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Science Frontiers ONLINE No. 134: MAR-APR 2001 |
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Toppling-Penguin Theory Overturned
Penguins, like most animals, are counter-shaded, dark on the back, light below. When the penguins are swimming, avian predators have difficulty seeing them against the dark sea. Marine predators below tend to lose their white bellies when seen against the bright sky.
But when the penguins waddle across the white snow, the avian predators can spot them easily. Unless, of course, the penguins are clever enough to flop over on their backs exposing only their white tummies. Since they perceive aircraft as threats, they topple backwards intentionally. Pretty smart of them!
(Browyer, Adrian; "White Out," New Scientist, p. 54, December 16, 2000.)
Comment. More seriously, an outstanding exception to the countershading rule is Africa's ratel or honey-badger. It is white on top, dark on its belly. But like its cousin, North America's wolverine, the ratel is so strong and fierce that even lions avoid it. It doesn't need camouflage.
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