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Baby white sharks learn to hunt instantly. Although the monthly fry feast on fish and other small fry, the larger fry are finally large enough to handle seals and other succulents.
Spotting a whale seal among the waves may seem easy. But young white sharks have less vision than stars and are likely colorblind, making the ocean appear in shades of grey. Therefore, you cannot blame a young white shark for seeing and chewing an appetizing shaded oval above.
For decades, scientists have put forward this theory of “false identity” as an explanation behind unprovoked shark bites, which are rarely seen in humans. An article published on Wednesday Journal of the Royal Society Interface tests this theory. Based on their simulations of how a baby white shark sees the world, they found no significant difference between a chubby sea lion, a human paddling on a surfboard, or even a person paddling on their own—supporting the theory that sometimes sharks make mistakes.
Charles Bangley, a marine ecologist at Dalhousie University in Nova Scotia who was not involved in the research, said the paper supports common sense advice for anyone looking to avoid being bitten by a shark: Swim in calm, clear water away from seals and other prey. .
Catherine Macdonald, lecturer and co-founder of the marine science program at the University of Miami Field School, said the study was “well conducted,” and opened new questions about sharks and humans.
“Does it make a difference if it’s an honest mistake?” said. “We cannot tolerate these risks to humans no matter what,” he said.
Baby white sharks are happily unaware of the bad rap they were born into. “White sharks have been described as these mindless killers,” said Laura Ryan, a neurobiologist at Macquarie University in Australia and author of the paper. But he hopes they can begin to be seen in “another light by understanding their world.”
White sharks, along with bull sharks and tiger sharks, are responsible for the majority of injuries and fatal bites to humans, often surfers. And those who bite most often, youth, eight to 10 feet long. But white sharks often release a person after the first bite, which may indicate that they are not actively hunting humans as prey.
Dr. “As a general rule for shark bites, the vast majority of them are single and done,” Macdonald said.
While the mistaken identity theory sounds plausible, it is easily refuted on the basis of our own visual perception: The average-sighted person could probably distinguish between the silhouette of a surfer and a seal paddling side-by-side.
End investigations The move to shark vision has broadened scientists’ understanding of how cartilaginous predators view their environment: possibly in grayscale and with the ability to see minimal detail. Dr. To try to see the world as a shark, imagine doing your underwater eye exam without glasses, Ryan said — things are a little less stark. Therefore, the visual cues that the hunting shark most rely on are probably the contrast of movement and brightness.
Based on this information, the researchers conducted an experiment. Under aquariums at Sydney’s Taronga Zoo, researchers attached a GoPro to an underwater scooter traveling at a cruising shark’s speed. They recorded videos of two sea lions, a fur seal, people swimming, and people paddling on three different surfboards (boards are from the personal collection of surfer Dr. Ryan).
Dr. Ryan and his colleagues edited GoPro images in a computer program to turn the lens of a video camera into the retinas of a young white shark. They decolorized the video a bit and rotated it all so that the top objects moved from the bottom of the screen to the top. Next, the researchers ran the videos through a series of statistical analyzes at various resolutions to see if a baby white shark could distinguish between objects.
The researchers found no significant differences between a shark-eyed swimmer, a paddle-boarding surfer, or a meandering seal or sea lion. Dr. Ryan said he was surprised that sharks could confuse even a swimming person without a surfboard with a seal.
Dr. Macdonald added that the study suggests that juvenile sharks should use other tactics to distinguish between humans and prey, adding that the number of humans in the water has increased significantly in recent years without any increase in bites.
Dr. “They eat seals every day, and it’s incredibly rare for them to bite humans,” Macdonald said. “So if they don’t solve the problem visually, how do we think they do?” If the answer lies in a shark’s other senses, such as smell, this could determine what interventions would make sense to avoid encounters in the wild, he added.
Dr. Ryan continues to surf. Whenever he thought of sharks, he would think about statistics: How unlikely a bite would be. After this study, he reminds himself of something new: “It gives me some relief to know that they are not mindless killers.”
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