| A paramecium is a microscopic, slipper-shaped organism that lives in fresh waters throughout the world. It has a tough outer covering known as a pellicle. About 2,500 tiny, hairlike projections, called cilia, extend from the pellicle; the cilia move back and forth like oars to help the paramecium move about. The paramecium eats tiny organisms, such as bacteria, that are swept by the cilia into an indentation in the cytostome called the oral groove. The organisms are eventually passed into a food vacuole, a small, round structure where food is digested, and are then passed into the cytoplasm. The contractile vacuole regulates osmotic pressure within the organism. The macronucleus is involved in protein synthesis and other cellular activities, while the micronucleus functions in sexual reproduction. |
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