Polar Bears May Have Yet Another Worry: Sharks

As if polar bears in the North Pole didn't have enough to worry about these days: Scientists have found the bone of a young bear in the stomach of a Greenland shark, Reuters reports. The unprecedented discovery prompts a "million dollar question," says one researcher: Do the bears now have to worry about sharks as predators? It seems improbable that the sluggish shark could catch and kill a bear, but the possibility raises intriguing questions.

As polar bears lose their habitat to warming waters, researchers speculate that they will have to spend more time in the water and thus be vulnerable to sharks. Others say the bone probably came from a scavenged carcass. "The Greenland shark simply cannot afford the risk of injury nor the expenditure of energy required to kill such a large and dangerous animal,” says one expert. "There is far easier prey to be found." (More polar bear stories.)