Camo Sharks documents the search for evidence that great white sharks change color

Camo Sharks documents the search for evidence that great white sharks change color

Camo Sharks Find out if these predators of the depths are able to change color to better sneak up on prey. ”/>

Zoom / Great white shark swimming off the coast of South Africa. The new documentary NatGeo Camo Sharks Find out if these predators of the depths are able to change color to better sneak up on prey.

National Geographic / Hansa Wenshaw

This year marks the 10th anniversary of National Geographic’s Sharkfest, and NatGeo is marking the occasion with an intriguing new documentary that explores whether great white sharks can change color to hunt more effectively. Camo Sharks Follow marine biologist and research coordinator for the Blue Wilderness Research Unit, Ryan Johnson and graduate student Gibbs Kuguru in the field as they try to gather evidence to support the hypothesis that these ocean predators can modify the skin cells in their skin to change color as camouflage.

Born in New Zealand, Johnson grew up in a seaside town, absorbing the conventional wisdom that dolphins are the “good guys” and sharks are the “bad guys”. When he decided to become a marine biologist, he wanted to work with dolphins. When he was about 20 he had the opportunity to do some research on the great white sharks of South Africa, which at the time were under enormous pressure from overfishing, leading to an increase in shark attacks.

“They’ve just become very popular as a delicacy,” Johnson told Ars. “The shark fin soup trade has gone crazy, and [sharks] mass slaughtered. It was an awakening of consciousness for me. I realized that this needed attention, much more than that in my view, at least, compared to dolphins.”

Since then, Johnson has studied questions such as whether the white shark cage-diving industry makes sharks an increased danger to humans, and has conducted audio and satellite tracking of great whites. He also studied the impact of ecotourism on sharks, studied the bite force of great whites, and studied predator-prey games among large eggs and the seals they hunt.

Based on his field experience, Johnson had long believed that great white sharks might be able to change their color. Shark scientists identify specific animals by their dorsal fins, scars, and other distinctive markings. Oftentimes, he remembers, he and his team would spot a light-colored shark in the morning and another dark-colored shark in the afternoon and assumed they were two different animals. But then you’d go back and look at the pictures and think, ‘Uh, that’s not a new shark,’ Johnson said. This is the same. The sign of the dorsal fin is the same.”

Then he met Gypsum Kogoro, who was conducting doctoral research in the Maldives on color changes in black-headed sharks. “I said, ‘Man, what if I told you that great whites change color, too?” Johnson recalls. Kogoro thought the idea sounded cool, and the couple started researching the topic. They found cases of hammerhead sharks in the sun and some rays that could change their color, for example.

Other previous studies have found that zebra sharks change color with age, and rainbow sharks can sometimes lose color due to stress and aging. As we reported in 2019, a new family of small-molecule metabolites in the lighter parts of the skin of puffer sharks (Abdominal cephalosporosis) and chained sharks (Scyliorhinus retifer) enables them to absorb blue light in the ocean and essentially convert the light to green, making it appear to glow. (This phenomenon is known as bioluminescence, and should not be confused with a related phenomenon, bioluminescence.)

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