Plankton are microscopic organisms that float freely with oceanic currents and in other bodies of water. Plankton is made up of tiny plants (called phytoplankton) and tiny animals (called zooplankton). The word plankton comes from the Greek word "planktos" which means "drifting."
Phytoplankton: Phytoplankton are primary producers
(also called autotrophs). As the base of the oceanic food web, phytoplankton use chlorophyll to convert energy (from sunlight), inorganic chemicals (like nitrogen), and dissolved carbon dioxide gas into carbohydrates.
Zooplankton: Zooplankton are microscopic animals that eat other plankton.