Known as coccoliths , these plates have a variety of shapes. Single coccolithophores are commonly smaller than 20 micrometers across and are often enclosed by over 30 plates. Coccolithophores can form enormous blooms , turning seas an opaque turquoise color. Phytoflagellates are diverse, crossing ten classes of algae. These motile organisms are so small they must be identified using powerful microscopes or biochemical techniques.
Photosynthetic bacteria are major contributors to oceanic primary productivity.
One type, Prochlorococcus , may be the most abundant species on the earth.