Amphibians

Amphibians are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic (or cold-blooded) tetrapods. Most Amphibians undergo metamorphosis from a juvenile water-breathing form to an adult air-breathing form, but some are paedomorphs that retain the juvenile water-breathing form throughout life. Mudpuppies, for example, retain juvenile gills in adulthood. When they make their transition into adulthood they grow lungs so they can breathe in air. They have thin and slimy skin. The skin is so thin that amphibians absorb water through it instead of drinking. But they can also lose water through their skin and easily become dehydrate. Amphibians are often called ecological indicators. In other words, unhealthy amphibians can be an early sign of changes in an ecosystem.