Judy Vessey, Age 12, Of Victoria, B.C., Canada, for her question:     

Why do ocean turtles lay their eggs on land?     

Turtles have been turtles for some 200 million years. Their ancestors were Among the first reptiles, and they developed before the lizards, the crocodiles and Long before the snakes. Turtles have not made many changes through all these years.  Long before the first bird built a nest, mother turtles were laying their eggs as they do today.     You may not suspect it, but the turtles are very successful animals, so Successful that they have no reason to change their ways. Slowly and stolidly they have been repeating the same turt1e habits since the permian period of earth's history, which dates back 200 million years.     

The ancient turtleb shared the early world with whopping salamanders and a few odd looking reptiles. There were no other backboned animals. The salamanders were land and water amphibians. They had to live in water through their egg and fishy tadpole stages, dust as amphibians do to this day. The salamanders and turtles had left the sea for life on the dry land, but the turtles made a more definite break with their watery cradle.     

The armor plated turtles were air breathers from birth. Their round white eggs were laid and hatched on the dry land. There was no need for these ancestor turtles to return to the sea at all. But some of them did. In the triassic period, about 150 million years ago, a few turtles gave up the successful life they had won for themselves on the land.  These stodgy fellows returned to the sea. In time, their stubby legs became flippers which were much more useful for swimming. But there were other changes that could not be made. To win a life on the land, turtles had developed legs. Their eggs and their youngsters needed air, and mother turtles had to go ashore to start their families

The huge, seagoing turtles of today rival the fishes in the water. But they Must surface for air to breathe, and their eggs would drown in the sea. A mother Turtle still waddles ashore several times a year to lay her eggs. She chooses a sandy slope and digs a hole with her back feet, then lays 200 to 300 round white eggs. The precious nest is covered so skillfully that you would never notice it. Then the female turtle returns to the sea.     There are half a dozen species of marine turtles in our seas, and all of them are whoppers. The shell of the loggerhead turtle is big enough to make a small row boat. The green turtle, which is used to make soup, may weigh almost half a ton. And the giant leatherback turtle often weighs three quarters of a ton. Except for the times when the female comes ashore to lay her eggs, all her time is spent in the deep ocean.