Curious Run-and-Tumble Behavior in Multicellular Organisms on the Water's Surface

We uncover a "run-and-tumble" motion in Rhagovelia, a water-walking predatory insect, a behavior previously well-documented only in microorganisms like E. coli. This motion consists of persistent directional movement (the run) followed by random reorientation (the tumble). We record the insect's position and orientation on water to understand the advantages of this unique locomotion. Our study also evaluates how environmental factors such as water flow and the presence of food or conspecifics influence this behavior. Our findings extend the concept of "run-and-tumble" to macroscopic organisms, offering insights into its evolutionary advantages. This research has implications for the development of search robots mimicking this efficient movement strategy and suggests a unifying principle behind "run-and-tumble" motion across different length scales.