Mice whistle like a jet engine to attract a mate
Mice make whistling noises to seek sex by using a mechanism similar to that of a jet engine inside their throats, research has found.
It was previously thought that these 'Clangers'-style songs were either the result of a mechanism similar to that of a tea kettle, or of the resonance caused by the vibration of the vocal cords.
But a study co-authored at the University of Cambridge and published in the journal Current Biology has found that when mice 'sing', they use a mechanism similar to that seen in the engines of supersonic jets.
The high frequency whistles are used by mice to attract mates and for territorial defence.
"Mice make ultrasound in a way never found before in any animal," said the study's lead author Elena Mahrt, from Washington State University.
The researchers found that mice do not use vibrating vocal folds in their larynx to make their ultrasonic sounds.
Instead, they point a small air jet coming from the windpipe against the inner wall of the larynx, causing a resonance and producing an ultrasonic whistle.
Using ultra-high-speed video of 100,000 frames per second the researchers showed that the vocal folds remain completely still while ultrasound was coming from the mouse's larynx.
"This mechanism is known only to produce sound in supersonic flow applications, such as vertical takeoff and landing with jet engines, or high-speed subsonic flows, such as jets for rapid cooling of electrical components and turbines," said Dr Anurag Agarwal, study co-author and head of the Aero-acoustics laboratories at Cambridge's Department of Engineering. "Mice seem to be doing something very complicated and clever to make ultrasound."
The study's senior author Dr Coen Elemans, from the University of Southern Denmark, said: "It seems likely that many rodents use ultrasound to communicate, but very little is known about this - it is even possible that bats use this cool mechanism to echolocate.
"Even though mice have been studied so intensely, they still have some cool tricks up their sleeves."
'Singing' mice have been used to study communication disorders in humans, such as stuttering.
Until now it was not understood how mice made these ultrasonic sounds, which may aid in the development of more effective animal models for studying human speech disorders.