Figure 1.

Measurements of the escape response stimulated by a predator robot. (a) The robot consisted of a dead adult zebrafish that was suspended in the centre of an aquarium populated with larvae and translated through the water at constant speed (11 cm s⁻¹), like that of a live predator while foraging. Escape responses were recorded with two high-speed video cameras (250 frames s⁻¹ at 640 × 480 pixels) that moved with the robot as it translated through a rectangular aquarium. The prey were generally motionless until exhibiting a fast start in response to the robot. (b) We calculated the stimulus angle (λ) presented by the robot in the prey's field of view (in grey), the direction of the escape response (θ) and the initial orientation of the body (ϕ). (c) The position (in grey) and displacement (black arrow) of the bodies of larvae achieved during the escape response were measured from the video recordings.