Rhagovelia uses interfacial run-and-tumble locomotion to improve prey capture in flowing environments

Rhagovelia orianderis a neustonic insect native to the rivers and streams of North and South America, known for its distinctive skating movement on the water’s surface. This movement resembles the correlated random-walk pattern seen in microorganisms such asEscherichia coli. Previous studies have primarily focused on limb adaptations and biomechanics, leaving the ecological significance inadequately addressed. We combine field observations with controlled laboratory experiments using a flow mill to investigate the dynamics ofR. orianderunder relevant flow conditions. Our findings indicate that this insect exhibits a two-dimensional run-and-tumble motion, often incorporating lateral tumbles following straight runs (run distance: 30.7 ± 9.7 mm). We find that this behavior is resilient to changes in flow speed. In-silico simulations of predator-prey interactions demonstrated that this locomotion method significantly enhances prey capture efficiency compared to linear movement, particularly when the prey is following a rapid flow field. Our results document run-and-tumble locomotion in a millimeter-scale organism, showcasing a unique example of convergent behavior across diverse taxonomic groups and providing valuable insights into locomotion ecology while serving as a source of inspiration for bioinspired robotics and environmental exploration algorithms.