Fig. 3. Biomimetic Tadros compete in phototactic forage navigation. (A) Three prototype Tadros swim during the initial light-detection phase. Note that Tadros interact physically and compete within a generation; thus they are an evolving part of the otherwise stable selective environment. (B) Trajectories of three Tadros in one trial (generation 1, trial 4 of 12), showing the differences in orbital radius around the light target. Fitness rewards a small orbital radius R, short time to find the target t, fast swimming speed U and low robot wobble W. Here tail stiffness k is correlated with fitness and navigational prowess NP.