Dolphins belong to the order of cetaceans, a suborder of toothy whales. In order to relax, it seems to us, just close your eyes and fall asleep. And people do not even suspect that this could happen otherwise. But how does a dolphin sleep? This question has always been interesting, because the toothed whales sleep in a completely different way than other representatives of the mammalian order.
These animals are literally sleeping on the wave. That is, they swim and at the same time rest. Dolphins are constantly on the move, so they get very tired, and, like any living creature, they also need to sleep.
Sleep or life?
For a long time, scientists were convinced that cetaceans did not sleep at all. Indeed, there were certain grounds for these assumptions. Therefore, how a dolphin sleeps was a mystery to everyone.
Firstly, if he falls asleep, they can eat him. Secondly, oddly enough it sounds, but it can drown. Yes, it is to drown, because in order to sleep, you need to breathe. But there is no air at the bottom of the sea.
Scientists also suggested that dolphins sleep in fits and starts. Another reason dolphins were supposedly awake is the cold. If mammals fall asleep, then it will easily freeze. This is due to the fact that with movement the dolphin's body warms up, and when sleep occurs, it quickly cools. Given all these features, for a long time, scientists could not determine how the dolphin sleeps, and whether he can do it at all. But soon the mystery was solved.
It turns out that there is plenty of evidence that sleep for these mammals is life threatening. But what to do? Without sleep, life is impossible not only for the dolphin, but also for any animal on earth, in the air and in the water. Everyone sleeps, but only each in his own way.
All the time on guard
Dream for dolphins is something interesting and unusual. After all, they should be vigilant, because predators do not sleep and can easily kill. Some observations have shown that dolphins cover one eye. However, why are they doing this? Then the following question arises: "Do dolphins sleep with one eye open?" We will try to answer it.
Dolphins sleep on the waves, as this allows them not to drown. So, they often take the breaths that are necessary for life. If the dolphins slept deeper, it would be harder for them to breathe, since they needed time to surface and take a breath. For these reasons, the mammal sleeps upstairs. But that is not all. An interesting fact remains how the dolphin sleeps, because his eyes are not completely closed.
It turns out that the two hemispheres of his brain are sleeping alternately. First, one rests, and the second is awake, and vice versa. The main thing is that the hemispheres sleep at equal intervals of time, and while one part of the brain is sleeping, the second is watching the world around it. This allows the animal to be safe.
"Lunatic sea"
Dolphins are often called “sleepwalkers” because they are in constant motion in a dream. This is necessary not only to take breaths, but also not to freeze. The body of the dolphin during swimming generates heat, which allows the mammal to warm up. In this case, "sleepwalking" is very necessary, since it is protection from both the cold and predators.
Not all cetaceans are sleeping in motion. This ability is possessed by those in which the body weight is tons. For example, a killer whale, which weighs about six tons, sleeps completely motionless on the surface of the water. Since there is a sufficient amount of subcutaneous fat in her body, which retains heat longer and “holds” it in water.
If the weight of the mammal is less than 100 kilograms, then sleeping will not work. You need to move during sleep. Killer whale cubs also sleep in motion, because they have not gained the weight they need. When they accumulate a sufficient amount of subcutaneous fat, they will also boldly doze in a stationary state.
Fantastic Dolphin Abilities
As you know, toothed whales sleep in motion, and this is not the only interesting feature of these amazing mammals. The second is that they rest with their eyes open, or more precisely, the dolphins sleep with one eye open. Why is this happening? Everything is quite simple: dolphins have a unique ability: when one hemisphere of the brain is sleeping, the opposite eye is open, in this way they watch others. For example, for their cubs. This is very convenient, because in this way they protect "their".
These animals do not have a paradoxical phase of sleep, which allows people to dream. Since dolphins sleep with their eyes open, they cannot be in the land of dreams.
