Amphibians make a natural grouping of animals, almost all other than the axolotls having a juvenile aquatic stage and an adult terrestrial stage.
Modern amphibians are the descendants of the first vertebrates to move out of the water onto the land. Most of them have evolved a great deal since that time.
The development of an egg into a tadpole and the metamorphosis of a tadpole to an adult may be observed with ease, making them ideal laboratory animals.
Frogs and toads fit the terrestrial vertebrate body pattern, having an endoskeleton with four pentadactyl limbs, and a brain located in the skull.
Many of the amphibians have well-developed powers of regeneration, and they may even be able to regenerate lost limbs. Other vertebrates lack this ability.
Many amphibians around the world are endangered species, but the reason is still a matter for debate. It may be caused by pesticides, Fungi, or something else.
Amphibians undergo a form of metamorphosis as they develop from tadpole to adult, a change in body form that is far greater than that of any other vertebrate.
The amphibians, which have external fertilization, gave rise at some point to the early reptiles, which had