A wall of bright signs warn me before I step closer: “Dangerous Animals – Do Not Touch”. As I carefully inch closer to the aquarium tank, I notice that sitting inside in a shell is an inconspicuous animal no bigger than a golf ball. A series of striking, metallic blue markings appear magically over its body, and it stretches its rubber-like arms to close the two shell pieces together, vanishing from view.
“Meet the most intelligent invertebrate on the planet,” Dr Wen-Sung Chung announces as he proudly introduces his “blueys” – blue-lined octopuses – that form part of his research. He’s studying the nervous system and behaviour of cephalopods, the group of molluscs that includes octopuses and squids. Despite their appearance, these tiny little blueys can be deadly, especially if you’re a crustacean. They carry tetrodotoxin (TTX), a neurotoxin for paralysing prey that’s 1000 times more potent than cyanide. But these creatures are far more astounding than the fearsome reputation that proceeds them. They have truly remarkable intelligence, evident in behaviours such as the tool use I just witnessed with a shell. It’s a surprising sign of higher cognition usually only seen in vertebrates such as birds and mammals.
Not so ‘dumb’
Aristotle, one of the greatest minds in history, claimed octopuses were “dumb”. But they have some serious sea smarts that seem to defy logic. They’re unlike anything in the animal kingdom, having survived ice ages and asteroids, outliving dinosaurs and spreading their arms to survive in every part of our oceans. In captivity, tales abound of these marine masterminds navigating complex mazes, unscrewing lids and outsmarting aquarists by escaping their tanks and raiding neighbouring ones for food. In the wild they team up with fish to hunt, rewire their own brains when it gets too cold and can even change colour, despite being colour-blind.
The mimic octopus, which lives in sandy habitats devoid of any shelter, even impersonates some of the ocean’s deadliest residents. Its repertoire includes lionfish and stingrays and it can choose which species to mimic based on the threat it faces. If harassed by a damselfish, for example, it transforms into a sea snake.
Wen-Sung’s fascination with these otherworldly animals began at Taiwan’s National Museum of Natural Science with a preserved giant squid. Their “weirdness” captivated him, inspiring a life-long career that has included some significant breakthroughs such as the discovery of cephalopod statolith structures, which allow octopuses and squid to detect sound pressures and hear.
An opportunity to take up a residency at The University of Queensland saw his journey come full circle when he became part of an international team filming the enigmatic giant squid at 750m using the deep-sea camera platform Medusa.
Wen-Sung is now an expert in cephalopod visual ecology and neurobiology. For the past decade, he’s been on a mission to unravel the secrets of octopus adaptability and cognitive abilities. It’s groundbreaking research that not only offers a window into the surprisingly sophisticated lives of cephalopods but is also inspiring human innovation.
Hidden beauties
I join Wen-Sung on one of his research expeditions at Minjerribah (North Stradbroke Island), home to The University of Queensland’s Moreton Bay Research Station. The island is the perfect location for his work. Its diverse habitats of sandy plains, seagrass meadows and vibrant reefs are home to more than 10 octopus species, including the blue-lined, reef, hammer, red-spot night, scribbled night, plain-spot, veined and southern star-eyed octopus. In fact, Australia could be considered the octopus capital of the world, boasting more than 70 of the 300 species documented globally.
Armed with booties, gloves, buckets and nets, we make our way across the sandy flats, navigating around armies of soldier crabs, and shuffle out into ankle-deep water. Finding octopuses is like playing a game of hide and seek with the world champions of the game. They don’t just blend in: they become part of their surroundings, breaking up the outline of their bodies in magical ways that is nothing short of marine sorcery.
Luckily, Wen-Sung knows the telltale signs. “You really need to understand the biology of the animals to find them,” he explains. It’s not long until he calls me over with excitement, pointing to what looks like nothing more than a tuft of seaweed. Amused by my puzzled face, he traces the outline of eight arms. It’s a cryptically camouflaged algae octopus. Not only has it taken on the colour of the surrounding seaweed, it’s changed the texture of its skin to match. It’s the ultimate 3D camouflage – unparalleled in the animal kingdom.
At nightfall, we head back out with our underwater torches to search for nocturnal octopus species, which would now be emerging from their daytime slumber to feast. Fish are darting around us as we wade through the shallows and our torch beam lights up a resting wobbegong shark.
It draws our attention to something bright red nearby that quickly vanishes into the sand – the red-spot night octopus. It’s an impressively large species nearly a metre long. Wen-Sung inspects the deep tunnel the octopus disappeared into. We need to be on the lookout as it may pop up elsewhere, because these crafty cephalopods often create multiple escape tunnels – another sign of intelligence.
What drives this level of brainpower in an invertebrate? The simple answer is survival. Millions of years ago, octopuses followed a different line of evolution to their clam and snail relatives by shedding the hard shell, trading security for freedom and flexibility. It made them into a tasty piece of unprotected protein in an environment where just about everything is looking for a meal.
To survive in the diverse habitats they share with a range of predators, octopuses have developed ingenious survival strategies. They’re also born into a world without parental guidance and have short lifespans, which means they must learn fast and constantly adapt. All this is done while processing multiple visual inputs, controlling eight agile arms with hundreds of information-gathering suckers, and coordinating millions of colour-changing skin cells. It’s enough to make your head spin – and certainly requires serious brainpower.
To investigate how all of these behaviours can be coordinated, Wen-Sung has been mapping the brains of various species of octopus and studying the structure and organisation of their nervous system, from hatchling all the way through adulthood.
To achieve this, he’s needed to modify existing MRI techniques by deviating from the standard protocol settings usually reserved for vertebrate brains such as those of humans and other mammals, which are more rigid with different neural pathways compared to the soft brain tissues of octopuses.
After hundreds of hours and much trial and error, he was able to successfully scan the brains of various octopus species in high resolution and, in a world-first, capture and map their complicated neurology in 3D. The insights this provides have been ground-breaking and changed what we thought we knew about the brains of these marine masterminds.
Updating knowledge
Most of our knowledge of the octopus brain has been based on research from the 1950s and the exploration of cognitive ability restricted to a single species, the common octopus, an accessible and abundant species that’s easy to keep in captivity. With more than 300 octopus species worldwide, this research certainly hasn’t painted a comprehensive picture of the intelligence or brains of the group as a whole.
This is why Wen-Sung’s work and the incredible breakthroughs he’s made are so important. One of his discoveries is that the octopus brain continues to grow throughout the lives of these animals. It can grow 100 to 5000 times in volume from hatching to adulthood, and the rate at which this growth proceeds is ridiculously fast, when you consider the average lifespan of an octopus is only two years. Compare that to human brains, which reach maximum size at 14 or 15 years of age, then start to gradually shrink.
As with the human brain, however, and unique among invertebrates (excluding their squid relatives), octopuses exhibit brain-folding, which is a sign of intelligence. The more folding there is, the more surface area is created, allowing more neurological inputs and greater processing power. Octopuses have the largest brain size-to-body ratio of any animals, which makes sense, given all the multi-tasking they do. This also tells us that the octopus is investing a significant amount of energy into its nautical noggin.
One of Wen-Sung’s biggest discoveries has been that not all octopus brains are the same. The design, level of folding and size of the visual processing centre of an octopus brain, are influenced by habitat and lifestyle and vary between species. For example, the reef octopus, which is only active during the day, has a more complex brain and larger optic lobes compared to the nocturnal blue-lined octopus.
Masters of deception
Coral reefs are busy and challenging environments to live in. The reef octopus has to process a large amount of information and camouflage is important to its survival. The species has the highest number of colour-changing cells of any species and has been recorded changing its appearance more than 300 times in a day. It’s also the species that has been recorded cooperatively hunting with gropers to flush fish out of coral bommies.
To support his work and explore the ability for the brain to change, adapt and learn – known as neural plasticity – Wen-Sung has also conducted a range of experiments to test octopus intelligence. This involved food incentives and problem-solving challenges such as identifying different shapes. “The most compelling evidence of intelligence is just how quickly they learn,” he says. He has even taught one octopus to count. It’s evidence that octopuses have brain structures, such as memory and learning centres, that are functionally similar to those in mammals, positioning octopuses as a valuable model group for neurophysiological studies in other higher-order species.
Scientists have even recently discovered octopuses can edit their own physiology to adapt to temperature change by editing their RNA (ribonucleic acid), which is responsible for reading and decoding information in the DNA, to build proteins to carry out cellular function. Unlike DNA-driven evolution, which takes generations, octopuses can make these changes in days, which is truly extraordinary.
The significance of Wen-Sung’s work and the benefit of it, even to us humans, can’t be underestimated. Creating a brain template that maps and understands octopus neurology will open the gate to understanding evolution of not only cephalopods but of land-based animals.
His work is also opening up a wealth of opportunities for human innovation. Octopuses are fast becoming marine muses for us mere mortals, sparking innovation and inspiring us in ways we never thought possible. The hormones that spur rapid brain growth in an octopus could prove useful for people who need growth stimulants.
Understanding the flexibility and remarkable autonomy of octopus arms that comes through a simple neural network (see below), could have applications for the engineering of soft robotics able to be used in natural disasters for accessing collapsed buildings or navigating terrain inaccessible to humans. Researchers are also exploring how octopuses can deliberately detach and regrow limbs – a process that could one day inform treatments for neural injuries or regenerative medicine.
For all the danger signs on the tanks where Wen-Sung keeps his blueys, there’s a deeper irony. The same venom that ensures humans keep their distance may one day help save lives. Research on the southern sand octopus has uncovered a compound in its venom that shows real promise in slowing the growth of cancerous melanoma cells.
Wen-Sung’s work underscores how truly extraordinary octopus brains are and he’s only just begun to unravel their mysteries. “Octopuses are the epitome of discovery science,” he says. “The more I find and watch, the more I realise how much is still to learn about these weirdly wonderful animals.” It’s impossible not to be swept along by his energy and enthusiasm.
We humans like to think we’re the clever ones, but these eight-armed teachers have some valuable lessons to share, proving that brains come in all shapes and are sometimes even shaped like a donut. Who’s dumb now, Aristotle?
Read more
The latest book by Victorian-based marine scientist Sheree Marris, Octopuses: Underwater Wonders, is a stunning journey into the lives of these otherworldly creatures.
