Jesse R. Barber and Akito Y. Kawahara

ScienceShot: Vibrating Genitals May Ward Off Predators

When a bat moves in for the kill, some moths jiggle their genitals. Researchers made the observation by studying three species of hawk moths—big moths that can hover—in Malaysia. They snared the insects with bright lights, tied tiny leashes around their waists, and let them fly while bat attack sounds played. All three species responded to the noises with ultrasound—which they made by shaking their private parts, the team reports online today in Biology Letters. Males have a structure they use for hanging onto females when they mate; to make the sound, they scrape a patch of large scales on the structure against the very end of their abdomen, letting out two bursts of rapid clicks. Females also make a sound, but the researchers aren't sure how. The scientists don't know exactly what the sounds are for, either. The noise may warn the bats that they're trying to mess with a fast-moving, hard-to-catch piece of prey, or it might jam the bat's ultrasound signals. Either way, the racy display may save their lives.

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