Among the adaptations reptiles have made to live on land is the ability to lay eggs on land. This is in contrast to amphibians, who lay their eggs in a watery medium. Reptile eggs often have leathery shells, which keeps the embryo within from drying out. Reptile eggs can also be fertilized internally, so because of this, reptiles such as garter snakes can give birth to live young.
The temperature at which some reptile eggs are incubated can also determine the sex of the embryo. Once hatched, baby reptiles don't experience the metamorphosis that many kinds of amphibians have to go through to transition from living in water to living on land.
Reptile skin is airtight, and reptiles don't need to stay close to a body of water like an amphibian. Therefore, the skin of a reptile is dry and scaly and not slimy. The scales are tough and made of the same material as nails and hair. They protect the animal from the type of injury that might kill a soft-skinned amphibian. Some reptiles moult or shed their skin now and then. Scales also allow the reptile to retain water. This allows some reptiles, such as the chuckwalla, to thrive in desert conditions.