Orcas (Orcinus orca) are often called killer whales, even though they almost never attack humans. In fact, the killer whale name was originally "whale killer," as ancient sailors saw them hunting in groups to take down large whales, Today, orcas are recognized as among the most widely distributed mammals on the planet, occupying every ocean. They are incredibly social, diverse and ferocious marine predators with a diet ranging from penguins to great white sharks. Orcas are apex predators, at the top of the food chain. No animals hunt orcas (except for humans). Killer whales feed on many different types of prey, including fish, seals, sea birds and squid. They can also take down whales larger than themselves, such as minke whales, and they are the only animal known to predate on great white sharks, according to The Natural History Museum in London. Killer whales have even been reported to kill swimming deer and moose.