Spirotrich

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
subdivision =
Hypotrichia
Stichotrichia
Oligotrichia
ChoreotrichiaThe spirotrichs are a large and distinctive group of ciliate protozoa. They typically have prominent oral cilia in the form of a series of polykinetids, called the adoral zone of membranelles, beginning anterior to the oral cavity and running down to the left side of the mouth. There may also be one or two paroral membranes on its right side. The body cilia are fused to form polykinetids called cirri in some, and are sparse to absent in others.

Forms with cirri are common throughout soil, freshwater, and marine environments. Individuals tend to be flattened, with cirri confined to the ventral surface. These are variously used for crawling over objects, acting as feet, swimming, or assisting in food capture. They are generally divided into hypotrichs and stichotrichs, but were originally all considered hypotrichs.

Forms with sparse or absent body cilia tend to be smaller and are mostly marine, but a few are common in freshwater. Again, they are generally divided into oligotrichs and choreotrichs, but were originally all considered oligotrichs. The latter group includes the tintinnids, which produce loricae or shells and are the predominant fossil ciliates.

As first defined by Bütschli in 1889 the spirotrichs were one of two orders, together with the now-abandoned holotrichs, and included all ciliates with prominent oral cilia: heterotrichs, hypotrichs, oligotrichs, and peritrichs, although the last were soon separated. The heterotrichs have an adoral zone of membranelles, but molecular and ultrastructure studies have shown they are a separate group that diverged from most other ciliates early on. A few of the smaller groups included with them may be genuine spirotrichs, however, such as the Protocruziida.

The remaining spirotrichs form a monophyletic group, but their relationships are uncertain. For the most part the oligotrichs and choreotrichs appear to form closely related, natural groups. However "Halteria" and its close relatives, originally considered oligotrichs, form a separate group and may even be modified stichotrichs. Studies also suggest the hypotrichs are paraphyletic to the stichotrichs, and possibly to the oligotrichs and choreotrichs as well. This stands in contrast to the earlier belief that they were the most advanced of all protozoa.


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  • spirotrich — ▪ microorganism       (class Spirotrichea), any of a group of ciliated protozoans characterized by nonuniform, sparse ciliation and prominent membranelles of fused cilia around the mouth opening. The subclass contains a number of orders. See… …   Universalium

  • spirotrich — noun Any of a large and distinctive group of ciliate protozoa, typically with prominent oral cilia in the form of a series of polykinetids, called the adoral zone of membranelles, beginning anterior to the oral cavity and running down to the left …   Wiktionary

  • spirotrich — spi·ro·trich …   English syllables

  • spirotrich — ˈspīrə.ˌtrik noun ( s) Etymology: New Latin Spirotricha : a spirotrichous protozoan …   Useful english dictionary

  • Hypotrich — Taxobox | color = khaki name = Hypotrichs domain = Eukaryota unranked phylum = Alveolata phylum = Ciliophora classis = Spirotrichea subclassis = Hypotrichia subclassis authority = Stein 1859 emend. subdivision ranks = Typical orders subdivision …   Wikipedia

  • Stichotrich — Taxobox | color = khaki name = Stichotrichs image caption = Stichotrich domain = Eukaryota unranked phylum = Alveolata phylum = Ciliophora classis = Spirotrichea subclassis = Stichotrichia subclassis authority = Small Lynn 1985 subdivision ranks …   Wikipedia

  • Heterotrich — Taxobox 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 =… …   Wikipedia

  • Peritrich — Taxobox color = khaki name = Peritrichs domain = Eukaryota unranked phylum = Alveolata phylum = Ciliophora classis = Oligohymenophorea subclassis = Peritrichia subclassis authority = Stein 1859 subdivision ranks = Typical orders subdivision =… …   Wikipedia

  • Litostomatea — Taxobox | color = khaki name = Litostomatea domain = Eukaryota unranked phylum = Alveolata phylum = Ciliophora classis = Litostomatea classis authority = Small Lynn 1981 subdivision ranks = Typical orders subdivision = Subclass Haptoria Haptorida …   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

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