Minding the miniscule: the scale prejudice in everyday life

I was recently weeding a vegetable bed in the garden when out of the corner of my eye I noticed a centipede frantically heading for cover after I had inadvertently disturbed its hiding spot. In my experience, most gardeners are oblivious to the diminutive fauna and flora around them unless they are pests targeted for removal or obliteration. It's only when the likes of a biting or stinging organism - or even just a large and/or hairy yet harmless spider - comes into view do people consciously think about the miniature cornucopia of life around them.

Even then, we consider our needs rather greater than theirs: how many of us stop to consider the effect we are having when we dig up paving slabs and find a bustling ant colony underneath? In his 2004 essay Dolittle and Darwin, Richard Dawkins pondered what contemporary foible or -ism future generations will castigate us for. Something I consider worth looking at in this context is scale-ism, which might be defined as the failure to apply a suitable level of consideration to life outside of 'everyday' measurements.

I've previously discussed neo-microscopic water-based life but larger fauna visible without optical aids is easy to overlook when humans are living in a primarily artificial environment - as over half our species is now doing. Several ideas spring to mind as to why breaking this scale-based prejudice could be important:

1. Unthinking destruction or pollution of the natural environment doesn't just cause problems for 'poster' species, predominantly cuddly mammals. The invertebrates that live on or around larger life-forms may be critical to these ecosystems or even further afield. Removal of one, seemingly inconsequential, species could allow another to proliferate at potentially great cost to humans (for example, as disease vectors or agricultural pests). Food webs don't begin at the chicken and egg level we are used to from pre-school picture books onwards.
2. The recognition that size doesn't necessarily equate to importance is critical to the preservation of the environment not just for nature's sake but for the future of humanity. Think of the power of the small water mould Phytophthora agathidicida which is responsible for killing the largest residents of New Zealand's podocarp forests, the ancient coniferous kauri Agathis australis. The conservation organisation Forest and Bird claims that kauri are the lynchpin for seventeen other plant species in these forests: losing them will have a severe domino effect.
3. Early detection of small-scale pests may help to prevent their spread but this requires vigilance from the wider public, not just specialists; failure to recognise that tiny organisms may be far more than a slight nuisance can be immensely costly. In recent years there have been two cases in New Zealand where the accidental import of unwanted insects had severe if temporary repercussions for the economy. In late 2017 three car carriers were denied entry to Auckland when they were found to contain the brown marmorated stink bug Halyomorpha halys. If they had not been detected, it is thought this insect would have caused NZ$4 billion in crop damage over the next twenty years. Two years earlier, the Queensland fruit fly Bactrocera tryoni was found in central Auckland. As a consequence, NZ$15 million was spent eradicating it, a small price to pay for the NZ$5 billion per annum it would have cost the horticulture industry had it spread.

Clearly, these critters are to be ignored at our peril! Although the previous New Zealand government introduced the Predator Free 2050 programme, conservation organisations are claiming the lack of central funding and detailed planning makes the scheme unrealistic by a large margin (if anything, the official website suggests that local communities should organise volunteer groups and undertake most of the work themselves!) Even so, this scheme is intended to eradicate alien mammal species, presumably on the grounds that despite their importance, pest invertebrates are just too small to keep excluded permanently - the five introduced wasp species springing to mind at this point.

It isn't just smaller scale animals that are important; and how many people have you met who think that the word animal means only a creature with a backbone, not insects and other invertebrates? Minute and inconspicuous plants and fungi also need considering. As curator at Auckland Botanic Gardens Bec Stanley is keen to point out, most of the public appear to have plant blindness. Myrtle rust is a fungus that attacks native plants such as the iconic pōhutukawa or New Zealand Christmas tree, having most probably been carried on the wind to New Zealand from Australia. It isn't just New Zealand's Department of Conservation that is asking the public to watch out for it: the Ministry for Primary Industries also requests notification of its spread across the North Island, due to the potential damage to commercial species such as eucalyptus. This is yet another example of a botanical David versus Goliath situation going on right under our oblivious noses.

Even without the economic impact, paying attention to the smaller elements within our environment is undoubtedly beneficial. Thinking more holistically and less parochially is often a good thing when it comes to science and technology; paradigm shifts are rarely achieved by being comfortable and content with the status quo. Going beyond the daily centimetre-to-metre range that we are used to dealing with allows us to comprehend a bit more of the cosmic perspective that Neil deGrasse Tyson and other science communicators endeavour to promote - surely no bad thing when it comes to lowering boundaries between cultures in a time with increasingly sectarian states of mind?

Understanding anything a little out of the humdrum can be interesting in and of itself. As Brian Cox's BBC documentary series Wonders of Life showed, a slight change of scale can lead to apparent miracles, such as the insects that can walk up glass walls or support hundreds of times their own weight and shrug off equally outsized falls. Who knows, preservation or research into some of our small-scale friends might lead to considerable benefits too, as with the recent discovery of the immensely strong silk produced by Darwin's bark spider Caerostris darwini. Expanding our horizons isn't difficult, it just requires the ability to look down now and then and see what else is going on in the world around us.

Back to nature: why saving other species could save mankind

Humanity has come a long way from reliance on biologically-derived materials such as wood, bone, antler and fur. Yet this doesn't mean that organic materials have been replaced or many respects surpassed by wholly artificial ones. There are of course new carbon-based materials such as 3D graphene and carbyne that may prove to be the 'ultimate' materials when it comes to properties such as strength, but the history of the past century has shown how natural substances can inspire research too.

Perhaps the most obvious example of this is the hook and loop fastener best known by the trademark Velcro, which is essentially a copy of the burr design on Arctium (burdock) plants. Considering that taxonomists disagree wildly on the global totals of current plant, animal and fungi species - many claiming that less than 20% have been scientifically classified - it seems apparent that nature has plenty more surprises up her sleeve.

Spider silk has long been recognised as an incredibly strong material for its weight, with that generated by many species being up to five times the strength of the equivalent amount of steel. The silk produced by the Madagascan Darwin's bark spider (Caerostris darwini) is ten times stronger than Kevlar, suggesting that bullet-proof clothing manufacturers could do well by investigating it. However, a discovery by an engineering team at Portsmouth University in the UK makes even this seem humdrum: the teeth of limpets are potentially so strong - thanks to a mineral called goethite - that artificial versions of them could be used in high-performance situations, even aircraft components.

In addition to their use in construction, natural substances may prove useful in the development of new pharmaceuticals. I've previously discussed animal defence mechanisms such as that of the bombardier beetle and how small, barely noticed critters such as the peripatus deserve far more investigation. Of course the problem has been that size and aesthetics directly correlate with public attention and newsworthiness, meaning that the likes of the giant panda are used as poster species despite offering little in the way of practical advance for science and technology.

I'm not of course suggesting that species should be judged on the merits of their usefulness to humanity, but that we could probably gain a lot of practical usage from much greater study of the less well known flora and fauna still 'out there'. The resilience of tardigrades is becoming fairly well known, but there are no doubt other seemingly insignificant species with even more astonishing properties. Hydra for example are small, tentacled animals that live in fresh water; thanks to being composed mostly of stem cells they appear to have life cycles that just keep going. There also been limited research on the 'immortal' jellyfish Turritopsis dohrnii; this is surprising, given that the advances in gene splicing technology such as CRISPR-Cas9 and TALEN might lead to important medical breakthroughs, not just glow-in-the-dark pets.

In addition, the race to generate new antibiotics to replace those ineffective against 'superbugs' would suggest any short-cuts that can be taken should be taken. I remember watching a 2006 British murder mystery programme in which people were killed during a hunt for rare South American seeds containing anti-malarial properties. This may be pure fiction, but considering that artemisinin-resistant 'supermalaria' is now on the horizon, the script was somewhat prescient.

The idea behind all this is simple: delving into an existing complex chemical compound is far easier than trying to generate a purely synthetic one from scratch. This is why it is important to conserve small and insignificant species, not just the pandas, elephants and rhinos. Who's to say that a breakthrough medicine or construction material isn't already in existence, just hiding around the corner (or rather, in the genome) of some overlooked species of animal, plant or fungi?

With superbug-beating pharmaceuticals and climate mitigation technology a priority, we're shooting ourselves in the foot if we let an increasing number of unconsidered species became extinct. As I discussed last month all sorts of organisms are now in serious trouble from global amphibian populations via North American snakes and bats to the mighty kauri trees of New Zealand. Just saving a few specimens of doomed species in freezers or formalin is unlikely to be enough: shouldn't we endeavour to minimise species loss for many reasons; and if we must have an economic motive, what about their potential benefit to mankind? Not for nothing has nature been deemed 'the master crafts(person) of molecules' and we lose volumes in that library at own expense.

Amphibian Armageddon and killed-off kauri: the worldwide battle against fighting fungi

I recently wanted to visit the Ark in the Park, an open sanctuary in the Waitakere Ranges west of Auckland that uses constant predator control to protect native plants and animals. However, I was stopped by a sign stating that Te Kawerau a Maki, the Maori of the district, have placed a rāhiu or prohibition on entering the forest. Although not legally binding, the rāhui is intended to stop people walking through the area and spreading infection, serving in place of any notice by the New Zealand Government or Auckland City Council, since the latter two bodies have failed to take action. Perhaps this inactivity is because the infection does not directly affect humans or farming. Instead a fungus-like pathogen is killing the native kauri Agathis australis, one the largest tree species on Earth.

Known to live for over a thousand years and grow to over fifty metres tall, the largest kauri are seen by Maori as the lords of New Zealand's northern forests. Yet since 2009 the microscopic water mould Phytophthora agathidicida has been causing kauri dieback at an ever-increasing rate. Surveys in the Waitakeres show that most of the infected areas are within ten metres of walking paths and therefore the mould is being spread by visitors to the lowland forests who fail to thoroughly clean their shoes with the supplied disinfectant spray. In a truly David versus Goliath battle between the miniscule mould and giant trees, introduced species such as possums and pigs are aiding the former by accidentally spreading the minute spores.

Auckland Council reported last winter that the amount of affected kauri has reached 19 percent, meaning a doubling in scale in only five years. Since there is no cure for infected kauri, some scientists are now predicting the extinction of this magnificent tree in the near future. The combination of the pathogen's microscopic size with its rain-based activation after dormancy means there are currently no methods that can prevent the infection from spreading. In a way, the rāhui may just slow down the inevitable. Considering the immense kauri are home to a unique ecosystem of epiphytes, orchids and associated symbiotic organisms, the future flora and fauna of kauri-free forests may well be markedly different from the Waitakeres as they are today.

I've previously discussed the ubiquity of the unsung fungi and how prominent they are even within totally man-made environments. It seems surprising that New Zealand's authorities, so keen to preserve native birds and reptiles, are failing to take any action to at least buy time for the kauri; perhaps they have already deemed extinction as unavoidable and not worth spending public funds on.

The kauri are far from being the only organisms currently threatened by fungi or their kin. Over the past decade more than thirty snake species in the eastern and mid-western United States have started succumbing to what has been termed Snake Fungal Disease. The culprit is thought to be a soil-based fungus called Ophidiomyces ophiodiicola, with a similar organism now also thought to be affecting snakes in the United Kingdom and mainland Europe. Research suggests that up to ninety percent of infected snakes die from the condition, so clearly if humans and their vehicles play unwitting hosts to the microscopic fungal spores, the future for the world's snake population looks depressing. Although many people might not like snakes, ecosystems without them may see an explosion in the numbers of their prey animals, including rodents; to say the least, this would not bode well for crop farmers!

Perhaps the best-known of the global fungal-caused epidemics is the amphibian-decimating Chytridiomycosis, whose affects were initially recognised twenty years ago but may have started much earlier. As its spores can live in water, the responsible Batrachochytrium fungi are ideally situated to infect about one-third of all frog, toad, newt and salamander species. Again, it is thought that man has inadvertently caused the problem, as the African clawed frog Xenopus laevis is an immune carrier of the fungus and has been exported worldwide since the 1930's.

Another contributor may be climate change, as amphibian-rich forests experience temperature variations that are ideal for the chytrid fungi to proliferate in. As a final nail in the coffin - and as with bees and Colony Collapse Disorder - pesticides may play a key role in the epidemic. Agrochemicals are shown to lower the amphibian immune response and so increase their susceptibility to infection. However, the situation isn't completely hopeless: here in New Zealand, researchers at the University of Otago have used chloramphenicol, an antibiotic eye ointment, to cure infected Archey's frogs (Leiopelma archeyi). This species is already critically endangered even without the chytrid epidemic; hopefully, the cure will prove to be the saviour of other amphibian species too. This would be just as well, considering the dangerous side effects found in other treatments such as antifungal drugs and heat therapy (the latter involving temperature-controlled environments that are lethal to the pathogen).

During the past decade, over five million North American bats have been killed by white-nose syndrome, which is caused by the fungus Pseudogymnoascus destructans. Again, humans have inadvertently spread the pathogen, in this case from Eurasia, where the bat species are immune to it, to North America, where they are most definitely susceptible. The bats are only affected during hibernation, which makes treating them difficult, although brief exposure to ultraviolet light has been shown to kill the fungus. This may prove to be a cure to infected colonies, although how the UV could be administered without disturbing the cave-roosting populations will take some figuring out.

It appears then that a combination of manmade causes (international travel, climate change and chemical pollution) is creating a field day for various tiny fungi or fungus-like organisms, at the expense of numerous species of fauna and flora. The culprits are so small and pervasive that there is a little hope of preventing their spread. Therefore if conventional cures cannot be found, the only hope for the likes of the kauri might be the use of genetic engineering to either give the victim resistance or to kill off the pathogen. This science fiction-sounding technology wouldn't be cheap and its knock-on effects unknown – and potentially disastrous. The former technique would presumably not be any use to the existing populations, only to the germ line cells of the next generation. Whatever happens, our short-sighted approach to the environment is certainly starting to have major repercussions. A world without the magnificent kauri, not to mention many amphibian, reptile and mammal species, would be a much poorer one.

Valuing the velvet worm: noticing the most inconspicuous of species

Most of the recent television documentaries or books I've encountered that discuss extra-terrestrial life include some description of the weirder species we share our own planet with. Lumped together under the term 'extremophiles' these organisms appear to thrive in environments hostile to most other life forms, from the coolant ponds of nuclear reactors to the boiling volcanic vents of the deep ocean floor.

Although this has rightly gained attention for these often wonderfully-named species (from snottites to tardigrades) there are numerous other lifeforms scarcely noticed by anyone other than a few specialists, quietly going about their unassuming business. However, they may provide a few useful lessons for all of us, including that we should acknowledge there may be unrecognised problems generated when we make rapid yet radical modifications to local environments.

There is a small, unassuming type of creature alive today that differs little from a marine animal present in the Middle Cambrian period around five hundred million years ago. I first read about onychophorans in Stephen Jay Gould's 1989 exposition on the Burgess Shale, Wonderful Life, and although those fossil marine lobopodians are not definitively onychophorans they are presumed to be ancestral. More commonly known by one genus, peripatus, or even more colloquially as velvet worms, there are at least several hundred species around today, possibly many more. The velvet component of their name is due to their texture, but they bear more resemblance to caterpillars than to worms. They are often described as the ‘missing link' between arthropods and worms but as is usually the case this is a wildly inappropriate term in this context of biological classification. The key difference to the Burgess Shale specimens is that today's velvet worms are fully terrestrial: there are no known marine or freshwater species.

Primarily resident in the southern hemisphere, the largely nocturnal peripatus shun bright light and requiring humid conditions to survive. Although there are about thirty species here in New Zealand, a combination of their small size (under 60mm long) and loss of habitat means they are rarely seen. The introduction of predators such as hedgehogs - who of course never meet peripatus in their northern hemisphere home territory - means that New Zealand's species have even more to contend with. Although I frequently (very carefully) look under leaf litter and inside damp logs on bush walks in regions known to contain the genus Peripatoides - and indeed where others have told me they have seen them - I have yet to encounter a single specimen.

There appears to be quite limited research, with less than a third of New Zealand species fully described. However, enough is known about two species to identify their population status as 'vulnerable'. One forest in the South Island has been labelled an 'Area of Significant Conservation Value' thanks to its population of peripatus, with the Department of Conservation relocating specimens prior to road development. Clearly, they had better luck locating velvet worms than I have had! It isn't just the New Zealand that lacks knowledge of home-grown onychophorans either: in the past two decades Australian researchers have increased the number of their known species from just seven to about sixty.

Their uncanny resemblance to the Burgess Shale specimens, despite their transition from marine to terrestrial environments, has led velvet worms to be described by another well-worn phrase, 'living fossils'. However, is this short-hand in any way useful, or is it a lazy and largely inaccurate term? The recent growth in sophisticated DNA analysis suggests that even when outward anatomy may be change little, the genome itself may vary widely. Obviously DNA doesn't preserve in fossils and so any such changes cannot be tracked from the Cambrian specimens, but the genetic variation found in other types of organisms sharing a similar appearance shows that reliance on just external anatomy can be deceptive.

Due to lack of funding, basic taxonomic research, the bedrock for cladistics, is sadly lacking. In the case of New Zealand, some of the shortfall has been made up for by dedicated amateurs, but there are few new taxonomists learning the skills to continue this work - which is often seen as dull and plodding compared to the excitement of, for example, genetics. Most people might say so what interest could there be in such tiny, insignificant creatures as peripatus? After all, how likely would you be to move an ant's nest in your garden before undertaking some re-landscaping? But as shown by the changing terminology from 'food chains' to 'food webs', in most cases we still don't understand how the removal of one species might generate a domino effect on a local ecosystem.

I've previously discussed the over-reliance on 'poster' species such as giant pandas for environmental campaigns, but mere aesthetics don't equate to importance, either for us or ecology as a whole. It is becoming increasingly clear that by weight the majority of our planet's biomass is microbial. Then come the insects, with the beetles prominent both by number of species and individuals. Us large mammals are really just the icing on the cake and certainly when it comes to Homo sapiens, the rest of the biosphere would probably be far better off without us, domesticated species aside.

It would be nice to value organisms for themselves, but unfortunately our market economies require the smell of profit before they will lift a finger. Therefore if their usefulness could be ascertained, it might help generate greater financial incentive to support the wider environment. Onychophorans may seem dull, but there are several aspects to them that is both interesting in itself and might also provide something fruitful for us humans.

Firstly, they have an unusual weapon in the form of a mechanism that shoots adhesive slime at prey. Like spider silk, is it possible that this might prove an interesting line of research in the materials or pharmaceutical industries? After all, it was the prickly burrs of certain plants that inspired the development of Velcro, whilst current studies of tardigrades (the tiny 'water bears' living amongst the mosses) are investigating their near indestructability. If even a single, tiny species becomes extinct, that genome is generally lost forever: who knows what insights it might have led to? Although museum collections can be useful, DNA does decay and contamination leads to immense complexities in unravelling the original organism's genome. All in all, it's much better to have a living population to work on than rely on what can be pieced together post-extinction.

In addition, for such tiny creatures, velvet worms have developed complex social structures; is it possible that analysis of their brains might be useful in computing or artificial intelligence? Of course it is unlikely - and extinction is nothing if not natural - but the current rate is far greater than it has been outside of mass extinctions. Losing a large and obvious species such as the Yangtze River dolphin (and that was despite it being labelled a ‘national treasure') is one thing, but how many small, barely-known plants and animals are going the same way without anyone noticing? Could it be that right now some minute, unassuming critter is dying out and that we will only find out too late that it was a vital predator of crop-eating pests like snails or disease vectors such as cockroaches?

It has been said that ignorance is bliss, but with so many humans needing to be fed, watered and treated for illness, now more than ever we need as much help as we can get. Having access to the complex ready-made biochemistry of a unique genome is surely easier than attempting to synthesise one from scratch or recover it from a long-dead preserved specimen? By paying minimal attention to the smallest organisms that lie all around us, we could be losing so much more than just an unobtrusive plant, animal or fungus.

We can't save every species on the current endangered list but more attention could be given to the myriad of life forms that get side-lined by the cute and cuddly flagship species, usually large animals. Most of us would be upset by the disappearance of the eighteen hundred or so giant pandas still left in the wild, but somehow I doubt their loss would have as great an impact on the surrounding ecosystem than that of some far less well known flora or fauna. If you think that's nonsense, then consider the vital roles that bees and dung beetles play in helping human agriculture.

Although the decimation of native New Zealand wildlife has led to protective legislation for all our vertebrates and a few famous invertebrates such as giant weta, the vast majority of other species are still left to their own devices. That's not to say that the ecosystems in most other countries are given far less support, of course. But without funding for basic description and taxonomy, who knows what is even out there, never mind whether it might be important to humanity? Could it be that here is a new field for citizen scientists to move into?

Needless to say, the drier climes brought on by rising temperatures will not do peripatus any favours, thanks to its need to remain in damp conditions. Whether by widespread use of the poison 1080 (in the bid to create a pest-free New Zealand by 2050) or the accidental importation of a non-native fungus such as those decimating amphibians worldwide and causing kauri dieback in New Zealand, there are plenty of ways that humans could unwittingly wipe out velvet worms, etal. So next time you watch a documentary on the demise of large, familiar mammals, why not spare a thought for all those wee critters hiding in the bush, going about their business and trying to avoid all the pitfalls us humans have unthinkingly laid for them?