Frogs take the intermediate place between land and water vertebrate animals. The class of Amphibia for life needs oxygen. His frog can receive on the land and partially under water through skin.
The frog can be a long time under water. Therefore many think that she breathes gills. Actually at frogs very big lungs. Before diving, the animal gathers full lungs of air. Under water oxygen is very slowly absorbed through blood arteries, it also helps a frog to be a long time under water. As soon as reserves of air come to an end, the animal quickly comes up and some time holds the head over a water surface again to gather full lungs of air.
But not only for this purpose the frog puts out the head over a water surface. The adult individual breeds in water, but prefers to carry out the most part of life on the land, choosing very crude and shaded places for dwelling.
On the land of a frog hunt, catching insects who are the main diet. In the kitchen gardens located in lowlands nearby of reservoirs, fruit-trees, bushes and vegetable cultures practically are never struck by wreckers as frogs treat animals cleaners. Only several young frogs are capable to destroy hordes of insects wreckers. In development from egg or a berry there is a tadpole who has gills and a tail. At first future young frog can be taken for a whitebait of fish, but during a short period the tadpole takes the forms of a little frog, the tail dies off, gills completely drag on skin. The little animal begins to breathe lungs and moves to the land. With approach of winter of a frog are dug in in silt at the bottom of lakes, streams and ponds. At this time exchange of gases happens through the skin covered with slime. In a condition of hibernation, or anabiosis, the frog needs insignificant amount of oxygen and by means of skin exchange the animal survives before heat for a long time.