Amphibia includes Frogs, Toads, Salamanders, and the worm like Caecilians.
Amphibians inhabit a great variety of ecological niches, including such arid regions as deserts.
In colder regions amphibians pass the winter by hibernating. Amphibians are cold blooded, relying on the temperature of their surroundings to regulate their body temperatures. They usually have porous skin through which they are able to absorb water and oxygen, some aquatic varieties retaining gills into adulthood. Amphibians developed during the early Devonian Period and were the first successful land dwelling vertebrates. Originally amphibians were fish like, similar to the Mud skipper of today.