Perhaps many did not ask how whales sleep. It turns out that this is a very interesting topic for thought. Indeed, having large body sizes, a significant part of the mass of which is fatty tissue, huge whales have little buoyancy. And this means that the animal will slowly plunge into the depths without moving its tail.
From this article you can find out how a whale sleeps. Scientists have recently found the answer to such a rather curious question.
Some general information about whales
Whales are mammals that are fully adapted to life in water, belonging to the order of cetaceans. Like porpoises and dolphins, these aquatic mammals are thought to have evolved from land animals that returned to water about 50 million years ago, after living on land for several million years.
In total, 2 suborders of whales live on the earth: baleen and toothy. Toothy include sperm whales, killer whales and beluga. They hunt large fish in the deepest waters. Baleen whales (filtrators): blue and humpback. They feed on smaller organisms, such as plankton, krill, etc. A large volume of sea water is filtered in their mouth due to a peculiar comb tissue called a whalebone.
Before we find out where and how a whale sleeps in water, we will conduct a short excursion in ancient times.
About the ancestors of whales
If you swim for a long time on the water, fatigue will take its course in any case, so any living thing needs rest and sleep. Absolutely all mammals also need to sleep, including those who live in the water: whales and dolphins. The cetaceans of our time, it turns out, cope with this problem "in limbo." But their ancestors, as you know, many millions of years ago were terrestrial animals.
Ancient whales (pacicets), having left the land, once went into the ocean. This is due to the presence in its depths of a diverse, plentiful and more affordable food.
At first, the Pakitsets hunted for shallow-water fish and returned after that to rest on shore. But the competition existing at that time forced these animals to swim behind prey farther and farther into the depths of the ancient Tethys ocean. And then they completely disappeared the opportunity to return to land, and therefore there was a need to learn to sleep in the water. Pakitsets managed to adapt to this over many millions of years. This period is not surprising, because an animal who wants to spend the night in the water has to overcome many obstacles, moreover, it is deadly.
How the whale sleeps: photo
In general, whales sleep often, but not for long. When these giants are immersed in water, they fall asleep for only a couple of minutes. In total, whales have time to sleep about 15 minutes in a few hours of swimming.
The immersion of this huge sea creature takes place at a shallow depth, after which the whale rises to the surface with the reflex movement of the tail to inhale another portion of air. Such a cycle is repeated again and again. This is similar to the state of a drowsy person, "pecking." In this way, big whales manage to get several tens of minutes of sleep in a few hours.
Scientists could not understand how a whale sleeps, constantly swimming and in constant motion. Now it has become clear. So scientists have refuted the theory that the process of sleeping in whales is similar to the process that exists in dolphins.
And how do dolphins sleep? A little earlier it became known that dolphins have a more complex biological mechanism. They have 2 hemispheres of the brain of the brain sleeping in turn, and therefore the dolphin, unlike a whale, is able to constantly stay awake.
About danger
How does a whale sleep in water? It is difficult to imagine, since this is for them a task of increased complexity. Why?
1) Asleep in water, mammals are at risk of dying from the cold, because the heat produced by the body quickly dissipates in its environment. And due to the fact that water has a higher thermal conductivity than air, the animal in it cools faster.
2) Unlike fish, whales need to periodically emerge in order to receive a certain portion of air. Therefore, they must make considerable efforts so that the body does not sink too deep. Otherwise, there is the opportunity to drown.
3) Smaller species of cetaceans (pinnipeds and dolphins) in a dream can be prey to predators, because there are no protected places in the water to hide for sleep, and you constantly have to float to the surface for inspiration. And there most often their predators attack.
It turns out that sleep for cetaceans, especially for their ancestors, is a real test.
A little bit about the features
The most important curious fact is how the whale sleeps. But there are other interesting points regarding these mammals.
1. According to most etymologists, the word "whale" comes from the German hwal. But there is still an opinion that it arose from the old English word, translated as “wheel”, since the back of this mammal, protruding on the surface of the water, resembles the edge of a huge wheel.
2. The peculiarity of whales and other cetaceans is that they move in water due to the movement of the tails vertically up and down. In this they differ from fish in which tails move from side to side when swimming.
