Chemical cues facilitate foraging across the water-land interface in a resident predatory fish

Abstract Transitional ecosystems, such as the land-sea interface, propagate nutrient flow and species interactions. Organisms spanning these boundaries act as important models for understanding the evolution of sensory modalities that promote movement between physically distinct media, and the ecological consequences of ecosystem connectivity. Behavior is fundamentally guided by sensory processing; yet how sensory information is transmitted and collected is heavily dependent on the physical environmental medium. The flow of stimuli across the land-sea interface and the behavioral responses to stimuli are understudied. Vertebrates that span the land-sea boundary offer the opportunity to document how stimuli can be used to complete complex behaviors across transitional ecosystems. We determined that California moray eels (Gymnothorax mordax) can use chemical stimuli (odor and taste) to locate prey across intertidal boundaries on Santa Catalina Island. We tested moray responses to chemical stimuli from 4 prey types during high and low tidal conditions, the latter requiring emergence from the water to navigate the land-sea interface. Gymnothorax mordax can navigate to a prey source using only chemical stimuli; both when fully submerged underwater and when emerged in the intertidal. Morays showed greater discernment between prey types when exposed in the intertidal zone. When emerged, we observed morays rubbing their faces on the substrate, suggesting odor may be important for detection, with taste further assisting in prey location. This research broadens our understanding of ecosystem connectivity, illustrating how stimuli can cross the land-sea boundary and be used to facilitate predation through a combination of multisensory modalities.