Tennis Eber, age 14, of Pittsburgh, Penna., for his question:

What is plankton?

Plankton is the basic diet for all creatures that live in the sea. Those that do not feed. on plankton directly eat other creatures who have fed on it. On land, all animals depend on plants. Those that do not eat plants directly feed on other animals that do. So it is in the ocean. For most of the plankton is plant life.

The word plankton comes from the same Greek root that gives us the word planet. Both plankton and planet mean wandering  planet is a wanderer over the skies. Plankton is a sort of wandering seafood salad, floating and drifting on tides and current throughout the ocean waters of the world.

Though basically plankton is microscopic plant life, it is mixed with small forms of animal life. Fish and sea creatures that dine on plankton get a well balanced diet. The quantity of this floating seafood varies from place to place and with the seasons. It may color the water red, brown, green or yellow, depending upon what plant life is most plentiful. And many forms of plankton plant life are luminous, glowing with a ghostly light of their own. .

In temperate waters, the spring plankton begins with a rich crop of diatoms. There are microscopic plants, each one encased in a jewel‑like case made from the silica in sea after. These little plants thrive and multiply in the spring sunshine. Puicioscopic algae are also present.

Into these drifting ocean meadows come countless little; sea animals. The waters teem with copepods, tiny crustaceans. There are hordes of prawns, armies of gaily colored sea worms and countless little jellyfish. In ocean waters, the plankton is joined by larvae from stay‑at‑homes on the ocean floor. For a few days, baby coral anal baby sponges enjoy a free swimming existence.

Soon the bigger fish lay their Eggs. These too may float among the plankton. The eggs  hatch into glossy free swimming larvae. Shrimps, prawns, and little jellyfish come to feed in the rich seafood meadows and they, too, become part of the plankton, A cupful of this soupy water may contain millions of microscopic plants and animals, plus a few shrimp­ sized animals.

Larger creatures soon move in to feed on the drifting seafood. Schools  of herring and mackerel arrive. Squids move in to feed herring and mackerel. Big tunas, sharks and monster sea turtles arrive to feed on herring, mackerel and squid.

The biggest animal in the world, the biggest who ever lived, feeds entirely on plankton. He is the big blue baleen whale, and he follows the meadows of plankton wherever they drift. This gentle giant eats nothing larger then a shrimp,