A male killer whale inserts its penis into a female whales vagina and releases semen to inseminate the female's eggs. The female vaginal opening is in the middle of three patches near the tail-end of the whale's body. The areas on either side of the vagina are mammary gland slits that contain the nursing nipples, which withdraw when not in use. A single black slit covers a male penis.
Killer whales are the largest members of the dolphin family. They reach reproductive maturity at 15 years of age for females and between 15 and 21 years of age for males. Females may reproduce until the age of 40. Males from different pods fight for the right to inseminate a female. Fertilization is not guaranteed upon insemination due to cycles similar to that of a human female. Generally, a female gives birth to one pup every five to seven years and nurses the pups for two years. Both female and male calves stay with their mother for life. According to the Killer Whale organization, the mortality rate for infant killer whales, with pups having only a 50 percent chance of survival during their first year. The pods are matriarchal in structure, so young killer whales are also cared for by other members, primarily young adolescent females.