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Orca/killer whale
Orcinus orca
Subspecies
None
Life span
Orcas have an average life span of 25-35 years. Females can live to around 80 years and males to around 60.
Statistics
They are the largest of the dolphin family. Males have a body length of 7-8m, females are 5-7m. Males weigh about 5,000kg, females weigh an average of 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 flukes are white. The males have a huge dorsal fin.
Their heads are conical with an indistinct beak and they have a white patch above and behind each eye.
There are powerful muscles at the rear of the upper jaw to prevent large prey escaping.
Distribution
They 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.
They have been seen to stun schooling fish by thumping the water with their tails.
Behaviour
Orcas are highly social and live in groups called pods. Resident pods can consist of 5-50 individuals and transient pod size varies from 1-7 individuals.
Pods consist of males, females and calves. They have a female dominated hierarchy and are organised around maternal groups. Mother/calf bonds last well into adulthood.
Reproduction
Mating takes place between pods to avoid inbreeding. Gestation is between 15 and 17 months and young are 2.1m long at birth. The males don't play a part in the care of their own offspring but may assist with those of younger siblings.
Conservation status
Orcas used to be killed by people to obtain meat and oil. During the 1980s, commercial hunting ceased.
Notes
Their dives last between one and four minutes. The screams, distinct tonal whistles and pulsed calls they make help with echolocation. Each group has a repertoire of discrete calls that is unique to the group.
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