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Whale Reproduction

Whales are mammals and are nourished in the womb through an umbilical cord. Whales even have a belly button after birth (this is the place where the umbilical cord was attached to).

Whales are viviparous, they give birth to live young (unlike fish, most of which lay eggs). Like all mammals, whale calves are nourished with milk from their mothers. The nursing period is long (more than one year in many species), which is associated with a strong bond between mother whales and their young. In most whales, reproductive maturity occurs late, typically at 7 to 10 years.

Whales breed seasonally, usually in warm tropical waters and females usually have one calf every 1 - 3 years. The gestation period ranges from 9 - 18 months. Whale calves can swim soon after birth.

The genital organs of male whales are retracted into cavities of the body during swimming, so the whale is streamlined and to reduce drag. Most whales do not maintain fixed partnerships during mating, in many species the females have several mates each season.

At birth the newborn whale is delivered tail first, so the risk of drowning is minimized. Whale mothers nurse the young by actively squirting the fatty milk into their mouths. Whale milk is a bit like Cottage Cheese, very thick. It has to be textured like this to prevent disolving into the surrounding water.

The table below indicates the gestation times for different species and length and weights of calves:

Whale Type
Whale Species
Gestation Period
Ballen Whales
Blue Whale
11 - 12 months
Calves are 25 feet long and weigh 6 - 8 tons
Bowhead Whale
12 - 16 months
Calves are 17 feet long and weigh 5 - 6 tons
Grey Whale
13.5 months
Calves are 15 feet long and weigh 1 - 1.5 tons
Humpback Whale
11 - 12 months
Calves are 14 feet long and weigh 2.5 tons
Minke Whale
10 months
Calves are 9 feet long and weigh 1,000 pounds
Right Whale
12 months
Calves are 16 - 19 feet long and weigh 6 - 7 tons
Toothed Whales
Baluga Whale
14 - 15 months
Calves are 4-5ft long and 100-150 pounds
10 - 16 months
Calves are 5.25 feet and weigh 176 pounds
Killer Whale (Orca)
16 - 17 months
Calves are 6 - 8 feet long and weigh 600 pounds
Sperm Whale
16 months
Calves are 13 feet long and weigh 1 ton



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