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:
“poems direct as what the birds said,
hard as a floor, sound as a bench,
mysterious as the silence when the tailor
would pause with his needle in the air.”
—Denise Levertov (b. 1923)
“While he hears in every spring
How the birds do chirp and sing:
Or before the hounds in cry
See the hare go stealing by:
Or along the shallow brook,
Angling with a baited hook,
See the fishes leap and play
In a blessed sunny day:”
—Nicholas Breton (1542–1626)
“Chaucer is fresh and modern still, and no dust settles on his true passages. It lightens along the line, and we are reminded that flowers have bloomed, and birds sung, and hearts beaten in England. Before the earnest gaze of the reader, the rust and moss of time gradually drop off, and the original green life is revealed. He was a homely and domestic man, and did breathe quite as modern men do.”
—Henry David Thoreau (1817–1862)