Hobbies And Interests
Sexual Maturity
In the wild, killer whales become sexually mature at around 10 to 18 years old, when the male is around 20 feet long and the female around 16 feet long. Females are thought to continue to be reproductively active into their 40s. In males, when the dorsal fin is fully grown, it indicates that the whale is sexually mature.
Mating Activity
Newborn calves have been spotted in the wild at any time of year, suggesting that killer whales do not have a specific breeding season. In some regions of the world there is indication of peak breeding months, for example, between October and March in the northeast Pacific Ocean. Females come into heat several times a year and there is no menstrual blood loss. Killer whales mate with several partners and do not choose a specific mate for life.
Reproduction
Females in captivity can bear up to one calf every two years, but in the wild, this lengthens to around 4 years. In some cases, females do not breed for as long as 10 years. The gestation period for young is around 13 to 17 months. Killer whales give birth to only one calf, twins has only ever been recorded once. Deliveries usually occur tail-first.
Calves and Nursing
When born a calf is around 8 feet long, weighing approximately 350 pounds. The dorsal fin on newborns is flexible and droops over, but stiffens after a few days. The white patches on a newborn killer whale are instead a yellowy color, but this changes to white after the first year. Calves nurse for about a year on milk from their mother. This milk is rich in fat, which allows the calf to build layers of blubber under its skin to protect it against cold weather. Fat is also a good source of energy. The mother arches her tail while the calf swims along side her, suckling on nipples concealed in abdominal mammary slits.