Meeting Abstract
When exposed to predators, most juvenile fishes exhibit escape response, which is composed of a swift initial turn and forward acceleration. A large number of studies have been conducted on the relationship between the components of escape response (e.g. flight initiation distance, prey speed) and escape probability; however, the relationship between prey’s body orientation relative to a predator at the onset of the escape response (initial orientation) and escape probability remains unclear. The initial orientation could be crucial for escape response, because prey’s sensory perception range can have spatial bias, and the turn duration before the initiation of escape locomotion can be smaller when the initial orientation is more away from the predator. We tested this hypothesis by recording the escape responses of juvenile red sea bream (Pagrus major) in response to the predatory scorpion fish (Sebastiscus marmoratus). Escape probability was higher when the flight initiation distance was larger. If the effect of flight initiation distance was offset, escape probability was higher when the initial orientation was more away from the predator. The flight initiation distance tended to be small when the prey was attacked from behind, compared to when attacked from front and side. The turn duration was smaller when the initial orientation was more away from the predator. These results suggest that the initial orientation affects escape probability through 2 pathways: flight initiation distance and the turn duration. These findings highlight the importance of incorporating initial orientation into other studies of the kinematics of predator-prey interactions.
