SYDNEY - If you want to minimise chances of a shark attack, leave those fluorescent boardshorts or your yellow polka-dot bikini in the drawer.
Australian researchers say sharks are attracted to bright colours that contrast with the ocean.
Scientists from the University of Western Australia set out to test the long-held theory that sharks are particularly drawn to the colour yellow.
They found they have no colour vision and so are likely to be attracted by any bright colour - detecting and identifying objects that contrast strongly with the ocean.
Together with colleagues from the University of Queensland, the UWA team - led by Associate Professor Nathan Scott Hart - investigated 17 species, including the man-eating bull shark.
"We found that all species are probably colour-blind," said Professor Hart. "They have only a single type of cone photoreceptor in the eye, which is what we use for our sense of colour.
"Certainly high contrast might be the wrong thing to wear. So you should wear perhaps more muted colours or colours that match the background in the water better."
Sharks respond only to green light, effectively viewing the world like a black and white television - all shades of grey. The findings were published in the international journal Naturwissenschaften (The Science of Nature).
Professor Hart said: "Now we know a bit more about how such sharks see the world, it may be possible to design swimming attire and surfcraft that have a lower visual contrast to sharks.
"After all, most shark attacks are thought to be the result of curiosity on the part of a shark that has been attracted to an unusual stimulus."
His team removed the eyes of 17 shark species and studied them under a microspectrophotometer to measure how much pigment in their retina cells was absorbed.By Kathy Marks Email Kathy