Phytoplankton

Phytoplankton (image )

Phytoplankton (Greek phyton, "plant") are the algal component of the plankton that drifts in the water column. Phytoplankton, like other plants, obtain energy by photosynthesis, and so live mostly in the well-lit surface layer (termed the euphotic zone) of an ocean, sea, or lake. Their cumulative energy fixation in carbon compounds (primary production) is the basis for the vast majority of oceanic (see chemosynthesis) and some freshwater food chains. One of the most remarkable and direct food-chains is that of phytoplankton fed on by krill fed on by whales.

• See also: Algae