Plankton is the name given to all the microorganisms that drift and hover in the ocean and freshwater. The name comes from the Greek language <math>\pi\lambda\alpha\gamma\kappa\tau o\nu</math> - term for "wanderer" or "drifter". If the organism has a method of propulsion, it is instead called nekton.
Plankton are divided into two classes:
Plankton concentration and distribution is very sensitive to chemical and physical changes in the sea water.
|larger images (http://www.ecoscope.com/ocean/index.htm); (photomontage by Uwe Kils)||Hyperia macrocephala (http://www.ecoscope.com/hyperia/index.htm) (Uwe Kils)|
|Copepod (Calanoida) (Uwe Kils)|