Run-and-Turn Dynamics in Tiny Water Striders

Among the smallest water-walking insects, Microvelia inhabit predator-rich surfaces where fish, larger striders, and backswimmers pose constant threats. Yet, these tiny insects thrive by swiftly detecting and feeding on prey trapped at the air–water interface. We investigated how Microvelia sp. use a distinctive run-and-turn locomotion, alternating straight runs with rapid pauses and sharp reorientations, to locate prey efficiently. Using springtails and fruit flies as model prey, we quantified their motion trajectories and found that prey activity generates directional cues that guide pursuit. Our findings reveal that Microvelia adapt their paths to run-and-stop sequences, minimizing travel distance while converging rapidly on prey. This adaptive strategy enhances foraging success in dynamic, predator-dense environments and suggests new design principles for microrobots, where run-and-turn navigation could enable efficient surface exploration and target acquisition.