What are phytoplankton?
Phytoplankton are microorganisms that drift about in water. They are single-celled, but at times they can grow in colonies large enough to be seen by the human eye 16. Phytoplankton are photosynthetic, meaning they have the ability to use sunlight to convert carbon dioxide and water into energy 11. While they are plant-like in this ability, phytoplankton are not plants. The term “single-celled plants” is a misnomer, and should not be used. Instead, phytoplankton can be divided into two classes, algae and cyanobacteria 10. These two classes have the common ability of photosynthesis, but have different physical structures. Regardless of their taxonomy, all phytoplankton contain at least one form of chlorophyll (chlorophyll A) and thus can conduct photosynthesis for energy.
Phytoplankton, both algae and cyanobacteria, can be found in fresh or saltwater 13. As they need light to photosynthesize, phytoplankton in any environment will float near the top of the water, where sunlight reaches 10. Most freshwater phytoplankton are made up of green algae and cyanobacteria, also known as blue-green algae 13. Marine phytoplankton are mainly comprised of microalgae known as dinoflagellates and diatoms, though other algae and cyanobacteria can be present. Dinoflagellates have some autonomous movement due to their “tail” (flagella), but diatoms are at the mercy of the ocean currents 12.
http://www.fondriest.com/environment...n-chlorophyll/
I found this article to be of erxtradinary interest to me, After 45 years of reefkeeping, I always learn.