What can take down a full grown orca apart from man?

What animal in the sea could pull it off and why? Assume that the orca is alone and not part of a pod.





Orcas may be tough but I have seen some huge and I do mean huge elephant seals over 10000lbs and 20 foot great whites, and even giant squid 50 feet long that could do it.

What can take down a full grown orca apart from man?
Orcas are at the top of the chain, Nothing can take them unless they are sick or injured. Man can only kill them with weapons. I always thought it was strange how this top predator is a killer, yet they seem to be friendly towards humans, they will sometimes swim along with boats just for fun.
Reply:I have once read an article that reported a fight between a great white shark and an orca. The great white won. However, this shouldn't be used as a yardstick for such fights because it's only one case, and no one really knew how fit each individual was. If that orca was sick or starving, then it's understandable that it lost.





Anyway, like the other posters wrote, it's generally not feasible for large predators to fight another equally large predator, because it is too dangerous to both. The winner might come away with serious wounds that may hamper its ability to hunt, thus ensuring a slow, miserable death.
Reply:The problem with this question is that Orca's are pack hunters. They pose a major threat from their size and intelligence, rightly putting them at the top of the food chain. However I would go with a adult bull Sperm whale. A male Sperm whale regularily reaches 18 metres and it is believed that Sperm whale's were far larger than they currently are, older, larger bulls being hunted by whalers. Some reputed tales are abound of bulls reaching lengths of 28 metres. An aggressive animal of this size would probably weigh more than100 tonnes. This makes it the largest known carnivore ever to have lived. No lone Orca would stand a chance.
Reply:A top or apex predator has very few predators. A human cant kill an orca with bare hands. They have to have a weapon. That's not one on one.





The only time orca could become prey is when they are very young, sick, hurt or very old. Elephant seal males never get to 10000 pounds. There is no such thing as a 50 foot squid. It would unwise of either a full grown white shark or an adult orca to attempt to mess with each other.
Reply:Chuck Norris.
Reply:Infection and/or time. For sure!