Researchers at Carleton University have been studying caterpillars that make shrieking sounds when they are attacked. During their investigation, the experts found that the caterpillars force out air to produce the noises in a process similar to how tea kettles whistle.
The study was focused on the Nessus sphinx hawk moth caterpillar, which lets out a high-pitched cry that sounds like static when approached by a predator. The research team captured female moths and hatched their eggs in a lab.
When the caterpillars were grown, the researchers mimicked an attack by pinching the creatures with forceps and recorded the noises produced by the moths in response.
The caterpillars kept their mouths open the whole time as they emitted the crying sounds, which the researchers discovered were coming from inside of their bodies.
Study co-author Jayne Yack explained that analyzing the insides of the caterpillars was not an easy task.
“Maybe one day it will be possible to observe what’s happening inside a live insect, which is quite small, when something fast is happening,” Professor Yack told Live Science. “Right now, we don’t have the equipment to do that kind of thing.”
When the scientists dissected the caterpillars’ throats, they did not find any structures capable of producing the sounds.
Study co-author Craig Merrett decided to analyze the noises recorded by the team. He ultimately found that the sounds are produced when the caterpillar forces air through a constricted area between its two foregut chambers, creating a turbulent air stream.
According to Professor Yack, it remains a mystery how the caterpillars get air in the upper portions of their guts.
The study is published in the Journal of Experimental Biology.