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)
“We must not make a scarecrow of the law,
Setting it up to fear the birds of prey,
And let it keep one shape, till custom make it
Their perch and not their terror.”
—William Shakespeare (1564–1616)
“My weary limbs are scarcely stretched for repose, before red dawn peeps into my chamber window, and the birds in the whispering leaves over the roof, apprise me by their sweetest notes that another day of toil awaits me. I arise, the harness is hastily adjusted and once more I step upon the tread-mill.”
—“E. B.,” U.S. farmer. As quoted in Feminine Ingenuity, by Anne L. MacDonald (1992)