By Will Dunham
March 25 (Reuters) – The octopus is an extraordinary animal – and the tragic fact that it dies after eight limbs, three hearts, blue blood, royal squirting, the ability to camouflage and mating is not the only reason.
A study by Brazilian researchers published on Thursday showed that the animal, already considered perhaps a clever derivative, has the same two main alternate sleep experiences in humans – and even dreams.
The researchers said the findings provide new evidence that the octopus has a complex and sophisticated neurobiology that exhibits a similar practical behavioral reserve, while the evolution of sleep also provides a broader understanding of a critical biological function.
Octopuses were previously known to experience drowsiness and to change color during sleep. In the new study, the researchers observed a species called Octopus insularis in a laboratory setting. They found that these color changes were associated with two different sleep conditions: “restful sleep” and “active sleep.”
During the “quiet sleep”, the octopus remains pale, with pale skin and eye pupils compressed with incisions. During “active sleep”, it dynamically changes its skin color and texture and moves both eyes while contracting its sucker and body with muscular twitches.
During the cycle a recurring cycle was observed. The “quiet sleep” usually lasted about seven minutes. The ensuing “active sleep” usually lasted less than a minute.
The researchers said the cycles appear to be identical, with alternating “rapid eye movements,” or REM, and “non-rapid eye movement,” or non-REM, sleep conditions experienced by humans, as well as other mammals, birds, and reptiles.
During REM sleep, vivid dreams occur, as a person’s eyes move rapidly, breathing becomes irregular, heart rate increases, and muscles become paralyzed to make dreams not work. Non-REM sleep results in deeper sleep and less dreaming.
Sylvia Madiros, the study’s lead author, said the findings suggest that octopuses may be dreaming or experiencing something similar.
“If octopuses really dream, it’s unlikely they’ll experience complex symbolic plots like ours,” said Madiros, a doctorate student in neuroscience at the Federal University of the Brain Institute in Rio Grande do Norte.
“The octopus has a very short ‘sleep active’ time, usually from a few seconds to a minute. If a dream is seen during this state, it should be more like short video clips, or GIFs.” .
Scientists are trying to gain more insight into the origins and evolution of sleep.
Because the last common ancestor of vertebrates, including humans and cephalopods, including top cotopes, lived half a billion years ago, their similar sleep patterns seem to have been established before their evolutionary anomalies, the researchers said.
They added that this similar sleep pattern also occurred independently in two groups, an event called “convergent evolution.”
“Investigating sleep and dreaming in octopuses gives us a favorable point for psychological and neurobiological comparisons with vertebrates, as octopuses have some practical cognitive features that are found only in some vertebrate species, but with a lot of brain activity.” Study co-author Cedarta Ribeiro, founder of the Brain Institute.
Ribeiro notes that previous studies have shown that octopuses with the most central nervous system of any vertebrate have extraordinary learning abilities, including spatial and social learning, as well as problem-solving abilities.
“To understand the general principles that shape the structure of the brain in different groups of animals, such as the human and the top octopus, to differentiate between different groups of different animals, like the sleep cycle. An understanding of how basic features can be shared, ”Madiros said.
(Reporting by Will Dunham in Washington, editing by Rosalba O’Brien)
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