Depending on the transfer TV about Antarctic - the homeland of penguins, many ask a question as these birds manage to live and breed in such unfriendly conditions. And the shiver passes on a body when the camera imprints naked paws of the penguins who got off in a small group on the ice coast. Why their extremities do not freeze?
Long time scientists of many countries tried to find the answer to a question why at penguins paws do not freeze. It was surprisingly simple. Extremities of this bird already cold! Their temperature - is slightly above zero degrees. Touching snow or ice, they are not cooled as not so warm in itself.
Why naked paws of a penguin have such low temperature? Everything is explained by their special building. Ornithologists found out that in stupnyakh this bird there is a huge number of blood vessels. And between the veins and arteries located there is a continuous heat exchange. The cooled blue blood rises from paws up, to a trunk of a penguin, heating up on the way. It is very important as if blood reached a body, keeping low temperature, the bird just would freeze, despite the dense and dense plumage. And blood arterial, on the contrary, goes down to the lower extremities, being on the way cooled, warming an organism. When it reaches paws, its temperature approaches zero. This phenomenon "reverse flow" is called. It not only helps a bird to survive in frosty Arctic winters, but also allows to keep ability to movement. If paws of a penguin were warm, they would freeze to ice. Besides, penguins keep heat not only in paws, but also in all body by delay of a blood-groove. During strong decrease in air temperature they get off in packs and try to move as little as possible. Being periodically interchanged the position, they allow the birds who are with edge to be warmed in group of companions. The organism of penguins enters at this time the state similar to that which happens at the animals falling into hibernation - bears, groundhogs, turtles. However this state less deep, and, in case of danger, penguins quickly recover and manage to react.