This is a prolific nitrogen-fixing species of bacteria that fixes approximately half of the nitrogen in the food chain of the ocean. Unlike other bacteria, it can also photosynthesize. This is a colonial species that forms long filaments. Some of the bacteria in the colony fix the nitrogen, and others are specialized for photosynthesis. However, the two processes must be done with two of them, because the oxygen byproduct that results from photosynthesis would interfere with the nitrogen-fixing process, so they must be done in separate cells.
This species can also literally turn the Red Sea a red color that can be seen from outer space. The cause of this is unknown, but most scientists believe that a species of bacteria of the Trichodesmium genus, most likely this species, is the cause.