Bats are the only flying vertebrates that use echo-location to find their prey. To do that, they emit a sound called the terminal buzz. Until now, scientists have not been exactly sure how they do it, but a recent study appearing in Friday’s edition of Science sheds light on how “superfast” muscles help bats emit calls at rapid rates and target moving prey.
Picture this: It is dusk. Your friendly neighborhood brown bat is flying around in search of dinner. It is making high-pitched squeaks and waiting for the echo to hear if there is a nearby house or tree to avoid. Then suddenly — a bug! It zeroes in on the prey, and those calls? They speed up.
“As a bat flies closer and closer to an insect, it produces shorter and shorter and shorter calls,” said Brock Fenton, a University of Western Ontario bat expert.
By the time a long call bounced off a bug and made it back to the bat, Fenton said the delicious morsel would have flown away. So the squeaks are quick, and close together–up to 190 separate calls per second.
Bats use throat muscles to produce sound, just like humans, but scientists had never found a mammal muscle that could turn on and off that quickly, said Andy Mead.
“You can tap your finger on a table, and you can try to tap your finger as fast as you possibly can,” said Mead, a biology graduate student at the University of Pennsylvania.
“Eventually you seize up, you get stiff and you can’t tap any faster … you can probably tap five, six, seven times a second if you really try, but you certainly can’t tap 190 times a second,” he said.
As part of a research team based in Denmark led by Coen Elemans from the University of Southern Denmark, Mead found muscles in a bat larynx that could turn on and off in less than one one-hundredth of a second.
“It was instantaneously really shocking and exciting to see yes, this is a very, very fast muscle,” Mead said.
It is a “superfast” muscle–the actual scientific term. They are responsible for the rattle of a rattlesnake and the mating call of a fish called the toadfish. This is the first time a superfast muscle has been found in a mammal, leading researchers to believe the muscles may be more common than previously thought.