Paramecium (caudatum) (par-a-mee-see-um) is a very familiar genus of ciliates. They eat bacteria and have the mouth recessed in a buccal cavity, and the cell is often shaped with a scoop leading to the mouth. There are cilia all over the body with a caudal tuft of longer cilia at the back of the body. Usually with a layer of extrusomes (trichocysts) under the cell surface and a large oval macronucleus. Contractile vacuoles star-shaped. This species is P. caudatum, and was photographed with the cell pushing itself into some debris. This is the normal feeding behaviour of this genus. Phase contrast. This picture was taken by David Patterson and Mark Farmer of material from freshwater sites in the vicinity of the University of Georgia in Athens, Georgia, USA) in April, 2001 and from collections of organisms maintained at the University. Image copyright: D. J. Patterson and Mark Farmer, image used under license to MBL (micro*scope).
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From the collection
Athens, Georgia, USA
|Description of Paramecium caudatum: Peniculine ciliate, 120-330 micrometres long (usually 200-300 micrometres). Body elongate, somewhat stiff, with rounded anterior; posterior tapering to a blunt point. Tuft of longer cilia at posterior; somatic ciliation otherwise uniform. Long oral groove, leading to deep buccal cavity lined with cilia. Two contractile vacuoles with stellate appearance (radial canals). Numerous trichocysts. Single ovoid macronucleus. Bacterivorous. Very widespread and common in salt, brackish and freshwater. |