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

Trichosomoides crassicauda drawing in Hall 1916.jpg
Trichosomoides crassicauda, young female with male in vagina, drawing in Hall, 1916 [1]
Scientific classification e
Kingdom: Animalia
Phylum: Nematoda
Class: Enoplea
Subclass: Dorylaimia
Order: Trichocephalida

Anatrichosomatidae Yamaguti, 1961
Capillariidae Railliet, 1915
Cystoopsidae Skrjabin, 1923
Trichinellidae Ward, 1907
Trichosomoididae Hall, 1916
Trichuridae Ransom, 1911




The order Trichocephalida includes, according to modern classifications,[2] the single suborder Trichinellina Hodda, 2007, which itself includes the single superfamily Trichinelloidea Ward, 1907, which itself includes 6 families:

Note that another slightly different arrangement of families exists,[4] with the Family Trichosomoididae including Anatrichosoma in a subfamily Anatrichosomatinae.


Male caudal extremity of Eucoleus aerophilus, the nematode causing pulmonary capillariasis in foxes. Bar = 50 µm

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


  1. ^ a b Hall, M.C. 1916: Nematode parasites of mammals of the orders Rodentia, Lagomorpha and Hyracoidea. Proceedings of the U.S. National Museum, 50, 1–247 Free PDF.
  2. ^ Hodda, M. 2011: Phylum Nematoda Cobb 1932. In: Zhang, Z.-Q. (ed.) 2011: Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness. Zootaxa, 3148: 63–95. ISBN 978-1-86977-849-1 (paperback) ISBN 978-1-86977-850-7 (online edition) Free PDF
  3. ^ Railliet, A. 1915: L'emploi des médicaments dans le traitement des maladies causées par des Nématodes. Recueil de Médecine Vétérinaire, Paris, 91, 490–513. [not seen]
  4. ^ a b Moravec, F. 2001: Trichinelloid Nematodes parasitic in cold-blooded vertebrates. Academia, Praha, 432 pp. (list of genera of Capillariidae in pages 30-32) (ISBN 8020008055)