Stylonychia is a genus of ciliates, in the subclass Hypotrichia. Species of Stylonychia are very common in fresh water and soil, and may be found on filamentous algae, surface films, and among particles of sediment. Stylonychia can also be found swimming on and through decaying vegetation and pond scum floating through the water. Like its relatives, Stylonychia has cilia grouped into membranelles alongside the mouth and cirri over the body. It is distinguished partly by long cirri at the posterior, usually a cluster of three. The largest can just be seen at a 25x magnification, and the smallest can just be seen at a 450x magnification. Members of the group are carnivorous and prey on other protozoans and bacteria.

Stylonychia mytilus - 250x (10427810844).jpg
Stylonychia mytilus
Scientific classification e
Clade: SAR
Infrakingdom: Alveolata
Phylum: Ciliophora
Class: Spirotrichea
Family: Oxytrichidae
Genus: Stylonychia
Ehrenberg, 1830


Stylonychia mytilus, with cirri labeled
Stylonychia mytilus, walking on its cirri

Stylonychia cells are roughly oval in shape, inflexible and flattened from back to front.[1] The organism's cilia are grouped into structures called "cirri," tufts of joined cilia that function together as a unit.The cirri on the ventral surface of the cell can function as legs, enabling the organism to walk along solid substrates, such as submerged algae, leaves or debris.

LIke other ciliates of the family Oxytrichidae, Stylonychia has a prominent group of eighteen large cirri on its ventral surface, arranged into six smaller groups: the frontal, buccal, frontoventral, postoral, pretransverse and transverse cirri.[2] The region around the cell mouth (cytostome) is partially encircled by a series of compound cilia which make up the "adoral zone of membranelles", or AZM. This structure, which resembles the collar and lapel of a jacket, is used mainly to circulate water and brush particles of food into the organism's cell mouth. On the right side of the oral area are two "undulating membranes", delicate scarf-like structures made up of fused cilia. At the posterior of the cell are three long, stiff "caudal cirri", attached to the body at the lower margin of its dorsal surface.[1][2]

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  1. ^ a b Caspers, H. (1983-01-01). "Colin R. Curds: British and Other Freshwater Ciliated Protozoa. Part 1. Ciliophora: Kinetofragminophora. = Synopses of the British Fauna (New Series), ed. by D. M. KERMACK and R. S. K. BARNES, No. 22.— With 243 figs., 387 pp. Cambridge: Cambridge University Press 1982. ISBN 0521 242576 (hard covers) 285585 (paperback). £ 27.50/11.95". Internationale Revue der Gesamten Hydrobiologie und Hydrographie. 68 (6): 899. doi:10.1002/iroh.3510680627. ISSN 1522-2632.
  2. ^ a b Berger, Helmut (2012). "B Systematic Section Stylonchinae". Monograph of the Oxytrichidae (Ciliophora, Hypotrichia). Monographiae Biologicae. 78. Springer. pp. 499–. ISBN 978-94-011-4637-1.

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