What Color is the Sea?

The ocean reflects blue light from the sky. But even on cloudless days, the ocean surface is not the same blue color everywhere.

Tiny, single-celled plants called phytoplankton float in the sunlit water near the surface, and add a green, yellow, and even red tint to the water. The green color is caused by chlorophyll within the phytoplankton cell.

The ocean contains a truly astounding number of phytoplankton. Each drop of water from the surface may contain hundreds of thousands or millions of phytoplankton!

Phytoplankton are at the base of the marine food web .

Phytoplankton can only live within 200 meters of the surface, within the photic zone. (Why?)

The main types of marine phytoplankton are diatoms and dinoflagellates .

To grow and reproduce, phytoplankton need all the ingredients for photosynthesis: Light, nutrients, CO2, and water.

All life in the ocean depends on phytoplankton for food.

All animal life on Earth depends on phytoplankton for oxygen.

Phytoplankton helps regulate Earth's temperature by absorbing carbon dioxide.