Ecology
Scientists have not been able to answer the question of how dolphins sleep for a long time. For a long time it was believed that they did not sleep at all! However, a recent study has shown that dolphins can stay awake for at least two weeks at a time.
A specific feature of their brain helps them do this: one half of this organ is asleep, while the other remains active. Why this happens is a topic for another conversation, but scientists already know that this feature of these mammals allows them to always be on the alert, preventing predators (mainly sharks) approach unnoticed.
Researchers believe that dolphins can use this feature all the time, giving one side or the other half of their brain a break from time to time. “If a person or other animal does not sleep for several hours or even days, sooner or later, the body's activity drops and sleep overcomes him,” explains researcher Brian Branstetter ( Brian Branstetter, a marine biologist from San Diego, California, USA. — Dolphins have no such restrictions. Otherwise, they would either drown or become easy prey.”
Scientists have long been interested in the question of how dolphin brains manage to function taking into account this specific feature. Researchers, in particular, drew attention to the ability of dolphins to scan their surroundings. As you know, these mammals use echolocation to map the world around them. This happens as follows: dolphins make sounds (specific clicks) and then pick up echoes, which allows them to navigate even in completely dark water.
The researchers organized a kind of collapsible floating pen in the water with eight sections, each of which had an underwater sound emitter and a microphone. As soon as the experimental dolphin scanned any of the modules using echolocation, scientists responded with sounds that simulated the echo as if the sound was reflected from different distances objects or surfaces. In fact, scientists have created a kind of false radar target that only acoustically modeled physical objects.
Dolphins (two of them took part in the study — a female named Say and a male named Nay) continuously sent signals towards floating sections. The animals were even trained to go fishing as soon as they received a signal from a false target. As a result of the research, scientists came to the conclusion that dolphins can successfully use echolocation with almost filigree accuracy for at least 15 days, while maintaining their ability hunt. The study was not conducted longer.
“Dolphins can continue swimming and brain activity for days without sleep or rest. Perhaps they can do this longer,” Branstetter assured. The scientist explained that their study suggests that dolphins have the ability to use only one part of the brain, allowing the other part to rest. This not only prevents them from drowning, but also allows them to remain vigilant. Thus, according to the biologist, these intelligent animals always remain awake.
Obviously, scientists need additional studies to determine whether dolphins can be active for more than two weeks without losing functionality. Branstetter noted that plans include installing portable encephalographs on dolphins that could operate in the depths of the sea. In addition, scientists hope to find out how dolphins manage to perform other cognitive tasks while staying awake for a long time.
