Some types of muscles, somewhat unimaginatively dubbed ‘superfast muscles’, can contract with amazing speed. According to research led by Coen Elemans of the University of Denmark, the mammalian speed champion is a muscle bats use in echolocation.
Just before bats catch an insect in flight, they let loose a burst of sound to pinpoint the insect’s exact location in space. That burst, known as the terminal buzz, is composed of over 190 separate calls per second. The vocal apparatus needed to produce sound that quickly requires the fastest muscles yet found in mammals. In contrast, human leg muscles are 100 times slower. The fastest muscles in the human body are used to slam our eyes shut, but even they take about a quarter of a second to function.
Interestingly, all superfast muscles appear to be involved in the production of sound. For example, many birds use this sort of rapid firing to produce their varied songs. The fastest vertebrate muscles belong to the toadfish, which produces sound by vibrating the muscles in its swim bladder 200 times/second.