Interfering with a shark's sensory system is one of the ways scientists believe we may be able to keep beachgoers safe – ankle bracelets that mimic the cries of an orca and stripy wetsuits that mess with their eyesight being just a couple of examples. Now scientists in Australia (where else?) are exploring a new way of deterring these apex predators, by fixing lights to surfboards to obscure their view.

The new research was led by Dr Nathan Hart, a comparative neurobiologist at Australia's Macquarie University, who has actually had a hand in the development of camouflage wetsuits like those mentioned above. Much of his research has involved investigating how animals like sharks see and interact with their prey.

"Studying the sensory systems of sharks and what triggers them to attack, and how they might mistake a human for a seal was where it all started," he says. "It's taken us to the forefront of developing shark deterrents."

The latest light-bulb moment for Hart and his team builds on their knowledge of the visual perception of sharks. Back in 2011, Hart made the discovery that the creatures only possess one type of cone in their retina. Unlike most other fish in the sea, this means sharks are likely completely color blind and see the world only in shades of grey.

The shark-deterring wetsuits are designed to leverage this by being finished in contrasting shades of blue. This helps the wearer blend into the water, breaking up their outline and their silhouette and making them seem like less of a solid object. The team has now found that fixing lights to the underside of a surfboard can have a similar effect, by also concealing the surfer's silhouette from hungry sharks.

They learned this by using foam decoys shaped to look like seals in Mossel Bay off South Africa, a region known to be a popular spot for great white sharks. These early tests are said to have shown great promise. So much so, the researchers are now teaming up with Sydney's Taronga Zoo and New South Wales state authorities to design a similar lighting system for surfboards. They will return to South Africa later in the year to put that system to the test.

"Pure basic research can sometimes lead to unexpected applications and potentially contribute to life-saving technology," Hart says.

Source: Macquarie University

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