Christine Velis, age 11, of Salt Lake City, Utah, for her question:
DO SNAKES REALLY HAVE LIVE BABIES?
Most snakes lay eggs, but others give birth to live babies. In North America, about 100 of the native snakes bear live babies and about 150 species lay eggs. In other parts of the world, the egg layers far outnumber the live bearers.
Our native king snakes and bull snakes, pine snakes and coral snakes all lay eggs. They are pale oval shape eggs with tough, pliable shells. As a rule, the female lays her brood on the ground and leaves them to hatch in the sand or warm soil. The youngsters are miniature copies of their parents and all ready to go as soon as they shed their shells.
Our native boas, water snakes and garter snakes give birth to live babies. So do our deadly copperheads and water moccasins and all of our poisonous rattlesnakes. In most live¬ bearing species the infants stay inside the mother's body from four to six months. This gives them plenty of time to develop, and when they emerge the youngsters also are ready to take care of themselves.
When the time comes to give birth, the live bearing mother snake is restless and irritable. But she settles down as the babies emerge one by one. Each infant snake arrives coiled up and neatly wrapped in a clear membrane, which looks like a plastic bag. It may take 10 minutes to emerge, and the next may begin emerging in just a few seconds.
In some species the mother snake takes a rest after each birth, so complete delivery takes many hours. In some cases the newborn babes break out of their plastic bags within a few minutes. Others wait an hour or even a day or more. The mother shows little or no interest in her offspring. When her delivery duties are done, she may rest awhile. Then she glides away in search of a good dinner. The deserted babies also are hungry, but they are able to find their own food.
In North America we have perhaps 30 different rattlesnakes, ranging from 2 to 7 feet in length. All of them bear live babies, usually in late summer or fall. The tail of each newborn infant ends with a small button.. He soon sheds his skin and gains the first section of his rattle. Thereafter a new bony bead is added to the rattle every time he sheds his skin.