Acanthocephala is a group of parasitic worms known as acanthocephalans, thorny-headed worms, or spiny-headed worms, characterized by the presence of an eversible proboscis, armed with spines, which it uses to pierce and hold the gut wall of its host. Acanthocephalans have complex life cycles, involving at least two hosts, which may include invertebrates, fish, amphibians, birds, and mammals. About 1420 species have been described.
The paraphyletic "Platyzoa" are a group of protostome unsegmented animals proposed by Thomas Cavalier-Smith in 1998. Cavalier-Smith included in Platyzoa the phylum Platyhelminthes, and a new phylum, the Acanthognatha, into which he gathered several previously described phyla of microscopic animals. Later it has been described as paraphyletic, containing the Rouphozoa and the Gnathifera.
Archiacanthocephala is a class within the phylum of Acanthocephala. 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 have nuclei that divide without spindle formation, or the appearance of chromosomes, or it has a few amoebae-like giant nuclei. 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.
Eoacanthocephala is a class of parasitic worms, within the phylum Acanthocephala. They feed on any aquatic cold-blooded creature such as turtles and fish. Their proboscis spines are arranged radially, with no protonephridia, and with persistent ligament sacs in female. The only reliable way to identify the group is that they only have one cement gland. This is a primitive characteristic and hence the name. The class contains 2 orders:
Apororhynchus is a genus of small parasitic spiny-headed worms. It is the only genus in the family Apororhynchidae, which in turn is the only member of the order Apororhynchida. A lack of features commonly found in the phylum Acanthocephala suggests an evolutionary branching from the other three orders of class Archiacanthocephala; however no genetic analysis has been completed to determine the evolutionary relationship between species. The distinguishing features of this order among archiacanthocephalans is a highly enlarged proboscis which contain small hooks. The musculature around the proboscis is also structured differently in this order. This genus contains six species that are distributed globally, being collected sporadically in Hawaii, Europe, North America, South America, and Asia. These worms exclusively parasitize birds by attaching themselves around the cloaca using their hook-covered proboscis. The bird hosts are of different orders, including owls, waders, and passerines. Infestation by an Apororhynchus species may cause enteritis and anemia.
Mediorhynchus is a genus of small parasitic spiny-headed worms. Phylogenetic analysis has been conducted on two known species of Mediorhynchus and confirmed the placement along with the related genus Gigantorhynchus in the family Gigantorhynchida. The distinguishing features of this order among archiacanthocephalans is a divided proboscis. This genus contains fifty-eight species that are distributed globally. These worms exclusively parasitize birds by attaching themselves around the cloaca using their hook-covered proboscis. The bird hosts are of different orders.
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.
Arhythmacanthidae is a family of parasitic worms from the order Echinorhynchida.
Diplosentidae is a family of parasitic worms from the order Echinorhynchida.
Echinorhynchidae is a family of acanthocephalan parasitic worms from the order Echinorhynchida. The adult worms live in the intestines of fishes, amphibians and reptiles. The family contains the following genera, organised by subfamily.
Polyacanthorhynchidae is a family of parasitic worms from the. It contains a single genus Polyacanthorhynchus.
Rhadinorhynchidae is a family of parasitic worms from the order Echinorhynchida.
Telosentis exiguus is a widespread intestinal parasitic worm. Its hosts are marine and brackish water fish of the Mediterranean basin.
Transvenidae is a family of parasitic spiny-headed worms in the order Echinorhynchida. This family contains three species divided into two genera.
Acanthocephala terminalis is a species of leaf-footed bug in the family Coreidae. It is found in North America.
Sauracanthorhynchus is a genus of thorny-headed worms. It is the only genus in the family Sauracanthorhynchidae in the order Echinorhynchida. It contains a single species Sauracanthorhynchus sphenomorphicola. It was found the intestines of the skink Sphenomorphus granulatus. The host is found from the Huon Peninsula to Milne Bay Province, and the adjacent D'Entrecasteaux Islands of Fergusson, and Normamby. The reported range of the parasite is restricted to Milne Bay Province, Papua New Guinea. The genus is named after the order of its host, and the species is named after the genus of its host.
Isthmosacanthus is a genus of thorny-headed worms. It is the only genus in the family Isthmosacanthidae in the order Echinorhynchida. Isthmosacanthus has only one species, Isthmosacanthus fitzroyensis. It is found in threadfin fish of Northern Australia.
Pachysentis is a genus in Acanthocephala that parasitize primates and carnivorans 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. There are eleven species assigned to this genus although P. septemserialis has an uncertain taxonomic status. Pachysentis species are distributed across Africa and the Americas.
Isthomosacanthidae is a family of parasitic spiny-headed worms.
