More than a century ago, people found that most whales that live in the cold seas of high latitudes migrate to the tropics in order to give birth to offspring. Scientists could not come to a consensus on why they are doing this. Indeed, due to its large size, whales should be able to successfully give birth in cold polar waters.
And during migration, when they cover a distance of 11 thousand kilometers in a few months, these mammals are very hungry. So why are they taking such a risk? Why do the plankton-rich polar seas leave so that the kittens can see the light in scarce places for food? Recently, the secret of the underwater world has been revealed. It turned out that the reason for the migration is just a cosmetic procedure. Which one? You will find out if you read this article to the end.
Molting
All mammals and birds discard particles of skin and feathers. In some animals, the molting period is noticeable. For example, hares even change color. People also molt, albeit imperceptibly. This process is natural. It comes from the fact that the flow of warm blood accelerates the regeneration of skin cells. Dead hairs and particles are subsequently removed by rubbing the body against other objects.
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But whales and killer whales that live in polar waters divert blood flow from the surface of the skin to maintain body heat. This reduces cell regeneration and stops the normal molting process. When animals migrate to warm seas, blood flow is restored, and the skin begins to exfoliate.
But why do whales give birth in the tropics?
For a long time, it was believed that marine giants travel vast distances to produce offspring in waters where killer whales are not found. But first, killer whales also have the habit of migrating. And secondly, it was not recorded at all lonely cases of finding newborn whale calves in the seas near Antarctica. No matter how icy the water is at high latitudes, it certainly will not kill the cubs of these giant mammals. In addition, the colder the water, the more plankton in it - the main feeding base of whales.
There are species that make small migrations. Such whales swim at the mouths of rivers flowing from warmer areas and “stand there on the roads” until the molting process starts and they renew their skin. And such short trips are not related to childbirth. It is worth noting that migrations are performed not only by pregnant females, but also by males.
Is molting important?
Terrestrial animals and birds, along with dead skin cells and feathers, throw off dirt and dust. But why should marine mammals molt? Whalers in ancient times noticed in animals living in polar waters a thick yellow film that discolored the natural color of their skin. Most often, it covered the belly of whales, for which this raid was called the "bottom of the sulfur."
Scientists have determined what this yellow film consists of. In fact, these are vast colonies of microscopic diatoms. "Sulfur bottoms" were found in both blue whales and killer whales. But time passed, and people met animals with a normal color - returning from migration. After all, with the regeneration of the skin, whales also lose diatoms.
