Shark attacks could be a case of mistaken identity
International and Australian scientists have tested the long-held theory that some shark attacks could be the result of mistaken identity, challenging the common notion that great whites are "mindless killers" or "fond of human flesh."
Researchers have studied the anatomy of shark eyes to gain a perspective on what they might see underwater while they look up to the ocean's surface for prey.
Lead researcher from Macquarie University Dr Laura Ryan said it is the first study of its kind.
"Until now, the potential similarity between humans and seals has been assessed based on human vision," she said.
"However, white sharks have much lower visual acuity than us, meaning they cannot see fine details, and lack colour vision."
Flinders University associate professor Charlie Huveneers said the studies are indicating sharks are likely mistaking the silhouettes of surfers for their natural prey like seals.
"Humans have three different types of cones to process colour, while sharks only have one type of cone — which means they're unlikely to see colour," Mr Huveneers said.
"While they're well adapted to see underwater, their acuity is not as good as previously thought and the ability to discern the resolution of images isn't that great.
"That's why, when you compare the silhouettes of seals and humans from a shark's perspective and from a vision and anatomical perspective, there are no differences between seals and the surfers."
Why sharks bite
Mr Huveneers said the study could contribute to reducing the risk of shark bites.
"In the last few years, we've seen an increase in the number of shark bites globally and also in Australia," Mr Huveneers said.
"There's been some questions about what could be the reason behind why sharks might be biting humans and a better understanding might help us mitigate these risks."
The researcher said a combination of devices that deter sharks and knowledge from this recent study could help reduce the risk of shark bites.
"There's no silver bullet, or one device or product which will completely reduce the risk; it's a combination of these devices that together can reduce the risk," he said.
The researchers acknowledged sharks can also detect prey using other sensory systems.
"What we're showing from a vision perspective and an anatomical perspective is there seem to be sharks that are not the best at differentiating different objects on the surface," Mr Huveneers said.
Dr Ryan noted "the findings of this study have inspired the design of non-invasive vision-based shark mitigation devices, which are currently being tested".
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