'Magical' abilities of water-striding insects could inspire new aquatic robots

Some use drag to turn, others use lift to propel themselves, researchers find
8 JAN 20245:50 PM ET
BY ELIZABETH PENNISI

SEATTLE—Many insects can dart across water, relying on the liquid’s surface tension to support the weight of their tiny, diaphanous bodies. Now, two teams have independently uncovered key details of how the most agile species—ripple bugs—and the fastest one—whirligigs—strut their stuff even on choppy turbulent water. The analyses might lead to advances in tiny aquatic robots.

Even though the water-striding abilities of both insects are now “beautifully explained by the physics of water surfaces, [they] seem magical anyway,” says Elizabeth Brainerd, a functional morphologist at Brown University who was not involved in the new work. Thomas Sanger, a developmental biologist at Loyola University Chicago, notes that the advances could help make aquatic robots more versatile and dependable. “Nature has solved many of the challenges engineers have encountered,” he says.

Biologists and physicists have long studied water-walking insects, and already, scooting water striders have helped engineers build robots that can leap from the water’s surface. However, species exploit different physical effects to get around, so the more work that is done to understand adaptations in these aquatic critters, the more information engineers will have to draw on in their designs.

Víctor Ortega Jiménez, an integrative biologist from the University of Maine, set out to understand how Rhagovelia water striders, or ripple bugs, maneuver in the water because when he first saw them in a river in Georgia, “it seemed to me they were flying,” he recalls. As the bugs darted back and forth on the water’s surface, they resembled bats and birds on the hunt, he says, an impressive feat because it’s much harder to make sharp turns on water than through the air. Others had noticed that these sesame seed–size insects have fans at the tips of their middle legs and had presumed that, using muscles in their legs, the ripple bugs open and close the fans to help themselves make sharp turns. To test that idea, Ortega Jiménez collected about 150 of the insects and filmed them under different conditions in the lab.

More:
https://www.science.org/content/article/magical-abilities-water-striding-insects-could-inspire-new-aquatic-robots