Meeting Abstract

S1-3.2  Friday, Jan. 4  The sensory cues for predator evasion in fish STEWART, WJ*; NAIR, AM; MCHENRY, MJ; Univ. of California, Irvine wstewart@uci.edu

Prey fish can survive an encounter with a predator fish by detecting the predator’s approach and quickly responding with an evasive maneuver. While the ability to detect predator attacks is critical for prey, the sensory signals that trigger prey responses are unclear. Predator fish produce both fluid and visual stimuli during approaches, but identifying the specific cues sensed by prey fish has been unfeasible due to the variable nature of predator-prey encounters. To simplify this behavioral variability and reveal the sensory cues that alert prey fish to predator attacks, we controlled the approach kinematics of a predator fish in light and dark conditions and recorded the resultant escape responses of prey in detail. This was achieved with a high-precision linear motor that translated a preserved predator (zebrafish adult, Danio rerio) towards live prey (zebrafish larvae, Danio rerio) over a range of repeatable and realistic approach speeds. Two high-speed cameras attached to the motor recorded prey escape responses in 3D from the predator frame of reference. The flow field around the approaching predator was quantified in 3D with particle image velocimetry, which allowed us to determine the fluid signals experienced by prey when startled. Video recordings and flow measurements showed that, in dark conditions, nearly all prey responded rapidly after encountering the disturbed flow ahead of the approaching predator. However, when approached slowly in light conditions, the prey behaved differently by swimming away from the predator at lower speeds before encountering the disturbed flow. These results suggest that flow sensing is critical for rapid prey responses to predators approaching at high speed or in the dark, while vision mediates more gradual responses when conditions permit.