Orcas are one of the fastest animals in the sea. The record holder is a male timed at 55.5 km/h (34.5 mph). They are also one of the most widespread mammals on Earth.

Subspecies
None.

Life span
In the wild, male orcas average 35 years or so, but lifespans of 50-60 years are possible. Females average 50 years, but can reach ages of 80-90 years.

Statistics
Male orcas can grow between 7-8m and weigh over 5,000kg. Females grow between 5-7m and weigh over 3,000kg. The largest ever recorded male weighed over 10,000kg and the largest recorded female weighed 7,000kg.

Physical description
Orcas are distinctively coloured. The dorsal surface is mostly black except for a grey saddle behind the dorsal fin. The underside of the body and underside of flukes are white and there is a white eyespot behind each eye. They have a huge dorsal fin - 1.8m (6ft) high - the tallest dorsal fin in the animal kingdom.

Distribution
Orcas inhabit all the oceans of the world. Their distribution is limited by pack ice and they prefer cooler waters.

Diet
Orcas are top predators in the ocean. Their food preferences vary according to their locality. Prey includes marine mammals (other whales, seals, sea-lions, walruses), fish, squid and occasionally sea birds, sea-otters and penguins.

Behaviour
Orcas are highly social and live in groups called pods. Pods consist of males, females and calves and have a female dominated hierarchy. There are three types of orca: residents, transients and offshores. Resident pods can consist of between 5-50 individuals and tend to have relatively small home ranges. They feed on fish, and hunt using echolocation. Transient pod size varies from 1-7 individuals. They have a much larger range and hunt mammals such as other dolphins, seals, sea lions and even whales. They use echolocation less than residents, probably because their prey can hear the clicking sounds. Offshores were only recently identified. They live a lot further out to sea than residents and transients and probably feed on fish.

Conservation status
Orcas are classified as Lower Risk by the 2000 IUCN Red List. Global threats include hunting, human disturbance, habitat loss, prey depletion, pollution, entanglement in nets and collisions with vessels. Orcas used to be killed by people to obtain meat and oil, but commercial hunting ceased during the 1980s.

Notes
Their dive lasts 1-4 minutes. The sounds they make help to echolocate, using screams, distinct tonal whistles and pulsed calls. Each group (usually 2-40 animals) has a repertoire of discrete calls that is unique to the group. Orcas belong to a group of cetaceans known as the 'blackfish', which are actually dolphins. This group includes pilot whales and melon-headed whales.