Who's Top Predator?
Already threatened by a thaw of ice around the North Pole, the polar bear's title as the top Arctic predator may under challenge from a shark.
Scientists researching how far sharks hunt seals in the Arctic were stunned in June to find part of the jaw of a young polar bear in the stomach of a Greenland shark, a species that favours polar waters.
"We've never heard of this before. We don't know how it got there," Kit Kovacs, of the Norwegian Polar Institute, said of the 10 cm (4 inch) bone found in a shark off the Norwegian Arctic archipelago of Svalbard...
"We can't say whether or not the shark took a swimming young bear" or ate a carcass, she said.
"We don't know how active these sharks are as predators."
Most shark experts contacted said it was likely the bear was dead before the shark found it. Even a young, two- or three-year-old bear would be a ferocious opponent for a Greenland shark, which can grow to up to 7 metres (23 feet) and weigh more than a ton.
