Nothing. Orcas eat everything-they are the top of the food chain!
Orcas, some sharks and man.
orcas eat the marine otter
orcas eat the marine otter
Sharks of all kinds and Orcas.
Polar bears, sharks and orcas will eat seals.
Orcas (killer whales) eat the sea otter which is partly why they are an endangered species.
Orcas, and many other larger sharks
sea lions, orcas, sharks
Not much is known about one of the largest animals on Earth, the blue whale being the largest. As for what eats them, I think the only creature in the ocean that might tempt to kill one and could achieve it, is a pod of orcas, they do attack and eat whales. Since I have not herd of orcas killing sharks to eat, I don't see why orcas would attack a whaleshark, but who knows?
Yes, orcas will kill and eat swimming polar bears.
I believe sharks and orcas sometimes take younger or solitary dolphins.
Orcas have been known to attack and eat polar bears that they catch swimming in their environment.