The squatter on the roof

Credit: HKU biology dept/Porcupine

If you were assigned the task of spotting one wild mammal in the next 24 hours your best bet in Hong Kong would be to find a bat. A quiet footpath at dusk will do, just a bit away from a main street or highway, near lampposts. Bats will soon appear as winged silhouettes against the fading light in the sky. They flit in and out of view in jerky aerobatics as they twist, dive and turn in a feeding frenzy on insects. If you’re lucky you might see one zigzag across the sky for a good few seconds before it disappears into a dark shadow.

     And there lies the paradox of bat watching. They are easy to find, but difficult to see. You would have to be an expert to even have a chance of identifying on the wing one of the 26 species of the territory. And much of that would probably be based on circumstantial evidence such as knowledge of known roosts and habits. Bat spotting is a frustrating activity, all the more so for these tantalising flickers they routinely offer. 

     Most people know bats through this constant peripheral, almost subliminal awareness, but only the most dedicated get to know them well. Thanks to their painstaking research, we know some surprising things about them. 

     Bats are the only mammals capable of true flight. There are gliders and jumpers, but no other aviators capable of powered flight. Some find in this a stumbling block for Darwin’s theory of evolution, which hinges on the idea that animals evolve when tiny changes give individuals an advantage. The theory rules out the possibility that shrew-like furry mammals one day sprouted wings whole and kept them. They must have gradually evolved. But what good is a shrew with two percent of a wing? The detractors asked, and still do today.

     The Latin name for bats gives a clue to how the wing is formed: chiroptera, meaning hand wing. This makes sense when you look at the bone structure, showing that most of the wing comes from skin that joins up disproportionately long fingers. When creationists argue that there are no “missing-link” species, the more coherent ones mean that there is no progressive fossil record showing bat ancestors with gradually elongating fingers. The solution to this “problem” has always been the same and simple, the fossil record is incomplete. Richard Dawkins points out that we are lucky to have any fossils at all, but the theory of evolution doesn’t hinge on the tiny percentage of extinct animals that have been preserved in rock. All fossils found necessarily support the theory, but there are of course huge gaps where millions of animals died in locations that lacked the precise coincidences required to preserve animal bones.  It is amazing to me that creationists fixate on this fossil gap, and ignore the fascinating phenomenon of homologous skeletons across species that allows us to call the bat chiroptera, or hand wing. 

Berkley.edu

     The fact that we can even talk about finger bones forming the structure of bat wings comes from the uniformity of skeleton design that cross vertebrate species and even classes, from reptiles, to birds and mammals. You can find upper arms, lower arms, wrists and fingers in lizards, eagles, monkeys, and bats. The same goes for skulls, rib cages and pelvises, because our skeletons are homologus, meaning that every major human bone has an equivalent bat bone. We carry the evidence of evolution in our spine and rib-cage, as bats do in their ‘fingers.’

Paradise tree snake in flight. Photo: Jake Socha/Nat. Geo

     The study of flying snakes offers a clue how to answer the two-percent question. The paradise tree snake in Malaysia has the disconcerting strategy of escaping tree climbing predators by throwing themselves off the higher branches of the jungle canopy. Curious observers noted that they manage to gain up to 100 metres horizontal distance before landing in a lower level of the forest. Researchers using high-definition cameras looked at what was going on at the physiological level. They came to the conclusion that the snakes are more than gliders, they actively fly forwards. They captured images of the airborne body changing shape into a flattened ‘wing,’ moving with a swimming motion to control flight. It is easy to see how such rudimentary aviation would tangibly improve with every two percent gain in efficiency.

     Whatever stages bats took to gain their wings, they became artful aviators. Since their emergence around 50 million years ago, they have spread right across the globe, forming twenty percent of all mammal species, and becoming the only mammals that made it to New Zealand without the aid of humans.

     Despite the success of the model, we’ve been strangely disdainful of the species, finding them creepy, and even suggestive of evil. Bat flight doesn’t fit into to satisfying human rhythms. They make erratic turns and jerky altitude changes. They don’t inspire us like soaring birds do. They look impossible to catch, but sometimes they come close.

     One touched my hair on an evening jog, it came from nowhere, a split second apparition from a parallel universe, may be hell. I assume it was swooping for a mosquito, either that or it came to anoint me with the seal of Beelzebub. 

     Another time I scared a bat, nearly slicing it with a Stanley knife. I was dismantling a roof canopy that had ripped to shreds in a storm months earlier. I cut through a roll of canvass rapped around a pole, to expose a cosy sleep-pod for a lone bat. The startled animal flapped away in panic, giving me the best broad-daylight bat viewing I’ve had chance to see. It did a few clumsy laps of my rooftop then landed on the back of a neighbour’s air-conditioning unit. 

     Bats airborne may not be smooth, but when they land they are even more awkward. Their wings are like cumbersome crutches made from broken umbrellas that refuse to close. Somehow the little beast clung to the back of the unit, quivering like a half-drowned pup, and forced itself into the narrow gap between the air-conditioner and the ledge that supported it.

     

Japanese pipistrelle: AFCD

It may have been a common Japanese pipistrelle, or perhaps a rare bamboo bat, like the species newly discovered to Hong Kong in 2005. Certainly its chosen tubular roost resembled a section of bamboo better than the cave dwellings of many species. But really there was no way I could tell what it was. The only identity I’m confident of is that it was one of the 24 diminutive microchiroptera species, rather than the larger megachiroptera fruit-bats, of which we have two kinds in Hong Kong.

     The short-nosed fruit bat, for instance is more likely to be found in an urban park, nesting under Chinese fan palms. Hong Kong’s only nest-building bats create shelters by chewing through the veins of upward pointing palms, and collapsing them down to form a ‘tent.’ The males do the work, and they use their creations to attract females for a harem. 

     The other fruit bat, the Leschenault’s Rousette, is the largest in the territory, with a wingspan of 40 cm. It plays a role in pollinating trees and dispersing seeds for Hong Kong’s forests. The species is a cave-dweller, which is unusual for fruit bats more commonly found to roost in trees. 

     I don't think it was a Rickette's big-footed bat either. I might have seen prominent hooked claws had it been, and these are also cave inhabitants, rather than solitary sleepers in tight tubes. They are known to roost in disused mines and their sharp, forward pointing toes give a clue to their unusual diet. 

    “The fish feeding behaviour of Rickett’s big-footed bat was first discovered during my thesis work at HKU in the early 1990s,” Dr Gary Ades of Kadoorie farm told me. “Bat droppings collected at Lin Ma Hang mines contained many fish scales which was quite a surprise at first.” 

     He said that they trawl water surfaces with their pointed toes to spear fish. They are often seen cruising freshwater reservoirs and slow-moving streams. Unfortunately the reliance of this species on freshwater sources is endangering its survival in mainland China, according to the IUCN which declared it ‘near-threatened’ on the 2008 Red List. It has a wide distribution from the far northeast to Hainan Island, but severe water pollution throughout the mainland is wiping out much of their hunting ground. The IUCN estimates a projected 30 percent decline of these piscivores over the next 15 years.

     I doubt if I was lucky enough that day to accidentally disturb the unidentified bat that became a contender for ‘new species’ status. In a 2005 AFCD study in Plover Cove country park, CT Shek and his team discovered a bat that didn’t exactly match any of the animals already recorded in the territory. A wider search offered no definite answers, but a similar rare Vietnamese species was found. Shek told me that they were hoping to name it pipistrellus hongkonggensis, but that is yet to be confirmed.

    One way of telling the smaller bats apart is to look at their hideous faces. In Hong Kong it could be a tiny whiskered myotis with its beady eyes and squashed up pig-face. Or a brown noctule that looks like it has a permanently sore face. Admittedly the pipistrelles tend to have relatively normal mammalian features, albeit on the ugly side, but it is the leaf-nosed and the horseshoe varieties that are the true shockers. 

     The Pomona leaf-nose with comedy giant ears, looks as if its real nose was bitten off in a fight outside a bar. The Chinese horseshoe really looks like it was branded on the face with a horseshoe, leaving a clear imprint, and a fleshy mess all around. But the gurning champion of the bat world has to go to the Himalayan leaf-nose whose face is a grotesque mess of wobbly grooves and pointy ends. The effect of looking at its face is disorientating and disturbing.

     There is of course a very good reason for the troughs and spikes of a bat face. What you are seeing is in fact a finely honed acoustic device. The leaf-nosed bats have dismantled their mammalian nose and reconstructed it into a highly specialised speaker that precisely targets powerful ultrasonic echolocation pulses. Once you understand the function, the hideous bat-face appears more forgivable, even admirable.

     Before WWII we didn’t know how bats hunted tiny insects in the dark, because before then we didn’t have radar. Radar taught physicists the principles of echolocation, and with that knowledge biologists discovered bats had developed a similar system millions of years earlier. 

     Radar uses radio waves, bats rely on sound, or sonar, but the principles are the same. Echolocation works by analysing data that bounce back from objects in the path of an outgoing signal. The bat emits a loud screech, everything in its path bounces sound waves, some of which make it back to the source. The bat learns where the food is, which way it is moving, how fast it is going, every thing it needs to make the kill. 

     That is the basic principle, but the details are breathtaking, as described brilliantly by Richard Dawkins in ‘The blind watchmaker.’ 

     Most bat echolocation calls are inaudible to human ears because they are in the ultrasound frequency. That’s just as well because if we could hear them we would be driven mad by the cacophony. They are blasted at extremely high volume. The emissions need to be loud because, as radar physicists discovered, out-going waves decay quickly as they spread increasingly wider, and so do the incoming waves. Which also means that the receiving or listening part of the system needs to be very sensitive. This explains the super-size lugs of the Pomona leaf-nose and other similar species. 

     But radar technicians discovered that this posed a tricky problem, that the powerful transmitter could damage the sensitive receiver. Or to pose the equivalent in the world of bats, the bat would deafen itself with outgoing shrieks.

     The communications specialists got round this by wiring up the receiving antennae to be momentarily switched off each time a signal went out. Biologists discovered that bats were doing the same with muscle contractions that dampened vibrations on sound carrying ear bones, as the outgoing shriek was projected.

     There is convergence too in other design solutions that refine echolocation. The ‘Chirp radar’ was introduced to put a marker on the outgoing signal, by using a frequency that shifts as it is transmitted. The frequency of the returning signal indicates which part of the outgoing found an object in its path. Bats use the same principle to sift through the data, emitting a swoop that can drop an octave. This helps the bat judge the distance to its target. Is the incoming sound at the C-sharp that emitted when the bat passed the third branch of the banyan tree? Or is it the B-flat it had dropped to by the time it had reached the lamppost? 

     Similarly the Doppler effect is exploited by both the manmade system and its biological equivalent. This is also known as the ambulance effect where an approaching vehicle has a higher siren tone because its sound waves are squeezed together. As soon as the ambulance passes the tone drops because the waves stretch out, as the source moves further away. Police radar traps are based on the Doppler effect, calculating the speed of targets by measuring the shift in the frequency of incoming radio waves. Astronomers also exploit the Doppler shift to find out if stars are moving away from us or towards us. Thus we learn about the expanding universe by utilising the same analytical tools bats use to hunt moths.

     Studies on horseshoe bats have shown up a complex set of 'calculations' dealing with a double Doppler shift from the movement of  both target and hunting bat. Not only that but rather than analysing the tone of the returning sound, these bats alter the pitch of their outgoing screech to keep the incoming pitch constant, at the best frequency for hearing. 

     All these split-second adjustments to focus bat sonar would be mind-blowing to human mathematicians trying to keep track without the aid of computers. But it would be a mistake to confuse our understanding of the physics with how bats experience the world.

     Bats don't do the sums dealing with frequency, velocity, distance and so on. They process the information instantly, as we do when we focus our eyes without doing the maths on the data involved. We convert light-waves into colour, while bats use sonar pulses that speed up as they close in on a target. Their focussed view of the world is at least as detailed as the world that humans see. Dawkins compares bat transmissions at 200 pulses per second on the hunt with mains electricity cycles at less than half the speed. Our perception of visual continuity inside a brightly lit room is an illusion half as informed as the world a bat 'sees.' 

     Whether information comes in sound or light, it is the brain that has to make sense of it. We see light, as bats hear sound, and our respective brains construct a three-dimensional model of space as detailed as necessary. Whichever form the data comes in, they are processed for the same ends.

     Human echolocation has been studied in recent years, including the development of practical systems to aid blind people. Accounts of visually impaired people riding mountain bikes or playing basketball have shown that echolocation can work for us. The systems on offer do not rely on superhuman perception, they are based on clicks of the tongue and training to interpret the incoming signals. 

     To a certain extent we all do it, for instance when we hear echoes in the mountains, we can detect the presence and direction of cliffs, and we can get an idea of how far away they are. I wonder how much more we do it subconsciously when we weave through a crowded street in Hong Kong for example? But a more refined system that can judge the distance of a moving ball, or allow firemen to find an exit in a smoke filled room, takes practice. 

     Tests suggest that echolocators don't necessarily have better than average hearing. fMRI studies have shown that the part of the brain most active during echolocation is the segment normally stimulated by visual cues, while audio areas remain dormant. 

Thaler, L. Arnott, S.R. & Goodale, M.A. (2011)

     The possibilities become even more intriguing by the suggestion that tongue clicking could be used as an x-ray device. An echolocator not only has the ability to tell that there is a soft bag in the vicinity, the bouncing sounds can give clues to the contents of the bag. Surely the next James Bond should have that written into the script.

     But back in the real world, as soon as the military use of radar became the norm, so did efforts to evade it. It should come as no surprise that pretty much everything we thought of to hide from, and foil, enemy radar already existed in nature. 

     The most expensive military plane in history, the B2 stealth bomber, looks like a moth. Its flat triangular morphology is designed to deflect probing radar pulses, its skin is sheathed in an absorbent material that dampens incoming beams. Its makers couldn’t have picked a more apt model than the moth.

Moths at first glance look like soft targets for night hunting bats. But the evolutionary arms race has not left them helpless and the outcome of an attack is not a given. Their powdery wings form a triangular shield over their abdomens. They are covered in uneven scales that dampen bat sonar. In bat ‘vision’ a moth must have a somewhat blurred outline.

     Some moths have developed hearing attuned to bat frequencies. With just two to four vibrating cells attached to the eardrum, they monitor the searching calls of their enemy. They combine this with sophisticated aerobatics, such as split-second twists, and sudden dives to evade the predator. This could explain the eratic flight path of bats at dusk.

     Co-evolution might be a more interesting way of looking at the bat-moth relationship than an arms race. Bats have had to adapt to moths as much as moths have to bats. For example some have dropped the frequency of their calls to foil the ultrasound detectors developed by moths. Others have dropped decibels to quietly sneak up to their vigilant prey. The European barbastelle bat is thought to have taken this strategy. Its oversized ears designed to detect feint echoes are a testimony to the form altering power of natural selection. 

European barbastelle: bio.bris.ac.uk

     Passively listening isn’t enough for all moth species threatened by sonar fitted destroyers. Some have developed clicks audible to bats. This can startle a hunting bat, buying a moth a crucial split-second. Studies have shown that the moth click can advertise toxicity, as colours do in other species. But the most sophisticated strategy is radar jamming. Tiger moths emit precisely tuned clicks at moments in the bat swoop calculated for maximum disruption of their sonar. Slow motion footage shows the effect of this split-second blip that throws the bat into a wrong turn.

     Moths are not the only creatures with an aversion to bats. Many human societies have had an irrational fear of these nocturnal apparitions. Though the old European association with vampires seems unfair to say the least. There are blood-sucking species, but only three, and they all live in central and South America. 

     In China however things often look different and bats are seen as a good omen, so good that people eat them for good health. In fact bat eaters have taken exotic cuisine to new levels by including faeces on the menu. Asthma, kidney ailments and general malaise form a familiarly vague list of complaints said to be cured by traditional medicine.

     This tradition led to tragedy in 2003 when the SARS virus jumped from horseshoe bats and infected humans, killing nearly 800 people in a matter of months. Civet cats were the first to be blamed, and thousands of them were killed for it. Later virologists pointed the finger at bats, often found jammed into cages near civets at southern Chinese markets. 

     Much as outsiders may be revolted by the idea of eating bat droppings, it should be noted that there was no evidence of direct human to bat infection. Feasting on their meat, or feces, was irrelevant to the spread of SARS. Virologists often have more to worry about from the transport and marketing of live animals, than how they are consumed after they are cooked.

     Bats are the reservoir species for several other viruses that have killed humans. Five different genotypes of the rabies virus for example have been found living exclusively inside bats. This may trigger alarm bells to anyone regularly seeing bats near their home, but it is unlikely there is any cause for concern. It should be noted that there are no known cases of bats infecting people with rabies in post-war Hong Kong, although there are rare cases elsewhere. By far the most dangerous animal when it comes to rabies, is ‘man’s best friend,’the dog.

     The last record of a person infected with rabies in Hong Kong was in 1981, the last animal in 1987. Ninety-five percent of animal cases since 1949 have been found in dogs, three percent in cats, and one each in pigs and cattle. There is no sensible argument to be made that bats are a rabies threat here.

     But on the surface the track record for bats doesn’t look that great. Hendra, nipah and ebola are three other terror-inducing viruses that have emerged from bats and killed people in recent years. Ebola is the most notorious, with the latest west African outbreak carrying a 53 percent death rate. The attack of the virus is truly horrific, taking over the immune system and spreading throughout the body to destroy every organ. It forms blood clots that deplete coagulants so that victims bleed both internally and externally, leaking blood from every orifice, mucus membrane and wound. Fruit bats of the pteropodidae family are considered to be the reservoir species for this nightmare microbe.  About another 60 less well-known viruses have also been isolated from bat species.

      So what should we do? Kill bats? Napalm their caves? Drone-strikes on their leaders?

      SARS, rabies, hendra, nipah and ebola have coexisted with their bat hosts for hundreds of thousands of years. They continue to do so even as the WHO monitors for outbreaks that put the fear of God into people. Most of the time these viruses stay in their reservoir hosts, and do not cause any trouble, though there are good reasons for virus specialists to be vigilant. 

     The relationship between viruses, their hosts, and other species is a relatively young topic that is expected to open up a huge area of scientific knowledge in the coming years. A recent study found that eight percent of the human genome is considered to have viral origins and we are only just beginning to get to grips with what that means. It could have huge implications for medicine and the study of evolution, and our understanding of who – or what – we really are. 

     That some of the most prominent viral outbreaks of recent years may have originated in bats is a point of interest, but it doesn’t hold any answers to how we can prevent disease. It certainly isn’t a reason to wipe out bats. We don’t have any way of ridding the world of harmful viruses, and if we did, we would have no idea about the impact on the environment. Our natural resources hold a balance far more complex than our recent ancestors realised when they discovered the power of modern tools to re-sculpt the evironment. 

     There are strong reasons for suspecting that human intervention is the biggest root cause of a virus jumping species. There is evidence for example that a combination of deforestation and economic pressures on legal and illegal bushmeat in Africa are pushing up the risk of viruses jumping species. The human population now is bigger than it has ever been before, our reach is further than ever before. The problem isn’t so much that we are being contaminated by an external threat. Environmental scientists say that there isn’t a single patch of the planet that hasn’t been affected by human activity. We are the contamination, not the other way round. 

Cedar, a viral cousin of the deadly hendra

    With the case of SARS it is well documented that crowded markets were vital to creating the circumstances that unleashed the virus from its bat host. In the past some policy makers would have taken that as enough reason to fire-bomb bat-caves, but surely it would have made more sense to burn-down the markets.

     In a world without bats what would we do with up to 4,000 mosquitoes per bat per night that carry on living and breeding? Mosquitoes are reckoned to be biggest killers on the planet with up to a quarter of a million human deaths per year attributed to their microbe-spreading behaviour, the vast majority of those fatalities being caused by malaria. They are even more dangerous than humans, the next item on the top killers list and by far the most lethal mammal on the planet.

    Bats are one of the most important natural weapons against mosquitos and other insect pests. One study has estimated that bats are worth about 23 billion dollars a year to the US agricultural industry through savings on pesticides. A colony of 150 bats in Indiana eats its way through 1.3 million insects a year, according to researchers at the University of Tennesee. Without bats, on top of additional economic costs, there would be a huge environmental impact from spraying tonnes of life-destroying chemicals into the air, and on to the land, all leaching through to waterways. 

     Fruit bats also play an important role in maintaining and regenerating forests by pollinating trees and dispersing seeds. And for centuries farmers have exploited bat guano, the name for the collected mass of bat droppings, for high quality fertilizer. It is a simple fact that humans have benefited from the existence of bats throughout our history.

     Have bats benefited from us? It isn’t easy to say that, especially as we know for sure that humans have cut down vast swathes of their natural forest habitats and hunting grounds. But in Hong Kong there is a case to be made that bats have at least adapted to our environment, and quite possibly have flown over from other places to make use of our structures.

     Hong Kong’s only natural caves have been carved by ocean surf, and are dotted around the craggier parts of the coast. Yet we host 11 species of cave dwelling bats inland, in water tunnels, disused air raid shelters, and old mine shafts, according to CT Shek at the AFCD. Water channels have been recognised as roosting sites and sections have been fenced off by the Water Works Deparment specifically to protect bats. An AFCD study in 2003 counted a total of 21,178 bats hanging upside down mostly in man-made homes. In the Lin Ma Hang abandoned lead mine alone there were two thousand bats on a count in 1994, and at least eight species in the vicinity.

     Shek is certain that artificial structures are contributing to bat biodiversity here:

     “The water tunnels or abandoned mines in the countryside are excellent roosting habitats for bats and that’s why most of the cave dwelling species are abundant and widespread throughout Hong Kong.”

     I suppose that my long neglect of the torn canopy gave one bat an artificial habitat for some weeks. If that one was eating 4,000 mosquitoes a night it was surely earning its keep, but it is a shame I never did get a positive identification. 

Two big snakes

King Cobra by Martin Megino

Snake catcher David Willot told me that the most dangerous snake on his beat is without doubt the king cobra. 

    “It is very fast and if you piss it off it is aggressive. The thing about them is that they can raise their body off the ground and within about half a second they can cover six foot. They glide. They are amazing. Obviously you have to be really careful,” he told me. 

    The danger comes from the massive dose of neurotoxin the snake is capable of delivering, enough to fell an elephant, some claim.

    When I saw one on a beach on Lantau it was so fat I thought it must be a python. There was no tell-tale hood, just a long thick body, sparkling in the sunshine after a swim across a bay of beach-goers. The police had it cordoned off and a gawping crowd stared, snapping pictures. A zoologist at Kadoorie farm identified our photos, noting that its unusual colouring could mark it as an escapee from the snake trade. He said it would be worth thousands of dollars. It looked calm but no one was volunteering to catch it that day.

    Willot told me that the only way to catch a king cobra alive is to sneak up on it and grab it by the back of the head. This is despite his own maxim that you should always keep the biting end as far away as possible. Which is doable with a smaller Chinese cobra, but with the king, “It would be like trying to catch a lion by its tale.”

    The snake is aptly named, everything about it is regal, its bulk, length that can reach 6 meters, its dreadful fangs, the threatening hood. But its name comes from its dominance over other snakes. It lives off other predators.

    The reptile can live for twenty years. It is the only snake species known to build a nest, and show maternal care over its young. The male builds the nest and the female defends it aggressively. In attack it is as if a two meter snake stands up and shoots forward, when in fact that is only the first third of its six meter body. It has unusually good eye-sight, which it uses to stare-out any threat, and it “hears” movement through vibrations in the ground.

    People in Hong Kong have had the snake rise to them to look into their eyes, dogs have been bitten and killed, houses have been infested, and yet recent records show no deaths from the species. It has killed here before but the snake has a paradoxical status as potentially the most dangerous in the world, yet a reluctant attacker. It is as if the species has learned that scaring the crap out of people is as good a defense as actually having to kill them.

    Their poison is different from the pit-viper’s blood-thinning agent. It acts instead on the nervous system, causing paralysis and a quicker death, usually by asphyxiation from failed respiratory muscles.

    

National Uni. Singapore

Biochemists are still struggling to understand the venom.  In 2010 after 50 years of research aiming to decode the complex cocktail of chemicals making up king cobra venom, scientists hailed the identification of one of its proteins as a major step forward. The discovery offered a tantalising glimpse into the workings of a “neurotransmitter” that could one day help in the treatment of Alzheimer’s, Parkinson’s and even schizophrenia. But it remains the case that we still don’t really know how king cobra venom works or how it is structured. One problem being that it changes depending on environment, season and diet.

    When the genome of the king cobra was decoded, its findings were published in 2013 by a team lead by the Liverpool School of Tropical Medicine. The study authors hailed the DNA clues that shed light on the evolution of complex toxins that are “required to overcome a variety of different prey and also circumvent any resistance to venom that may have developed in such prey.” Snake venom is a dynamic chemical weapon system that co-evolves with the defences of its prey. Not only that but trying to understand snake poison gives insights on the evolution of all proteins -- the stuff of life itself, according to the researchers. Those snakes on the ancient symbol of the Hypocrattic Oath, are beginning to make more sense to me, as I’m sure sure the biologists at the Liverpool School of Tropical Medicine would appreciate. 

    The snake’s value to medicine may yet be understood better in the future, but in the traditional Chinese market it has a clear commercial price-tag worth several thousand dollars.

    David Willot offered his services as a snake catcher to Hong Kong’s police force partly because of his concerns about the practice of calling out snake shop workers to remove problem snakes. The old deal was that the catcher would be given a small fee by the police for labour, and the right to do what they wanted with the offending reptile. That usually meant snake soup in a Sham Shui Po or Shueng Wan restaurant. Now partly through Willot’s and other conservationists’ petitioning, the caught snakes are delivered to Kadoorie farm for a controlled release back into the wild. It wasn’t a move that was popular with commercial snake catchers and there are still rumours that snake shop owners will arrive at a police removal with a rat snake in a hidden bag, ready to make a switch in case the target turns out to be a valuable cobra.

HK snake shop: Catherin Karnow/National Geographic

       Even the most seasoned expert should never drop his guard when handling these deadly snakes, or dead snakes. A chef died in a southern Chinese snake soup shop when he was bitten by an Indochinese spitting cobra that he had decapitated 20 minutes earlier, according to reports that emerged last year. It is a plausible scenario, as I saw first hand many years ago in Japan. A friend of mine who used to boast of outdoor survival skills he had learned in the Turkish army spotted a common looking greenish brown snake at a building site we were both working on. He leapt at it with a shovel and chopped its head off, quickly bagging up the carcass. The head lay on a pile of gravel snapping and gasping for a good twenty minutes. The rest of its coiled body writhed and twitched for several hours as we travelled back to the migrant labourers’ dorm we shared. Later he skinned, boned it and grilled it. It was tough and tasteless.

     Venom has another use, ravers in India discovered some years ago. It gets you high, they say. Four people were arrested near Mumbai in November 2013, the Indian press reported, for illegal possession of 1.7 litres of cobra venom, the equivalent to 400 doses from a single cobra or 40 from 10 snakes.  A forestry official quoted in the story was quite sure what the contraband was for, “cobra venom is used as a drug in rave parties these days. It is converted into powered form...and then mixed with alcohol,” he said. In February 2014 another man was arrested under wildlife conservation laws in the same region. He had a litre of cobra toxin on him. Indeed the first reports of snake venom smuggling were coming from animal rights groups two or three years earlier.

     Turned into powdered form for mixing with alcohol the designer drug known as K-72 or K-76 is reckoned to sell for $320 - $400 per pinch.  The effect, they say, is a powerful high and a rush of energy. Is that a sensation that a bite victim would experience moments before his organs shut down for good? I don’t intend to find out, so I think I will try to stay clear of king cobras in genral.

      A different venomous snake got closer to my home than I was comfortable with. The king isn’t the only cobra in the territory, we also have the Chinese cobra, a smaller snake but possibly more aggressive and more likely to strike. One climbed up the stairwell of my 2nd floor flat. Luckily my family and I were away on holiday, but our downstairs neighbours had a close encounter with the black snake, coiled at their eye level on higher steps. If I or any member of my family had been stumbling home in the dark we would have unknowingly pushed an increasingly irritable reptile further up the stairwell, until it would have nowhere to escape, leaving it very uncomfortable with limited options. One option of course would be to bite. As it was, the plucky downstairs boys called for help and police experts arrived to somehow pull the beast back down towards the exit, from where it slithered away never to bother us again.

     The Chinese cobra’s poison is more concentrated than that of its larger name-snake, but it doesn’t have the capacity to flood the victim with the giant dose the king can administer. It also has a hood that exaggerates its size to intimidate enemies.

Chinese cobra, Taiwan

    While Willot has been lucky enough to avoid the bite of the king, he has felt the fangs of a Chinese cobra. He was holding a captured snake when it swung up and bit him in the hand while he was distracted by a passerby who was telling him to be careful. He threw the snake down into a swamp, calmly got into his car and drove to hospital where had himself admitted for a night under observation. He was lucky, no poison had entered his bloodstream. With hindsight he thinks that the snake probably spent up its venom in lunging attacks during its earlier struggle against capture.

    It may be relatively small at about 1.5 metres but the Chinese cobra isn’t any pushover. I’ve seen footage of one repeatedly trying to attack a confident young snake expert in a Hong Kong forest. The charmer was well beyond the comfort zone of the agitated reptile, and well within striking distance. The snake made frequent stabbing strikes and even spat its poison at the man, but never landed a decisive blow. I’m sure it was a very dangerous game the person was playing, but it looked like he knew what he was doing. If the snake had got him, he wouldn’t have been the first to die here from the bite of a Chinese cobra, although no-one in Hong Kong has died from a snake bite in the past 20 years.

    In recent years snake venom was used as a murder weapon in neighbouring Taiwan in an outlandish insurance plot that involved a train-derailment. Lee Shuang-chuan’s Vietnamese third wife was in a train carriage that slid down a mountainside. She survived the crash, but later died in hospital. Lee stood to pocket about US$3 million payout specifically awarded in the event of death by an accident. But suspicions were raised by the sudden death of the woman in hospital when the medics had seen her improving in health. An examination showed she was killed by snake venom, and Lee and his brother were arrested. Lee had gained from an insurance payout previously when his second wife, also Vietnamese, had also died of a snake bite. He committed suicide during police investigations, but his brother was jailed as an accomplice, linked to both the train derailment and the poisoning.

    Under normal circumstances the key to surviving a snake bite is in correctly identifying the attacker. The Chinese cobra is relatively easy because of a mysterious cream coloured pattern on the back of its hood. It looks like Egyptian hieroglyphics. I found the give-away sign on the head of a dark snake in a drainage ditch struggling to swallow a frog. The frogs use the concrete channels on rainy nights to amplify their booming croaks, but the snakes use them just as well, as a highway to prey, hoovering up slugs, lizards and toads.

    It would have been too late for the paralysed half-swallowed frog but at least I would have been able to offer a clear identification. It is vital information, as anti-venom is specific to the unique set of toxins in each poisonous snake species. 

    Anti-venoms have been around for more than a 100 years, but they come from a laborious production process that involves a third species, usually a horse, sheep, goat or cat. An animal is first injected with a mild dose of venom to trigger an immune response. Then the doses are increased to build up immunity against a full attack. Once it has reached that stage, blood is taken and purified to extract the anti-bodies that have accumulated. These animal anti-bodies are then processed and turned into anti-venom for humans. So if you’re ever saved from a cobra bite, you’ll have a horse, sheep, goat or cat to thank.

Burmese python

Dave Willot catches a Burmese pyton (China Daily)

While all the venomous snakes deserve great respect, a non-poisonous species may have to take on the title of most awesome animal in Hong Kong. That would be the mighty Burmese python, the largest snake in the territory, a bulging 90kg, 6-metre monster. I saw one on my running path at night, or at least the tail end of it. I crouched down with my torch to look at the glistening scales on the slowly moving reptile disappearing into the dark undergrowth. It was a rippling tube of pure muscle, fatter than the thickest part of my thigh. I stopped myself from poking, reluctant to annoy the beast, but it gave me plenty of time to have a go, clearly un-phased by my presence. Watching that snake for a minute in silence threw me out of my small post-work world of petty annoyances and thrust me into the presence of a primeval natural wonder.

    It was near the spot where some people had released a 4-meter python that had been caught in a chicken pen a few weeks earlier. The snake had been preying on the illegally kept poultry for some months, but its greed was its undoing when it finally got stuck in the wire fencing, unable to pass through with a chicken sized lump in its stomach. Four people helped to carry the snake away from the scene of its crime and release it back in the wild. When they dropped it on the ground it regurgitated the partially digested bird and whizzed away into bush.

Not the one caught on Lamma, but same species

    Snake catchers like David Willot help to relocate up to 100 nuisance pythons a year from Hong Kong  properties. That is a lot of pythons caught and the number tentatively suggests a healthy population living and breeding mostly out of sight. The count is almost certainly up on previous decades of deforestation and unfettered hunting. Traditionally the snake had great value for meat, medicine and its magnificently decorated leather. In fact it still does, but it is now a protected species in the wild, and conservation measures seem to be having some success.

    Some pet owners might think that there has been too much success, especially after a spate of attacks on dogs in recent years. Three separate attacks in the same area of Saikung one year had people wondering if a rogue python had developed a taste for pet dogs. The one successful attack was on a 22kg husky, and the other two almost certainly would have succeeded had it not been for the fight put up by the dog owners. More recently there were two attacks within a fortnight. In the second brazen attack a 5-metre python ambushed a 28kg dog that was walking in a pack of five with its owner, who was also with her 7-year-old daughter, and a 5-year-old son who was about the same size as the dog. 

       Pythons start all ambushes by launching their massive jaws at the head of a target, then they wrap their bodies around the victim to suffocate by crushing their lungs. The owners of two of the unsuccessful attacks punched, kicked and pulled at the attacker, causing the snake to uncoil and retreat, leaving the dogs panting for their lives. There were calls after the first set of attacks, even from nature lovers, for the possible rogue python to be caught and packed off to some distant wilderness, but as far as we know the earlier “dog-eater” is still lurking in Saikung, and experts acknowledge that it could be the same one that ambushed dogs in new attacks.

    There were rumours many years ago, that elderly people were going missing on Lantau Island, possibly falling victim to man-eating pythons. But the rumours remained just that, and then they were forgotten. Experts doubt that six-meter pythons would target humans, although bigger pythons outside of Hong Kong have been found with human remains. Perhaps more reasonably, people express worry that children may be taken, but these fears have never proven justified. It just hasn’t happened. That is most probably testament to the finely honed instincts of mums and dads who always avoid leaving babies on their own in places where pythons might be. Or it’s almost as if wild pythons somehow know that there is a line that shouldn’t be crossed, because once crossed it could mean a whole lot of trouble.

    Though we do have plenty of examples of Burmese pythons killing humans elsewhere. Almost all of these come not from the wild, but from the homes of snake owners, in places elsewhere like New York, Virginia Beach and Papillion, Omaha. My theory is simple, its about proximity and opportunity. Pet owners give their wild reptiles hundreds of opportunities to kill them, and just once in a while a snake strikes. This kind of familiarity never happens in the wild. Field notes show that like many snakes, the Burmese python is essentially a solitary animal, not even seeking its own type for company other than to procreate.

    Biologists have called the python one of the most primitive snakes, meaning its basic form hasn’t changed since snakes first evolved. While other snakes have completely shed all external signs of ancestral leg parts, the Burmese python still has a pair of spurs that jut from where its hips would have been in lizard days. Like the vipers, the Burmese have heat-sensing pits, which they use to find and identify prey. Their large jaws are filled with rows of razor-sharp teeth that point backwards to trap struggling prey. Their lower jaws are in two separate parts, the right and left sides unfused at the front. The famous jaw dislocation is a two-step movement with an unhinging of the lower from the upper, and then the left and right sides swinging open.

    In Hong Kong the Burmese python is protected under the government’s wild animal ordinance, and so each one captured is by law handled by AFCD. Until recently the department regularly transfered captured pythons to mainland wildlife agencies, for release in nature reserves in Guangdong province. It was a policy much criticised by environmentalists. When I asked the department about where the snakes were released they wouldn’t say where. I don’t know if it was a secret, or if they didn’t know themselves. They said that the policy was necessary given Hong Kong’s small size and dense population. 

    The risks were obvious. While it would be impossible to openly sell a python in Hong Kong outside of the licensed pet trade, conservationists reported seeing them caged in wet markets across the border. The skin of the species itself can reportedly fetch 10,000 yuan on the black market. As one animal expert said, “Why China, where there is a huge market for snakes as food?”

    Thanks to pressure by committed environmentalists like Dave Willot, the government quietly changed its policy around 2011, halting the deportments and working with Kadoorie farm on a local release programme. It also adopted another one of Willot’s suggestions, the chipping of caught snakes to build-up data on their ecology.

    Willot catches up to ten pythons a year and for him one of the issues was that there were no follow-up studies in population dynamics and conservation. As much as anything else the shipping out of rogue pythons to mainland China was an opportunity lost for learning more about how and where they live in Hong Kong. That includes the impact on local ecosystems of removing even one Burmese python. It is well known that removing top predators from an area will skew the balance between all the animals and plants there. These giant opportunists feed on anything they can get hold of. That would include native fauna we want to protect, but the non-discriminating carnivores are just as likely to eat feral cats and dogs, rats and other snakes. They have also been known to eat monkeys, whose spread out of Kowloon towards Saikung is being noted by residents who fear that AFCD numbers are short of the true picture. It’s still early days for the chipping programme but at least there is now hope that we will build up a richer, more detailed picture of these incredible giants that are indigenous to the Hong Kong ecosystem.

    On the other side of the world we are getting reports of the Burmese python as an invasive species. The giant snake was first recorded in the Florida Everglades in 1979 and has since thrived in there. There are now tens of thousands estimated to be breeding in the national park, entirely the fall-out from a huge global pet trade. In the mid-2000s the United States was importing about 30,000 Burmese pythons a year and hatchlings were selling for as little as 20 US dollars each. All too often owners captivated at first by the beautiful and apparently easily managed reptiles, find out too late that living with a giant serpent is a bad idea. A classic response in the US is to take them to the Everglades and grant them freedom. It probably feels like the kindest thing to do, but economists, amongst others, may beg to differ after a 1999 study found that trying to control invasive species was costing the US 137 billion dollars a year. And the Burmese python is one hell of an invader. 

    The wide-ranging snakes are eating their way through a good proportion of Florida’s native fauna. Grey squirrels, possums, black rats and house wrens have all been consumed, along with at least 25 different species of birds according to one study. Four of the birds taken – snowy egret, little blue heron, white ibis and limpkin -- are listed as “species of special concern.” These mighty snakes are even taking on the park’s top predators.

    Alligators in the Everglades can reach four meters. They play an important role in the ecosystem of the park, from the control of predatory fish species, to the creation of watering holes that become a refuge for wildlife in dry seasons. But the top native predator of the park needs to be treated with caution. Since 1948, according to Florida’s wildlife records, alligators have killed around 25 people. Other than the occasional person, these gnarly carnivores will attempt to eat anything they can catch. They’ll go for turtles, chicken, deer and cows, and they’ve been known to kill panthers and black bears. They are one of the only animals – other than humans – known to attack a six-meter Burmese python. 

    It is a testament to the power of the Burmese that alligator-python conflicts are fairly evenly matched. Stunned tourists have watched alligators battle with pythons, struggling in the midst of a strangle hold. In one epic battle an alligator held a python in its jaws for 24 hours, only to let it slip away from its grip and swim away to freedom. 

    

National Geographic

The most famous symbol of the struggle for dominance in the Everglades has to be a photograph that surfaced in 2005 showing the back half of a crocodile carcass protruding from what can only be described as a burst python. The best accepted theory is that the Burmese python managed to swallow the crocodile but its last meal was too much to digest. It may have been injured in the epic battle, or else the crocodile may have had an accomplice, either way in the course of swallowing, the python exploded. Its head blew clean off and its torso ripped open to expose the rear end of the doomed alligator. The scores were even that day in the war of the Everglades.

    It is hard to imagine that the small baby snake I saw on the Lamma beachfront was a potential alligator slayer. A crowd stood around the 50 cm snake, curled defenceless against a restaurant wall. It could have been flushed into the bay through a drainage channel that cut through a valley of former agricultural land. It was thin and delicate, but undefeated, as if it knew it was the rightful heir to the top of the food chain. Its unmistakable Burmese leather was a natural design of perfect beauty. But that day, surrounded by curious humans, it was very vulnerable indeed. And I wish I could say with certainty that it now lives quietly at the head of the valley it was flushed out of.

One small snake

People love a good snake story, whether true or not. Like the one about Japanese forces using vipers to flush out communist resistance during their occupation of Hong Kong. Although I've heard it recounted as fact several times, I haven't found any records to confirm it. For starters it doesn't make military sense, snakes are far too shy and unpredictable to employ in an army. But that doesn't stop the myth from circulating. It taps into strong feelings of revulsion about both snakes, and the Japanese occupation.

    Local snake catcher David Willot told me another version that sounds more likely. He had heard that the Japanese bred snakes on Stone Cutters’ island in Victoria Harbour. The purpose for breeding wasn't clear. Was it for bio-warfare, or for anti-venom? Knowing now what we know about Japanese chemical weapons labs in northern China, anything is possible. In the final hours of the occupation, as liberation forces were steaming in, the lab-workers abandoned the snakes on the island. Many decades later Willot went to check out the place, hoping to find exotic Southeast Asian rarities, but his faith in the story was weakened when all he found was a mundane crop of local snakes.

    But of course there is nothing mundane about snakes. They are highly evolved reptiles that have shed their limbs in the pursuit of efficiency. So far we have counted 2,800 different species indigenous in pretty much every corner of the globe, except very cold places and New Zealand. Snakes feature in our oldest stories, blamed for millennia in the West for humankind's corrupted nature. They are the subject of crippling phobias and intense fascination. They are worshipped as symbols of power.

    All snakes are predators, though not all of them are poisonous. Some kill by strangulation, others overcome prey with jaws that separate on elastic ligaments. It looks like a tremendous struggle, but this trick, along with their expanding bodies, allows them to eat things that are bigger themselves. Snakes kill a minimum of 40,000 people a year, and a maximum of 150,000 depending on which study you believe.

    Hong Kong is home to 52 species, 14 of them are terrestrial venomous varieties, another eight or so are highly poisonous sea snakes. Four species have been discovered here. A quarter of all snake species found in China are represented in this small territory. The subtropical sun suits them, heating their blood for action. But in the sweltering mid-day heat in summer even snakes seek cooling shelter. 

    Here you are seldom more than a hundred metres from a red-topped minibus, half a kilometre from a Seven-Eleven, or a couple of blocks from an MTR station. But in most places where people live you can make a safe bet that a snake, possibly lethal, will be hidden closer to you than any of these things.

    Snakes have no ears and no eyelids and they use their famous forked tongues for sampling air-borne chemicals in stereo, to detect direction and movement. But perhaps the best-kept secret of snakes is the male's double penises. Herpetologists call them hemi-penes. Casual snake observers are unlikely to see the paired appendage, as they are kept tucked up in a special pocket on the underside. They are used one at a time in an otherwise ordinary act of sexual reproduction.

    The females lay leathery eggs in hidden shelters, unless they are ovoviviparous, meaning egg-layers that keep eggs hidden inside their bodies. Tiny worm-like blind snakes however, have no time for double-penis males, they are parthenogenic – self cloning -- like Garnot’s gecko.

    All snakes are natural wonders but I have to admit that most snake talk fixates on the lethal poisoners, and of course the monster strangler, the Burmese python.

    

Bamboo pit-viper

Hospital records show that the bamboo pit viper is the most prolific biter of Hong Kong snakes, being the likely culprit some 80 or so attacks a year. The aggressive bright green thing can put a person in hospital for days but it doesn’t usually land a fatal dose. It is quite small at around 60 or 70 cm in length, and skinny, but it will hold its position if it thinks it’s under threat, and lunge for a quick strike if the enemy comes within range. Most bites result from people trespassing unaware into a viper’s personal space, often in the dark or at twilight.

National Geographic

    A wound can lead to a lot of bleeding and painful swelling. And though it is rare, there have been cases of necrosis and gangrene. This can lead to amputation of the odd finger tip every now and then.

    Attacks are fast and vicious. The viper’s fangs, kept folded back in the roof of the mouth during rest, swing forward and lock into position in a split second strike. Some bites are dry, the poison held back in reserve or already spent, but others inject a toxic dose. Muscles around the venom glands squeeze the liquid like a plunger, shooting poison through a pair of hypodermic needles. The violence of the strike can leave the attacker with broken teeth, but new fangs quickly move forward from the back of the mouth to replace the old.

Sciencemuseum.org.uk

    Pit-viper venom is a hemotoxin, destroying blood cells, blood vessels, and preventing clots. It is a medical complication for humans, but a slow death to small animals. Once hit the targeted prey will move on with poison running through its body, followed by the silent predator. After a while the victim collapses from internal bleeding and organ failure, as the snake methodically dislocates its jaw and swallows.

    The venomous snakes with their sophisticated poisons are highly evolved. They came about long after their lizard ancestors shed their legs. There is much we don’t understand about their biochemical weaponry, manufactured in modified salivary glands behind their eyes. But there is plenty of interest from biochemists and pharmaceutical companies. The poisons are unique compounds of proteins with evidently powerful effects on living creatures, each major breakthrough in understanding the molecular biology of snake toxin holds a good chance of unlocking future drugs and patents.

    Pit-viper venom, an anticoagulant, has huge potentials in heart and blood pressure medicines. Indeed the poison of similar vipers are already producing registered drugs.

    Snake oil salesmen of the past had a reputation for peddling dubious potions to gullible people, but maybe they were appealing to uncannily knowing instincts.

Today there are several drugs on the market synthesised from snake venom, and there are strong expectations about the future. 

    The first snake-derived drug came about in the 1970s, after researchers noted the speed with which victims collapsed following the bite of a Brazilian pit-viper. They discovered in the venom a protein that caused a sudden drop in blood pressure, and its synthesized version became the first of many ACE (angiotensin-converting enzyme) inhibitors on the market today for the millions of people who suffer from high blood pressure.

    Now Rattle snakes and African saw-scaled vipers also provide two heart disease drugs called eptifibatide and tirofiban. They prevent fatal blood clots in veins and arteries weakened by a build up of plaque. 

    

Malayan pit viper VenomousReptiles.org

Malayan pit-vipers are the hope in research on new drugs for stroke victims. This also focuses on the venom's action against clots, this time in the brain. A protein called Ancrod, found in the venom is known to dissolve stroke forming blood clots up to 6 hours after symptoms start. Trials show promise, and the protein is already used in Europe on patients with deep-vein thrombosis and complications after surgery. 

    Today research continues in cancer treatment, looking in particular at proteins assembled in the venom glands of southern copperhead snakes. Contortrostatin plays a key role as an anticoagulant by preventing blood platelets from attaching to each other. The mechanism it uses to stop the bunching of platelets also has potential use against cancer cells grouping. In addition the protein inhibits the growth of new blood vessels, devastating to tumours, which need to create new capillaries as they spread from organ to organ.

    It isn't just the venom that is interesting to science, the ability to "see" heat is a vital part of the snake's armoury. The name pit-viper suggests a sit-and-wait predator lurking in a pit, a sinister image for a sinister snake. But the "pits" referred to are in fact a pair of small holes below the eyes, housing a heat sensitive organ.

    

University of Georgia

The pit is lined with 7,000 nerve endings able to detect minute differences in temperature, sending signals back to the brain. Key to this action is a gene that humans and snakes hold in common. 

    Biologists call it TRPA1, but I recommend its popular name, the wasabi receptor. In humans the gene helps us to feel pain, in particular the irritation experienced when taking in a dose of mustard, tear gas or wasabi. In vipers the same gene makes a protein that detects heat, triggering signals back to the brain along the nerves. It acts like a switch, activating when a targeted heat spot surpasses a certain temperature. As the snake scans the object in front of it, the data quickly builds up to form a thermal image of the small mammal or bird that forages unsuspectingly within striking range.

    Animal nerds may be interested to note that it is a misnomer to say that snakes can “see” infrared light, at least in the way a specialised camera picks up wavelengths of light in the infrared range. Instead, the snake takes temperature readings at tiny spots, in stereo to help judge distance. The data builds up in the brain, like a jet printer with its tiny dots of ink but each minute dot representing a temperature rather than a colour.     

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.