About Plankton
Plankton are organisms that drift in water but are unable to actively propel themselves against currents. Marine plankton include drifting organisms that inhabit the saltwater of oceans and the brackish waters of estuaries. Freshwater plankton are similar to marine plankton, but are found in lakes and rivers. An individual plankton organism in the plankton is called a plankter.
Biography source:
Wikipedia
