Whales are marine mammals and share many of the same characteristics that are common among almost all mammals including, the need to breathe air (whales get their oxygen above the surface of the water), being warm-blooded (whales have thick layers of blubber to keep them warm), having hair (some species have hair at birth) and giving birth to their young (not laying eggs as most fish and amphibians do).
In regards to giving birth the gestation period for whales is very similar to human pregnancy in a number of ways.
In fact it is nearly identical to human birth with the exception that a whales gestation period can last significantly longer than a humans depending on the whales species.
Average gestation period
Depending on the species of whale the average gestation period can range anywhere from 10 – 18 months.
While it is possible for some species to mate throughout the year the most common time of year for whales to mate/bear offspring is during the colder winter months when various species travel to the warmer tropics to mate and give birth.
During mating season males will compete with one another for the right to mate with the female.
Some species will show their youthfulness by performing various acrobatic stunts, charging one another and displaying dominance over each other.
Other species will sing to attract a mating partner or herd off the female so that competing males have less of a chance to mate with her.
In a single season it isn’t uncommon for a female to mate with several males in order to maximize her chances of bearing a healthy child; in fact some male species will attempt to wash the competing males sperm out by producing significant amounts of their own.
Once the female becomes impregnated she spends 9 – 18 months developing and carrying her child in her uterus.
After several months of mating these marine mammals will travel back to their feeding grounds until the next mating season comes around.
During this time the female whales goes through a gestation period where her child develops and her uterus and is given nutrient rich blood through an umbilical cord until it is fully developed and ready to be born.
Once birth occurs the umbilical cord is separated leaving the whale with a belly button, just like in humans.
After birth the female whale feeds her young by producing milk from her mammary glands which the young baby whale receives from the mothers nipple.
Most baby whales will continue to receive nutrients from their mother’s milk nipple for 6 months to 2 years depending on the species.
This nursing period continues until the young whale is able to hunt for food on its own.
In some situations a young whale will continue to suckle from the mothers nipple even when the mother stops lactating and producing milk.
In these cases young whales often form a psychological dependency that takes longer than average to grow out of, however eventually all young whales separate from this psychological bond.
After a number of years of hunting and living on their own the young whales reach sexual maturity and are ready to find other whales to mate with.
For these marine mammals the age of sexual maturity can range anywhere from 5 – 20 years depending on the whales species.
After sexual maturity occurs these whales will then repeat the process of their parents and begin mating and bearing offspring of their own.
Lastly, depending on the whales species the average lifespan of a whale can vary from 20 – 200 years.
Gestation period comparison
To give you a better idea of how long it takes for whales to reproduce once impregnated here the gestation periods of various whale species:
- Minke Whale: 10 months (females average 1 offspring about every 2 years).
- Narwhal Whale: 14 – 15 months (limited data suggests females bare 1 offspring every 3 years).
- Sperm Whale: 14 – 16 months (females reproduce every 3 – 6 years).
- Gray Whale: 13.5 months (data not available)
- Humpback Whale: 11 - 12 months (reproduction occurs every 2 – 3 years).
- Beluga Whale: 14 – 15 months (females give birth to a single calf every 3 years).
- Blue Whale: 11 – 12 months (females breed every 2 – 3 years).
- Killer Whale: 15 – 18 months (average is about 17 months). Females give birth every 3 – 5 years.
Note: Killer whales are part of the dolphin family and are the largest among the dolphin species. They are not whales as their name may suggest.
As you can see their is a large variation in terms of the gestation periods of different marine mammals.