name = Heterotrichs

image_width = 200px
image_caption = "Stentor roeseli"
domain = Eukaryota
regnum = Chromalveolata
superphylum = Alveolata
phylum = Ciliophora
classis = Heterotrichea
classis_authority = Stein 1859
subdivision_ranks = Typical orders
subdivision =
The heterotrichs are a class of ciliates. They typically have a prominent adoral zone of membranelles circling the mouth, used in locomotion and feeding, and shorter cilia on the rest of the body. Many species are highly contractile, and are typically compressed or conical in form. These include some of the largest protozoa, such as "Stentor" and "Spirostomum", as well as many brightly pigmented forms, such as certain "Blepharisma".

A number of ultrastructural details characterize the group. The cilia on the body are in dikinetids, in which either the anterior one or both kinetosomes may be ciliated, and which are associated with fibers composed of overlapping postciliary microtubules, called "postciliodesmata" and found only in this group and the closely related Karyorelictea. A series of oral polykinetids, each containing two or three rows of kinetosomes, support the membranelles. These run from the left to the anterior of the mouth, and often spiral out of the oral cavity. The macronucleus is divided by external microtubules, whereas in the Karyorelictea it forms by differentiation of micronuclei, and in all other ciliates it is divided by internal microtubules.

Traditionally the heterotrichs have been treated as a subgroup of spirotrichs, but more recent work has found that they are not closely related to the other groups placed there, and accordingly they tend to be given their own class. Most belong to the order Heterotrichida; the position of the other orders is not clear, and Lynn has suggested that they do not really belong here, tentatively returning some to the Spirotrichea and treating others as a new class (Armophorea).

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  • heterotrich — heterotrichous /het euh ro treuh keuhs/, adj. /het euhr euh trik/, n. any ciliate of the suborder Heterotricha, having the body covered uniformly with short cilia. [ < NL Heterotricha name of the order. See HETERO , TRICHA] * * * ▪ protozoan… …   Universalium

  • heterotrich — het·er·o·trich …   English syllables

  • heterotrich — ˈ ̷ ̷ ̷ ̷rōˌtrik noun ( s) Etymology: New Latin Heterotricha : one of the Heterotricha * * * heterotrichous /het euh ro treuh keuhs/, adj. /het euhr euh trik/, n. any ciliate of the suborder Heterotricha, having the body covered uniformly …   Useful english dictionary

  • Climacostomum — sp. Scientific classification Domain: Eukaryota Ki …   Wikipedia

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  • Stentor (protozoa) — Taxobox | color = khaki name = Stentor image width = 200px image caption = Stentor roeseli domain = Eukarya regnum = Protista superphylum = Alveolata phylum = Ciliophora classis = Heterotrichea ordo = Heterotrichida familia = Stentoridae genus =… …   Wikipedia

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  • Spirotrich — Taxobox | color = khaki name = Spirotrichs image caption = Euplotes, a spirotrich domain = Eukaryota unranked phylum = Alveolata phylum = Ciliophora classis = Spirotrichea classis authority = Bütschli 1889 subdivision ranks = Typical sublasses… …   Wikipedia

  • Holotrich — Holotrichs are ciliate protozoa that have relatively uniform cilia over their body, and lack or only have a few prominent oral membranelles. Most of the major lines of ciliates are holotrichous. They do not form a natural group, so the term is… …   Wikipedia

  • -trich — a combining form meaning one having hair of the kind or number specified by the initial element; often used to name a single member of a taxonomic group ending in tricha: heterotrich; hypotrich. [ < Gk trichos haired, adj. deriv. of thríx (s.… …   Universalium

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