In waging millions of years of battle, both moths and their predators, bats, have adapted certain evolutionary tactics to give their species the upper hand. Bats have a “stealth mode” of hunting, and some use clicks that are out of the frequency of moths’ hearing ranges to locate prey. Some kinds of moths, though, have one-upped them with a battle tactic that’s way cooler: defensive sonic genital blasts.
Researchers from Boise State University and the University of Florida studied how hawk moths, a family of moths found most commonly in the tropics, responded to the ultrasonic hunting calls of bats. Though their techniques are a bit different (for obvious reasons), both the male and the female in three different species of hawk moth seem to rub their genitals across their abdomens to produce their own ultrasound clicks, they found in a study online today in Biology Letters.
As Nature describes the process:
The males did so by rapidly grating stiff scales on the outer surface of their ‘claspers’ — structures normally used to grab females during mating — against part of the abdomen, the researchers report. Females also seem to pull part of their genitalia inwards so that genital scales rub against their abdomens.
They aren’t sure yet exactly how this genital clicking works as an anti-bat defense. It’s possible the ultrasound could startle or warn the bats off, or maybe even jam their echolocation, as one species of tiger moth does. It could be an instance of what the authors call “cross-family acoustic mimicry,” since the clicks are much like the bats’ own. In any case, it’s a neat bit of convergent evolution–the evolution of the same trait in different kinds of animals.
Fascinating moth genital video below: