The orca (sometimes called the killer whale) is the largest species of the oceanic dolphin family. They are found in all of the world's oceans, from the Arctic and Antarctic regions to tropical seas. Some orcas only eat fish, while other populations hunt marine mammals like seas, sea lions, walruses, and even large whales.  Orcas are top predators (they have no natural predators).

They spend their lives in groups, called pods. Orcas have a black back, white chest and sides, and a white patch above and behind the eye. Male adult killer whales can reach up to 32 feet (9.8 m) in length and can weigh nearly 22,000 pounds (10,000 kg); females can reach 28 feet (8.5 m) in length and can weigh up to 16,500 pounds (7,500 kg).  Orcas use underwater sound for orientation, feeding, and communication.