Scientists analysed data from tiger sharks tagged with acoustic transmitters, and found that they took directed paths from place to place. Other species such as blacktip reef sharks or thresher sharks did not show this behaviour.

Working out whether or not sharks were using so-called random or directed walks (for explanation, see link below - ed) was difficult, as the researchers had no way of knowing where the animal wanted to go.

But the researchers were able to tell the difference between a random walk and directed walk by looking at the shape of the sharks' movements at different spatial scales.

They compared the overall distance the sharks had moved to those estimated by random walk models, mathematical equations that predicts how far an animal will move if it is moving randomly at these different scales.

"Our research shows that, at times, tiger sharks and thresher sharks don't swim randomly but swim to specific locations," said research leader Yannis Papastamatiou from the Florida Museum of Natural History in Gainesville.

"Simply put, they know where they are going."