Harry White, Age 12, Of Plainfield, Ind., for his question:

Why are there no snakes on some Hawaiian Islands?

Several of the world's islands are free of snakes. As everyone knows., there are no snakes in Ireland. The irish people have their own way of explaining this fact, but science does not agree with them, the people of Hawaii, however, do not argue with the scientists who explain why their islands are free, or almost free, of snakes.

The family tree of the reptiles is more than 200 million years old.. One branch of the family developed into the birds, another into the snakes. And the snakes are the most recent reptiles of the world. They date back perhaps 100 million years. What's more, the snakes are not great travelers.

During the ice ages, all the snakes of northern europe were destroyed by the crushing glaciers. When the ice melted, some of the land areas were left as island8 surrounded by water. In time, birds, rats, insects and a wide variety of plant life reinhabited these islands. But land snakes cannot cross a wide stretch of water, and most of them never returned to their old homes.

This is the scientist's explanation of why there are no snakes in Ireland. But there are no snakes in New Zealand and many other ocean islands which were never covered by glaciers. Until recently, there were no snakes at all in the Hawaiian Islands.

It seems likely that the snakes developed on the large continental land masses. They are, by nature, poor travelers and not likely to stray far from home. They never reached New Zealand and Hawaii, because these balmy islands were cut off from large land. Areas by wide stretches of water. These lonely islands have had. No contact, no land bridges, with the large land masses in the past 100 million years.

When naturalists reached the Hawaiian islands, there vcre no native snakes of any kind. Later, the Indian blind snake was found there in the wild state. What’s more this fellow seems to be increasing in numbers and spreading to more aril more of the islands: the reason for its appearance is easy to explain. A few of these snakes almost certainly reached the islands as stowaways on ships. Perhaps they arrived unnoticed, hidden in the cargo. Once ashore, they made themselves at home and began to increase.

There are about 3000 different kinds of snakes in the world, and all of them have developed in the past 100 million years. We do not find them in Alaska and the frozen north. Though no snakes reached New Zealand, they are very common in Australia. In most of the world, the poisonous snakes are the rare ones. But in Australia, the poisonous snakes outnumber the non poisonous ones.