Whale development: how does it happen? How long does it last?
One might think that whales, the largest creatures on the planet, have the longest incubation time of all the animals in the world combined. However, the record is held by the elephant with a normal development time of 22 months. How do whales reproduce? How long do females stay pregnant? How do whale calves feed? All about cetacean mating.
Sexual development in whales
All in all, males reach sexual development between 7 and 10 years of age, while females, who are more gifted, can reproduce around 5 to 7 years of age. In all cases, the generation time differs starting with one category of animals and then the next. For example, the male of the blue whale is an adult around 5 years old, while the sperm whale must wait no less than 18 years before mating. Whales can give birth to a calf every 2 or 3 years, or even every year (more extraordinary), like the harbor porpoise. Whales are polygamous warm-blooded animals, both females, and males.
The time of multiplication of the whale
Depending on the species, processing takes place at a particular season (from pre-winter to pre-spring for the blue whale) while others can duplicate all year round, such as Bryde's whale in South Africa. During the mating season, strains rise among the whales. To attract the blessing of a female, a savage rivalry sometimes ensues between the males in the form of battles. The humpback whale, for example, hits his rival with his fins or his head. To frighten their opponents, some individuals leave the water and then fall on their side, causing a mist of foam and a solid explosion. Because of the blue whale, the admirers contest to accompany the female and dedicate a melody to her. Consisting of monotonous melodic groups, the vocalizations can last about ten minutes each and can be heard from nearly 10 km away.
Growth of the whale: interaction and length
To mate, the male rotates and positions himself halfway under the female. Then, at this time, he takes out his regenerative armature and enters the female. During mating, cetaceans swim progressively or remain practically immobile. Like all vertebrates, the whale is viviparous, which implies that its calf is created in the mother's womb. The incubation time of the marine creature depends on the species and not on the size, but in doubt, the pregnancy regularly lasts more than a year. In mysticetes (baleen whales), this duration is between 10 and 13 months, while in odontocetes (toothed whales), it reaches 10 to 17 months.
The introduction of the calf
Nature being well done, the litter includes only one calf, because the mother can barely meet the energy needs of twins. In many species, the birth takes place after a long trip to warm waters, because the calf, having little fat, could not survive in cold seas or oceans. Deployed with the tail first, the calf can quickly swim, see, hear and make sounds. Its mother quickly helps it reach the surface to breathe and avoid suffocation. If the weight of the calf depends on the species, it represents in general 6 % of the weight of the mother. On the other hand, the offspring of the humpback whale is now 33% the length of its mother and one 20th of her weight.
The development of the calf
By breastfeeding its mother during the first months of its life, the young whale calf receives all the supplements it needs, especially fats. The mother's milk contains 20 to 40% of these fats, depending on the species: this is how the blue whale calf grows by 4 kilos per hour or more than 80 kg per day! As the sire has left shortly after mating, it is the female's responsibility to protect her offspring from hunters and to provide them with the vital data for their endurance. The calf has difficulty staying submerged as long as the adults, that is why a constant maternal presence is fundamental: it never moves away from its mother and speaks to her with cries that no other creature can hear. Weaning depends on the cetacean family. In the baleen whale, the adolescent is released around the age of one and a half years, while many toothed whales delay the release of their young after nursing. This is the case of some toothed whales that can stay with their mothers for a very long time or even... their whole life!