They are usually small in size generally microscopic (microns, 1/1000th of a mm). Plankton are the most abundant form of life in the ocean. In fact, all other marine life is dependent upon plankton. The plant forms and many protozoans are known as phytoplankton.
“Plankton” is from a Greek word for “wanderer.” It is a collective term for the various organisms that drift or swim weakly in the open water of the sea or freshwater lakes and ponds. Plankton is composed of viruses, bacteria, phytoplankton, zooplankton and the pelagic larvae of many marine invertebrates and fishes. This group displays a wide range of behavioral capabilities that bridge the transition from being a passive particle to being able to determine vertical and horizontal position in the ocean.
Plankton can range in size from microns to meters. The smallest plants living in the ocean are the phytoplankton, which vary in size from about 5 microns to 50 millimeters. Single-celled plants called diatoms, constitute more than half of the phytoplankton in the ocean.
Plankton can be divided into two large groups: planktonic plants and planktonic animals. The plant plankton or phytoplankton are the producers of ocean and freshwater food chains. They are autotrophs, making their own food, using the process of photosynthesis. Phytoplankton are producers, transforming sunlight into food energy.
The animal plankton or zooplankton eat food for energy. Zooplankton is food for many secondary consumers.
What is plankton?
