Madonna Campbell, age 11, of Brazil, Indiana, for her quest on:
Can an oyster change his sex when he chooses?
The stolid little stay at home oyster does not have much choice about anything. He spends his life, or most of it, rooted to one spot in a sturdy house made of two shells. His is a dreamy world where sunlight weaves wavy patterns as it filters through the green blue water. Tides wash in and out around him. The oyster may sense some of the things that go on in his dreamy, watery world. But he cannot think about them; he cannot make a decision or a choice of any kind. For he has no brain.
A higher animal such as a dog can make a decision. A dog may decide he wants to go outdoors and he may know how to get your attention to help him get there. He may even be one of those smarties who knows how to open a door. But an oyster is a far more simple animal. He belongs to the Mollusca phylum, which makes him cousin to the clam and the snail. This phylum places him a little above the flatworms in the scale of development and a little below the starfish and the sea urchins.
In the higher animals, there is no question about which are males and which are females. In many of the lower animals, things are not always so definite. Some multiply simply b y dividing in two. Others are both male and female. A little higher on the scale of development we have animals that change from one sex to another.
The private life of the oysters is most confusing and the zoologists have sorted out all the faots. There are many types of oyster and they do not all follow the same rules. The Atlantic coast oyster does not change its sex. The Mamas remain Mamas and the Papas remain Papas all their lives. The European oyster and the native Pacific coast oyster do change from male to female and back again. They seem to make this switch every five years but they certainly have no choice in the matter
As you can imagine, it is no easy matter to study the private life of all the different kinds of oysters for they must live in tidal waters. What's more, there is often a variety of different oysters in any oyster bed. Both the Japanese and the European oyster have been established with the native oyster along the Pacific coast.
In any case, a baby oyster grows from two cells, one from a .male and one from a female parent. The egg cells from the female and the sperm cells from the male parent may be poured into the water and meet by chance. But in the case of Pacific oyster, the sperm and egg ccl is rn;ot and develop inside the shell of the female.
The baby oysters are called larvae and they look like miniature water melon seeds wearing toupees. They use the hairs of the toupee to fan themselves through the water in search of food, Most of them are eaten by hungry sea dwellers. The lucky one gets to be about two weeks old and gives up the perils of his free swimming life. He settles on some solid object, builds his shells and becomes a dreamy stay at home like his parents.