The killer whale (Orcinus orca), also referred to as the orca whale or orca, and less commonly as the blackfish or grampus, is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member.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.