Debra Capozzoli, age 10, of East Norwich, Long Island, New York, for her question:

How many kinds of snake are poisonous?

Some people shudder when snakes are mentioned. Certainly some of the creepy crawlers are deadly horrors, but most of them are harmless creatures. It seems unfair to detest them all just because a few cannot be trusted. It is also sad because snakes are handsome, interesting and often useful.

Many experts have had a go at counting the kinds of poisonous snakes one by one. But their answers do not agree. Perhaps some get missed or a few get counted more than once. In any case, you will find different answers in different books and if you ask several snake experts they, too, will give you different answers. However, all the answers are close. We can study them and settle on an approximate figure, one that is more or less in the middle. Most experts might agree that there are approximately 250 poisonous kinds of snake. But there may be a few more or a few less than 250.

This seems like a lot of poison packers to be crawling around the world. But when you consider all the harmless snakes, the poisonous types are in a minority. In fact, they are a very small minority. Altogether, there are almost 3,000 snakes in the world, though not all of them have been named and classified. Only about eight per cent are poisonous. You could list all the snakes and divide them into 30 groups of 100. Chances are, only eight snakes in each group would be bad guys and 92 of them would be good guys  or fairly good guys.

This does not mean that we can take chances. You may meet a poisonous snake almost anywhere outdoors in the wilds. The polar regions are safe, because snakes cannot abide the cold. But almost everywhere else, several snakes live in the neighborhood and at least one day be poisonous. Some types stay on the Western prairies and others lurk in the Southern swamps. There are Midwestern types and New Englanders. It is wise to learn about the poisonous snakes in your own neighborhood, what they look like and where they are likely to be found.

In North America, most of our poisonous snakes are dangerous rattlers. We have at least 20 different rattlesnakes living in various states. We also have two rattlesnake cousins. One is the handsome copperhead, the other is the cottonmouth, alias the water moccasin. These bad guys are rattlesnakes without rattles on their tails. Our list of North American poisonous snakes is complete with two coral snakes. These fellows wear gaudy rings from head to tail    black and yellow, black and red and red and yellow. These are beautiful but also among the most deadly snakes on our continent. '

A few snakes tan inject poison from their small back or side teeth. But they are not deadly dangerous to human beings. A really poisonous snake has a pair of fangs in his upper jaw. The cobra's fangs are straight and fixed in an upright position. The viper type and the pit viper have fangs that fold back out of sight when not in use. Our coral snakes are cobra types. The rattlesnakes, the copperhead and the water moccasin all have fold away fangs and belong in the dangerous pit viper group.