nuclear large subunit ribosomal RNA gene demonstrated that this worm forms a well-supported monophyletic group within the genus Moniliformis.

M. saudi is morphologically identical to M. cryptosaudi, apart from the metal content of the hooks and genetic analysis.

[2] M. siciliensis has been found infesting the brown rat (Rattus norvegicus[15] reported as Mus decumanus), and the garden dormouse (Eliomys quercinus) in Sicily, Italy.

[9] M. tarsii was found infesting the small and large intestines of Horsfield's tarsier (Tarsius bancanus) in Poring, Sabah, Malaysia.

The males also have eight cement glands each with a single giant nucleus located posterior to the testes.

This stage involves penetrating the wall of the mesenteron or the intestine of the intermediate host and growing.