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Contractile Vacuole

A vacuole is a large membrane-bound compartment in certain eukaryotic cells that serve a variety of different functions. Vacuoles may capture food or unwanted structural debris around the cell. They allow a cell to transport, eliminate, lock out, or trap a variety of different substances in the cell. Without a vacuole, eukaryotic cells might not be able to synthesize nutrients or eliminate toxins.

A contractile vacuole helps protists eliminate excess liquid in the cell. This pumping function reduces osmotic pressure and prevents the cell from bursting, a condition called cytolysis or osmotic lysis. Contractile vacuoles are most often found in freshwater protozoa like paramecium and amoeba.

All vacuoles including contractile vacuoles are generally filled with cell sap, which is a liquid of varying composition. The size and shape of vacuoles may vary widely as well, with some cells cycling from season to season as to whether they have one large vacuole or a number of small ones. Some vacuoles have the dual purpose of also keeping photosynthetic materials close to the cellular membrane, and thus close to light.

Web Resources On Contractile Vacuole

Answers: vacuole
Britannica: Contractile vacuole

Book Resources On Contractile Vacuole

The contractile vacuole by Francis Ernest Lloyd
Contractile vacuoles of protozoa by John Alwyne Kitching

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