Class: Cyanophyceae Abundant in waters warmer than ca. 24oC, Crocosphaera can reach high cell densities in the natural environment due in part to a rapid growth rate. By segregating its metabolic processes on a diel cycle, this cyanobacterium is capable of photosynthesis as well as nitrogen fixation, in which inorganic nitrogen gas (N2) is converted to organic nitrogen. Cyanobacteria are key components of marine phytoplankton, especially in oligotrophic regions where they are often found to be the main primary producers. Cells are ca. 3-6 um in diameter.