I’m being engulfed by my own namesake. Dave’s arms wander, unfurling along my own, and I’m taken aback by the sheer strength of his grip—I can feel the tacky pinch of his suckers on my skin as he embraces me in spiral coils. Before we’d even finished lifting the lid off his tank, Dave had flipped upside down and risen to the surface, reaching for me.

To stare into his underbelly, all suckers and fleshy webs like some nightmarish, gelatinous flower, triggers childhood memories from torchlight readings of Jules Verne. To submit to an octopus’s inexorable bondage requires a certain inner calm, because they’re beautifully equipped for entrapment and murder.

“Don’t let him pull you too close to the centre,” says Victor Anderlini. “That’s where his beak is.” I’m not sure that I have a choice—Dave is like plasma, amorphous yet forceful; he is, after all, 90 per cent muscle. I can sense the strength of his multiplex body, and his will too. Engage with an octopus and you meet a mind of towering acuity among the invertebrates.

A marine research scientist, Anderlini has run a marine education centre and aquarium at Island Bay on Wellington’s south coast for 18 years, along with centre director Judy Hutt. In that time, they’ve hosted hundreds of octopuses. Most are brought in by cray fishers who have found them in their pots. I once worked on a cray boat and still remember the carnage of an octopus attack: the pot would come to the surface with an angry red octopus in one corner and terri­fied lobsters huddled in the opposite one: at least, those left alive. Many times limp corpses littered a pot, their essence turned to mush by the octopus’s neurotoxic, necrotising venom. At anything up to $100 a kilogram for crayfish, it’s an enlightened fisher who spares their executioner.

Octopuses don’t stay long at the aquarium: they live an average of only three years—five at most—so after a year or so, Anderlini and Hutt like to release them back into the adjacent Taputeranga Marine Reserve “so they can have a shot at life out there”.

Interestingly, many of the females the fishers bring in lay eggs a week or two later. Octopuses can decide if, and when, to fertilise their own eggs. In fact, the whole tryst is bizarre—frankly, barbarous. The modified third arm on the right of octopus males is lined with sperm packets, which a suitor will try to place in an opening in the female’s mantle. “She’ll either accept them,” says Hutt, “or reject him, depending on her physical condition.

“If she’s ready to have a family, she’ll allow the male to place them. If she’s not, she’ll wrench them off instead, and store them until the time is right.” A female can keep the sperm alive inside her for weeks until her eggs are ripe. Ordinarily, the male will die a few weeks later. But if he happens to belong to one of a select few particularly violent species, the female will suffocate and devour him in the midst of their lovemaking, even if she’s accepted his spermato­phores. Scientists presume she uses the male’s body as a shot of protein to help form strong, healthy eggs. Once she’s laid, she’ll sweep them with the male’s amputated sperm sac.

Hutt says it’s remarkable that so many females decide the aquarium is the right place to raise a family. “Perhaps this feels like a safe environment—after all, we feed them pretty well.” Maybe, but once they’ve laid their eggs, the mothers-to-be reject all ministrations. “For two and a half months, they don’t eat. We’ve tried to feed octopuses during that time, and they’re not interested.” The female’s obses­sion is now her developing eggs.

“When she’s caring for them,” says Anderlini, “she’s brush­ing them the whole time, and using her siphon to keep blowing clean water over them, so that nothing attaches to them.” In the wild, he says, a female would be spread-eagled across her brood, protecting them from unremitting raids by hungry predators. “She never leaves them. That’s a big deal when you think about it. That’s definitely intensive care.”

In shallow temperate waters, octopus eggs take anything from two to 10 months to mature. But in the cold of the deep, raising progeny becomes an epic of devotion and endurance: scientists from California’s Monterey Bay Aquarium recently announced the hatching of an estimated 160 baby octopuses 1400 metres down in the Monterey Canyon. They’d been monitoring this particular brood­ and its indomitable mother—for four and a half years, during which time they never once saw her leave her nest to eat. So it was that a little octopus—just 200 millimetres across­ set a new record for maternal commitment. And all this for the slimmest of prospects: the chances of survival for octopus hatchlings hover around just one per cent.

From time to time, the octopuses at the Island Bay aquarium will lay their eggs on the acrylic wall of the tank, giving visitors a rare opportu­nity to observe their contents. “We’ve learnt that when the baby octopuses near full development, the eggs start to change colour,” says Anderlini. “They get a bit of redness to them. And the juveniles will invert just before hatching, just like a human baby does before birth.” Very occasionally, he says, they “start hatch­ing like popcorn” in front of hundreds of spellbound visi­tors. “It’s really quite exciting.”

That’s when Anderlini and Hutt release the mother back to the sea, because within weeks, she’ll be dead. For octopuses, replicating is a zero-sum game. Some aquariums have reported that after mating, or laying eggs, their octopuses went doolally, swimming loop-the-loops in their tanks and ignoring fresh prey. They slid into a sort of molluscan dementia, and some even climbed out of their tanks, secreted themselves in some terrestrial cranny and desiccated.

Dave and I are still entwined. His clasp is so strong that I can haul him halfway out of the tank, and Italian research­ers recently found out why: when they scanned octopus suckers with high-resolution x-rays, the images showed tiny, concentric grooves ringing the sides and edges of the suckers. While their outer cups were relatively soft, the bases of the suckers were found to be much tougher, the better to generate negative pressure within the sucker, leaving the micro-grooves to form a tenacious seal on the most irregular of surfaces, like a crayfish shell. The more pressure exerted on the cup, the more inevitable the prey’s fate. So effective is the octopus’s adhesion that engineers want to mimic their adaptation for artificial applications such as soft-bodied robots.

Now Dave is investigating my tee-shirt. If curiosity is a sign of intelligence—and researchers believe it is—he’s a pretty smart cookie. I can at least feel superior in one respect: he might have 130 million brain neurons, but I have 100 billion. I can’t, though, hope to match him for sheer weird­ness: while my neurons are all packed into a single brain, his are shared among nine. That’s right, nine brains: one in his mantle, and one in each arm. (He also has three hearts; one for each set of gills, and one for the rest of him.) Sixty per cent of Dave’s neurons are in his tentacles. He’s liter­ally thinking on his feet.

In order to manage all those limbs, his central brain sends messages to ganglia at the base of each arm, which is controlled by an elaborate nervous system powered by around nine million neurons, arrayed as a nerve cord and lateral fibres opposite his suckers. When researchers cut off an octopus’s arm (don’t worry, they can grow a new one inside six months) they watched it take on a life of its own, crawling about the tank and even trying to pass food to where a mouth used to be.

I stroke Dave’s rubbery skin, and feel him respond. He goes a lighter shade of relaxed. It’s hard to reconcile that I’m having an intelligent, tactile transaction with some­thing related to a pipi.

Hutt and Anderlini once tested the intellect of one of their octopus guests here, handing a new arrival a screwtop jar with a crab inside it. It took him two days to work out how the lid came off, but once he had that knowledge, he got his opening time down to 42 seconds.

(Hutt ran online sweepstakes in which Facebook followers could try to guess the crab’s remaining seconds on Earth.) “But here’s an interesting thing,” says Anderlini, “a week later, he lost interest in the experiment.”

It seems octopuses need almost constant stimulation, new challenges. In the early days, he and Hutt used to close the aquarium to the public when they went on holiday, leaving just a couple of volunteers to feed the residents. “One time we got a call to say that the octopuses had stopped eating,” he recalls. “We asked people at Seattle Aquarium about it, and they asked us if our staff ever played with the octopuses during quiet times, then they showed us a cupboard chock-full of all sorts of bizarre toys. That’s what they used to keep their octopuses stimulated.”

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The devil, it seems, makes work for idle tentacles: in 2000, Hutt and Anderlini mounted a live display, which contained an octopus, in the Wellington Airport terminal. “One night, about two in the morning, we got a call to say that it looked like the tank had a leak. So we raced down there to find the floor a little bit wet on one side. We checked everything, but couldn’t find anything wrong, so we figured maybe the octopus had just spewed a bit of water out over the top.” Just a couple of hours later, the pair had to scramble again to what this time was a much bigger spill. Anxious to stay on good terms with the airport, they cleaned up the mess, but just two nights later, it all happened again, and this time it was biblical: water had soaked through the floor into the baggage-claim area, and it took giant fan heaters and commercial cleaners to put it all straight.

“It turned out that our octopus had figured out how to shove his arms into the tank outlet pipe,” recalls Anderlini, “so that the outflow was blocked while the inflow was still going strong.”

So Anderlini cut five more holes in a perspex divider, “so that he couldn’t possibly block all the outflow holes. I forgot, of course, that he had eight legs.” That very night, the pair got a call from an anxious pilot. “He said: ‘You’d better get down here right now, because he’s trying to block all the holes again’.” This time, they caught the miscreant in the act, with an arm shoved into every drain hole. “We thought he would get us evicted from the airport,” says Hutt, “but they loved him so much that they got everything cleaned up themselves. He was there for another couple of years— we still get people asking where he is.”

Octopuses are superbly adapted for mischief. Overseas, captive individuals irritated by glaring downlights shining into their tanks have learnt to blow them up with a well-aimed shot of water from their siphon. They will also squirt people they take exception to:

“We had David Shearer [then Labour Party leader] standing on top of a ladder, ready to hold hands with an octopus. We were telling him to just relax, when the octopus soaked him head to toe. Three-piece suit, the works… That’s happened a number of times. One got Lloyd Morrison a beauty…”

So just how smart are octopuses? Compared to humans, not especially. Among invertebrates, though, they’re the scholastic elite. Uniquely for molluscs, two regions of their brain are devoted to memory storage. That means they can learn: either by their own experience or by watching other octopuses. When given novel challenges by researchers, they try different strategies, rather than simply repeating what doesn’t work. And they play—a classic mark of intellect.

Aquarium octopuses have learned how to navigate mazes to reach food, and some, switched mid-way between two experiments, have learned to memorise both solutions con­currently. So why is an octopus so smart when its cousin the pipi is so brainless? Because while a pipi takes refuge in the relative sanctuary of deep sand, octopuses have chosen to live in the most dangerous marine habitats going: rocky reefs and open water, without the protection of hard shells. Here, if you’re not armoured or toxic, you’d better be clever. Octopuses, as we all know, are delicious. Sharks know it, too, and so do fur seals and preda­tory fish such as wrasses and blue cod, which, says Anderlini, will simply bite down on a tentacle then spin, turning their teeth into a cir­cular saw, until the limb is severed.

Octopuses weren’t always this vulnerable. Their distant ancestors, the ammonites, lived inside buoyant, chambered shells. (One of their relatives, the nautilus, still does.) But at some point, at least 300 million years ago, octopuses cast theirs off and drifted to the seafloor. Sharks had already been around for 150 million years, and bony fish were evolving into rapacious predators, so going soft-bodied was a risky gambit.

We may never know why they did it, because their new shell-lessness made them very poor fossilisers—300,000 millenniums of octopod evolution have so far given up just eight fossils. But researchers have theorised that perhaps the middle waters were becoming a crowded and perilous place. Surrendering to gravity may have given octopuses a place to hide from evermore powerful, perceptive preda­tors. One bonus was that they could now inhabit far greater depths, at greater pressure, without fear of their shells imploding (chambered nautiluses cannot descend beyond 500 metres without being crushed). The ancient deeper reefs were still largely unexploited, and the decapod crus­taceans (lobsters, shrimps and crabs) were starting to crawl about them.

Perhaps the most plausible selection pressure is that hard shells would have been a nuisance to animals trying to adapt to a new world of nooks and crannies. So malleable is a modern octopus that it can squeeze through any gap big enough to accommodate the only hard part of its body­ the beak and its muscles. Researchers have filmed a 230- gram adult practically flowing through a 25-millimetre hole, and smaller individuals off the coast of Australia routinely use small beer bottles—‘stubbies’ with a neck the width of a 20 cent piece—as dens.

That phenomenal elasticity is just one adaptation in a formidable quiver that makes octopuses the bane of inshore and deep-reef prey. They have excellent vision, delivered by an eye similar to a single-lens reflex camera and our own, although we know it evolved completely separately. In fact, in one important respect, an octopus’s is superior: it has no blind spot, because the nerve cells are arrayed around the outside of the eyeball instead of the centre, as ours are. Just like us, octopuses see through a lens that projects an image onto a retina. But unlike us, many have no cornea, and their eye focuses by internal movement (like your binoculars do), rather than using muscles to alter the lens’s shape, as ours does.

For all its sophistication, an octopus’s eye has no cones, only rods—or the invertebrate version of them. This means it cannot see colours, just shades of light and dark. Octopods can, however, see polarised light, thanks to the way their photoreceptors are organised—at right angles to one another—in the eye. They can also determine the orienta­tion and relative strength of polarised planes of light. Just why, we’re not sure, but it may help them spot prey or threats in the glaring light of shallow reefs, or help them read colour-shifting messages from others of their own species.

The octopus is Anderlini’s favourite animal, “not just because it’s so intelligent, but because it’s so beautiful in lots of different ways. It has its own special grace when it moves, something you don’t see in the lower orders of marine life.”

The more we come to understand about octopuses, the shakier become our traditional notions of intelligence and consciousness. Over millennia, coerced by pressures and perils, they have risen from the ranks of life’s primordial dullards to engage with us in something close to an under­standing. Looking into Dave’s eye, I couldn’t help but wonder what he was thinking. One day, we will probably be able to tell. And I get the distinct sense that octopuses will then amaze and delight us all over again.

Masters of Deception

An octopus can match its skin to the colour and pattern of any surrounding medium more or less instantly. How? Think of octopus skin as a colour television— combining a few basic colours to form many more complex hues and dynamic patterns. There are millions of elastic, pigmented cells—chromatophores—under its skin, which combine three different pigments, each controlled by a neuron. Bands of muscle radiate from each chromatophore like the spokes of a wheel, so an octopus can change hue or opacity at will, simply by contracting or relaxing those muscles to expose or conceal the appropriate colour layers. By turning some cells on and leaving others switched off, it can create patterns over its body that match exactly any background it wishes to hide against.

But the perfect finishing touch comes from two other types of cell, which work in concert with chromatophores to fine-tune this light show to match any background it rests upon. Iridophores and leucophores lie beneath the chromatophores, but unlike them, they are entirely passive, unmoved by nerve or muscle. Instead, iridophores contain stacks of thin plates that reflect a range of wavelengths— greens, blues, silvers and golds. They work much as a soap bubble does, reflecting different colours according to the thickness of the plates.

These reflections complement the palette created in the chromatophores, so that an octopus can match against the entire visible spectrum. Interestingly, iridophores also reflect polarised light at the same angle they receive them. Because octopuses can also see polarised light, it’s thought that they may use iridophores to flash messages to others. These would be truly encrypted missives, because fish, sharks, marine mammals and even humans can’t detect the difference between light of one polarity or another.

Finally, the bottom layer of the octopus’s skin is lined with leucophores. Translucent and colourless, these contain clusters of colourless granules around a thousandth of a millimetre long. These spherical proteins reflect and scatter whatever colour of light falls upon them: visible, infrared or ultraviolet. So in the daylight of the aquarium, Dave’s leucophores will reflect white. If he were at depth, however, they would reflect the blue-greens of his surroundings.

They also match the intensity of that light (right down to 0.0003 lux—or weak starlight), from any angle of view, which is important when an octopus is hiding both from sharks hunting above and moray eels at seabed level. These protein reflectors, virtually unknown in any other animal orders, create the basic ambient canvas across which the chromatophores and iridophores above can then ‘paint’ their contrasting patterns.

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