Tailless amphibians, belonging to the family of real frogs, lead both terrestrial and aquatic life. Frogs living in water raise their heads above the surface to breathe. They are also forced to stay close to the surface of the reservoir by the ambient temperature and the need for food.
The respiratory organs of amphibians, which include frogs, are the lungs, skin and gills. Unlike tadpoles, which lead an aquatic lifestyle, adult frogs have no gills. Oxygen dissolved in water enters the blood of these creatures through the skin. This breathing method can provide the body with the necessary gas only if the frog is in hibernation. The exception is a number of species of tailless amphibians, the body of which is supplied with oxygen exclusively through gas exchange in the skin. A common European grass frog in the summer can survive due to skin respiration for no more than eight days. Sticking her head out of the water and inhaling air, she replenishes the oxygen supply in the blood.
The frogs' need for a certain ambient temperature can make them stick to the surface of the water. In spring and summer, when amphibians are especially active, the upper layers of water are better warmed up by the sun's rays. This makes the surface of water bodies more comfortable for amphibians. Grass frogs are known to hibernate when the water temperature drops to six or ten degrees. Lakes go into hibernation when the average water temperature drops to eight degrees. For spawning, frogs also choose the most heated areas of water bodies.
Insects play a significant role in the feeding of frogs. Amphibians leading a land lifestyle get the bulk of their food on land. Species that have chosen reservoirs as habitats hunt insects, sticking their heads above the surface of the water. During the breeding season, which frogs spend in water, amphibians living on land do the same. The exception is the species that at this time adhere to the so-called "mating fast" and do not eat.
