Killer whales (Orcinus orca) are the largest member of the dolphin family. They are found in all oceans, from the cold waters off Antarctica to the warm waters off Central America. Killer whales are predators, and their diet includes fish, squid, penguins, seals, sea lions, walruses and even large sharks. Some populations of killer whales also eat other mammals, such as moose swimming between islands off Alaska.
Killer whale calves stay with their mothers for at least five years before becoming sexually mature and leaving to join another pod (group of killer whales). Males live an average of 50 years; females about 80 years.
The name “killer whale” comes from their reputation as fearsome predators. In reality however they rarely pose a threat to humans: there have only been two confirmed cases of wild killer whales attacking people since 1998 – both were non-fatal. Orcas in captivity have killed several people however – usually after being provoked.
Scientists believe there are two types of killer whale: resident orcas that stay in one place year-round; and transient orcas that travel long distances following migrating prey such as seals and dolphins. Transient orcas have been known to attack and kill residents – possibly because they compete for food sources. Resident pods tend to be smaller than transient pods, which can number up to 60 individuals.
Despite their fierce reputation, killer whales are very social animals and often work cooperatively in hunting prey or caring for young calves. They communicate using a variety of sounds including clicks, whistles and pulsed calls unique to each pod.
Killer whales are not considered endangered but some populations are threatened by pollution,hunting (in Japan) and entanglement in fishing gear .