During their larval stage, amphibians respire through gills and live entirely in water. They lay their eggs in water, and the larvae hatch and develop in the water. As they mature, they undergo metamorphosis, a process during which their gills disappear, their lungs develop, and they develop the ability to walk on land.
Once they have completed metamorphosis, amphibians move from water to land, although many species remain closely associated with aquatic environments as adults. They still require access to water for breeding and for keeping their skin moist. Some species may also spend part of their time in trees or other elevated locations.
Examples of amphibians that live both on land and in water include:
- Frogs: such as the common frog (Rana temporaria), which can be found in a variety of habitats including ponds, lakes, rivers, and marshes
- Toads: such as the American toad (Anaxyrus americanus), which lives in damp environments including forests, fields, and gardens
- Salamanders: such as the spotted salamander (Ambystoma maculatum), which spends much of its time on land but returns to water to breed