“This overall speculation about dreams must be taken with caution,” said Sidarta Ribeiro, a senior author and neuroscientist at the Federal University of Rio Grande do Norte Brain Institute in Brazil. He said octopus active sleep episodes occur in short bursts that last from tens of seconds to just over a minute.“In mammals … active sleep, what we call REM sleep is much longer. It lasts minutes, tens of minutes,” Ribeiro told Live Science. So, “even if some kind of inner story is happening in the octopus’s mind when the octopus is getting a good night’s sleep, it’s very unlikely that it’s the whole story,” he said. Said. Perhaps the octopus may dream of a short scene like a video clip drawn from a long movie, he said.
But even if the octopus does not dream in these fleeting moments of active sleep, sleep states play an important role in the learning and memory of living things, as well as intensifying human memory during REM. Ribeiro said it could do so. In the future, the authors plan to study the effects of various sleep states on octopus learning.
Psst, are you sleeping?
Octopuses use chromatophores, or special pigmented organs that swell and contract under the skin, to change color and change the color and pattern of their surface. Live Science previously reported .. While awake, the octopus can change color to blend in with its surroundings, but it is unclear why the animal keeps changing color while it is stationary, and there are few studies on octopus sleep.
In past studies Common octopus Common octopus ), Scientists only describe the so-called “quiet sleep,” in which the animal becomes very stationary and its skin turns a ghostly white color, said the first doctoral student at the Brain Research Institute. Author Sylvia Medeiros told Live Science. A vibrant “active” sleep state Common squid (((Sepia Officinalis ), Related cephalopods, but these studies did not confirm whether the squid was really asleep or in a “quiet awakening state,” Medeiros said in an iScience report. ..
To make sure an animal is really asleep, scientists test its “awakening threshold,” the time it takes for an organism to respond to a stimulus. For example, while awake, the octopus reacts quickly to the physical vibrations of the aquarium and the video of the crab’s scuttling playing just outside the glass. A sleeping octopus must first wake up from sleep, so it may take a much longer time to react or it may not react at all.
The team conducted these awakening experiments using four tropical octopuses of this species. Octopus insularis , Medeiros has collected 6 miles (9.7 km) from the Brazilian lab. The author captured video recordings of the octopus to assess the behavior of the octopus during alert and resting. Focusing on cephalopod behavioral patterns, we tested animal arousal thresholds in a variety of behavioral states. For example, they tested animals both when they were vigilantly exploring tanks and when they appeared to be stationary and resting.
Researchers have found that not only do octopuses truly sleep during active sleep, but animals also switch between quiet and active sleep in a predictable pattern.
“The relationship between quiet and active sleep they identified is particularly exciting,” said Sara Stevens, an aquarist at the Butterfly Pavilion in Westminster, Colorado, who was not involved in the study. “It examines the patterns we have anecdotally witnessed across the octopuses we have taken care of for years,” Stevens told Live Science in an email. However, she said the new work contained only four octopuses of the same species, requiring more extensive research to confirm the results.
Clear sleep pattern
The team observed that during “quiet sleep” the color disappeared from the octopus’s skin and the pupils contracted into thin slits. In this state, the animal is fairly stationary, except for the occasional soft and slow movement of the suction cups and arm tips. A period of quiet sleep can last from a few minutes to about 30 minutes.
“Quiet sleep almost always precedes active sleep,” Ribeiro said. “It’s usually a long, quiet sleep episode that lasts more than six minutes and” leads to an active sleep episode, “he added.
Dramatic visual changes indicate a transition between quiet and active sleep. Chromatophores in the octopus head and mantle (the bulbous structure that houses the animal’s organs) exhibit “sudden simultaneous darkening.”Animals then start Cramps , Shrink the suction cups, move your eyes and increase ventilation. The octopus also expands and contracts its pupils, and the bright colors wash away the whole body.
The pupil may dilate, but in this state the octopus does not respond to visual stimuli. This is the same as being able to sleep with your eyes open. These sudden movements and color attacks occur regularly at intervals of approximately 30-40 minutes.
“It’s really similar to what you see in reptiles and birds. A long, quiet sleep is followed by a short, short episode of active sleep,” Ribeiro said. Mammalian sleep follows a similar pattern, but active sleep, or REM, usually lasts longer than other animals, he said.
In mammals, the transition to REM sleep involves physiological changes that help convert short-term memory to long-term memory. brain
The authors plan to study whether changes in the octopus sleep cycle affect their ability to learn new tasks. For example, they may study how well sleep-deprived octopuses can learn and remember how to release food from closed containers. In addition to behavioral tests, the team plans to study whether octopuses express specific genes or build specific proteins during active sleep, as mammals do during REM sleep. I am.
At some point, they also want to record the electrical activity of the octopus. Neuron While sleeping, it presents an incredible challenge, the author said. For starters, fluffy boneless creatures lack solid body parts that scientists can easily attach electrodes to, Ribeiro said. In addition, curious animals pull and pull what is placed on their body, Medeiros said.
“Adding water to the equation makes it a whole different level of difficulty,” Stevens added.
Among these many challenges, there are still big questions. Is the octopus dreaming?
“My premonition is yes, but we are open to everything,” Ribeiro said.
He said it might be possible to study their theoretical dreams by taking detailed records of their skin color and patterns until the team is able to collect neural records from the octopus. If an octopus wears a particular color scheme while sleeping, it may respond to awakening life behaviors such as courtship and provide a window to what the animal is dreaming about. The scenario is similar to observing a dog growls and cramps during sleep, as if you were dreaming of chasing a rabbit.
But, again, the use of pigment patterns to read octopus dreams may be achievable at this time, as further research is needed to understand octopus sleep at a basic level. Maybe, Ribeiro said.
