Whether we like it or not, bugs are everywhere, even in places you might not want them to be. However, there is one environment they don’t call home: the open ocean. One lasting explanation for this absence is that the pressure of deep water would fill their tiny respiratory systems with air and they would then sink. But one insect larva in particular challenges this idea.

Meet the lake flies (chaoborus edulis). In Lake Malawi in East Africa, billions of their larvae spend their days more than 200 meters (656 feet) below the water surface before returning to the surface to feed at night.

“Only, chaoborus “Mosquito larvae have modified their respiratory system into two pairs of air-filled sacs that they use to control their buoyancy,” says Philip Matthews, co-author of the study and a researcher who studies respiratory adaptations in insects at the University of British Columbia. popular science. “By regulating the pH of the alveoli walls, they cause them to expand or contract through a different ‘chemomechanical’ system.”

‘Chaoborus edulis’ larvae close up

Matthews and his team were intrigued by how this mechanism works, but realized that using air bags to regulate buoyancy during diving presented a problem.

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

The team decided to investigate this in Lake Malawi. chaoborus edulis larva, to solve this puzzle. The findings, detailed in a study published today in the journal Sciencetracks the larva’s daily diving routine with a sonar system and observes what happens on a biological level.

the walls of C. edulis‘ Air sacs have resilin, a substance that grows or contracts in volume depending on the pH of the wall. This dynamic gives the larvae the ability to change their buoyancy.

But how long can their air sacs last? Pressure chambers provide the answer. The researchers placed larvae in these small chambers to see how much pressure they could withstand before their air sacs imploded. The larvae’s air sacs could withstand pressure equivalent to more than 400 meters (1,213 feet) below the water surface, which is much deeper than they typically descend.

Ultimately, the study suggests that pressure is not what keeps insects out of open oceans, and its findings on resilin could be relevant to materials science.

“Resilin was previously known as a passive, flexible part of the insect exoskeleton, but through its ability to swell and shrink in response to changes in pH, it generates force of its own in chaoboruschanging the shape and volume of the air sac,” says Evan McKenzie, a co-author of the study and a doctoral student in the Department of Zoology at the University of British Columbia. “We think this could do chaoborus “Resilin is of great interest for materials science, where it could be developed as a dynamic material that changes its shape in response to changes in its chemical environment.”

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