A group of living things
Amphibians
Amphibia
Double lives in water and on land.
Its members' last common ancestor lived about 330 million years ago.
You and amphibians last shared an ancestor about 350 million years ago (on 1 December, if life's history were one year).
The name amphibian means double life. Most start life in water and later live partly on land. Frogs and toads, salamanders and newts, and legless caecilians look very different, yet they are grouped together here as animals with backbones. Their closest relatives on the tree, their sister group, are the amniotes, the group that includes mammals, reptiles and birds.
Most start life as soft eggs laid in water or very damp places. Many young, such as tadpoles, have no legs and breathe through gills like fish, swimming by wriggling their tails. In many frogs, the body then changes: it grows lungs and legs, gets a new mouth, and loses the tail to become an adult that can often live partly on land.
Even as adults, many stay tied to damp places to keep their skin moist for breathing and to breed. Their moist skin lets oxygen and water pass through, and they take in most water this way rather than drinking. In many, the lungs and the lining of the mouth help too, giving three ways to breathe.
Meat eaters with sticky tongues
Every adult amphibian eats meat, and some that live on land catch prey with a sticky tongue.
Needing outside warmth
They rely on outside warmth to get active and become sluggish in cold weather.
As long as a grown-up
The largest living amphibians are the giant salamanders of China. They grow to nearly 1.8 metres long and about 63 kilograms, about as long as a tall grown-up lying down.