The Sensorimotor Basis of Predator Evasion for Larval Zebrafish

Predator-prey interactions are critical to the biology of fishes, but it is unclear how sensory and motor systems of prey fish impact predator evasion. In this dissertation, I present work that provides a better understanding of how a prey’s sensorimotor system can impact its survival of a predatory encounter. The results of my dissertation give a holistic view of how physiology, behavior and game theory can be used to explain predator evasion in larval zebrafish.My first dissertation chapter described how larval zebrafish use a fast start to move withthree-dimensional trajectories. Classically, fast starts have been described purely as a two-dimensional motion. However, in previous studies, anecdotal evidence suggested that larvalzebrafish can escape in three dimensions. To study this phenomenon, I made careful three-dimensional kinematic measures of larval zebrafish performing fast starts. The first dissertation chapter revealed that rotations of the larvae’s body around its center of mass were indicative of the three-dimensional trajectory the whole body translated towards.My second dissertation chapter investigated the relative importance between the sensoryand motor systems in prey survival in a predator-prey interaction. Many studies have studied the importance of the sensory and motor system for predator evasion, but no study has measured one system’s importance to survival relative to the other system. In the second chapter, I created a probabilistic, agent-based model to simulate predator-prey interactions between adult and larval zebrafish in silico. After running the model with varying parameter changes, I observed that the sensory system of a larval zebrafish had a greater impact on prey survival than its motor system.My third chapter studied the escape strategy of larval zebrafish. Prey fish have analgorithm to choose an escape direction to flee with. However, there are two competing schools of thought about how prey fish should choose their escape direction. In my third chapter, I recorded larval zebrafish reactions to a robotic predator and measure escape angles. My investigations revealed that larval zebrafish use a mixed strategy that combined both competing theories of escape strategy