Jason Cissell, age 9, of Marquette, Mich., for his question:

IS THE BOA CONSTRICTOR POISONOUS?

A boa constrictor is a large snake found in the tropical parts of the Americas. It kills animals for food by squeezing them with its long body. The boa constrictor is not a poisonous snake.

Boa constrictors grow to be between 10 and 14 feet long. Some people mistakenly believe that they are the largest snakes in the world, but this isn't true. They are smaller than the anaconda of South America, the python of Asia, Africa and Australia and the king cobra of India.

You'll find two types of small boa constrictors living in the southeastern part of the United States. Longer kinds can be found living in the Guianas and in Brazil.

Boa constrictors defend themselves by striking as other snakes do, by throwing their heads and the front part of their bodies at the enemy.

Their teeth can make bad wounds because they point inward.

Boa constrictors cannot swallow horses, cattle and other large animals, as many stories say they can. But they can swallow animals much larger than their heads because the bones of their jaws can be stretched far apart. The stretching of a boa constrictor's jaws allows big things to pass into the throat and body and these parts can be stretched too.

Boa constrictors hunt while hanging from trees. They attack animals that pass under them.

Like other snakes, boa constrictors can live for many months without food. They sometimes sleep for a week after a single large meal while they digest their food.

Boa constrictors do not lay eggs. Their young are born alive. They may give birth to as many as 50 young snakes at one once.

Boa constrictors living in captivity usually eat mice. In the wilds, they eat birds and small rodents.

Often called the water boa is the anaconda of tropical South America. It can grow to be more than 30 feet long. All adults are more than 20 feet long.

Anacondas, like the boas, live on birds and small mammals. They also kill their prey by wrapping their coils tightly around them to keep them from breathing.

Also measuring up to 30 feet long is the python. You'll find this monster living in the East Indies, Africa and Australia.

Pythons, like boas, are also called constrictors because they squeeze their prey to death. They do not squeeze hard enough to break the victim's bones or to change its shape. They squeeze just enough to stop the victim's breathing and blood circulation.

Pythons have been known to kill and swallow pigs that weigh as much as 100 pounds. As you can imagine, it takes the snake many days to digest a meal of this size.

Like most snakes, pythons hatch from eggs. A female may lay as many as 100 eggs at a time.