Most amphibians, animals who live on both land and water, reproduce by laying eggs. A minority of amphibian species, however, reproduces by giving birth to either live young or larvae.
Although some species lay their eggs on land, most amphibian females deposit their eggs in water. These eggs have a soft exterior rather than a hard shell and develop into larvae called tadpoles. The tadpoles live underwater until they grow lungs. While living in the water, they use gills to breathe. Once their lungs are present, the tadpoles are able to breathe air and live on land as well as water.