Peritrich

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Peritrichs
26-2-1 Vorticella patellina.jpg
Scientific classification
Domain: Eukaryota
(unranked): Alveolata
Phylum: Ciliophora
Class: Oligohymenophorea
Subclass: Peritrichia
Stein 1859
Typical orders

Sessilida
Mobilida

The peritrichs (Latin: Peritrichia) are a large and distinctive group of ciliate protozoa. They are usually bell or disc shaped, with a prominent paroral membrane arising from the oral cavity and circling counter-clockwise around the anterior of the cell, accompanied by a smaller series of membranelles. The oral cavity is apical and funnel shaped, with a contractile vacuole discharging directly into it. When disturbed, the anterior of the cell can contract. The rest of the body is unciliated, except for a telotroch band circling the posterior in mobile species and stages.

The larger order of peritrichia are the Sessilida. Most of these have modified posterior kinetosomes which secrete a contractile stalk. The unattached stage, called a telotroch, is mouthless. These are common in both freshwater and marine environments, and many live attached to aquatic plants and animals. They are either solitary or produce branched colonies. A few secrete a lorica. Vorticella is one of the best-known genera. Stalks may be as long as 2 mm, and in some cases where they are highly contractile can be extended up to 3 mm.

The other peritrichia make up the order Mobilida. In these the posterior of the cell is enlarged and modified to form a complex holdfast, allowing the cell to temporarily attach to some host organism. Most live on the integument or gills of freshwater and marine invertebrates, but other hosts occur, including fish and even other ciliates, and other locations as well. Some can be pathenogenic in high populations.

The peritrichs were first defined by Friedrich von Stein in 1859. Initially they were considered spirotrichs, then treated as a separate category, before receiving their modern placement.

Further reading[edit]

Liu, Xihan; Gong, Jun (December 7, 2012). "Revealing the Diversity and Quantity of Peritrich Ciliates in Environmental Samples Using Specific Primer-based PCR and Quantitative PCR". Microbes and Environments 27 (4): 497–503. doi:10.1264/jsme2.ME12056. 

Safi, Lucia SL; Fontoura, Nelson F; Severo, Henrique J (April 2014). "Temporal structure of the peritrich ciliate assemblage in a large Neotropical lake". Zoological Studies 53 (1): 17–29. doi:10.1186/s40555-014-0017-3. 

Wang, Hongliang; Clamp, John C.; Shi, Xinlu (July 2012). "Evolution of Variations in the Common Pattern of Stomatogenesis in Peritrich Ciliates: Evidence from a Comparative Study Including a New Description of Stomatogenesis in Pseudepistylis songi Peng et al., 2007". Journal of Eukaryotic Microbiology 59 (4): 300–324. doi:10.1111/j.1550-7408.2012.00621.x. 

Gouda, Hanaa A. (November 2006). "The effect of peritrich ciliates on some freshwater leeches from Assiut, Egypt". Journal of Invertebrate Pathology 93 (3): 143–149. doi:10.1016/j.jip.2006.06.005. PMID 16905145. 

Amos, A. (January 1972). "Structure and coiling of the stalk in the peritrich ciliates vorticella and carchesium". Journal of Cell Science 10 (1): 95–122. PMID 4622792. Retrieved 9 February 2015. 

Alvarez-Campos, Patricia; Fernandez-Leborans, Gregorio; Verdes, Aida; San Martin, Guillermo; Martin, Daniel; Riesgo, Ana (October 2014). "The tag-along friendship: epibiotic protozoans and syllid polychaetes. Implications for the taxonomy of Syllidae (Annelida), and description of three new species of Rhabdostyla and Cothurnia (Ciliophora, Peritrichia)". Zoological Journal of the Linnean Society 172 (2): 265–281. doi:10.1111/zoj.12168. 

External links[edit]