Froggy Amphibians form a Class of Vertebrates .
Vertebrates are animals that have backbones that surround their nerve cords.
The nerve cord is found along the back of an animal. The bodies of most vertebrates have a head and a trunk. They are called ectotherms or cold-blooded. That means that amphibians do not hold their body temperature constant like mammals, but their body temperature depends upon that of the surrounding environment. Amphibians have soft, generally moist skin without scales.