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THE MENAGERIE AT THE PORCH
FROGS

WHY FROG COLD

In fact, why it is not heated from the inside? Yes because of the size of red blood cells (erythrocytes). The frogs they are huge: length 23, and the width of 16 microns. No good in this - the smaller the cells, the better. Milliliter frog blood accommodates 400 thousand erythrocytes, our 5 million, and goat - even 18 million. The total surface of red blood cells in a milliliter of goat's blood gives a mind-blowing figure, we value will also be impressive, and the frog is modest.

Because of this, it is cold. The more the surface of the erythrocytes, the more intense the gas exchange. Tiny red blood cells more quickly absorb oxygen and give easier than the red-giants. After the oxygen in the red blood cells came into contact with hemoglobin, it should be delivered to the tissues and organs. Here the principle is the same: inside all animal acts pipeline transport. And the more powerful the motor, Sipper blood through the veins, the faster it will come again into the lungs for the next batch of oxygen. But with the pump in frog is doing poorly - low. Weighs her heart nine times less than equal to her weight swallows. However, the frog might argue that she had not one, but many motors that she had two pairs of hearts. But this is not the assistants and hangers-on of the main heart. They transport the lymph fluid, which occupies a large cavity under the skin. (One cavity even called the big tank.)

And with light frogs no luck - very small surface, it would not be enough even to cover the body. If, for example, carefully flatten the lungs of a bull and wrap it formed fabric, you get the cocoon of nearly a hundred layers. Little frog's easy need help skin breath. Instead, it absorbs oxygen stomach, back and even the mucous membrane of the mouth. In summer, cool skin allocates up to 3/4 of all carbon dioxide emitted by the body. So that the skin is a more powerful fan than light.

Even with a big mouth from ear to ear," the frog had to acquire in order to get more air. But vain his mouth to open, it will not - will suffocate. After all edges in frog no, and the air from the mouth into the lungs pumping into the lower wall of the mouth.

Constant problems with oxygen supply caused the frog to mute metabolism. She and food digests slowly: beetle, not severely injured when caught, remains in her stomach alive for more than an hour (usually a pest who disdain birds). And on cool days, frogs, and lizards, and absolutely no appetite. Mammals and birds at this time terribly hungry: they have to cover the loss of energy to maintain body temperature. But cold-blooded creatures such hassle no, they do not tremble from the cold, even completely freezing.

To avoid the risk, frogs in a hurry to winter quarters, barely the air steadily become colder water. Most amphibians in the winter asleep in the water. But, for example, moor frog underwater overnight't like it, she prefers to spend the winter in the pits near stumps, among the fallen leaves and pine needles.

In collective underwater bedroom gathers two dozen cold-blooded guests. But sometimes side by side in a particularly cosy place to bury themselves in the mud and one hundred individuals of different sex and age. It can curl up and another frog species wouldn't hurt her. In the team's easier to maintain force: individuals, wintering along with their own kind, the level of metabolism by almost 40% lower than the single!

During the winter under water frogs breathe only the skin, the pulse weakens, moves blood pH... If the bedroom will be uncomfortable, they move to another place. So sleep in them sensitive. Moreover, they do not lose time in vain and the long winter nights grow - albeit slower than in the summer.

But if the pond during the winter will freeze - it's gone. For example, severe winters 1828-1830 years killed all the frogs in the whole of Iceland. Warm winter too dangerous. In 1924 near Moscow not all frogs lay dormant, and in the spring of their choir sounded watery road.

Hard-eyed at life. And enemies have a lot. And so five frog - rare. Meanwhile, in captivity they quietly live 15 years.

Frogs grow life. For the first year they increased by three inches, for the second - half, and then quite little by little. The development of the head stops before other parts of the body, and the rear feet grow faster and longer than most. Our large lake frog sometimes up to 17 inches and weighs three hundred grams, and the frog-bull pulls and six hundred grams. But this is not the limit: in 1906 in Cameroon found a frog is the Goliath. This tridtsatisantimetrovaya person weighed 3.5 kg.

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The menagerie at the porch

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