Phytoplankton are microscopic organisms that form the base of the marine food web and about half of the oxygen on Earth. The concentration of their green pigment, chlorophyll, can be seen from space because it changes the color of the water. From measurements collected at sea and analyzed through microscopes, we know there are many of thousands of types of phytoplankton. Computer models combine observations from satellites and ships with physical forcing to estimate where diverse species live an