a The octopus called Marshmallow falls to the bottom of its reservoir and suddenly changes color. From a pale greenish white to brown and then orange, his muscles twitch, his suction cups contract and his closed eyes move, Which indicates that you may dream.
The moment was captured in a movie by Brazilian scientists this week that published a study in the journal iScience, according to her Octopuses experience at least two types of sleep.
One of those states that they called it ‘Active sleep’Similar to rapid eye movement (REM) sleep of mammals, birds, and some reptiles, it raises the intriguing possibility that, like humans, octopuses are dreaming.
“Octopuses are unique “In terms of behavioral and neurological complexity,” said Siddhartha Ribeiro, a neuroscientist at the Brain Institute of the Federal University of Rio Grande do Norte in Brazil.
For Ribeiro, octopuses are the invertebrates with the most complex brain. “But they are very different from us,” he explains.
To study sleep patterns Four octopuses are permanently photographed by researchers In their lockers for several days and then analyzed the photos.
They noticed that they remained still during “quiet sleep” with pale skin and the pupil of the eyes completely contracted. However, during “active sleep”, they drastically changed their skin tone and texture, twitching and constricting, and their eyes moved.
The style was cyclicalor. The period of calm lasted 6 or 7 minutes Then came a 40-second active moment.
Which – which The cycle may repeat or the octopus may wake upBut he usually fell back to sleep after 30 to 40 minutes. In total, they can sleep a quarter of the day.
To determine if these states truly represent dreams, Researchers designed both visual and tactile stimulation testsSaid the article’s first author, graduate student Sylvia Medeiros.
The first test involved rMake a video of a crab on a screen next to octopuses.
“When they are awake, because the crab is prey, they try to attack them,” he said. But they did not try in the states That they were supposed to be sleeping in.
In other tests, the researchers They hit the tanks with rubber hammers. Octopuses react and change color when they’re awake, but not when they’re asleep.
Learn more about what makes us similar to the octopuses, from which our species separated 500 million years ago. It could throw a new perspective on our various evolutionary pathsRibeiro says.
“If we see a similar phenomenon, in this case a sleep cycle that includes calm sleep and then active sleep, it is most likely due to convergent development,” which means thatTwo species independently arrived at the same biological mechanisms In their evolutionary paths.
In mammals, REM sleep is a time for strengthening memory and triggering a variety of molecular mechanisms Which has a restorative effect on brain health and knowledge, the authors believe this will also be the case with octopuses.
Most human dreams occur during rapid eye movement (REM) stage. Would it be the same in octopuses? “We cannot be sure,” Medeiros said.
But if so, It is unlikely to be comparable to the complexity of the narrative that He added that humans, due to the short duration of the active phase of the octopuses, “will be like small videos or even animated images.”
Then the team waits Finding ways to record neural data from octopuses, A complex suggestion given that they move in water, and to learn more about the role that sleep plays in the metabolism and cognition of these animals.
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