What is an Amphibian?
Amphibians are a diverse and exciting class of animals that include frogs, toads, salamanders, newts and caecilians. The term Amphibian comes from the Greek word amphibious. Amphi means “both” and bios means “life”. Those names refer to the two lives that many amphibians live – one in water during their larval stage and the other on land during their adult stage.
The life cycle of Amphibians begins with an egg. A larva usually hatches from an egg (frog and toad larva are commonly referred to as tadpoles). The larva slowly develops into an adult by growing legs and arms and by developing lungs. The larval stage can last anywhere from 2 weeks to 2 years! Once the change is complete, the adult amphibian will emerge from the water and spend the majority of its life in the moist, surrounding habitat.
Not all amphibians go through the same metamorphosis process. Some frogs and salamanders, like the greenhouse frog and the red-backed salamander, lay their eggs on land. The larva develops inside the egg and the adult will hatch out of the egg on land. They will live their entire lives away from water. The marsupial frog puts her eggs in a pouch on her back. Within that pouch the larva develops into frogs. Once the larva has fully developed, it emerges from its protective pouch as a small frog.
Amphibians are vertebrate animals (have a backbone) like fish, mammals, reptiles and birds. They are cold-blooded, which means their body temperature is regulated by their surrounding temperature. Amphibians are also characterized by their smooth, slimy skin and their lack of scales, feathers or hair. Their skin is permeable and many amphibians breathe through their skin instead of through their lungs.