The term "plankton" refers to any small form of life living in the water and drifting with the currents, ranging from bacteria to jellyfish. Phytoplankton, such as Diatoms and dinoflagellates, grow in the presence of sunlight and nutrients, such as nitrogen and phosphorus. These single-celled organisms are the "grasses of the sea" and form the basis of the ocean productivity. Some of these plants, but not all, are grazed by zooplankton, which is dominated by small crustaceans, such as copepods, shrimps and their larva. Most phytoplankton contain photocynthetically active pigment chlorophyll, which enables them to use energy from sunlight to convert carbon dioxide into complex organic molecules, such as sugar and protein (they are autotrophs). Other "plants" do not fix their own carbon, but engulf and consume other plant cells (they are heterotrophs). Other phytoplankton may produce red tides and toxins, but there are only a few species responsible for these crimes. Most phytoplankton are enormously beneficial.
Algae are saprophytic organisms widely distributed in the environment, especially in water. Many contain chlorophyll. Some species of algae cause diseases in domestic animals. Colorless algae Prototheca can invade tissues causing skin and other organ disease in many species of animals, including dogs and cattle.
- Plankton: A Guide to Their Ecology and Monitoring for Water Quality. Iain M. Suthers, David Rissik
- Veterinary Microbiology and Microbial Disease. P. J. Quinn, B. K. Markey, F. C. Leonard, E. S. FitzPatrick, S. Fanning, P. Hartigan
Micrograph by Larysa Johnston