photosynthesis (converts sunlight and nutrients to energy)
to 15 microns
other microalgae; Division: Chrysophyta; Class: Bacillariophyceae
sunlit oceans and freshwater habitats worldwide
Diatoms are microscopic water plants. Like all plants, they need sun to grow, so they live only in sunlit waters. In spring and summer, when conditions along our coast are just right, diatoms grow so fast and in such numbers they turn the water green. The seasonal abundance of diatoms is one reason for the rich marine life in Monterey Bay.
The open ocean is the world's "plankton pasture," home to the tiny drifting plants and animals that power enormous food chains. Diatoms are key members of the plant plankton. Plankton feeds small fishes, which in turn feed bigger fishes, sea birds, seals and whales. We, too, depend on fishes nourished by ocean plankton.
Diatoms live in glass houses. Their cell walls are made of silica, the same material that's in glass.