Archiacanthocephala is a class within the phylum of

Acanthocephala Acanthocephala (Greek , ', thorn + , ', head) is a phylum 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 p ...

. They are

parasitic worms Parasitic worms, also known as helminths, are large Parasitism#Basic concepts, macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted helminth, soil-transmitted and intestinal parasit ...

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. Typically, there are eight separate

cement glands Cement glands are small organs found in Acanthocephala that are used to temporarily close the posterior end of the female after copulation. Cement glands are also mucus-secreting organs that can attach embryos or larvae to a solid substrate. The ...

in the male, which is one of the few ways to distinguish the dorsal and ventral sides of these organisms.

Taxonomy

Genetic data are not available for the genus ''

Apororhynchus ''Apororhynchus'' is a genus of small parasitic spiny-headed (or thorny-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 phy ...

'' in public databases, and ''Apororhynchus'' has not been included in

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses thus far due to insufficiency of morphological data. However, the lack of features such as an absence of a muscle plate, a midventral

longitudinal Longitudinal is a geometric term of location which may refer to: * Longitude ** Line of longitude, also called a meridian * Longitudinal engine, an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, ...

muscle,

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

receptacle flexors, and an apical sensory organ when compared to the other three orders of class Archiacanthocephala indicate it is an early offshoot (

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

). There are four orders in the class Archiacanthocephala: *

Apororhynchida ''Apororhynchus'' is a genus of small parasitic spiny-headed (or thorny-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 phy ...

Gigantorhynchida Gigantorhynchida is an order containing a single family, Gigantorhynchidae of parasitic worms that attach themselves to the intestinal wall of terrestrial vertebrates. Gigantorhynchida contains the following three genera: *'' Gigantorhynchus'' H ...

Moniliformida Moniliformidae is a family of parasitic spiny-headed (or thorny-headed) worms. It is the only family in the Moniliformida order and contains three genera: ''Australiformis'' containing a single species, ''Moniliformis'' containing eighteen specie ...

Oligacanthorhynchida Oligacanthorhynchida is an order containing a single parasitic worm family, Oligacanthorhynchidae, that attach themselves to the intestinal wall of terrestrial vertebrates. Taxonomy and description Species ''Oligacanthorhynchida'' contains tw ...

Description

All species in the class Archiacanthocephala are terrestrial and use terrestrial insects and

myriapods Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. The fossil record of myriapods reaches back into the late Silurian, ...

as intermediate hosts and predatory birds and mammals as a primary host.Ribas A, Casanova JC (2006) Acanthocephalans. In: Morand S, Krasnov BR, Poulin R (eds) Micromammals and macroparasites. From Evolutionary Ecology to Management. Springer–Verlag, Tokyo, pp 81–90 They attach themselves to the intestinal wall using a hook covered

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elonga ...

. The worms are also 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.

References

Acanthocephalans Animal parasites of vertebrates Microscopic animals {{Acanthocephalan-stub

Taxonomy

Description

See also

References