Birds
In birds with webbed feet, retia mirabilia in the legs and feet transfer heat from the outgoing (hot) blood in the arteries to the incoming (cold) blood in the veins. The effect of this biological heat exchanger is that the internal temperature of the feet is much closer to the ambient temperature, thus reducing heat loss. Penguins have them also in the flippers and nasal passages.
Read more about this topic: Rete Mirabile
Famous quotes containing the word birds:
“...here he is, fully alive, and it is hard to picture him fully dead. Death is thirty-three hours away and here we are talking about the brain size of birds and bloodhounds and hunting in the woods. You can only attend to death for so long before the life force sucks you right in again.”
—Helen Prejean (b. 1940)
“Over Sir John’s hill,
The hawk on fire hangs still;
In a hoisted cloud, at drop of dusk, he pulls to his claws
And gallows, up the rays of his eyes the small birds of the bay....”
—Dylan Thomas (1914–1953)
“These beginnings of commerce on a lake in the wilderness are very interesting,—these larger white birds that come to keep company with the gulls.”
—Henry David Thoreau (1817–1862)