Recently we posted about an octopus that may have been filmed having a nightmare. The question whether an octopus dreams is a real one and now there is more evidence, but still not definite proof an octopus dreams.
The latest comes from the Guardian. Researchers in Japan have been looking at the two sleep patterns an octopus shows. The recent research was conducted at the Okinawa Institute of Science and Technology (OIST). OIST is a graduate university on the large island. According to the newspaper:
“Octopuses are thought to undergo two different stages of sleep: “quiet sleep” and “active sleep”, the latter of which involves twitching body parts and rapid changes in the texture and patterning of the skin.
Researchers at the Okinawa Institute of Science and Technology (OIST) in Japan have said they have not only confirmed octopuses are asleep during this active stage, but that the stage shows close similarities with REM sleep seen in vertebrates including humans – a phase of slumber associated with dreaming.” Professor Sam Reiter was the lead author of the research which was published in the journal Nature.”
Professor Reiter is an assistant professor and heads the computational neuroethology unit at OIST. Computational neuroethology is a new interdisciplinary field. It uses computers and other machines to help understand neural behavior.
Of particular interest is the color changes an octopus goes through about every hour.
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“Writing in the journal Nature, the team reported how they studied 29 octopuses of the nocturnal species Octopus laqueus, revealing how during daylight the creatures closed their eyes and adopted a resting posture associated with sleep. (Italics in original,)
Every 60 minutes or so, the animals underwent rapid changes of skin colour lasting about one minute, together with changes in breathing rate, as well as body and eye movements.
When the team tapped on the tanks and watched how the animals responded, they found the octopuses showed different reactions depending on whether they were awake, in the quiet stage of sleep, or in the active stage.”
Nature can be reached here.
It is still impossible to know exactly what is going on. There are other explanations, such as fine-tuning their coloration. But the parallels with human sleep are interesting. As with the researchers who thought octopus dreams may be night mares, the researchers feel no certain answers have been found.
In the previous research an octopus showed behavior that could be consistent coming out of a bad dream.