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Scientists think orcas are removing sharks’ livers with ‘surgical precision.’ But why?

By Greg Hadley

ghadley@mcclatchy.com

Watch killer whales feast on a shark off California's Central Coast

A drone captured this scene of a pod of orcas feeding on a sevengill shark on Dec. 13, 2016, off the coast of Monterey. The drone footage, by Slater Moore of Monterey Bay Whale Watch, shows about 25 rarely seen offshore killer whales and two babie
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A drone captured this scene of a pod of orcas feeding on a sevengill shark on Dec. 13, 2016, off the coast of Monterey. The drone footage, by Slater Moore of Monterey Bay Whale Watch, shows about 25 rarely seen offshore killer whales and two babie

In four days, three great white sharks have washed ashore near one South African town, dead but mostly intact, except for one detail: None of them has a liver.

Scientists and researchers in Gansbaai, South Africa, are pretty sure they know who’s killing the sharks: Orcas, one of the only animals in the ocean that hunt sharks.

What they don’t know and are trying to understand is how these killer whales were able to remove the sharks’ livers with “almost surgical precision,” according to one scientist, and why they left the rest of the carcass alone.

A Facebook post by Dyer Island Conservation Trust shows one of the sharks, looking almost entirely intact.

“The dexterity these enormous animals (orcas) are capable of is mind blowing, almost surgical precision as they remove the squalene-rich liver of the white sharks and dump their carcass,” the post reads.

While orcas have been known to hunt and kill sharks in other regions of the world, according to Live Science, local scientists were surprised by the incidents, which one called “unprecedented.” Great whites are normally considered “apex” predators, meaning the only real predatory threat they face is from humans or other great whites.

But orcas have been known to hunt other, smaller sharks in the past, and sharks’ livers are “very energy- and nutrient-rich,” according to Live Science. Still, that does not explain why the rest of the carcass went untouched, especially because orcas need to consume as much as 3 percent of their body weight each day.

According to Newsweek, an orca has once been observed attacking a great white shark near San Francisco, flipping it upside down before consuming most of the body. One researcher told Newsweek that killer whales are known to learn and spread new hunting tricks, but the distance and time between attacks would make that unusual.

According to the New Zealand Herald, these attacks are not just mystifying, they’re also scaring away sharks from an area of the western coast of South Africa that is normally considered one of the best in the world for seeing sharks, so much so that Gansbaai calls itself the Great White capital of the world. Local shark diving tours, which normally benefit from millions of dollars in tourism, report no sightings of the animals in recent expeditions.

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