January 19, 2011 Featured Article Read More →

Colour blind sharks

Adapted from this article

A new study suggests sharks may be colour-blind, challenging the long-held belief they were mainly attracted to yellow. The joint study by researchers at the University of Queensland and University of Western Australia says it is the contrast that is important, not the colour itself.

The researchers say more studies need to be done, but their advice is to avoid wearing bright costumes of any colour when swimming in the ocean. Sharks were thought to be mainly attracted to yellow, based on tests carried out by the United States navy. The researchers in Australia measured light-sensitive cells in the sharks’ eyes to determine whether they could see colours.

“We looked at a number of different species and we found that in all cases they are probably colour-blind,” said the paper’s lead author, Prof. Nathan Hart of the University of Western Australia.

“They have only a single type of cone photoreceptor in the eye, which is what we use for our sense of colour, but we have three — red, green and blue. “They only have a single one, sensitive to green, so effectively they’re colour-blind. It is just like looking at a black-and-white TV.”

Hart says it is likely sharks are attracted to any bright colours.

“They were probably attracted to yellow because it would have had a very high contrast against the surrounding water,” he said. “That’s why [life jackets] are made yellow, so that people can spot people who are floating in the water.”

Posted in: Shark Bites
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