Amphibians were the first animals to adapt to terrestrial life and acquire four limbs millions of years ago. Nowadays, they are at grave risk, more than any other vertebrate class.
Amphibians are ectothermic (cold-blooded) vertebrates with an interesting life cycle. They normally begin their lives as aquatic fish-like larvae after hatching, developing into terrestrial adults. They breathe through gills in the first part of their life cycle and then via the lungs as adults. We call this change of shape metamorphosis. While adults live mainly on land, they typically return to water to breed. Amphibian eggs lack shells and are instead encased in a gelatinous material.
In contrast to reptiles, amphibians have smooth, fragile skin that requires constant moisture. Since many amphibians have large eyes, they may easily identify their prey even at night. Depending on the temperature, amount of light, or mood, some amphibians also alter the color of their skin.
Orders in this class
Toads are kind of frogs, with shorter legs (to crawl & hop rather than leap) and dry skin (and not moist like frogs)
They only four-limbed animals that can grow back entire limbs and regenerate organs when injured
Caecilians are limbless, serpentine amphibians distributed in the tropics of South and Central America, Africa, and southern Asia