Amphibians are the transition between aquatic and terrestrial animals. Frogs lay their eggs in large lumps of frog-rit in the water. From the egg hatches a tadpole that can only survive in water: it has a long tail and gills to breathe. But in a few weeks time the tadpole changes entirely: its tail gradually disappears and four paws start to grow, the gills are replaced by lungs. The animal has become a real land animal and climbs ashore.