Paramecium
From Biocrawler, the free encyclopedia.
| Paramecium | ||||||||||||
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 Paramecium aurelia | ||||||||||||
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Paramecium is a genus of unicellular ciliate protozoa, formerly known as slipper animalcules from their slipper shape. They are commonly studied as a representative of the ciliate group. Paramecia range from about 50 to 350 μm in length, depending on species. Simple cilia cover the body which allow the cell to move with a synchronous motion; and there is a deep oral groove, containing inconspicuous compound oral cilia, as found in other peniculids which is used to draw food inside. They generally feed upon bacteria and other small cells. Osmoregulation is carried out by a pair of contractile vacuoles, which actively expel water absorbed by osmosis from their surroundings. Paramecia are widespread in freshwater environments, and are especially common in scums. Paramecia are attracted by acidic conditions.
Paramecium
The division into species is still in flux - for instance, P. aurelia has recently been divided into 14 species - but the following are representative:
- P. aurelia Ehrenberg, 1838
- P. bursaria (Ehrenberg) Focker, 1836
- P. calkinsi Woodruff, 1921
- P. caudatum Ehrenberg, 1838
- P. duboscqui Chatton and Brachon, 1933
- P. jenningsi Diller & Earl, 1958
- P. multimicronucleatum Powers & Mitchell, 1910
- P. nephridiatum von Gelei, 1925
- P. polycaryum Woodruff, 1923
- P. putrinum Claparede & Lachmann, 1858
- P. trichium Stokes, 1885
- P. woodruffi Wenrich, 1928
A number of doubtful species have also been recorded.
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