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Rete mirabile (February 4, 2010) Have you ever seen a goose stand on one leg? The geese at the park often stand on one leg, heads turned backward and beaks tucked underneath their wings. It made sense to me that geese's wings double as a 'face mask' when it's windy or cold. But the one-legged stance was a mystery. So I decided to find out what that was all about.
This is what I discovered. Birds' legs have an amazing adaptation called "rete mirabile." This adaptation explains why songbirds and cardinals can perch on icy metal feeders. It explains why geese and ducks can stand on ice and walk on snow without freezing their webbed feet and skinny little limbs. Rete mirabile is Latin for "wonderful net." (My new favorite phrase!)
The rete mirabile describes the fine, weblike pattern of arteries in birds' legs and feet. These arteries weave nets of warm blood, coming from the bird's heart, around veins of cold blood, coming from the bird's feet. The arteries' warm blood effectively provides a wonderful net of warmth for potentially frigid legs and feet. The plural term, used in speaking of both legs and feet, is retia mirabilia. Wonderful nets for those unfeathered appendages!
Amazing. But what does that have to do with standing on one leg? By standing on one leg a bird reduces by half the amount of heat he might lose through his unfeathered limbs. The bird only has to rely on rete mirabile for one of his limbs. And that way he stays warmer. Rete mirabile is really miraculous. More accurately, I'd say God is an amazing miracle-worker! Jeremiah 32:17, "Ah, Lord God! Behold, Thou hast made the heavens and the earth by Thy great power and by Thine outstretched arm! Nothing is too wonderful for Thee..."
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Survivorship
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