The surprising effects of MDMA on octopuses

Despite 500 million years of evolutionary divergence and drastically different physiology octopuses behave in an incredibly similar way to humans when given the party drug MDMA.

A Californian two-spot octopus

What do ravers and octopuses have in common? Well as of recently they have both experienced the effects of MDMA, also known as Ecstasy. Giving a recreational drug to an unsuspecting cephalopod sounds like questionable science, however it has actually produced some quite intriguing results. Neuroscientist Gül Dölen, from Johns Hopkins University in Baltimore, and Eric Edsinger, a researcher from the Marine Biological Laboratory in Massachusetts, came up with the study. To their surprise they found that octopuses given the party drug behave in a more sociable and less aggressive way with one another. This is similar to how humans react to the drug despite the many difference between the two species. The results suggest that the chemicals associated with triggering social behaviour in the brain have been around since early evolutionary history. Their work published in Current Biology is just one of a string of recent discoveries made about octopuses in recent years that suggest that they may be one of the closest animals to ourselves in terms of intelligence.

What is MDMA?

MDMA (3,4-Methyl​enedioxy​methamphetamine), also known as ecstasy or molly, is a synthetic drug which alters mood and perception. It is a class A narcotic meaning that it carries a 7 year jail sentence for possession in the UK. However that doesn’t seem to stop millions of people from around the world taking it every year. That’s because it creates feelings of euphoria, alters perception and increases social behaviour, including talking and physical interaction, all of which makes it popular with ravers and party goers. It comes in a pill or powder form and the ‘high’ it creates can last anywhere from 2 to 6 hours and even longer depending on dosage and body mass. However there are some negative side effects such as the ‘comedown’ where the user can feel down and low the day after taking the drug. It can also lead to complications and in rare cases death from overdosing. It is not entirely known whether MDMA can cause addiction with some people showing symptoms and other who feel no long term effects.

MDMA can come in a range of shapes and forms

Tripping octopuses

Dölen and Edsinger used four Californian two-spot octopuses for their experiments. In each experiment a sober octopus was secured in a tank by a mesh pot. This was to prevent fighting which is common between octopuses due to their aggressive nature. A second sober octopus was then introduced and as expected acted in a very nervous way, choosing to spend most of its time on the far side of the tank away from the other individual and refusing to make physical contact. The free-swimming octopus was then removed and placed in a second tank containing dissolved MDMA. The now high octopus was re-introduced to the first tank and the change in behaviour was drastic and unexpected.

An octopus in laboratory conditions

Their muscles relaxed resulting in a more fluid movement, they spent significantly more time near the other octopus, attempted to touch them and were even described as ‘hugging’ the mesh cage. As well as this they were seen exposing the underside of their body, where their mouth is, which is something unseen in nature. Their behaviour was so relaxed that the researchers even described their movement through the water as ‘water ballet’. So it seems that a high octopus acts in a very similar way to a high human and probably experiences the same euphoria we do.

This is not the first time that researchers have found these behavioural changes in an animal other than humans. Rats and mice, that neuroscientists like Dölen often work on, also show the same changes when given MDMA. But they have similar brain structure and physiology to us.  This is the first time that an animal as distinctly different from ourselves have shown the same results. That is what makes the results of this experiment so fascinating because it could change everything we think we know about how social behaviour works in the brain. Dölen describes it as “a little bit like studying alien intelligence”.

Why do we react the same?

Having last shared a common ancestor over 500 million years ago it is remarkable that octopuses appear to behave in a very similar way to ourselves when exposed to MDMA. The octopus’s invertebrate brain is very different to ours, for start it is shaped like a donut. They also lack regions such as the cerebral cortex and basal ganglia that that we associate with complex social behaviours. The key to why they react the same as us is the chemical called Serotonin which acts on the brain. Ecstasy works by binding to a protein called the serotonin transporter which normally reduces levels in the brain. But the drugs presence reverses that flow, creating a massive, mood-altering dump of serotonin.  So despite the differences in brains it appears that serotonin is increased in both. Dölen says “this reiterates the importance of understanding function at the level of molecules” she adds “focusing on brain regions does not give us the whole story.”

Surprising cephalopods

It is becoming increasingly apparent that there is more to octopuses than we previously thought. They have always managed to capture our imagination with abilities such as squirting ink, camouflage and limb regeneration. But despite being more genetically similar to a slug than a human it has become clear that they are incredibly intelligent creatures. They are capable of escaping aquarium enclosures, navigating complex mazes and even unscrewing jars to obtain food. It has even been argued they can feel pain and actively protect injuries on their arms. This new MDMA study now shows that although they are naturally aggressive and lonely creatures they have the capacity to be much more social and interactive, just like us.

There may be much more going on inside their heads than previously realised

Ethical implications

Due to the originality of the study there is no real protocol for doing the experiment in terms of ethics. It is believed the drug will have little chance of permanently damaging the octopuses in any way. But this is the first study of its kind and there is no real way of knowing for sure. The octopuses were anaesthetised using ethanol before being drugged which is a safe procedure. But Dölen did admit that on their first attempt the dosage was too high and the octopus “freaked out and did all these colour changes”. So if we now believe that octopuses are capable of feeling pain and more intelligent than we first realised, is this acceptable? Like all scientific studies effecting animal subjects in a direct and potentially damaging way the ethics can be a complex and divisive issue. As a general rule if they are being monitored for stress, removed if they are showing signs of distress and given safe doses that don’t cause addiction it is considered safe.

To sum up

Before getting too excited about this latest discovery it is important to remember that a very small number of octopuses were used and the results have yet to be repeated. In science it is important to get repeatable results and though significant behavioural changes were observed there could be other factors at play. There are many things that remain unclear like for instance do octopuses experience a ‘comedown’? And are there any long term effects? That is why Dölen and Edsinger have urged more researches to attempt the study. But their results are the first clue that social behaviours might be linked much further back in evolutionary history than previously thought and that molecules may play a more important role, compared to brain structure.


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