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Orcas are hunting whale sharks, the largest fish species on Earth

JUANA SUMMERS, HOST:

Killer whales are known for being intelligent, which makes them powerful hunters. Now, new research shows how they take down one of the planet's largest animals. NPR's Lauren Sommer has more.

LAUREN SOMMER, BYLINE: For years, Erick Higuera has followed a pod of killer whales in the Gulf of California. He's a marine biologist in Mexico. And one day, he was sent a tourist video of the whales.

ERICK HIGUERA: They were very smart. And when we saw the video, we got excited.

SOMMER: It showed them hunting a whale shark.

(SOUNDBITE OF WHALE SHARK BREATHING)

SOMMER: Whale sharks are the largest fish species on the planet, as long as a school bus. This whale shark was a juvenile, though still about 16 feet long, and the killer whale was hunting it. Then other videos came out showing the same thing.

HIGUERA: My surprise and my amazement is that they are definitely specialist hunters.

SOMMER: Here's how the killer whales do it, which Higuera published in the journal Frontiers, along with co-author Francesca Pancaldi. She says first, the orcas take away the whale shark's defenses by ramming it and keeping the whale shark at the surface.

FRANCESCA PANCALDI: It's relatively slow compared with other sharks, and it cannot defend itself rather than dive down. The whale shark is a great diver.

SOMMER: The orcas then flip the whale shark over because when sharks are upside down, they're immobilized in a kind of trance. Then they bite the soft underbelly so the whale shark starts bleeding out. After that, the killer whale seemed to be eating the most prized part - the liver.

PANCALDI: Sharks in general, they don't have a lot of fat. The only fatty part in the body of a shark is the liver.

SOMMER: This coordinated hunting strategy is likely taught within the close-knit family group, Higuera says.

HIGUERA: They organize the efforts. They organize the hunt. They're like snipers.

SOMMER: And it's not the first time killer whales have been seen eating sharks, says Salvador Jorgensen, a marine ecologist at California State University Monterey Bay.

SALVADOR JORGENSEN: We've been seeing killer whales going after sharks, and particularly larger sharks, which is the more surprising part of this, around the world.

SOMMER: Off California, Jorgensen says even great white sharks aren't safe from orcas.

JORGENSEN: When the orcas come around, it creates this sort of landscape of fear that white sharks, for example, are able to detect and respond to.

SOMMER: The white sharks book it, leaving the area for up to a year. That's because killer whales are known to eat their livers, too. Jorgensen says it just shows why killer whales are at the very top of the food chain.

Lauren Sommer, NPR News.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.

NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.

Lauren Sommer covers climate change for NPR's Science Desk, from the scientists on the front lines of documenting the warming climate to the way those changes are reshaping communities and ecosystems around the world.