Killer whales are one of the top predators in the sea. They tend to eat almost anything that they come across, their diet depending on exactly what is living in their home waters. They are known to eat fish, squid, seals, sea lions, penguins, and even other whales, such as sperm whales.ou can thank the Greeks and the Romans for the name Orca, and the early Spanish sailors for the term Killer Whale. Ancient Romans originally applied the name Orca to these animals, possibly borrowing it from the Greek opue. One other thing, they are not really whales, but a type of dolphin.