Ocean phytoplankton types. Mollweide projected map of global distributions of four types of ocean phytoplankton, a crucial part of the Earth's carbon cycle. Colours represent the most dominant type of phytoplankton based on their size and nutrient uptake. Red represents diatoms (big phytoplankton, which need silica), yellow represents flagellates (other big phytoplankton), green represents prochlorococcus (small phytoplankton that cannot use nitrate), and cyan represents synechococcus (other small phytoplankton). The data (1994-1998) is from the Darwin Project using the ECCO2 ocean circulation model. Image published in 2015.