'Burning Ears'

The ears of the Yellow Underwing moth become more sensitive to a bat's calls when being attacked.

As a bat gets closer to the moth, both the loudness and frequency (pitch) of the bat's calls increase. Surprisingly, the sensitivity of the moth's ear to the bat's calls also increases. This occurs because the moth's ear dynamically becomes more sensitive to the frequencies that many bats use when attacking moths.

"Because the moth cleverly tunes its ear to enhance its detection of bats, we must now question whether the bat in turn modifies its calls to avoid detection by the moth," said James Windmill from the University of Bristol, UK. "In view of the vast diversity of bat calls, this is only to be expected."

It has been known for over 50 years that moths can hear the ultrasonic hunting calls of their nocturnal predator, the bat. Previously it was thought that these ears were only partially sensitive to the sound frequencies commonly used by bats and that bats would make their hunting calls inaudible to moths.

But now it appears that even though moth ears are among the simplest in the insect world - they have only two or four vibration sensitive cells attached to a small eardrum - moths are not as deaf as previously thought.

"To date, this phenomenon has not been reported for insects or, in fact, for any other hearing system in the animal kingdom. These findings change our understanding of the co-evolution of bats and moths and have implications for the hearing of many other animals."

---LiveScience Staff

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Credit: James Windmill