The Orca or Killer Whale (Orcinus orca), less commonly, Blackfish or Seawolf, is the largest species of the oceanic dolphin family (Delphinidae). It is found in all the world's oceans, from the frigid Arctic and Antarctic regions to warm, tropical seas. Orcas are versatile and opportunistic predators. Some populations feed mostly on fish, and other populations hunt marine mammals, including sea lions, seals, and even large whales.