Sonar-Absorbing Moths Evade Bats
Some bats eat insects, such as moths. The bats use echolocation (biological sonar) to track moths. Some moths have ultrasensitive ears to help the them evade bats. Others emit their own acoustic signals to confuse the bats.
The scales on the bodies of moths also help them evade bat sonar by absorbing sound rather than reflecting it. Thus, moth scales function as stealth technology on radar-evading airplanes.
The scales on the bodies of moths resemble hairs. They also resemble many natural materials that are used as sound insulation. This inspired the scientists to test the sound-reflecting properties (echoes) of the scales using acoustic tomography.
They compared the echoes from earless moths with the scales intact or removed and showed that the removing the scales increased the strength of the reflected sound. Additionally, removing the scales made the echo from the body louder than the echo from the wings. Thus, earless moths rely on acoustic camouflage to avoid detection by echolocating bats.
T. R. Neil. Z. Shen, D. Robert, B. W. Drinkwater, M. W. Holderied, Thoracic scales of moths as a stealth coating against bat biosonar. J. R. Soc. Interface 17, DOI: 10.1098/rsif.2019.0692