Researchers found Chaoborus edulis larvae regularly descend more than 200 meters into Lake Malawi’s oxygen-free bottom layer by day, then return to surface waters at night to feed.
Sonar tracking showed the dives help the larvae avoid predatory fish, revealing an insect survival strategy previously thought impossible at such pressure.
Laboratory tests tied that ability to a modified tracheal system: reinforced air-filled sacs regulate buoyancy in shallow water, then stiffen at depth to resist crushing.
The largest larvae’s sacs withstood hydrostatic pressure equivalent to about 500 meters, suggesting some insects may be capable of colonizing pelagic marine environments after all.