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 descending in the west,
The evening star does shine;
The birds are silent in their nest,
And I must seek for mine.”
—William Blake (1757–1827)
“Let us not succumb to nature. We will marshall the clouds and restrain tempests; we will bottle up pestilent exhalations; we will probe for earthquakes, grub them up, and give vent to the dangerous gas; we will disembowel the volcano, and extract its poison, take its seed out. We will wash water, and warm fire, and cool ice, and underprop the earth. We will teach birds to fly, and fishes to swim, and ruminants to chew the cud. It is time we looked into these things.”
—Henry David Thoreau (1817–1862)
“Birds which are the same color as the foliage in which they nest are less likely to be disturbed by other birds who want to drop in and chat, and therefore last longer.”
—Robert Benchley (1889–1945)