This moment was captured in stunning images shot by scientists in Brazil, a new study published in the journal iScience on Thursday states that the solemn cephalopods are experiencing co-existence. at least two types of sleep.
One of these states, which they called “active sleep,” is similar to rapid eye movement (REM) in mammals, birds, and some reptiles – raising the interesting possibility that octopuses, as humans, experiencing dreams.
“Octopuses are unique in their complexity, both behavioral and neural,” senior author Sidarta Ribeiro of the Federal Institute of Rio Grande do Norte do Brazil, Brazil, told AFP, noting that the brains most complex of any invertebrates.
“But nonetheless they are very different from us.”
To investigate the question of octopus sleep pattern, the researchers recorded four octopuses in their tanks over several days, and then returned to examine the films.
They found during “quiet sleep,” the animals were still, with fair skin and their pupils contracted for a slit. During “active sleep,” however, they changed the color and texture of the skin, visibly swept and twisted, and the eyes moved around.
The pattern was cyclical, with the silent period lasting about six or seven minutes and followed by an active cycle lasting about 40 seconds.
The cycle could then recur, or the octopus could wake up, but he usually fell back asleep 30 to 40 minutes later. Everyone said, their slums take up a quarter of the day.
To determine whether these states actually represented sleep, the researchers designed visual and tactile stimulation experiments, the first author, a graduate paper Sylvia Medeiros told AFP.
The first test involved playing a video of a crab on a screen placed next to the octopuses.
“When they are awake, because a crab is a natural prey, they try to attack,” she said, but they did not try to push in the two states where they intended to sleep. .
iStockMost human dreammaking comes through REM sleep – so maybe this is also true for octopus molluscs?
In the second experiment, they hit the octopus tanks with a rubber hammer, with the animals reacting physically and changing color when awake, but not when asleep.
‘Video clips, or even gifs’
Learning more about what makes us like octopuses, which moved our species 500 million years ago, can provide new insights into our unique evolutionary pathways, Ribeiro said.
“If we see a similar phenomenon, in this case, a sleep cycle that involves a quiet and then active sleep, it is more likely the result of convergent evolution,” he said, implying that our two species independently altered the same biological mechanisms.
That in turn sheds light on the evolutionary pressures that shaped this behavior.
For mammals, REM sleep represents a time of memory consolidation and stimulates a number of molecular mechanisms that regenerate the effects on brain health and psychiatry.
The authors believe that this may be true for octopuses as well.
Most human dreammaking comes through REM sleep – so maybe this is also true for octopus molluscs?
“We can’t prove it for sure,” Medeiros said.
But if they do, it is unlikely to resemble the complex statements we can experience, given the shortness of the active stage for octopuses, she said. “It should look more like small video clips, or even gifs.”
The color patterns that octopuses create on the skin during sleep may bring a window into their mind, as they can mirror patterns they exhibit while they sleep. when awake.
For example, the “half and half,” where they are black on one side and white on the other, can be seen during courtship – so an octopus showing this pattern during sleep may be dream about romance?
Maybe, but it’s too early to say, Ribeiro said, and the subject of a future study.
The team then hopes to find ways to record cloud data of octopuses – a difficult proposition as they move around in water – and to learn more about where sleep plays for the metabolism and experience of animals.