When Alisa Schulman-Janiger heard great white shark carcasses had washed up on South African beaches without their livers a few years ago, she was shocked.

“I was thinking, Déjà vu, here we go again,” says the biologist, a research associate at the Natural History Museum of Los Angeles County.

In October 1997, tourists in a whale-watching boat off the Farallon Islands, near San Francisco, witnessed two killer whales attack a great white shark and consume its liver.

It was, at that time, the first documented sighting of killer whales eating white sharks. The incident sparked new lines of research, as well as some intriguing questions for Schulman-Janiger and many others: How could any ocean predator, even one called