Phytoplankton is the "Grass of the Sea". Well, not really grass, but it is the microscopic cells of phytoplankton that play a similar role to that of grass and trees. Drifting phytoplankton cells account for more than half of the photosynthesis on earth. They give oxygen to the atmosphere and they regulate the production of carbon dioxide that controls the earth's climate. Phytoplankton is the base of the aquatic food chain: large fish eat smaller animals that eat phytoplankton. Ifyou eat seafood, you consume phytoplankton. Imagine a blade of grass 1/4 inch or 1/2 cm thick. A typical phytoplankton individual would be about 1/100th that size, smaller even than grass cells.Every milliliter of water near the surface of the ocean contains hundreds of thousands or millions of these plants. Yet most people have never seen a phytoplankton cell. Using satellite, we are able to measure the amount of a green pigment called chlorophyll contained within the phytoplankton cells. It is this green pigment that makes thewater reflect more green light which is seen by the satellite.