Book 32, Question 88
Why do some reptiles have live babies instead of laying eggs?
A few snakes and lizards, including boas and garter snakes, give birth to live young.
The mother keeps the eggs inside her body until the babies are ready, and they hatch just as they are born. This can be a good plan in cool places, because the mother can move to sunny spots and warm her babies. Live babies then enter the world ready to go.