To follow the scent trail left by their prey across the ocean, sharks swim in the direction of the nostril that sniffed the odour first, scientists have found.

Findings, just published in Current Biology1, suggests that when a shark moves into a patch of odour, the smell hits one nostril before the other — and that tells the shark to turn either left or right.

By moving from side to side from one patch to another, the animal maintains contact with the odour plume as it tracks its prey, says Jayne Gardiner at the University of South Florida in Tampa, co-author of the study.

The narrow sub-second time window in which this bilateral detection causes the turn response corresponds well with the swimming speed and odour patch dispersal physics of our shark species known as Mustelus canis or the smooth dogfish,' Jayne Gardiner explains

All in all, it means that sharks pick up on a combination of directional cues, based on both odour and flow, to keep themselves oriented and ultimately find what they are looking for.