Tim Kaver, ago 10, of St. Louis, Missouri, for his question:

Are any lizards poisonous?

We share our world with lots of poisonous snakes and some people suspect that many other reptiles also inflict poisonous bites. It is true the bite of a lizard or any other animal may cause a dangerous infection. But this sort of poisoning results from enemy germs that enter wounds that are not treated with medication. Only two of the lizard reptiles have special glands for manufacturing venom to be injected into their victims.

In our southwest deserts, there lives a lizard whose bite may be as deadly as a rattlesnake's. We call him the Gila monster because his favorite haunts are around the basin of Arizona's Gila River. Strictly speaking, he is the only poisonous lizard of North America. But south of the Mexican border lives his equally poisonous cousin, the beaded lizard. So far as we know, these two rather lazy characters are the only venomous lizards in the world.

As far as size goes, the fat, flat Gila monster is not much of a monster. From his bulldog jaws to the tip of his thick tail, his average length is about 18 inches. He happens to be quite a gaudy fellow. This is partly because his scales do not overlap like most lizard scales. They are separate little bumps set in the skin, close enough to touch each other, and arranged around his body in straight lines. He appears to be wearing a rather loose jacket embroidered all over with neat beadwork. What's more, his outfit is designed in eye catching colors.

The Gila monster's Mexican cousin is actually called the beaded lizard. He may be one third larger than our monster and his bite is just as deadly. However, his beaded embroidery is less gorgeous. As a rule, his coat is mainly black with pale blotches on his body and six or seven yellowish bands around his f at tail. The Gila monster's skin has a black or brown background, lavishly embroidered with pink or yellow speckles. And there are four or five bands of beadword around his tail.

Both these lizards love to bask in the golden desert sunshine and visitors do not scare the lazy fellows away. After all, they are masters in the art of self defense. If either of them feels threatened, he just waits for the suspicious character to come  within reach. Then he grabs and holds on tight with his stubborn bulldog jaws. When he gets a chance, he bites people. So beware of the Gila monster and his cousin the beaded lizard. Drop for drop, their poison is as deadly as rattlesnake venom. As a rule, their poison is not jabbed down deep into the flesh. But a person bitten by a poisonous lizard needs a doctor as soon as possible.

Poisonous snakes and lizards make their deadly venoms in special glands in their jaws. When they bite a victim, a dose of the deadly stuff drains to the teeth. The snakes have hollow fangs that inject the poison deep into the wound, where it spreads fast. The lizards have grooves on the outside of their teeth and the poison flows more slowly. But the stubborn creatures hang on like bulldogs and often the poison has time to reach deep into the flesh.