A Matador-like Predator Diversion Strategy Driven by Conspicuous Coloration in Guppies

Understanding the adaptive function of conspicuous coloration has been a major focus of evolutionary biology for much of the last century. Although considerable progress has been made in explaining how conspicuous coloration can be used in functions as diverse as sexual and social signaling, startling predators, and advertising toxicity [1], there remain a multitude of species that display conspicuous coloration that cannot be explained by existing theory. Here we detail a new “matador-like” divertive antipredator strategy based on conspicuous coloration in Trinidadian guppies (Poecilia reticulata). Guppies encountering predatory fish rapidly enhance the conspicuousness of their eyes by blackening their irises. By pitting biomimetic robotic guppies against real predatory fish, we show this conspicuous eye coloration diverts attacks away from the guppies’ center of mass to their head. To determine the function of this seemingly counterintuitive behavior, we developed a method for simulating escape probabilities when live prey interact with ballistic attacking predators, and find this diversion effect significantly benefits black-eyed guppies because they evade capture by rapidly pivoting away from the predator once it has committed to its attack. Remarkably, this antipredator strategy reverses the commonly observed negative scaling relationship between prey size and evasive ability, with larger fish benefiting most from diverting predators. Taken together, our results introduce a new antipredator divertive strategy that may be widely used by conspicuously colored prey that rely on agility to escape their predators. [Display omitted] •Guppies, particularly large females, blacken their eyes when encountering predators•Predatory fish attack black-eyed guppies toward their head•Guppies more easily evade these diverted attacks using a pivoting evasive maneuver•This offsets the reduced agility of larger prey, possibly allowing the evolution of larger body sizes Combining biomimetic robots and predation simulations, Heathcote et al. detail a new “matador-like” antipredator strategy in guppies. By blackening their eyes, guppies divert predator lunges to their head, which they evade via a split-second maneuver. This strategy may allow increased body sizes by ameliorating the reduced agility of larger prey.