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Superfast muscles found in bats

Close up of a Daubenton's bat.
[Image courtesy of Knud Ladegaard Pedersen]

As bats swoop in on their prey, their sonar-based calls—used to locate and track their meals—increase to an incredible speed of about 160 calls per second. This kind of super-fast sonar call is known as the "terminal buzz," and it is often the last thing an insect ever hears.

Now, a team of researchers has discovered that bats need a special group of superfast muscles that are capable of flexing more than 100 times per second in order to create this terminal buzz. These rare muscles, like the ones in a rattlesnake's tail, have been found in a small number of reptile species, birds and fish—but until now, researchers did not know that mammals could have them too.

Coen Elemans and colleagues studied the airborne attacks of bats with 12 sensitive microphones and realized that the muscle-flexing needed to make the bats' terminal buzz could not be done with regular skeletal muscles. The researchers then looked at small bundles of muscle fibers in the bats throats, and found that they were able to flex up to 200 times per second.

These findings are published in the 30 September issue of the journal Science, and they suggest that these special, superfast muscles may be more common than researchers have believed.

Elemans and his colleagues also discovered that bats don't need to limit their calls during the terminal buzz in order to keep track of their prey. Instead, it seems that the only thing limited the number of sonar calls a bat makes per second is the muscles in their throat!