Prochlorococcus

Unicellular, coccoid, Small size, obligately photoautotrophic, red fluorescence, generally restricted to waters > 15°C, Non-motile, Possess distinct pigment complement. Proliferates in oligotrophic areas of the world oceans and seas, the most abundant photosynthetic organism known to date on Earth, is able to sustain growth and photosynthesis under a very wide range of irradiance from the surface, can also grow in waters with low levels of inorganic nutrients