Plankton - Soup of the Sea, Biosphere Food

Plankton in the oceans (and fresh-water, too!) differs depending on where you are. In the open ocean, sometimes there isn't much plankton -- not much life there, so the waters resemble a watery version of a desert. Along coastal areas and in the Artic and Antarctic, there exist ocean currents called "upwellings" that bring nutrient-rich waters from the ocean floor up to the surface. This nutrient-rich water provides food for the photosynthesizing or plant plankton -- phytoplankton -- and which also provides food for the swimming and animal plankton -- zooplankton. This planktonic life is fed on by the baleen whales (which use their baleen--the strainer-like structures in their mouths--to strain out the organisms that they feed on).

Some of the plankton is visible to human eyes as small shrimps, fish larvae, and small jellyfish. Other varieties of plankton include egg cases of various kinds of fish, juvenile squid, tunicates, radiolarians, and foraminifera.

Squid graphic courtesy of Squidoo Squid Graphics For Your Lenses! by GreekGeek.