Science Can't Improve on Bat's Bizarre Nose
Acoustic studies show why one horseshoe bat has such a long nose.
WASHINGTON, Aug. 22, 2009 -- In a dark place, people generally use a flashlight to emit light waves and pierce the darkness. The returning waves of photons fire cells in our eyes, enabling us to see which way to go. Cave dwelling bats don't have flashlights, so instead they send out sound waves. Bats use the echo of the waves to "see" in the dark, allowing them to maneuver and to catch insects.
A new study attempts to understand how bats' noses operate in producing sounds, and the purpose of the elaborate surrounding creases and grooves (called nose-leaves) which give the horseshoe bat such a scary visage.
The sonic equipment of bats, modified by evolution over millions of years, is quite sophisticated, but can give the animals a bizarre appearance. In horseshoe bats, elaborate folds of skin in the shape of a horseshoe surround the nose and help to sculpt sound pulses emerging from the nostrils.
One horseshoe bat species in particular, discovered 58 years ago in the rainforests of Southeast Asia, has defied explanations as to why it should have such a long nose. The species, called paradoxolophus, has now been the subject of an experiment by scientists from Shandong University in China and the Vietnam Academy of Science and Technology in Hanoi. Performing a digital scan of the animal's actual nose, the researchers tried to simulate the animal's sound production. They artificially made the nose shorter and then longer.
Could they invent a better nose? What they found was that nature knows best. Whenever the scientists made the bat's nose shorter the sonar beam lost some of its sharp focus. In other words, having a long nose was necessary for navigation, at least in the bat's particular habitat. Making the nose longer didn't result in any significantimprovement. So, the bat's long nose is quite useful. If a human had the same proportion of nose to body height, her nose would be about 12 inches long.
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