Sleeping octopus shows off spectacular colour changes, but is it dreaming?

In a beautiful new video an octopus named Heidi can be seen rapidly changing between multiple colours and patterns as she hangs suspended in a deep sleep. But does this fascinating behaviour mean she is dreaming?

The Octopus in my House: Natural World
Heidi the octopus in her living room tank

It is safe to say that marine biologist David Scheel has a rather unique house guest living in a tank in his living room. A female day octopus called Heidi. The researcher, based at Alaska Pacific University, and Heidi first found fame in a BBC documentary titled ‘The Octopus In My House’ which looked at how octopuses interacted with humans. But when he was asked to film Heidi sleeping overnight as part of a new PBS Nature documentary he found something very unexpected. As she slept Heidi showed of a dramatic set of colour and pattern changes in quick succession. The footage, which has since made the rounds on the internet, got David thinking that maybe Heidi was dreaming. The science of sleep and dreams is something that is still not very well understood in humans, yet alone marine invertebrates like octopuses. But the technicolour transformations of the sleeping cephalopod do seem suspiciously like dreaming to the casual observer. So what is causing the spectacular shifts in colour and is it really the result of dreaming?

Dreaming in technicolour?                                                                                                     

In the video Heidi can be seen hanging upside down in her tanks as she sticks to the glass roof by the powerful suction of her arms. We can tell that she is asleep because of the lack of movement in her body apart from her mantle, the ball of muscle behind her eyes, which expands and deflates as she breaths. The question of whether or not this could be considered snoring is something to discuss at a later date. But as she hangs suspended in her slumber she begins twitching, with each twitch resulting in a pulsating change of colour in her skin. In the short space of a minute Heide displays multiple and distinct colours and patterns which suggests some strong brain activity is at work. It appears very similar to dogs ‘chasing cats or rabbits’ when they sleep and Heidi’s owner David Scheel strongly agrees. Listen to him narrate the transformations in the video below part of PBS’s new documentary ‘Octopus: Making Contact’ which debuted today in the states.

Although David seems pretty convinced Heidi might be dreaming in the video he also admits that he is not a sleep scientist and that this is only his opinion. So how do we tell if it is? Well dreaming in humans and other mammals is strongly linked with REM sleep. The state of sleep where brain activity is at its highest. Recent research has actually shown that REM cycles are more common in fish than previously thought and the octopuses close relative the cuttlefish have also been shown to exhibit REM sleep. But it is something that has not been properly studied in octopuses who hide inside crevices and holes when they sleep. More lab research into their sleep cycles is needed to tell if they also experience REM cycles. Even then dreaming is a very human construct made up of our subconscious thoughts and we can only know we dream through our own experiences. It is also possible that the colour changes were caused by random involuntary muscle contractions. So it is very hard to tell for sure if Heidi was dreaming.

Colourful chromatophores

Regardless of whether Heidi’s colour changes are the result of dreaming or not it is hard to argue that the shifting between pigments and patterns isn’t beautiful to watch. But what allows her and other octopuses and cephalopods to alter their appearance like this? The answer is specialised structures called chromatophores which they have in their skin. Chromatophores are essentially elasticated sacs of pigments which when they contract or expand in a certain way produce a uniquely coloured ‘pixel’. Octopuses use these chromatophores to change the colour of their skin quickly and easily at the ‘flick a switch’. They do this primarily to camouflage themselves against their surroundings to both avoid predators and sneak up on their prey. This can involve block colours like a dark blue in the open ocean or a sandy yellow on the seafloor but can also be complex patterns that let them disappear in just about any marine environment. The result is that octopuses can not only be extremely beautiful but also completely invisible.

Alien intelligence

Octopuses are generally considered to be one of the most intelligent animals in our oceans. In fact some people would argue that they are one of our closest intellectual rivals. But for most people it is hard to associate such intelligence with a creature that seems so alien and different from ourselves. After all they have three hearts, blue blood, no bones and eight arms, physically you would be hard pressed to find an animal that is more drastically different from us. Even in our brains there are some big differences. For starters octopuses actually have more neurones, or brain cells, than humans. Over 500 million of them compared to our own measly 100 million. As well as this their neurones aren’t just confined to their brains and can actually be found in high quantities in their arms. They also lack areas of the brain we have such as the cerebral cortex and basal ganglia.

Heidi 2
Up close and personal with Heidi, her story shows us octopuses are much more like us than we previously realised

 

However it is the connections between different neurones in our own brains, not the size or shape, that has allowed us to rise above other animals in terms of intelligence. And it seems that octopuses may have much more connected brains than we previously thought. Multiple studies into octopus intelligence have shown us they are capable of some pretty impressive feats. They are capable of escaping aquarium enclosures, navigating complex mazes, unscrewing jars to obtain food and solving basic puzzles. They are also believed to feel pain and react in an identical way to humans when exposed to the party drug MDMA despite their alien brain layout. Their intelligence is so great some scientists even joke that if humans were wiped off the face of the Earth octopuses would be the next species to rise to power.

As for whether or not they can dream in their sleeps? You’ll have to watch the video again and make your own mind up.


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