Sharks are colourblind new research finds
Wearing a white or light blue wetsuit could protect you from a shark attack, suggests a new study that found the predators are colour blind.
By Richard Alleyne, Science Correspondent 2:10PM GMT 18 Jan 2011
Researchers discovered that the eyes of sharks, including bull and tiger sharks, are not designed to distinguish different colours and so they see the world in black and white.
That means against the light blue of the sea, it would be better to wear light coloured swimwear in order to reduce the contrast with the water.
The study backs up statistics from the International Shark Attack File (ISAF) which shows that the vast majority of attacks happen to divers and surfers wearing black wetsuits.
The team at the University of Western Australia and the University of Queensland examined the eyes of 17 species of shark including bull sharks, tiger sharks, reef sharks and Port Jackson sharks.
They found that their retinas had only one kind of cone – or light detector – that was only able to detect light or dark. That means a red apple would be just a dark shade to them.
Humans, in contrast, have three cones to distinguish colour, red, green and blue. Professor Nathan Hart, the lead author, said a shark's vision could be compared to watching black and white television.
"If they lack colour vision, it means that brightness contrast is more important for detecting and identifying objects," he said.
"We may be able to use this information to help design surf craft and swimming attire that are less attractive or more repulsive to sharks and thus reduce attacks on people.
"We might also be able to use it to design longline fishing lures that are less attractive to sharks … and reduce the huge numbers of sharks that are killed by catch each year."
Professor Hart said more research was needed to determine which patterns might work best to repel sharks. "The next step really is looking at behaviour, he said.
While most bony fish and stingrays possess some form of colour vision, whales, dolphins and seals are also believed to have only one cone. The new study, published in Naturwissenschaften – The Science of Nature, is surprising as sharks are some of the most formidable hunters in the world.
Until now, experts believed that sharks' amazing evolutionary success was based on their highly-adapted sensory systems, vision included. But now it would appear that the sharks actually rely on other mechanisms as well, whose actions combine to allow the creatures' effectiveness in hunting.
