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An Acoustic Arms Race

Bats and other animals use sound as a hunting tool—but their prey has also evolved ways to thwart detection

William E. Conner

2013-05ConnerF1.jpgClick to Enlarge ImageThe sophistication of military radar and sonar systems may seem to eclipse the efforts of animals that navigate and hunt using echolocation. But new discoveries about biological sonar show that is a marvel of sophistication, not only in how signals are produced and detected, but also in the evolutionary combat of countermeasures used by predator and prey. The author describes the discovery that bats can switch between frequencies during their calls, depending on whether they are detecting prey at a distance or require close-up accuracy. Their ears are often tuned to best receive the frequencies they use. But insects are not passive in this fight. Some will cluster to blend in with echoes from vegetation. Others have scales that dampen echoes. And others release their own streams of noise to jam signals. Bats have responded by reducing the intensity of their calls, so insects can’t detect them until it’s too late. The author suspects that there are many more surprising countermeasures awaiting discovery.

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