Killer whales are apex predators, meaning that they themselves have no natural predators. They are sometimes called the wolves of the sea, because they hunt in groups like wolf packs. Killer whales hunt varied prey including fish, cephalopods, mammals, sea birds and sea turtles.iller whales are apex predators, meaning that they themselves have no natural predators. They are sometimes called the wolves of the sea, because they hunt in groups like wolf packs. Killer whales hunt varied prey including fish, cephalopods, mammals, sea birds and sea turtles.