BOCK, Natika L; WYETH, Russell C; CAIN, Shaun D; Friday Harbor Labs, University of Washington; Friday Harbor Labs, University of Washington; Friday Harbor Labs, University of Washington: The Temporal Structure of Multiple Guidance Cues During Prey-finding Behavior of the Marine Mollusc Tritonia diomedea

Motile animals often use multiple sensory cues while navigating through their environment. The relative importance of these cues is typically structured both hierarchically and temporally. In this study, we investigated three distinct sensory modalitities (chemoreception, rheo-sensation, and magnetoreception) used by the marine mollusc Tritonia diomedea when orienting and navigating toward prey. Even over small spatial scales, the benthic habitat of these animals presents a challenge for rheotactic navigation, due to local currents that can vary rapidly in amplitude and direction. To investigate how T. diomedea localizes its prey effectively within an ever-shifting environment, we characterized the orientation and prey localization of T. diomedea in a flow tank, surrounded by a circular magnetic coil system (that reverses the horizontal component of the ambient magnetic field), with both sea pen odorant and current flows. Using time-lapse video, we recorded the behavior of individual slugs exposed to different temporal combinations of chemical, water current, and magnetic cues navigating towards prey. Preliminary results indicate prey odors act as a gate to initiate positive rheotaxis, correctly aligning the slug in the proper direction, after which current cues are not necessary for continued successful navigation. Attempts to determine if this later portion of navigation is dependent on magnetic cues have been unsuccessful. The results of this study, combined with ongoing investigations of the neural pathways underlying these sensory modalities, will allow us to examine the neuroethological questions of how multiple sensory cues drive a given behavior.