Insects survive 1,213 feet of pressure under water, defying physics

Like it or not, insects are everywhere, including places where you may not want them to be. Yet there is one environment that they don’t call home—the open ocean. An enduring explanation for this absence is that deep water pressure would fill their tiny respiratory systems with air and they would then cave in.

But one particular insect larva is challenging this idea. Meet lake flies (Chaoborus edulis). In East Africa’s Lake Malawi, billions of their larvae spend their days over 656 feet (200 meters) below the surface of the water before coming back up to feed at night.

“Uniquely, Chaoborus midge larvae have modified their respiratory system into two pairs of air-filled sacs which they use to control their buoyancy,” Philip Matthews, a co-author of the study and a researcher who studies insects’ respiratory adaptations at the University of British Columbia tells Popular Science. “By regulating the pH of the air sacs’ walls, they cause them to expand or contract via a distinct ‘chemo-mechanical’ system.” Matthews and his team were intrigued by how this mechanism works, but realized that using air sacs to regulate buoyancy while diving presents a problem.

“The gas inside an air sac is not pressurized (it is roughly the same as the atmospheric pressure at the water’s surface),” he explains. “This begged the question: how deep can these insects dive before their air sacs cannot expand against the pressure? And at what depth do they fail completely and implode?”

The team decided to investigate this in Lake Malawi’s Chaoborus edulis larva, to solve this puzzle. The findings, detailed in a study published today in the journal Science, trace the larva’s daily diving routine with a sonar system, and look at what is going on at the biological level. The walls of C.

edulis’ air sacs have resilin, a substance that grows or shrinks in volume according to the wall’s pH. This dynamic gives the larvae the ability to change their buoyancy. A swarm of the lake fly larvae over Lake Mal