Life Cycle Reproduction in whales is essentially the same as in other mammals. Sexually mature animals go through a courtship period followed by copulation, which in the whale takes place belly to belly in the water. The pregnant female carries her unborn young for 9 to 16 months, depending on the species, and usually a single large, well-developed calf is born underwater. A healthy calf can swim from the instant it is born, rising unaided to the surface for its first breath. Soon after, it begins to nurse from either of two mammary teats enclosed in slits located on either side of its mother's genital opening.
Whale milk is very rich, and calf growth is rapid.
In some species, such as the killer whale, young animals appear to remain permanently in the family pod, which usually numbers 5 to 12 animals. A whale reaches sexual maturity at 6 to 13 years of age. As with all other animals, not all whales survive to old age. Disease, injury, and predation by killer whales, sharks, and whalers all take their toll. Senses and Intelligence Sound and hearing are to whales what vision and smell are to most land mammals.