Shape shifters in "smart-skin"

    

I was still digesting a tasty portion of fried squid when I looked down at the cuttlefish in the sea. It was a large bluish blob skirted by a fin that it gently waved to hold its position in the water below the Potoi ferry pier. It was doing an aquatic version of a kestral's hover. The silver rims of its large eyes glinted in the sun, and it held its tentacles bundled together in front of its face. I am sure it was looking at me. When it did move backwards, forwards, sideways, up or down, it was a smooth glide in any plain, like you would expect from a well designed robotic submergible. 

    All life is a mystery, but some forms appear more mysterious than others. Small dogs and sparrows for example, are not mysterious, but the cephalopods -- cuttlefish, squid and octopus -- are inherently weird. 

     Unless you are a diver, it is not easy see a cuttlefish in its natural environment in local waters, but we always have the opportunity to make close contact at restaurant aquariums. 

    You'll see them displayed in prime viewing spots at the front of seafood eateries, along with crabs, lobsters and a variety of tropical fish. They look at you as they try to manoeuvre out of the glass tank, tentacles waggling like a bunch of tethered snakes. Some have given up, as if they've worked out our intent. Backed into the corner, they stoically live out their final nightmare. They look angry.

    If you look closely you can see cloud bands of colour rippling over their body, "smart skin,"  leading cephalopod researcher Roger Hanlon calls it. Sometimes you see pulsating zebra stripes, other times pixilating dot matrixes, always a mesmerising natural wonder.

    I saw similar dots on baby squid, yanked out of the water on barbed hooks. Tiny fluid spots darted over glistening skin. The design effect was ultramodern, like a sheath Apple would invent for a new elongated device. Squid are cousins of cuttlefish. Not lumpy, more tubular, they look speedier. They are easier to see on the sea surface if you go out at night and shine a powerful light. We fished without bait, relying only on light to draw them in. The hooks are lowered on a line and randomly jerked to catch passing prey. We were told this works well in the right season, when a single expedition to Tseng Kwan O bay could yield dozens of tentacled ink-squirters pulled from the water one after another. Unfortunately we were late in the season and only caught two 10cm infants, and a string of woeful pufferfish who blew up like car crash airbags.  

    Just one fully grown squid, about 30 cm long, came within the arc of our lights. It showed red-ish through the murky water, a large eye turned upward towards us. We caste our hooks in its direction but it avoided all our efforts, it was probably an experienced veteran of the squid fish parties. 

    Cuttlefish, squid and octopus are closely related animals that all appear in Hong Kong waters. Their ancestral form would have looked something like a modern day nautilus, a strange shelled mollusk with dozens of tentacles. Ditching the outer shell may have spurred something along the lines of a cephalopod revolution. They gained versatility, and exposed an amazing skin surface that has become a sophisticated cloak for camouflage, illusion and communication. 

    Cuttlefish retained a hard shell, but it became a segmented internal scaffold that is uses to control bouyancy. They can adjust the amount of gas in the pores of this inner shell to control depth.

    Except for this unique internal structure, the cuttlefish shares with squid and octopus the wonderfully pliable body that gives flexibility and incredible shape-shifting powers. These animals can be a blob one second, and in the next a slithering sheet disappearing into a crack in a sea cliff.

    They all have eight arms, but the cuttle and the squid have an additional two tentacles, longer than the arms. These are their weapons, equipped with suckers and hooks that grab at passing prey. 

    The squid we caught on the fishing trip were left carelessly on a styrofoam plate. When I came to release them their attacking tentacles were stuck fast to the surface. It was a struggle to prise them off without snapping their spindly tendons. 

NZ govt

     Cephalopods all also have a hidden parrot like beak, a surprisingly effective device for slicing open the guts or arteries of passing prey, or cutting the carapace of captured crabs, like a tin opener. For years whalers knew about giant squid that never surfaced, from the massive chitin beaks they found undigested in sperm whale stomachs. Only in recent years have deep sea submergibles captured footage of colossal squid violently attacking invasive probes, confirming old maritime lore of deep sea monsters.

    It isn’t much of an exaggeration to describe these as monsters either. The bulky colossal squid and the 13m long giant squid are the world’s largest invertebrates, they have the biggest eyes in the animal kingdom. The deadly tentacles of the colossal are lined with razor rimmed suckers and a double row of screw-like rotating spikes. Inside its lethal beak there are teeth on its cheeks and a serrated conveyor belt that shreds flesh as it shovels food down the beast’s throat.

    It is not just the giants that are aggressive, all cephalopods, from the tiny and appealing bobtail squid to the ghostly blanket octopus, are active hunters. They attack like a torpedo, powered by a jet propulsion system that can even eject flying squid out of the water on an assisted glide.

    Their tentacles have an eerie life of their own that induces terror. They are messy and nightmare-ish. Ruthlessly efficient at scooping up prey and entangling them long enough to suck the flesh out of the struggling victim. Half of octopus brain cells are in their arms.

    Some cephalopods are cannibals. They may work together to hunt in packs, but if one is snagged on a fisherman’s jig, there is a good chance passing brethren will take an opportunistic bite. One study found that a quarter of jumbo flying squid had their own kind in their stomachs. Other than family, they’ll go for fish, shrimp and other mollusks. In return they are preyed on by larger fish like marlin and swordfish, marine mammals such as dolphins, seals and whales, and an ingenious primate that worked out how to harvest food from the oceans -- people.

    Other than these generally intriguing qualities, one characteristic avidly studied by biologists is the magical ability of cephalopods to change colour, recognised by experts as the best in the animal kingdom. Cuttlefish and octopus in particular have a superb range of skin changes that show them to be masters of disguise, surprise and communication. A cuttlefish will swim before a new background and, as if announced by a magician’s “abracadabra,” instantly disappear into an almost perfect blend of pigments. An octopus hiding on sea rock will submerge directly into the exact shade of peppered grey, with another of the same species flattened and barely visible on the sandy sea floor.

    In one well-circulated piece of footage, an underwater camera closes in on a clump of sea-weed. No matter how much you strain to see the octopus, nothing but vegetation is visible, until suddenly an octopus blanches to a pale grey like a ghostly apparition. 

    "Ceph skin is pretty amazing and we are studying it in detail," Roger Hanlon, the man who filmed the sequence, told me.

    “They take available light and manipultate it in the skin to produce an impressive array of colours, contrasts and patterns,” he said.

    Colour is only a part of the equation, texture makes it a 3D experience. Skin as smooth as a balloon one minute will break into into high dimples and knobbly protrusions on an octopus hiding over a surface of uneven stones. Another will fold layers of skin into lacy edges and ribbons, green tinted in a bed of sea-weed, tentacles waving flat in the wash of the current. 

    More than skin changes, the octopus arranges itself in ingenious body positions to maximise its disguise. New Scientist magazine published a photograph of an octopus mimicking a diamond bodied sting ray. The octopus lay on the sea floor, its legs arranged in a flattened rhombus, one leg unfurled as a tapering tail. 

    Indonesian mimic octopuses have been seen disguised as a bunch of sea snakes in the high-risk strategy of becoming strikingly prominent rather than invisible. They also turn themselves into the difficult to eat flatfish, and the poisonous lion fish. Evolutionists are puzzled as to why the species used its inherited invisibility cloak to turn into a showy mimic. 

New Scientist

    But then there could be a clue in the second line of defense that some octopuses employ. If hiding hasn’t completely thrown off a persistent invader, a sudden flash of colour and splayed tentacles could freak it out and send it packing. And if that doesn’t work, it can always squirt a puff of black ink and disappear in the confusion. This all looks like evolutionary evidence that the octopus is by nature a prankster.

    Scientists like Hanlon have tested beyond natural materials to see how far these masters of disguise can take their abilities. Cuttlefish have tackled checker boards and stripy backdrops, holding their legs parallel to bars of various angles in an effort to match the background. 

    And if blending in doesn’t look feasible another options is to simply avoid looking like a squid. "I think the illusions are produced at a wider scale," Hanlon explained. This is achieved by using disruptive patterns to disguise the giveaway outline of the body. "The overall pattern is for camouflage meant to deceive predator's visual systems," he said. It is all about confusing the enemy. 

    The cephalopod achieves this array of colour display with a sophisticated triple layered skin. A white leucophore layer provides the base canvas. On top of that there is a unique light reflecting surface called the iridophore. Colour pigment is found in the top chromatophore layer, surprisingly limited to just red, yellow, brown and black. From this small palette the cephalopod mixes a full spectrum, the luminescent greens and blues being a trick created by reflected light.

    

While it is most likely that defence needs for invisibility were the main evolutionary driver for the sophisticated skin structure of cephalopods, a by-product appears to be communication. 

    Squid, cuttlefish and octopus all signal to each other through skin patterns and colour changes. There is even some evidence that large pack hunters such as Humbolt’s squid signal to each other to round up shoals of fish, flashing in unison as they close in on prey. Less communally, individual male cuttlefish broadcast to love-rivals with jagged zebra patterns, warning them to keep away from a marked female, while a different pattern shown to the female signifies the desire to mate. Sometimes a cuttlefish will flash one signal on half its body, facing a female, and another on the other half, warning males.  Other males have been known to disguise themselves as females to get close to a guarded female. The behaviour suggests intelligence and scientists have accumulated a lot of laboratory evidence to back that up.

    Octopuses score high on problem solving including finding their way through mazes, opening food jars and ingenious escapes.  They seem to learn from past experience too. One octopus worked out how to open a child-proof medicine bottle over the course of an hour. In subsequent attempts it was able to open the same bottle in a matter of minutes. In another account a lab octopus repeatedly short-circuited a night-light it disliked by squirting a jet of water at the bulb. And elsewhere a reluctant aquarium captive learned how to open its tank and head to a drainage system that pumped sea-water.

    One extraordinary story from New Zealand recounts a kept octopus that stole lobsters from an adjacent fish tank. The series of thefts remained a mystery for some time because there were so few clues, until the cephalopod was caught in the act. The octopus was seen removing the lid of its own tank, climbing out and across the floor to the lobster tank. Its genius was in the way it covered its tracks, by closing the lid of the lobster tank after the plunder, as well as its own when it returned.

    Some in the wild have shown signs of tool use. One octopus was filmed climbing into a coconut shell for shelter, and carrying it around on the sea-floor apparently to keep it for future use. There are also tales of octopuses climbing aboard fishing vessels and hiding in refrigerated crab containers -- although that story arguably denotes the limit to octopus intelligence.

National Geographic

    The anecdotes inspire a healthy curiosity in cephalopod intellect, sometimes yielding dubious results. 

    Back during the 2010 World Cup the most popular animal story in the media was about Paul the “psychic” octopus, said to be able to predict football match results. The reports from a German aquarium were heavily cloaked in irony, but their popularity hinged on a wishful fantasy about animal powers. It was a lame stunt that helped to keep ideas about animal intelligence at the level of a joke, for stories to be filed under the “off-beat” label. At work I ranted against the stories, but my colleagues looked at me as if I was mad, and a killjoy at that. “Why, even in the impossible event that an octopus could see the future, would it express any view about football?” I would implore. They would look at me thoughtfully and conclude, "yes, but it's amazing, when you think about it, how many Paul got right. There must be something in it." 

    It was a thankless task, but underlying it all may be a strange unease about cephalopod intelligence.  We live with the prejudice that humans are at the pinnacle of animal intelligence, and all other forms must be a less complete version of the same phenomenon. That line of thinking allows us to be comfortable with ape and monkey braininess, as well as other mammals such as dogs, whales, even pigs. 

    There could even be a convincing evolutionist argument to back up the idea that true intelligence should be a mammalian monopoly. If the start of life itself was an unlikely chance event that only happened once in billions of years, surely the development of intelligence and consciousness was another almost miraculous accident that could only happen once. It would then remain on a single evolutionary line as it gradually improved toward its ultimate human goal.

    But theories of cephalopod braininess undermine the single origin view of intelligence. We branched off from these creatures a very long time ago, long enough for an ancestor of ours to have looked similar to an ancestor of theirs. That means an ancestor that looked like neither of us and, to make a random guess, may be looked a bit like a stain, or perhaps just a soft blob. Chances are, that ancestor had no idea it existed, nor had the ability to solve puzzles or tell other males to back off from a female we're are planning to mate. So from a common heritage of an intellectual void, two diverging animal branches, at least, may have independently invented, and developed intelligence. 

    In which case we really are seeing an alien intelligence in the social, ingenious cephalopods, one that evolved independently of ours. They think, they share, they may know that they exist, and they may know that we do, they may be watching us, and waiting to see what we do, but they do it all on circuitry they developed without help or reference to our lineage. No wonder we think they might be all knowing.

    One species found in Hong Kong takes tool use to a higher level than just the odd manipulation of a coconut shell. Male blanket octopuses have been seen with poisonous jelly fish tentacles attached to their limbs. The Portuguese man-of-war (technically not a jellyfish, nor a single individual animal but a colony of jelly-like clones called syphonophores) is feared around the world for its nasty sting, but the blanket octopus is apparently immune. Although it hasn't been proven, the frequency with which the tentacles have been discovered dangling from the octopus arms, and the methodical regularity with which they are attached, suggest that the octopus deliberately seeks out the jellyfish. They apparently rip off the deadly tentacles for their own use, either for defence or on the hunt. They arm themselves with biological weapons capable of paralysing fish.

    Only male blanket octopuses have been caught with man-of-war stingers, females have a different line of defence, size. The species has a sexual dimorphism that makes breeding golden orb-web spiders look like well-matched couples. The males grow to a mite-sized 2.4cm, while females reach a mighty 2 metres. With webbing caste between eight arms these females spread their silhouette wide like an unfurled blanket, making any medium sized predator think seriously before launching an attack. 

    With such a level of dimorphism there is a good chance that females are not even aware that males exist. Hence their sex lives are predictably strange, with males climbing into crevices in the female mantle, the part non-biologists think of as the head. Like other cephalopods they carry packets of sperm into the female with one of their arms, but in the case of this species they detach their arm and leave it behind. Before biologists had discovered blanket octopus males, some supposed that the tiny worm-like arms attached to female mantles were some kind of parasitic hitchhiker.

    

Marinebio.org

One species that can deliver a toxin without the aid of jellyfish is the blue ringed octopus. It is best known in Australian waters, but divers here have also found the dangerous yet beautiful creature lurking among local coral reefs. These octopuses are able to inject a powerful neurotoxin called TTX that induces paralysis, and in the worst-case scenario, asphyxiation. They are intensely feared in Australia, but they don’t kill half as often as their reputation would suggest. In fact recorded deaths amount to just three or four in the last few decades, far less than the 40 or so a year who die of TTX poisoning in Japan by knowingly and willingly eating fugu pufferfish.

    More common in Hong Kong waters are the Bobtail squid, featuring prominently in many local dive photo and video galleries. The diminutive cuttlefish is an absolute gem, with its twinkling luminescent spots and shimmering layers of pastel shades. Its fairy-like illumination is achieved by a symbiotic relationship with a marine bacteria called vibrio fishceri. 

    In almost 15 years of daily sea travel across the Lamma channel, I've seen the night surf lit up by large blooms of phosphorescent microbes just twice. It is a stunning effect, a gorgeous aquamarine in the churning wake of the boat. Bobtail squid load up their light-organ with a daily dose of such a microbe, turning themselves into little tentacled marine lanterns. Ironically, this trick of the light is done for camouflage, which doesn't make sense unless you place yourself below the squid and look up through the water at the moonlit sky.

    The squid, which feeds the bacteria with a sugar solution in its part of the deal, uses the glow to eliminate its shadow from the perspective of a predator looking up from below. It adjusts the amount of bacteria it holds according to the strength of the moonlight, thus achieving invisibility by glowing. 

    With so many tricks up their many sleeves, it is inevitable that cephalopods generate intense scientific interest, especially for their remarkable manipulation of light and colour. 

    "We are working with several large engrineering groups to develop new materials that emulate ceph skin," Dr Hanlon told me. His department at the Marine Biological Laboratory reportedly won a $6 million grant from the US office of Naval Research in 2010, to delve deeper into cephalopod skin and its potential applications. One of the remarkable discoveries from the MBL is the presence of a light-sensing protein inside the skin. That would help to explain how cephalopods "read" their surroundings so effectively to blend into them.

    Artificial attempts to reproduce the technological wizardry of ceph-skin still pale beside the real thing, but research is ongoing. It is a dizzying thought that the submarines of the future, and stealth bombers, may eventually be sheathed in light-sensing skin of fluid camouflage inspired by squid, cuttlefish and octopus. Personally I hope there will be more useful applications, like festival wear for people celebrating life, and high-tech camouflage for animal spotters.

    Elsewhere researchers are developing a dexterous, soft-bodied robot inspired by the "morphology and behaviour of octopus." An EU7.6 million grant has been used to commission the Octopus Project, to create a robotic cephalopod. Much interest has been generated by the so-called decentralised nervous system, where eight arms appear to work independently of the brain and each other in response to stimuli, while remaining coordinated. So far a single octopus-inspired robot arm has been created which twists and turns like a living snake. In addition an eight legged aquatic contraption has done test demonstrations, but it has a long way to go before it can be called a genuine slithering, shape-shifting automaton, with eight legs, each independently responding to stimuli, but controlled and directed by a central processing unit, the octopus brain.      

    Finally if you are still not impressed by cephalopods be aware that bobtail squid were taken to space on board Endevour in the United States’ Shuttle programme’s last ever mission. They were part of an experiment that looked at the effects of gravity in the development of body shape.  And who knows, perhaps NASA in all their wisdom also had them aboard in case of an encounter with aliens.  I think they may have helped out as interpreters.