Frogs occupy an intermediate position between terrestrial and aquatic vertebrates. The class of amphibians requires oxygen to live. A frog can receive it on land and partially under water through the skin.
The frog can be under water for a long time. Therefore, many people think that she breathes with gills. In fact, frogs have very large lungs. Before diving, the animal takes in full lungs of air. Under water, oxygen is very slowly absorbed through the blood arteries, which helps the frog stay under water for a long time. As soon as the air supply runs out, the animal quickly emerges and holds its head above the water surface for some time in order to regain full lungs of air.
But not only for this does the frog stick out its head above the surface of the water. An adult reproduces in water, but prefers to spend most of its life on land, choosing very damp and shaded places for habitation.
On land, frogs hunt by catching insects, which are their main diet. In vegetable gardens located in the lowlands of nearby reservoirs, fruit trees, shrubs and vegetable crops are almost never affected by pests, since frogs are cleaner animals. Only a few frogs are capable of destroying hordes of insect pests.
In the process of development, a tadpole appears from an egg or egg, which has gills and a tail. At first, the future frog can be mistaken for a fish fry, but within a short period of time the tadpole takes the form of a small frog, the tail dies off, the gills are completely covered with skin. The small animal begins to breathe with its lungs and moves to land.
As winter approaches, frogs burrow into silt at the bottom of lakes, streams and ponds. At this time, the exchange of gases occurs through the skin covered with mucus. In a state of hibernation, or suspended animation, the frog requires a small amount of oxygen and with the help of skin exchange, the animal survives for a long time before the onset of warmth.