The Cape fur seal has been seen feeding on fish that usually hunt it. Divers off Cape Town have seen the seals feeding on 1m-plus blue sharks, a behaviour never seen before. At just over 2m in length, the seals are attacking prey nearly their size.The behaviour is so unusual that marine biologists have written a scientific paper on it.But the concern, said marine photographer Chris Fallows, is that this new feeding strategy could be because of food pressures on seals caused by overfishing."This is definitely David knocks Goliath, and it is something you wouldn't expect to see," he said.Fallows usually watches great white sharks preying on the seals.One seal was spotted hunting down and feeding on five sharks over a two-hour period. Once they have bagged a shark, the seals have been seen eating the liver and stomach contents, which provide high-energy nutrition.Divers have seen the Cape fur seals target large rays heavier than themselves. Seals have also been seen feeding in close proximity to killer whales, presumably scavenging pieces of dolphin the orcas had been preying on.Fallows said killer whales are known to feed on seals."I don't think this is natural feeding behaviour; I think they have been forced to progress to this [level of predation] because their normal food is in short supply."Why would they change their feeding strategy after tens of thousands of years unless forced into it?" asked Fallows.Cape fur seals usually prey on smaller bait fish and crustaceans.But what marine biologists haven't seen yet is a Cape fur seal take on its ultimate Nemesis: the great white shark.Even a small great white shark, Fallows believes, would be difficult for a seal to take down."A 2m great white shark would be too powerful for them."..