The Trichocephalida (Trichinellida or Trichurida in other classifications) is an order of parasitic nematodes.

Taxonomy

The order Trichocephalida includes, according to modern classifications, the single suborder Trichinellina Hodda, 2007, which itself includes the single superfamily Trichinelloidea Ward, 1907, which itself includes 6 families: * Family

Anatrichosomatidae Anatrichosomatidae is a family of nematodes belonging to the order Trichocephalida. Genera: * ''Anatrichosoma ''Anatrichosoma'' is a genus of nematodes The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitu ...

Yamaguti, 1961 (1

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

, 5 species) including the single genus '' Anatrichosoma'' * Family

Capillariidae ''Capillariidae'' is a family of parasitic nematodes. All its members are parasites in vertebrates when they are in their adult stage. Taxonomy The family Capillariidae was created by Railliet in 1915. It is accepted in the most recent classifi ...

Railliet, 1915 Railliet, A. 1915: L'emploi des médicaments dans le traitement des maladies causées par des Nématodes. ''Recueil de Médecine Vétérinaire, Paris,'' 91, 490–513. ot seen/ref> (1 subfamily, 18-22 genera according to classifications,Moravec, F. 2001: Trichinelloid Nematodes parasitic in cold-blooded vertebrates. Academia, Praha, 432 pp. (list of genera of Capillariidae in pages 30-32) () 390 species) including '' Capillaria'' * Family

Cystoopsidae Cystoopsidae is a family of nematodes belonging to the order Trichocephalida The Trichocephalida (Trichinellida or Trichurida in other classifications) is an order of parasitic nematodes. Taxonomy The order Trichocephalida includes, according ...

Skrjabin, 1923 (2 subfamilies, 2 genera, 7 species) * Family

Trichinellidae The family Trichinellidae includes the genus ''Trichinella''. ''Trichinella'', also known as the trichina worm, is responsible for the disease trichinosis Trichinosis, also known as trichinellosis, is a parasitic disease caused by roundwor ...

Ward, 1907 (4 genera, 16 species) including ''

Trichina ''Trichinella'' is the genus of parasitic roundworms of the phylum Nematoda that cause trichinosis (also known as trichinellosis). Members of this genus are often called trichinella or trichina worms. A characteristic of Nematoda is the one-w ...

'' * Family

Trichosomoididae The ''Trichosomoididae'' is a family of nematodes. Morphological characteristics The Trichosomoididae, as most nematodes, have an elongate body, vermiform and covered with a cuticle. There is often a cuticular ornamentation in form of cephalic ...

Hall, 1916Hall, M.C. 1916: Nematode parasites of mammals of the orders Rodentia, Lagomorpha and Hyracoidea. Proceedings of the U.S. National Museum, 50, 1–24
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(2 subfamilies, 5 genera, 25 species) including ''

Huffmanela ''Huffmanela'' is a genus of parasitic nematodes, belonging to the family Trichosomoididae. Morphology As other nematodes, species of ''Huffmanela'' are elongate and vermiform. They are especially thin and small. The male is smaller than the fem ...

'' * Family Trichuridae Ransom, 1911 (1 subfamily, 6 genera, 107 species) including ''

Trichuris ''Trichuris'', often referred to as whipworms (which typically refers to ''T. trichiura'' only in medicine, and to any other species in veterinary medicine), is a genus of parasitic worms from the roundworm family Trichuridae, which are helmin ...

'' Note that another slightly different arrangement of families exists, with the Family

including '' Anatrichosoma'' in a subfamily Anatrichosomatinae.

Biology

All members of this order are histiotrophic, meaning that in at least one stage of their

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring * Life-cycle hypothesis ...

, they develop in

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

s or tissues. They are all parasites in

vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

in their adult stage. The anterior end is narrower than the posterior end in most of these worms, and the

esophagus The esophagus ( American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to ...

is slender and embedded in cells called stichocytes which form a stichosome. Eggs of members of this order have bipolar or biopercular plugs (except in a few species).

References

{{Taxonbar, from=Q4051744 Parasitic nematodes of vertebrates Nematode orders es:Trichurida sk:Nitkovky