Why Octopuses Are Extraordinary Animals

Why are octopuses one of the ocean's most extraordinary animals? Because so much about them is real and still surprising: camouflage in seconds, three hearts, blue blood and documented learning. They have become one of the best-known symbols of ocean wonder, and for good reason. They move through the sea with a quiet kind of intelligence that feels almost unreal. They change colour in seconds, slip through tiny spaces and solve problems in ways that keep researchers curious. For ethical ocean travel, they offer something deeper too. The more carefully we look at octopuses, the more clearly we see that the ocean is full of specialised, sensitive life that deserves thoughtful and respectful encounters, not exaggerated ones.

That last point matters more than it seems. Octopuses already sound close to fiction, which makes them an easy subject for online content to overstate. What follows sticks to what is documented: their biology, their behaviour, and what real research says about their intelligence.

Octopuses are built for adaptation

One of the most remarkable things about an octopus is how fast it can change how it looks. Its skin is packed with chromatophores, small sacs full of pigment that open and close as tiny muscles pull on them, changing colour and pattern in moments. Together with reflective cells called iridophores and leucophores, this lets an octopus melt into a reef, break up its own outline, or signal to another octopus, all with variations of the same basic system. Because muscles controlled by the nervous system work these sacs, the change is something the animal does, not a passive reaction. It is actively responding to what is around it, not matching a background at random.

This matters most on shallow reefs and rocky places, where camouflage is not only beautiful to see but close to essential. It helps an octopus avoid predators and approach prey unseen. It does not make the animal "invisible" in a general sense. It responds to the texture, brightness and complexity of what is really around it, which is part of why the same octopus can look completely different from one rock to the next.

Their flexibility goes beyond colour. Octopuses have no inner skeleton. The only hard part of the body is the beak, so they can squeeze through gaps barely wider than that. This soft body makes them excellent escape artists, able to vanish into cracks, dens and rocky gaps that almost nothing else on the reef can reach.

Three hearts, blue blood, and a very different body

Some octopus facts sound invented, but they hold up. Octopuses have three hearts. Two branchial hearts push blood through the gills, and a third, the systemic heart, pumps oxygen-rich blood to the rest of the body. That systemic heart is known to stop working while an octopus swims, which helps explain why octopuses crawl whenever they can. For them, swimming costs much more energy than it does for a fish.

They also have blue blood, carried by an oxygen-transport protein called hemocyanin. Human haemoglobin is iron-based and looks red; hemocyanin is copper-based. Overall it binds oxygen less well than haemoglobin, but it works fairly well in cold, low-oxygen water, which is a real advantage in many places octopuses live. Smithsonian magazine lists the three hearts and the blue, copper-based blood among the strangest true facts about octopuses. One honest caveat: hemocyanin carries less oxygen than our haemoglobin, and sources describe its cold-water advantage in different ways, so take the simple version with a little care.

These details are often shared as "fun facts", and that is why we remember them. But they are also a reminder that sea animals are not just ocean versions of land animals. Octopuses evolved along a very different path, and that difference is part of what makes them fascinating. Their biology invites some humility: the ocean holds forms of life that do not think, move or survive the way we do.

Are octopuses really intelligent?

The short answer is yes, although "intelligence" in animals is always more nuanced than a headline. Octopuses have interested researchers for decades because they show learning, memory and flexible problem-solving that is unusual for an invertebrate. A widely cited 2020 review of cephalopod cognition in Biological Reviews credits octopuses with truly sophisticated perception, learning and memory. It also warns that some of the more dramatic online claims about octopus "genius" rest on anecdotes, not controlled studies, and should be read carefully instead of repeated as fact.

The evidence that does hold up is fascinating. In controlled experiments, octopuses learned and remembered the location of a den for at least a week, and could learn a new location once the old one was moved. Researchers use that kind of task to test real learning rather than instinct. Separate maze studies found octopuses capable of conditional discrimination: choosing the right escape route depending on which of two maze layouts they had been placed in, a task once linked mostly with vertebrates.

The best-known case of tool use in an octopus involves the veined octopus (Amphioctopus marginatus). In a 2009 study in Current Biology, Julian Finn, Tom Tregenza and Mark Norman described veined octopuses digging up discarded coconut shell halves, carrying them clumsily across the seafloor, and later putting them together as a shelter. Using the definition of a tool as "an object carried or maintained for future use", they called it the first documented tool use in an invertebrate. Not every scientist agreed: some argued it is closer to a hermit crab using a shell. That debate is itself a nice example of how carefully the word "intelligence" needs to be used.

None of this means octopuses think like humans, and it is worth staying sceptical of viral videos and stories that suggest they do. Octopus content travels fast online, and claims get simplified or stretched along the way. But the real, peer-reviewed research is already remarkable on its own. When we watch an octopus investigate an object, change tactics or explore a new corner of its world, we are looking at an animal with a sophisticated way of relating to its surroundings. For anyone who cares about responsible wildlife encounters, that matters: intelligence like this asks for more patience and more restraint, not less.

The ethical layer: why this matters in ocean travel

For Ocean Calling Retreats, marine life is not scenery. It is part of a living world that asks for awareness, sensitivity and continuous learning. Octopuses show well why responsible ocean travel is less about rigid rules and more about understanding.

With octopuses, that can mean something simple: not touching, chasing, cornering or overstimulating an animal just because it looks calm or curious. An adaptable animal is not automatically an untroubled one. Camouflage, pulling back into a den or sudden stillness can all be signs of mild stress rather than curiosity. On our trips, sightings tend to happen with the guides in our network of local experts, who know which cracks are worth a careful look and how to hold a light steady instead of sweeping it straight into a den. Touching is never part of it; we explain why in why touching marine animals harms them.

For your part, the simplest kit helps most. A well-fitting low-volume mask lets you hover still and look closely without fiddling, and if you want pictures, a small underwater camera used without flash, from a respectful distance, is plenty. Our note on no-flash wildlife photography explains the thinking.

There is a wider lesson too. Octopuses challenge the idea that charisma in the sea belongs only to whales, dolphins or sharks. Smaller, quieter animals can be just as extraordinary, and paying attention to them slows travel down in a good way, towards something more observant, lower-impact and closer to sustainable ocean travel.

Wonder without exaggeration

One difficulty in writing about octopuses is that they already sound made up. Because of that, articles and social posts easily slide into overstatement: dramatic claims about intelligence, viral stories repeated as fact, comparisons that do not hold up. But the real science does not need the help. Fast camouflage controlled by the nervous system, a very unusual body, and documented spatial learning and tool use are not decorations. They are established, checkable parts of what makes octopuses one of the ocean's most extraordinary animals.

For an ethical ocean brand, that difference matters. Accuracy builds trust, and it makes for a different kind of reading: considered, not sensational. Wonder does not need to be loud. Often it is strongest when it is accurate.

A more respectful way to look at marine life

Maybe that is why octopuses stay with people long after an encounter. They feel mysterious but not distant, intelligent but not familiar, a reminder that the ocean is full of lives shaped by needs and abilities very different from ours.

So octopuses offer more than fascinating facts. They invite a change of perspective: slow down, look more carefully, and accept that some of the most extraordinary parts of the ocean are also the easiest to miss. If you explore marine life through travel, choosing experiences that value learning, small groups and careful wildlife practice tends to make that relationship deeper. That, more than control or performance, is the heart of ethical ocean travel: attention and respect.

If this made you curious to look for octopuses yourself, you can explore our upcoming retreats.

Questions people ask

What is so special about octopuses?

They change colour and pattern in moments for camouflage, squeeze through narrow gaps because the beak is their only hard part, and have three hearts and blue, copper-based blood. Peer-reviewed research has also documented learning and problem-solving that is unusual for an invertebrate.

Are octopuses really intelligent?

Yes, with care in how we say it. Controlled studies show spatial memory lasting at least a week and maze-based discrimination tasks. Reviews also warn that many dramatic online claims are anecdotes, not tested science.

Why do octopuses have blue blood?

Their blood uses hemocyanin, a copper-based protein, to carry oxygen, instead of the iron-based haemoglobin in our red blood cells.

Why do octopuses prefer crawling to swimming?

Their systemic heart, the one that supplies the body, slows or stops while they swim, so swimming is tiring for them. Crawling is the cheaper option.

Do octopuses really use tools?

The veined octopus carries coconut shell halves and later uses them as a shelter. The 2009 Current Biology study called this the first documented tool use in an invertebrate, although some scientists dispute whether it counts as tool use.

Wildlife encounters are never guaranteed and never forced. Ocean Calling works only with vetted, ethical local operators, and every animal is free to approach, or not, entirely on its own terms.

Sources & further reading

1. Finn, J.K., Tregenza, T. and Norman, M.D., 2009. Defensive tool use in a coconut-carrying octopus. Current Biology.
2. Schnell, A.K. et al., 2020. How intelligent is a cephalopod? Lessons from comparative cognition. Biological Reviews.
3. Boal, J.G. et al., 2000. Experimental evidence for spatial learning in octopuses. Journal of Comparative Psychology.
4. Hvorecny, L.M. et al., 2007. Octopuses (Octopus bimaculoides) and cuttlefishes (Sepia pharaonis, S. officinalis) can conditionally discriminate. Animal Cognition.
5. Smithsonian Magazine. Ten wild facts about octopuses: they have three hearts, big brains and blue blood.
6. National Geographic, 2009. "Bizarre" octopuses carry coconuts as instant shelters.
7. Live Science, 2009. Clever octopus builds a mobile home.

Further reading on Ocean Calling: More from the journal · Wildlife & the law · See the retreats · Ocean Atlas