Killer whales are large predators that sometimes attack people who enter their territory. While the exact reasons are uncertain, it is thought to be because they mistake people for seals or other more natural prey, but it can also be because they see humans as a potential food source.
if you are in the water and playing around with them they can attack human.
no but they do attack humans
Orcas are harmless to humans unless they are provoked. They typically do not want to attack humans because they are not desirable prey.
yes
Killer Whales or Orcas are immensely strong. They are largest member of dolphin family with no natural predators beside humans which isn't natural. Orcas have been known to attack great white sharks and blue whales and win.
Certain species of sharks and orcas will attack whales.
Dolphins, Porpoises and humans
Yes they could, especially if humans were a food source for orcas, however wild orcas are not considered a threat to humans.
Swimming polar bears are vulnerable to being killed and eaten by orcas. On land, they only are vulnerable to humans with guns.
Polar bears are apex predators. Only humans regularly hunt and kill them.
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?
Orcas will eat seals, and seals are mammals.
They have no predators they are apex predators.