The Sensory Ecology of Shark Navigation: Multimodal Guidance of Complex Behaviors

In the natural world, animals must attend to multiple sensory cues simultaneously. Although the senses are often studied individually, very few behaviors rely only on unisensory input. Recently, we found that sharks integrate information from multiple senses simultaneously in order to accomplish a complex behavioral task, feeding. As sharks approach prey, different cues become available at different spatial scales, and sharks can switch their focus from one signal to another, as new information becomes available. Odor is generally the first cue encountered, but the addition of a directional vector (flowing water) is required for source localization. Once near the prey, vision, the lateral line, electroreception, and touch are used to precisely coordinate successful striking (forward body movement) and capture (jaw movement). Interspecific differences in the cues used for particular tasks are linked to differences in ecology. Sensory switching across different spatial scales is also believed occur during natal homing: the Earth’s magnetic fields may guide broad-scale long-distance movements, while visual and/or olfactory cues may guide navigation to precise locations. We have recently begun testing this framework, using the blacktip shark as a model. Initial results support a biphasic model for navigation, with olfaction allowing recognition of specific home ranges.