The Trichocephalida (Trichinellida or Trichurida in other classifications) is an

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

of parasitic

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

Taxonomy

The

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 Yamaguti, 1961 (1

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

, 5 species) including the single genus ''

Anatrichosoma ''Anatrichosoma'' is a genus of nematodes belonging to the family Trichuridae The roundworm family Trichuridae includes the type genus ''Trichuris'' and some less widely known members. They are (after the abolishment of the artificial "Adenoph ...

'' * Family Capillariidae

Railliet Louis-Joseph Alcide Railliet (also known as Alcide Railliet, born 11 March 1852 at La Neuville-lès-Wasigny in the Ardennes – died 25 December 1930) was a French veterinarian and helminthologist. Professor at the Veterinary School of Alfort, ...

, 1915

, 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 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 nomenclat ...

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 ''Capillaria'' ( hu, Capillária, 1921) is a fantasy novel by Hungarian author Frigyes Karinthy, which depicts an undersea world inhabited exclusively by women, recounts, in a satirical vein reminiscent of the style of Jonathan Swift, the firs ...

'' * Family Cystoopsidae Skrjabin, 1923 (2 subfamilies, 2

, 7 species) * Family Trichinellidae Ward, 1907 (4

, 16 species) including '' Trichina'' * Family Trichosomoididae 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

, 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 The roundworm family Trichuridae includes the type genus ''Trichuris'' and some less widely known members. They are (after the abolishment of the artificial "Adenophorea" assemblage) placed in subclass Dorylaimia of the class Enoplea; however, th ...

Ransom, 1911 (1 subfamily, 6

, 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 helmint ...

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

'' in a subfamily Anatrichosomatinae.

Biology

All members of this order are histiotrophic, meaning that in at least one stage of their life cycle, they develop in cells 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, ...

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 the ...

is slender and embedded in cells called

stichocyte Stichocytes are glandular unicellular cells arranged in a row along the posterior portion of the oesophagus, each of which communicates by a single pore with the lumen of the oesophagus. They contain mitochondria, rough endoplasmic reticulum, abund ...

s which form a

stichosome Stichosome (from Greek ''stichos (στίχος)'' = row; ''soma (σῶµα)'' = body) is a multicellular organ that is very prominent in some stages of nematodes and consists of a longitudinal series of glandular unicellular cells ( stichocytes) a ...

. 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