Fireflies may use ultrasonic "musical armor" to fend off bats
When we think of camouflage, it’s usually a visual pattern. But how do you hide from a predator that uses sound to find food, like a bat? If you’re a firefly, it turns out you might resort to a cacophony of ultrasound that acts like “musical armor.”
Fireflies are famous for their glow, which is mostly used as a mating signal. It’s easy to assume that broadcasting your presence like that might get you eaten more often than it gets you laid, but scientists believe that it’s actually the opposite – fireflies are poisonous and unpalatable to most predators, and it’s thought that the glow is a warning.
Unfortunately that defence mechanism isn’t going to help much when one of your most prolific predators – the bat – is all but blind. But in a new study, researchers from Tel Aviv University and the Vietnam Academy of Science and Technology (VAST) discovered that fireflies may have developed a clever audio armor instead. And the discovery came accidentally.
"We were wandering around a tropical forest with microphones capable of recording bats' high frequencies, when suddenly, we detected unfamiliar sounds at similar frequencies, coming from fireflies," says Yossi Yovel, lead researcher on the study.
On closer inspection, the team found that the bugs make the noise by moving their wings, and follow-up lab tests found the behavior in at least four different firefly species. Importantly, the noise is at ultrasonic frequencies – meaning the fireflies can’t even hear it themselves. That suggests that they aren’t using it for any kind of communication between other members of their species.
Bats, however, can hear it, which led the team to its working hypothesis that the ultrasound is a kind of musical armor to warn off the predator.
"The idea of warning signals that the sender itself cannot detect is known from the world of plants but is quite rare among animals,” says Yovel. “Our discovery of the 'musical battle' between fireflies and bats may pave the way for further research, and possibly the discovery of a new defense mechanism developed by animals against potential predators.”
The research was published in the journal iScience.