Optimal approach strategies for fish predators based on lateral line sensation

Meeting Abstract

P1.69  Friday, Jan. 4  Optimal approach strategies for fish predators based on lateral line sensation NAIR, A.M.*; STEWART, W.J.; MCHENRY, M..J.; Univ. of California, Irvine; Univ. of California, Irvine; Univ. of California, Irvine amnair@uci.edu

In order to survive, predatory fish must effectively strike and capture prey. In a darkened environment, prey fish can use their lateral line system to sense a disturbance in the water created by a predator’s approach. Given this ability, it is in the best interest of the predator to minimize this perturbation by decreasing its approach speed. However, a slower approach gives the prey more time to react. Given this trade-off, is it beneficial for a fish predator to move fast or slow? We addressed this question by varying the approach speed of a robotic predator while measuring the response of prey with high-speed video. Particle image velocimetry (PIV) was used to measure the extent of the flow perturbation, known as the bow wave, around the predator. These measurements revealed that the bow wave’s size and intensity increases with speed. Given the prey’s sensitivity, the smallest change in flow that the prey can detect, we measured the distance between the prey and the oncoming predator when the prey detects the bow wake, from which we determined to time to strike the prey (TTL). We identified two major strategies that predators may adopt to maximize their capture success. One strategy would be for the predator to advance slowly enough that the prey will never sense the bow wave. Ideally this strategy guarantees a successful capture but may be difficult for the predator to realistically accomplish with highly sensitive prey. The other strategy is to approach the prey at maximal speed to minimize TTL, but allow the prey to detect the predator. Ultimately, the sensitivity of the prey and the predator’s maximum speed determines which of these two strategies is optimal.

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