Sharks, apparently, have some kind of in-built navigation system that helps them get from A to B. According to a new, scientific report released today, some species of sharks make 'mental maps' that help them to spot destinations up to 50 kilometres (30 miles) away.
According to the BBC, American scientists tagged tiger sharks with acoustic transmitters and found that they took directed paths from one location to another. Interestingly other types of sharks, such as blacktip reef sharks didn't display the same behaviour.
Writing in the Journal of Animal Ecology, the researchers suggest this shows a capacity to store maps of key sites and that this is further evidence that the great fish can navigate, possibly using the Earth's magnetic field.
Previous studies in Hawaii have shown tiger sharks can swim across deep channels to find food-rich shallow banks 50km away.
"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."
Sharks aren't alone in doing this, of course. Tuna, turtles, ducks and geese are reckoned to be able to navigate using the earth's magnetic fields.
As we say, it seems like GPS devices were around a long time before ibox and the 'tracmate'.