Paramecium aurelia^[1] are unicellular organisms belonging to the genus of Paramecium of the phylum Ciliophora.^[2] They are covered in cilia which help in movement and feeding.^[2] In order for the paramecium to move forward, its cilia beat at an angle, backwards in unison. This means that the paramecium moves by spiraling through the water on an invisible axis. The paramecium can also move backwards when the cilia beat forward at an angle in unison. When the paramecium runs into a solid object, the cilia change their direction and beat forward, causing the paramecium to go backward. The paramecium turns slightly and goes forward again. If it runs into the solid object again it will repeat this process until it can get past the object.

Paramecium can reproduce asexually, ‘sexually’ or by the process of endomixis. ^[3]Paramecium aurelia demonstrate a strong “sex reaction” whereby groups of individuals will cluster together, and immerge in conjugant pairs. This pairing can last up to 12 hours, during which time the micronucleus of each organism will be exchanged.^[4]

Paramecia are widespread in freshwater environments, and are especially common in scums. They generally feed on bacteria and other small cells.

(From Wikipedia, June 3rd, 2010)

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Ovoid or elongate in shape, both the anterior and posterior are rounded, 80-170 microns long. The oral groove is wide for most of its length. There is an ovoid macronucleus and two micronuclei pressed against the sides of the macronucleus. There are two contractile vacuoles with radial collecting canals.

(From EOL via Biopedia).

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