Meeting Abstract
In the natural environment, animals use multiple sensory cues simultaneously to perform complex behaviors. Chemicals can be mixed in nearly limitless combinations, allowing animals and even specific locations to have unique chemical signatures. Sharks have a renowned sense of smell and odor plays a major role in identifying important resources, such as prey, detecting the presence of predators, and recognizing critical habitats, such as nursery areas. Carried by flow, odor disperses over large distances in water and is often the first sensory cue encountered by a shark searching for food. For some shark species, odor is critical for prey detection, while other species can recognize prey either visually or by smell. Recent evidence also suggests that olfaction plays a major role in another important behavior: homing. Blacktip sharks migrate over hundreds of kilometers to return seasonally to their natal nurseries. While other cues, possibly geomagnetic, guide navigation over the broad scale, olfactory cues are required for recognizing their specific home range. To locate odor sources, sharks initially orient to chemical cues based on the timing of odor arrival at the nostrils, turning to the nostril that receives the signal first. This bilateral odor information aids in steering into patches of odor. Animals with more widely-spaced nostrils would be expected to be capable of resolving smaller angles of attack, which may have contributed to the evolution of the cephalofoil of hammerhead sharks. To follow an odor plume, however, sharks cannot use chemical cues alone due to the spatially and temporally chaotic nature of turbulent odor plumes. These animals require a directional vector, provided by flowing water. The direction of flow can be perceived using the lateral line or visual systems, or, in benthic species, using tactile cues, allowing sharks to follow odors to their source.
