Susan Kass, Age 11, Of S1ingerlands, N.Y., for her question:
How do oysters have babies?
Hundreds and perhaps thousands of oysters are crowded together on the floor of some quiet bay. But each one of them is a stodgy stay at home. A papa oyster cannot leave the spot on which he lives to go courting. Two parent oysters cannot go off to share a home and raise a family. Yet every baby oyster starts life as an egg which forms from two ce11s, an egg ce11 from the mother oyster and a sperm ce11 from the father oyster.
When time comes to launch a family, the parent oysters are very fussy about the temperature of the water. It must be between 66 and 70 Fahrenheit degrees. Off New England, the breeding seasons start in early July. In the Gulf of Mexico, it lasts from march to November. The parent oysters pour clouds of tiny cells into the quiet, balmy water, and some of these cells will form eggs from which will come a new generation of baby oysters.
The female parents pour forth egg cells. A mother oyster may send out nine million egg cells at a time, and, during the season, she may produce four billion of these microscopic cells. The male oysters send forth sperm cells that drift around and mix among the egg cells afloat in the water. A few, ,just a few, sperm ce11s unite with egg cells. Each pair of cells, one coming from each parent, forms a tiny oyster egg.
The clouds of oyster cells soon perish and so do most of the tiny oyster eggs. Only one in perhaps four million has a chance to grow up. Some are swept by the tides out to sea. Some become choked and smothered in sand and mud and others are eaten by hungry fishes. Here and there a lucky survivor drifts through the water, a glassy egg which measures one 500th part of an inch.
In five to 10 hours the lucky survivor becomes a free swimming larva. It looks lips a miniature melon seed wearing a wig. In a day or so, the flat, oval body is encased in a pair of glassy shells, and the tuft of fine hairs waves to propel the oyster larva through the water. The little swimmer feeds on drifting sea food, and after two weeks he is six times larger. It is time now to give up his dangerous life of freedom.
The young oyster sinks down to settle on the spot where he will spend the rest of his life. If he is lucky, he will land. On a rock or perhaps a shell. He starts at once to secrete a sticky cement which soon hardens and glues him to the floor. Sea water flows between his shells, serving him oxygen and scraps of food. In a month, the young oyster measures a quarter inch, and after four years of this lazy life, he is big enough to be sent to market.
In the egg stage, and the free swimming larva stage, the life of a baby oyster is very risky. But his most hazardous time comes when he settles in his permanent home. He may land in soft, smothering sand or where the next tide will leave him high and dry. Latter he will need a barrel of water to supply his daily needs. If he is lucky, he will settle on a smooth, hard surface where a constant supply of sea water flows gently around him.