Creationist's nightmare - part 1

Credit: HK wetland park

  The first time I saw these fish they were climbing onto rocks. Jerky bogle-eyed mudskippers crawled, hopped and flipped at the water's edge in southern Lantau, their thin tubular bodies glistening in the sun. Close-up they have bulging hamster cheeks, or sagging fat-man chops, and eyes that sit on top of their heads. They walk on their front fins, which are jointed at the "elbow" in nature's imitation of cartoon fish.

    I say walk but I admit that may be stretching it a bit. Their arms are used more like crutches, with a mermaid's tail dragged behind, sometimes with an arched push to assist the labour. Like other fish of the goby family that they belong to, they have a fin on their underside that has been redesigned as a sucker. It gives them a hold on surfaces while they bring their fins around for the next thrust forward, in a lazy locomotion described by some as “crutching.”

    But the skipper label works better when these land hopping fish shift up the gears to fight, hunt, or escape. Imagine a human swimmer doing a vigorous butterfly as the tide goes out. He finds himself in the soft mud after the water has sucked away, but he's so absorbed in his task that he hasn't noticed the water has gone. He continues all the way up the beach to his towel, in a lumbering, laboured skip. That's the mudskipper in second or third gear. It would be a good idea to rename the swimming stroke to the "mudskipper." 

    But the true skipping only kicks in in fourth gear, usually triggered by terror, for example by the sight of a curious human, like me, or a hungry stork. For this, think of a world class triple jumper executing a perfect hop-skip-and-jump. The rapid motion will see them shoot off the mud flats, across the water’s surface, to then sink with a plop when the momentum has fizzled.

    If you stay still long enough, beady eyes will rise back out of the water, like a pair of periscopes. These amphibious fish can see better out of water than in. Once it feels safe enough it will crutch-walk out of the water, gain momentum with its butterfly flips, and get back to business in the mud.

    Note the adjective “amphibious,” not the noun. Mudskippers are fish, they just happen to spend more time outside of water, than in, which admittedly is strange behaviour for fish. But that makes them of great interest to evolutionary scientists.

Credit: HK wetland park

     Mudskippers are specialists of tropical inter-tidal mud flats and humid mangrove forests, both of which are little known facets of Hong Kong. They make their living in the zone where tides creep up into shallow estuaries twice a day, only to draw back long distances leaving an inhospitable but nutritious shimmering surface of organic sludge. While other fish float in and out of that space with the tide, mudskippers stay put, exploiting resources the others are forced to give up twice a day.  Contrary to their aquatic evolutionary heritage, mudskippers live out the most active parts of their lives outside of water, during low tide, including feeding, fighting and finding mates.

    In Hong Kong we have three species of these truly strange fish, and they are easy to spot as long as you go to the right place. You won’t find them along the Victoria harbour waterfront because there is no mudflat for them to ply their trade, but their existence elsewhere is proof that not all the coast has been tamed, blasted and caste in concrete. The common mudskipper is carnivorous, feeding on little crustaceans and insects, while the blue spotted and the blue eat the microbes and algae that fill the inter-tidal shore. You’ll find the three species dotted variously on coastal marshlands and mangrove swamps from Mai po to Sai Kung, and around the remote shores of Lantau island.

HK mangroves. Photo: HKU

  

    Around the world there are 29 other recognised species, mostly circling the tropics and sub-tropical belt. They all share a similar morphology: funny looking slimy tubes with cartoon flipper-arms, decorated with exaggerated flag-like dorsal fins, with Dizzy Gillespie cheeks and alien bauble eyes sticking up above their heads. There’s good reason for the shared characteristics, they’re closely related, plus they’re equipped for similar environments.

    The arm-like jointed fins are an obvious adaptation to walking on muddy land.  And with so much time spent out of the water their exaggerated dorsal fins are mostly redundant as swimming aids. Un-needed for locomotion, they have grown into decoration for attracting mates and scaring enemies, like the peacock’s showy curtain of tail feathers. 

   The bulging cheeks are filled with water to help breathing, in a deceptively simple adaptation often described as a reverse aqualung. Like any other fish, mudskippers use gills to extract oxygen from water. But unlike the others they have developed pouches around their gills to carry water on their expeditions out of water. Inside the water-filled pouches, the gills carry on working as if they were submerged. You’ll see the skippers coming out of the water with swollen cheeks that gradually deflate until another dip is required. 

    But they also breathe through their skin, and through their mouths and throats, which are lined with tiny capillaries for exchanging air and carbon dioxide. They have to keep moist for skin diffusion to work, which means frequent rolls in muddy puddles and quick dives into pools they can never stray too far from. This activity keeps them very busy all the time.

    Their mad periscope eyes can be dipped completely into their heads for a swirl in the water-filled gill chambers. It is the mudskipper’s equivalent to a blink, partly serving the same function a blink serves mammals, to moisten the eye and remove dust. They’re the only fish that can blink, but if you think about it they are the only fish that need to blink. But the eye-ball dip serves another purpose. Pulled into the gill chambers they swirl the carried water around, helping to circulate oxygen. In other words, they blink for air. 

    Another acquired skill for inter-tidal survival is burrowing. Male mudskippers dig holes to create security bunkers, love-nests, and egg hatcheries. In low-tide they need to duck and dive from shorebirds, and other predators, like humans, that learn to negotiate the treacherous mud. In high-tide bigger fish come exploring for snacks. The burrow works for both occasions, as a bolt-hole from danger.

    Anyone watching mudskippers for the first time will easily see how territorial these fish are. They are constantly squabbling with aggressive flag-waving fin displays and muscular wrestling bouts. Some species build a muddy wall around their burrows, like a fortress against raiders. They chase off male rivals that come too close, and wait for passing females, eager for an opportunity to impress with their prowess.

    They do that by jumping up and down. Their fins unfurl in handsome display, and they flip themselves into the air, as high as 60 centi-metres at a time. Women say men are simple, but at least humans try to add conversation or wine to the mix to express the biologically-driven desire to mate. 

Credit: info@gov.co.hk

    But surprising for us, jumping does the trick for mudskippers. A suitably impressed female will follow the male into the burrow and lay her eggs in a specially designed chamber. The romance ends there, as the now sated male will sometimes chase the female out of the burrow and start duties himself as “mother.” 

    One of the main jobs of the primary care-giving male, is to regularly supply oxygen to the incubating eggs. The eggs are laid on the ceiling of a chamber that holds a small air pocket below the waterline. The only way to maintain air circulation is for the adult fish to swim above water, gulp air into its mouth, carry it to the bottom of the burrow and release it in the chamber. The male does this repeatedly as the eggs develop. When they are finally ready to hatch, he floods the chamber at high tide, for the new born to disperse like floating microbes in the ocean.

    These surprising traits are enough for any fish-appreciating person to award mudskippers an array of worthy titles such as coolest fish on the planet, or top water-beasts. But there’s one title I’ve come across that really beats them all: creationists’ nightmare. 

The bionic lizard on your wall - part 2

Powerful and influential forces are evidently backing up the elusive search for what could be the world’s next awesome war accessory – the full-sized gecko suit – but it’s not just the military that’s got an interest in the vocal lizards, medical scientists are also studying them them.

    There is a lot of interest in the tail the gecko discards to escape predators in a trick called autotomy. Not only does the gecko survive self-amputation but it grows back a new tail, a vital store of fats and nutrients in lean winter months. 

    A group of scientists at Adelaide University wondered if the gecko's recovery from what is evidently a major trauma, could have any implications for humans undergoing radical surgery such as masectomies and amputations.  They focused on a common and painful condition called lymphoedema, which is brought on by damage to the lymphatic system causing swelling in parts of the body. The symptoms can occur in one or two limbs or in the trunk or guts. In extreme form the disease can cause elephantitis, an enormous swelling of the limbs. 

    When working properly the lymphatic system drains off excess proteins and fluids from body tissue and filters it through lymph nodes before dumping the cleaned up fluid into the blood stream in the lower back.   Masectomies and other forms of surgery can damage or remove lymph nodes, leaving the body with a broken lymphatic system. So does autotomy. Other than noting the general sheer genius of re-growing an amputated body part, scientists reckoned that something clever must have been going on specifically with the lymphatic system, or else new tails would have come out all blotchy and bloated. They discovered a protein that the gecko increased in production after dropping its tail. This growth factor helped to regenerate the lymphatic system at the site of the trauma. The promising news for lymphoedema victims is that the gecko growth protein has a similar human equivalent. 

    The discovery hasn’t led to a cure, or human limb regeneration for that matter, but it’s a lead towards possible new treatments and a better understanding of how humans and other animals are held together.

    A different study looked at how the tail whips into a manic frenzy after it undocks from the central nervous sytem of the gecko, to become a decoy to predators. The authors at Canada’s University of Calgary noted that the flipping movements of the detached tail didn’t fit the dying rhythmic convulsions expected. Instead, they were surprised by the complexity of the movement including flips, lunges and jumps as high as three centimetres in to the air. Not only that but the tail changed directions after hitting objects, in a sign that it was responding to stimuli as if it had a mind of its own. 

    The study authors suggest that there is a control centre at the end of the tail, furthest away from the brain, which kicks into action after severance from the main body. They said that understanding this back-up system could shed light on the mysterious spontaneous muscle movement observed in humans who have suffered from spinal cord injuries. And understanding that could in turn lead to more effective treatment. 

    Indeed geckos appear to hold important keys to our bionic future, and yet their secrets have been locked into their genes for a lot longer than the possible few million years of humanoid existence.

    In 2008 a lizard limb embalmed in 100 million year old amber was decoded. It was the perfectly preserved lamellae on the toes that proved it belonged to a gecko. The find, from the tropical rain forests of today's Myanmar, put back their genesis by 40 million years in our eyes, placing them for the first time within the age of the dinosaurs. The ancestor of the beast that crawls the wall of a Hong Kong flat survived the trauma that wiped-out the velociraptors and the tyrannosaurus.

Credit: OSU

    But that leaves an unanswered question. Before modern building design and urban development, what surfaces were so smooth that any animal needed Van der Waal forces to survive? Even the smoothest rocks found in nature can’t compare with the uniform flatness of tiles, glass and steal. These materials only became ubiquitous in urban Hong Kong after the second World War. Until then the smoothest of rock faces had enough profile to give geckos and other animals strong claw-holds. And the smoothest pre-war house wall would have been a positive climbing frame compared to today’s gleaming tower blocks and floor to ceiling glass pains that geckos can  tackle with ease. 

    The first gecko to climb up a glass wall must have been thrilled by the discovery of sticking powers that lay untapped to full potential in rough forests and rocky wildernesses. All along the evolutionary arms race had honed nature’s best climbers with minute advantages over rivals. The result was so refined that it couldn’t even be fully expressed until modern architects constructed a new world of shiny polished surfaces. 

    Is it because of all these incredible attributes that there are rumours of a “reptilian conspiracy”? I’ve just described my favourites: supreme predators, objects of faith with healing powers, self-perpetuating clones, supreme climbing champions of the animal kingdom, bio-inspiration for future human superpowers, self-amputating experts in regeneration, shedders of self-conscious intelligent body parts. But some people think there is even more to geckos than mere biology. There is a suggestion that geckos, along with other lizards and slithery snakes, are the true rulers of our planet. 

    David Icke, once the kind face of solid normality when he was a well-known sports presenter on British TV, is now one of the people warning the world against the “reptilian conspiracy.”  Its not so much the lizards you see on your walls you need to worry about, although they’re probably in cahoots with the others. But some reptiles have actually used magic powers to take on human form to control the planet. You would have heard of many of them including count Dracula, all European royalty, and the Bush family that produced two presidents of the United States. 

   The evil reptilians interbreed only with their own kind and keep the rest of the world subjugated in a state of ignorance and fear. And if geckos have got anything to do with this dark scheme, with their talents they must be the ninja soldiers of the conspiracy, spies eaves dropping on us.

    A nice metaphor perhaps for nepotism, corruption and cronyism, but taken literally it is insane of course. For starters, if they really are the all powerful masters of the universe, why do these beasts so often meet an abysmal ending in and around our homes.  I’ve seen them with their heads stuck in discarded Band-Aids, trapped in plastic water bottles and flattened behind door hinges like crispy skeletal bookmarks. Sometimes they explode in plug sockets or they force themselves into tubes they can never leave.

    Once I found a doomed individual stuck inside a cockroach trap made from glue-lined cardboard. The small gecko was gasping for life. It had struggled a few centimetres from its dead, separated tail, and it was shedding its own skin in a futile bid to escape the noxious adhesive. A swift execution with a sharp knife was the most merciful action I could take.

    That one was certainly no master of the universe, or member of a ruling conspiracy. It was just an unlucky lizard that had awesome powers but still lived a precarious life in a hazardous world.  In another case of misadventure a friend of mine had an expensive British brand ‘intelligent’ washing machine destroyed several times over by Hong Kong geckos that fried themselves on the motherboard that controlled the system. After repeatedly sending off for replacement parts he finally gave up on the high-tech that proved so alluring to the lizards and replaced it with a cheap conventional washer.

    In some ways it is obvious that evolution hasn’t caught up with a relatively new habitat for these ancient reptilian wonders – our flats. After all they developed their superpowers millions of years before the first Fortress and IKEA stores opened in Hong Kong. But lizards may not be the only inhabitants struggling to come to terms with modern domesticity. We may not have been around as long, but hundreds of thousands of years in pre-electric, pre-plastic, pre-flat-pack days must have left an imprint. And that might explain some of the scrapes we get into ourselves, as we navigate the very recent physical and social environment we have constructed, for better or for worse.     

The bionic lizard on your wall - part 1

     

Geckos gather upside down on my balcony ceiling at night, watching insects swarm a lamp. Their ability to defy gravity mystified scientists for years. Many searched for the elusive glue, or the gecko’s answer to spider silk, but it was all in vain as the stealthy killers left no footprint where they walked.

    This single-minded predator makes itself practically invisible during a hunt by locking its body and limbs down to perfect stillness. The only movement while it watches is a flick of the tongue to moisten vertically slit eyeballs, wired for night-vision by the relentless attrition of evolution.

     There is no escape from the final lightening strike. In a split-second two or three insect legs bicycle uselessly out of the gecko’s stuffed mouth, half a wing trembles. They'll eat all sorts of small animals, but their favourite are the winged insects. The predator chews its prey to death, mashing them up with sharp teeth.

    In any Hong Kong apartment it could be a Bowring’s gecko, or a four-clawed gecko with purple and peach skin stretched almost translucent over a potbelly full of dead bugs. You can hear their devilish clicks at night. They are the only reptiles with vocal chords. Like chameleons they can adjust skin colour for camouflage, though their range is restricted to tone, light to dark.

Four-clawed gecko. Source: AFCD

    Eight different species reside in Hong Kong. In addition to the common Bowring's and four-clawed geckos, there are large biters like the Chinese and the tokay, warty spike-tailed specimens in the Brook’s, and a shy forest dweller in the tree gecko. The house gecko, on the other hand, loves to hang out in our homes, and inside our stuff, especially electrical gear like air conditioners, toasters and at the back of the fridge. 

    

Chinese gecko. Source: AFCD

Some are regional such as the Chinese gecko limited to central and southern China and northern Vietnam, while others are far travellers like Brook’s that spread across Asia and also appear in the West Indies and tropical Africa.

    The tokay, reaching 40 cm in length, is the second largest gecko in the world, beaten for size only by the New Caledonian giant gecko. Named after their distinctive "To-kay" calls, these blue-skinned, red-spotted carnivores are our most aggressive species. Males will fight each other for a mate, but they’ll make peace for long enough to hunt in packs. They are known to attack small mammals and birds, and they will bite a human finger if given half a chance. 

Tokay gecko: AFCD

    But these dragons-in-miniature have much more to fear from us than we have of them. Wanted dead or alive, tokay geckos are hot items in both the global pet trade and the Chinese medicine market. 

    Hong Kong's "native" tokays, sometimes spotted on Lantau island and around Lion Rock, are thought to be mostly the decendents of drug-trade escapees. And in urban areas we are more likely to see them dead and splayed flat like small grizzly kites outside a snake shop, than surviving unmolested in some crack in an old wall. In the old quarters of Hong Kong, such as Shueng Wan, you can see hundreds of these gecko lollipops on their bamboo crucifixes. 

    As with much of Chinese medicine it is difficult to pin down a convincing description of how ingesting an exotic species can have health benefits. But medicine shops list a diverse range of benefits brought by the tokay from “replenishing the lungs and kidneys” to “receive qi and stop asthma” and “reinforcing yang and essence.” It is also indicated for pulmonary tuberculosis, impotence and “seminal emission,” quite a potpourri of unrelated complaints.

Credit: Krishna, Public Domain Photos

     Whether for medicine or the huge global pet trade, there is a long history of trapping, eating, breeding these geckos, and as a result the tokay is endangered in China, and ironically, a protected species.

    But however tentatively, several other gecko species live well on the peripheries of the built environment, hunting, sheltering and breeding inside things made by people. 

    Female geckos typically lay two eggs at a time, a few times a year. Whether a gecko lays eggs inside apartments, on the eaves of a pagoda or beneath a park bench, the main thing is that the eggs are kept out of the rain. I've discovered them attached to my disused spare shower wall, lodged behind a water pipe. They were perfect little eggs, slightly squashed balls of shiny and speckled ivory.

    I inadvertently destroyed another batch when I pulled out a long redundant plastic poncho from a basket hanging on a wall. Three eggs dropped and two of them smashed to reveal miniature gecko forms, one of them was alive but it didn't last long. The shell of the third egg cracked and fell away, revealing a tightly packed ball of baby gecko inside a soft sack. I carefully placed it in a plant pot in the hope that it would hatch, but the the little lizard never woke up.

    When geckos don't have the convenience of the facilities humans have built, they resort to tree crevices under a canopy of leaves to lay eggs,  an old world they knew for millions of years before we discovered bricks, mortar, metal and glass.

    

A self-cloning Garnots's gecko

Geckos generally follow the usual practices of sexual reproduction, popular with most animals, but one Hong Kong species has dispensed with sex altogether. The Garnot’s gecko practices the strange art of parthenogenesis – self-cloning.  All of them are females, with no use for males, as their eggs develop into embryos without the help of fertilisation – an exact copy of the mother, who is also an exact copy of her mother, give or take a few random mutations. 

   While examples of self-cloning can be found quite frequently in plants and simple invertebrates, it’s reckoned that there are only a few dozen vertebrate species that practice asexuality. 

    Some biologists believe that parthenogenisis is a great idea. If a parent has lived long enough to produce viable eggs, she has obviously got perfectly good genes. Why change anything by introducing the DNA of a random stranger?  Considering how hard relationships are to manage, the parthenogenic lizards such as Garnot’s geckos may have chosen an unusual but perfectly reasonable method to reproduce. But strangely enough this biological choice hasn’t necessarily let them escape the trials and tribulations of courtship and relationship after all.

    Not if a lizard study published in 1979 has implications on Garnot’s anyway. In this account self-replicating reptiles still have to pair up and go through the motions as lovers, to kick their hormones into action and set the reproductive process off. 

    Other than the rare and mysterious self-cloning powers of Garnot’s, geckos in general have evolved into biological machines of wonder, avidly studied today in the hope that they will unlock superhuman powers. There are two traits in particular that interest powerful and sometimes shadowy institutions, their ability to stick to walls and ceilings, and their ability to re-grow their tails. 

    Their powers of adhesion are amongst the best in the natural world, with an intriguing clamp and peel mechanism on their foot pads that offers potentials in robotics such as wall-climbing spy-bots of future warfare, or even bionic prosthetics for tomorrow’s special agents. Until recently many biologists believed that these agile stalkers used some kind of secretion to stick to walls, like spiders with their silk, but now we know better. Less than two decades ago scientists proved that submolecular electrical forces of attraction -- called Van der Waal's supplemented the gecko's otherwise ordinary use of claws and friction.

    The same forces of attraction that keep molecules together, from gasses to liquids and solids, keeps a gecko stuck to your wall.

    Their claws naturally play a part in finding a toe-hold on surfaces, but millions of tiny hairs called lamellae cover the toes and foot pads, and each of these splay into billions of nanoscale split-ends called spatulae. This multiplies the total surface area of gecko foot in actual contact with any wall or ceiling by a huge factor. In contrast, when we put a bare foot on the ground, at a microscopic level there are huge gaps between our skin and the surface it it is touching. We think we are making firm contact, but in reality we are balancing on a rough terrain of invisible ridges and pin points. In the case of geckos, all the tiny nanoscale holes are filled up by billions of microscopic hairs. This allows Van der Waal’s forces to interact with surface molecules to make a bond strong enough to suspend the body weight a gecko from a ceiling.

    But that’s just half the story. The other half is letting go. Stealth and speed are vital to the gecko’s survival strategy, contributing to the 100-million-year durability of their basic body design. That means adhesion must be backed up by split-second release. 

    It’s all in the subtle directional pull applied by the muscles. A gecko can hang on glass by one toe, if it pulls it back, according to researchers at Stanford University. They explained that its sticking-power only works when there is a force pulling in a certain direction, described as a kind of “one-way adhesive.”

    The team created an adhesive that mimics the lizard’s directional bonding system, made up of a rubber-like material with polymer threads a fifth of the thickness of a human hair.

    

Credit: IB.Berkeley.edu

They spent years creating a prototype robot dubbed Stickybot that can scale up smooth glass surfaces. Its form even resembles a lizard, with four limbs and a tail, and it is hoped that eventually its descendants will be doing real practical work for human masters, by reaching dangerous and tricky places.  

      Another line in development is a scaled up version of the system for grown-up human use. They call the technology Z-Man, and one appeared in a demonstration in 2014. A 98kg man climbed up 8 metres of smooth glass carrying a 20kg backpack. His only climbing aids were a pair of paddles lined with an adhesive inspired by gecko skin. His well publicised antics triggered a slew of awkward headlines around the world where Spiderman references were deemed essential to explain the gecko-inspired technology.

      But what was it for?

      “The gecko is one of the champion climbers in the animal kingdom,” said Dr Matt Goodman,  one of scientists working on the project. “So it was natural for DARPA to look to it for inspiration in overcoming some of the maneuver challenges that US forces face in urban environments.”

    So what is this mysterious DARPA? It’s got a darkly Orwellian name and it pays grown men to goof around all day dreaming of soldiers in giant gecko suits.    

    The Defense Advanced Research Projects Agency came in to being in 1957 after the United States was caught flatfooted by the communist Soviet Union when it launched Sputnik into space, the world’s first communications satellite. 

    The new agency, set up to ensure America would never again be caught by surprise, went on to help invent the F-117 stealth fighter, which dropped 2,000 tons of bombs in the 1991 Desert Storm campaign to oust Iraq’s Saddam Hussein from Kuwait. It also invented the M-16 assault rifle, the US army’s shoulder weapon of choice. But DARPA’s most ubiquitous invention was the Internet, which came about when the agency sought ways to link up computers between researchers spread across the United States. No one can doubt the enormous influence the Internet has had on the world since it spilled out of DARPA’s secretive world and ignited a communications revolution.