Frogs are amphibious animals, meaning that they live in and out of the water. Frogs lay their eggs in large numbers. Pond frogs lay their eggs in water; tree frogs lay their eggs on the undersides of leaves.

The eggs hatch as tadpoles. Tadpoles begin life as plant-eaters, using their rasping mouths to pull away algae growing on leaves and rocks. They breathe using gills. They move by wiggling their tails.

Later on the tadpoles develop back legs, and later still, front legs. After this, the tadpole loses its gills and develops lungs. It also loses its tail.

Adult frogs spend some time in water, but they mostly live on land, in shadowy places where they can find food such as insects and worms, and where direct sunlight does not cause their skins to dry out. They are active mainly at night.

Frogs mainly live alone, except at the mating season. Then frogs gather in large numbers. This is when male frogs puff up their cheeks and send out their famous call.

A frog is very well adapted for life in water. Its body has a streamlined shape so that it can move quickly through water. It has powerful leg muscles and webbed feet so it can generate a strong pushing force backwards on the water which thrusts the frog forward quickly. The skin of the frog is blotchy so that it is camouflaged among the water plants. The frog has eyes on the top of its head. They allow the frog to see out of the water while the rest of the body is kept safely below the water surface.

The long back legs and powerful leg muscles are also useful when the frog is on land. If the frog is attacked by a predator its simply straightens its legs quickly and springs into the air. Some frogs can travel several metres in one leap whereas others may make a series of smaller hops. The main predators on frogs are thought to be herons and grass snakes, although they are eaten by birds of prey, hedgehogs and crows.

The frog is also a predator. It feeds on snails, slugs, worms and insects. The frog's tongue is attached to the front of its mouth not the back as in most other animals. When the frog sees an insect close by it flicks out its tongue and the insect is caught on the tongue's sticky surface.

The slimy skin limits the places where a frog can live on land. The skin cannot keep water in like that of a snake or lizard so the frog has to stay in damp surroundings.