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:
“The sun, the hero of every day, the impersonal old man that beams as brightly on death as on birth, came up every morning and raced across the blue dome and dipped into the sea of fire every evening. Water ran down hill and birds nested.”
—Zora Neale Hurston (1891–1960)
“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)
“Calico Pie,
The little Birds fly
Down to the calico tree,
Their wings were blue,
And they sang “Tilly-loo!”
Till away they flew—
And they never came back to me!”
—Edward Lear (1812–1888)