Stereo Smell Allows Sharks to Track Prey

According to a new series of investigations, it would appear that sharks are more likely to follow the direction and timing of a scent rather than its concentration. That is to say, the beasts are capable of analyzing minute differences between when scent hits one of their nostrils as opposed to when it hits the other. These variations are processed in its brain, and inform the animal of the direction in which it needs to go in order to capture its target. Generally, scientists say, the creatures swim either left or right, depending on which nostril first picked up the scent, Nature News reports.

Established knowledge thus far had it that the sharks were more prone to detecting minute variations in the concentration of scents in each nostril, and that they based their actions on this data. But the new investigation challenges those beliefs, showing that the notion may be erroneous. Researchers at the University of South Florida in Tampa, who conducted the new work, say that the sharks basically track plumes of odor left behind by their prey. By swimming in the direction of the nostril which first picked up the scent, the predator is able to “jump” from plume to plume, always remaining in its target's wake.

The team also says that using concentration cues to inform their swimming direction is unpractical and time-consuming. In order to assess concentration differences between nostrils, in the vast mix of scents that exist in the world's oceans, the predators would have to wait for several minutes, in order to process all scents they come across. Establishing a clear-cut direction through this method would be extremely difficult, the group adds. Details of the work, conducted by USF expert Jayne Gardiner, appear in the June 10 issue of the esteemed scientific publication Current Biology. The main conclusion is that, by using timing cues, sharks can identify the direction of their prey in less than one second.

“The previous dogma has always been that sharks orient towards odor by detecting greater concentration on one side of the head over the other. In this study, timing seems to trump concentration. It's an exciting alternative way of looking at how we understand shark processing,” explains expert Stephen Kajiura, who holds an appointment as a shark sensory biologist at the Florida Atlantic University in Boca Raton. “With these new batches of information, maybe we can finally lay some myths to rest after decades of misinformation,” he concludes.