How Vibrating Genitals Help Moths Evade Bats
When researchers began feeding hawkmoths to bats, they noticed something strange happening. A bat would locate a moth and begin pursuing it — but suddenly, the bat would veer off course.
Akito Kawahara, a biologist at the University of Florida, became intrigued with these special insects. Even after hawkmoths stayed in the bat cage for several nights, they remained consistently effective at thwarting attack. As the team watched and listened closely, they noticed something interesting: Immediately prior to the bat’s change in direction, an ultrasonic signal was detected coming from the moths themselves. These sounds jammed the bats’ sonar, rendering attackers unable to locate their prey.
To determine how these moths were producing ultrasound, Kawahara tethered them to plastic straws and trained high-speed cameras on them. When the researchers watched the footage in slow motion, they discovered tiny scales located on the moths’ claspers (very special organs located near a male’s rear end). As it turns out, these claspers also have the ability to become erect and latch onto a female’s cercus. And the clasper’s primary function is to transfer seminal fluid to the female.
Believe it or not, the secret behind these moths’ anti-sonar technology lies within their penises.
“Talk about a multi-purpose tool,” writes Traci Watson, associate editor for Nature, “[This] species of tropical moth can rasp their genitals against their abdomens to beam loud ultrasound signals at approaching bats.”
As Kawahara and his team examined the moths further, they discovered that females were similarly able to generate ultrasound by pulling their genitals inward. This, of course, indicates that ultrasound is an important part of these moths’ courtship rituals.
Did you ever want to know how moths have sex?
In that case, nevermind. But if you change your mind, keep reading.
During mating season, females will spray pheromones into the air (one researcher described the scent as that of ripe pineapple). When a male detects it, he will begin flying upwind, making ultrasonic chirping sounds with his singing penis. The female will respond with a series of clicks, and the two of them will continue calling out until they locate one another.
The two become locked in an embrace, but it only lasts a few seconds before the female pulls away. At this point, the male needs to resume the courtship song to persuade his mate to come back. If she feels inclined, the female will return time and time again — some researchers have observed moths repeating copulation as many as one hundred times in a row, but only when the male has a particularly impressive song.
As it turns out, a singing penis isn’t just a crude way to attract a mate. Ok, maybe it is. But when researchers placed muted moths together, females were highly prone to flying away.
Jesse Barber, co-author of the groundbreaking paper on the genitals of hawkmoths, remarked that this use of ultrasound is “a really good strategy for insects to deploy.” Even though singing penises primarily help moths sire more offspring, this ability is now being used in combat against bats.
Perhaps the most surprising thing about male hawkmoths is that they have the ability to hold a female in place to prevent her from escaping. But still, they choose to use courtship songs to gently persuade their mates. Not that this makes singing penises any less weird.
But who would have thought that learning to sing to a lady would end up saving a moth’s life?
Although singing penises have been proven advantageous for moths, please do not consider anything outlined in this article as relationship advice. The author’s wife would like to discourage readers from trying to imitate moths’ courtship rituals. Apparently, an unfavorable outcome will ensue. You have been warned.