As the ice shrinks in the Arctic, polar bears are struggling to survive in a fast melting world. Although classified a marine mammal, the polar bear is not adapted to hunting in the water. And it is certainly no match for the world's greatest aquatic hunter -- the killer whale. In the last few years, scientists have noted an ever-growing number of killer whales in Arctic waters in the summer months. More and more have been attracted to these hunting grounds by the growing expanse of open water. ...