Scientists finally understand why octopuses change color while they sleep

Scientists finally understand why octopuses change color while they sleep

Sleeping octopus changes color.Bild Sylvia LS Madros

Heidi octopus spread in 2019 with Video That showed how she changed her color while she slept. Biologists wondered what’s going on here. Is she dreaming?

Researchers from the federal University of Rio Grande do Norte in Brazil took a closer look at the strange behavior. In the scientific journal iScience They have now concluded that octopuses have two phases in their sleep cycle: a silent phase and an active phase.

To prove this, researchers made videos of octopuses in the lab. When the octopus is sleeping, the two phases alternate. In a silent sleep, the white octopus lies motionless. The difference with active sleep couldn’t be greater. Octopus constantly changes its color pattern as well as the texture of its skin. Suction cups contract and twitch their tentacles.

Can we talk about falling asleep in that active phase? The researchers tested this by measuring the octopus’ response to external stimuli, such as touch or bright light. Only when researchers gave the octopus very powerful stimuli did it respond. In other words, he was really asleep before that.

It developed independently

Previously, biologists believed that only mammals and birds had two stages of sleep. In humans, this is, for example, REM and non-REM sleep (the word “REM” stands for Rapid eye movementRapid eye movement). Recent scientific research shows that this sleep cycle also occurs in reptiles, and now also in invertebrates. They are far from humans in the evolutionary family tree, our evolutionary branch separated 500 million years ago. So researchers believe that the octopus sleep cycle developed independently, although it is very similar to the human sleep cycle.

Sander Gripsma, biologist at the Sea Life Aquarium in Scheveningen, “is glad this was properly researched once.” According to Griepsma, an octopus’ sleep patterns are related to its intelligence. For example, they can open shells, build stone fortresses to spend the night in, and flip pot lids. And anyone watching the Netflix documentary My octopus teacher Knows the extent of their curiosity and eagerness to learn. Animals with higher brain function may have more processing. So they need more complex operations while they are asleep.

In humans, we know that this treatment occurs during REM sleep. That comes with dreams. Would an active octopus sleep work similarly? “Of course we cannot ask them if they dreamed, and this is possible with people.”

Flupsma suggests following the octopuses during their waking hours in another experiment to see if their dreams revolve around their past activity. Suppose they were sitting on a red rock earlier in the day. Do they also turn red during active sleep?

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