The Dream of the Octopus

Why cephalopods are philosophical superstars

Few animals capture our imagination like the octopus does. Suckered arms (which are technically not tentacles), camouflage, and remarkable cunning, what’s not to like? It's both the brain and the brawn of these eight-limbed ocean dwellers that inspire philosophical inquiry - even deserving an entire philosophy book dedicated to them. Brain and brawn are (of course) inseparable, but this distinction will allow us to start from specific observations to tie together afterward.

Let's start with the brawn.

Cephalopods (squid, octopuses, cuttlefish, and nautiloids) are invertebrates. They don't have a skeleton, but instead control their body shape via a hydrostatic skeleton, a set of muscles that controls the fluid distribution inside the body. This control of body shape control is extensive – an octopus the size of a basketball has no issues compressing itself into a small empty peanut butter jar – as well as fine-grained, turning from baby-smooth skin to sandpaper to a bed of nails in the blink of an eye thanks to muscular skin cells called papillae.

Beyond body shape, their body art is also something to behold. Octopuses and several other cephalopods are well-known for their rapid and complex color changes. Their pigment-containing skin cells enable such rapid and detailed control of their skin color and pattern that even chameleons watch with amazement.

Moving on the brain, octopuses and cuttlefish are well-known as the invertebrate Einsteins. Already in the 19th century, naturalist Henry Lee wrote about an octopus who repeatedly left his aquarium to show up in another tank:

The marauding rascal had occasionally issued from the water in his tank, and clambered up the rocks, and over the wall into the next one; there he had helped himself to a young lump-fish, and, having devoured it, returned demurely to his own quarters by the same route, with well-filled stomach and contented mind.

Octopuses are also good learners and tool users – mostly in the form of using coconut shells as carry-along shelter. Some of them even co-opt the tentacles of a Portuguese man o’ war as both a means of protection and assistance for predation.

Octopuses, though, have a differently organized nervous system compared to other species we consider highly intelligent (primates, whales, corvids…). The octopus brain is more distributed, with roughly two-thirds of its neurons in the arms (which can act independently of brain input). Also, unlike us and many other animals, octopuses don’t have a somatotopic map, which maps certain areas of their body onto specific parts of the brain. Instead, the stimulation and control of different body parts are all spread across large regions of the octopus nervous system.

Cephalopod philosophy

Their apparent intelligence, coupled with the large evolutionary distance between them and other animals we tend to consider as ‘intelligent’, has made cephalopod minds one of the truly other other minds in the philosopher's real-life toolbox.

Of course, the term 'intelligent' can mean many things. Let's refine it here to 'possessing a relatively large brain and displaying complex and adaptable behavioral complexity that includes responsiveness to environmental changes and the ability to acquire and use new information'. I'm sure not everyone agrees with that proposal, but if we stick to it for now, cephalopods certainly seem to tick the box.

If we welcome the cephalopods into the group of highly intelligent animals, though, we run into some questions about the evolution of intelligence. After all, as a group, these invertebrates lack several lifestyle traits that – according to some theories – are tightly bound to the development of complex intelligence. A long life, an extended period of parental support, intricate social networks... To the best of our knowledge, octopuses and their cousins don't live lives that include these things. They're short-lived (even the giant squid is hypothesized to tap out after five years or so — nautiloids are the exception with a lifespan of potentially twenty years), will not win any parenting awards, and, while recent research gives them more social credit than they once had, are not all that gregarious.

In other words, they grow smart and die young.

This suggests that either we've got intelligence all wrong or – more likely – that different evolutionary paths can lead to similar outcomes. Some of the proposed selective pressures behind octopus intelligence include predator avoidance following the evolutionary loss of their shell and prey acquisition. Octopuses also tend to engage in extractive feeding in which they have to pry open shells, for example. That requires dexterity and spatial reasoning. Add to that a body that has evolved to contain a multi-sensory communication mechanism, and perhaps you end up with an alternative recipe for intelligence.

Intelligence is not mind, though. Or rather, mind is not (just?) intelligence. Again, vague term alert, so let's continue with self-awareness and subjective experience.

As far as I know, cephalopods have not yet passed the (in)famous mirror test. However, since we're among the curious here, how about a thought experiment?

Let's assume an octopus is self-aware. It knows the extent of its body, it knows it can causally interact with the world, and it knows that it is 'separate' from its environment. What would that be like? Historically, the question has always been "what it's like to be a bat?", but the octopus might be a good replacement. Thomas Nagel suggested a bat because it would force human philosophers to admit that they couldn't imagine what it would subjectively be like to be gifted with echolocation. (Unless, perhaps, blind philosophers? Human echolocation has been documented.).

Octopuses present another challenge in the self-awareness arena. Whereas bats – like humans – still have a strongly centralized locus of control in their skulls, cephalopods' cerebral organization is more dispersed throughout their bodies. The eight arms have, almost literally, a mind of their own. Most of the time, the arms go their way unbothered by the brain in the head. Only when needed does the head brain take over to guide the arms. Of course, you could argue that our two arms also do things without our conscious control. Imagine dropping a glass of water. You probably instinctively reach for it without having to think about it first. However, if we grant that, we'd have to admit that the octopus' eight-armed subconscious appears far more developed than ours.

What is it like to be an octopus? We don't know. (Although science fiction writer Adrian Tchaikovsky does an admirable job in trying in his book Children of Ruin.) But thinking about it makes us ask questions about intelligence, mind, consciousness, qualia… Cephalopods seem quite adept at invading the philosophers' realm.

Do cephalopods dream of sea sheep?

The next realm we'll explore is that of sleep. Only recently has it been confirmed that octopuses do indeed show a sleep cycle with different states. Quiet sleep – pale skin, unmoving eyes – alternates with active sleep – a firework display of color and texture changes in the skin, accompanied by rapid eye movements.

Sounds a lot like REM sleep, which is the sleep state in which we ourselves do (most) of our dreaming. Is the sleeping, color-changing octopus dreaming or are we anthropomorphizing? Are its chromatophores simply going through a physiological ‘checkup’ process, memory consolidation of its busy day, or is the small Kraken subjectively experiencing an imaginary voyage?

Even if they dream, their different way of experiencing the world implies that their dreams are very much unlike ours. Perhaps they dream in textures, tastes, and/or abstract shapes rather than in images. Do their arms dream different dreams?

Finally, the previous questions, in some shape or other, were about what it’s like to be an octopus. An equally (or more?) important question is 'what’s good for an octopus?' Among animals, invertebrates tend to draw the short stick when it comes to welfare considerations. After all, they're more different and often considered cognitively 'simpler', which somehow translates into 'less likely to suffer' for most of us. The octopus and its cephalopod cousins challenge that assumption.

Improving octopus welfare, however, is not an easy task. Their sensory experience might be vastly different from ours, which means that what they might experience as pleasurable or noxious might not be apparent for us. Nevertheless, their likely complex inner experience and a capacity to feel — and experience? — pain warrants thorough consideration of their welfare, and, certainly, a strong commitment to improving it. Ther is progress, though. A recent amendment to the Animal Welfare (Sentience) bill in the UK recognizes octopuses, crabs, and lobsters as sentient creatures that deserve greater welfare protection than they previously received.

Dream on, little octopus.

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