What are phytoplankton?

What are phytoplankton?
by David Herring
NASA Earth Observatory

Phytoplankton are microscopic plant-like organisms that live in the ocean. There are many species of phytoplankton, each of which has a characteristic shape. Phytoplankton grow abundantly in oceans around the world, and they are the foundation of the marine food chain. Small fish, and some species of whales, eat them as food.

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