Scientists have discovered that echolocation, the biological sonar system that lets bat hunt in the dark, is produced by yet another unique property of bats: they have superfast vocal muscles, the New York Times reports.
"The last thing an insect hears before it is eaten by a bat is what scientists call the terminal buzz, a sonar-based call that bats use to track their prey," reports Anahad O'Connor. That buzz consists of up to 190 echolocation calls per second.
With echolocation, bats "see" in the dark by emitting beep-like sounds into their path and analyzing the echoes that come bouncing back. Shorter, faster calls should produce a more precise picture.
Until now, scientists hadn't been able to figure out exactly how bats produced so many calls so quickly. But, the newspaper said, researchers at the University of Southern Denmark and the University of Pennsylvania report in the journal Science that bats make that terminal buzz because of superfast vocal muscles. These rather weak muscles can contract, O'Connor wrote, "100 times as fast as ordinary human muscles and 20 times the speed of humans' fastest muscles, the ones in the eye."
Such superfast muscles had previously been documented only in songbirds, rattlesnakes and some fish, all of which use them to produce sound. They had not been found in any mammal until the research team decided to go looking.
"I thought, 'If we're going to find them in mammals, it's going to be bats,' " researcher Coen Elemans, an assistant professor at Southern Denmark, told the Times. "If you hunt prey that is fast-moving and also evading you, it's very important to produce these calls at a very, very high rate."
The team studied Daubenton's bats, a species found throughout Europe and Asia. They recorded the bats' calls and determined when the echoes reached the bats' ears.
The scientists found, O'Connor reports, that the bats' brains could process the sounds even faster than their muscles could generate them: a rate of up to 800 calls per second in some cases before the calls begin to overlap with the echoes and cause confusion.