All higher animals, birds and mammals spend a certain time in a dream, restoring the vitality of their body. This order is predetermined by nature itself. In humans, sleep is associated with a state of rest, immobility, and complete relaxation. Therefore, many are interested in how dolphins sleep, since they are never completely motionless.
Breathing in dolphins
Usually, people do not think much about their breathing, since it is a natural process. But for dolphins, things are more complicated, since they have to emerge from the water every 5-10 minutes to replenish their oxygen supply. To do this, they need well-coordinated joint actions of the brain and muscles.
Dolphins are secondary aquatic mammals. The latter belong to the descendants of animals that first lived in the water, and then got out on land, where they were able to learn to breathe with their lungs. Then, for reasons unknown to science, they returned to the water element. Leading the life of a fish, the dolphin breathes with its lungs. Rising to the surface of the water, he opens a special valve, exhales and inhales, after which he closes the valve and plunges into the water with a fresh supply of oxygen. Such a complex process is almost impossible to combine with muscle relaxation and peace of mind.
Scientists discover how dolphins sleep
Scientists have had several different assumptions about how dolphins sleep:
- these marine mammals sleep like a somnambulist, with open eyes and tense muscles;
- they sleep from inhalation to exhalation, then wake up from a change in the chemical composition of the stored air;
- dolphins do not sleep at all because they do not need sleep.
To unravel this extraordinary mystery of nature, the registration of biocurrents in the brain of dolphins allowed. The electroencephalogram reflects the stages of sleep and wakefulness using a certain pattern. The experiments were carried out by researchers L. M. Mukhametov and A. Ya. Supin from the Institute of Evolutionary Morphology and Ecology of Animals (IEMEZH) of the USSR Academy of Sciences at the Black Sea biological station, where marine mammals were studied both in the pool and in enclosures. Electrons were implanted into the brains of several bottlenose dolphins and azovki. The animals frolicked, and the recording was carried out remotely, via wires and radio.
Before this discovery, many paid attention to one eye of a dolphin, but they did not even know that he was just sleeping.
The results of the study turned out to be a sensational discovery: nature has endowed dolphins with the opportunity to rest and stay awake at the same time!
It was found that the cerebral hemispheres of this animal sleep in turns. While one of them is awake, controlling breathing and movements, the other falls into sleep, which lasts up to 1.5 hours. After that, there is a kind of change of "watch" and both hemispheres change roles: the one that was active before now falls asleep, and the rested one is awake.
When the dolphin wakes up, both of its hemispheres are connected to work.
Thus, the "duty" hemisphere provides control of the dolphin's body and makes sure that it rises in time to breathe air to the surface and does not choke. So he sleeps.
