Showing posts with label peripatus. Show all posts
Showing posts with label peripatus. Show all posts

Tuesday 13 February 2018

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.

Monday 11 September 2017

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?

Sunday 11 August 2013

Birds, bugs and butterflies: attracting nature to your garden

For many years I've tried to attract wildlife to my garden; perhaps there's something extremely relaxing about watching other components of the biosphere go about their business. Even the closest I lived to the heart of London, a largely overgrown garden provided a haven for all sorts of creatures from tiny wrens via boisterous squirrels to the odd, slightly mangy fox. Although I've discussed the behavioural changes seemingly present in urban animals I thought it would be worth exploring the pros and cons of attracting various critters to your garden.

As a child our family supported winter visitors, usually with bread crusts for birds and cow's milk - for some unknown reason - for hedgehogs. I've since learnt that the latter is a very poor choice as hedgehog food, so where the idea came from I don't know. Mind you, much bacon rind is probably too salty for birds, so I wonder how many animals we killed with our kindness! If you want to feed hedgehogs, cat and dog food is apparently among the suitable alternatives. Not that these days we put anything out for the hedgehogs that occasionally appear in our garden, often disappearing behind the wood pile at night when I'm out at the telescope (and startling me with their sudden snuffling). The reason isn't due to being anti-hedgehog, but the food would most likely attract other, less welcome rodents such as rats and mice.

Interestingly, hedgehogs are amongst the survivors brought to New Zealand by acclimatisation societies in the Nineteenth Century, along with many European bird species that also congregate in our garden: sparrows, blackbirds, starlings, song thrushes and various finches. As a side note, it would be interesting to tabulate these against the many imported species that didn't survive their first year in the New Zealand wild, such as robins and emus; clearly, there's some unknown adaption criteria going on here.

One problem I frequently faced in the UK but don't any more is the seemingly inexhaustible ingenuity of squirrels in getting to the content of bird feeders, as described in the post above. However, possums imported from Australia fulfil a similar, if nocturnal role in New Zealand, and are a major pest for numerous reasons. Again, keeping bird food for only birds is a primary consideration. Not that birds don't show cunning when it comes to getting at food: I remember visiting the Zealandia eco-sanctuary near Wellington many years ago and seeing the kaka bush parrot feeding from mini bins opened via foot pedal - that's the parrot's foot, not a human one.

Back to now. So why attract wild animals to your garden? Usually it's a two-way gain - humans watch the antics for minimal expenditure and the fauna get food, shelter or even a bath. It offers children a close up view of nature and the realisation that you don't have to go to zoos and wildlife parks for the experience: nature is all around us. It also introduces them to the diversity of the local biosphere as opposed to just the typical, ‘grand' fauna such as African savannah species or large sharks and rays that are kept in zoos and aquaria. To this end, the UK's Royal Society for the Protection of Birds (RSPB) organised the Big Wild Sleepout last weekend, the idea being to camp in your own garden or at an organised event in order to hear and possibly even see the nocturnal creatures we don't usually come into contact with. I only tend to be outside at night if I'm at the telescope, and must confess to frequently hearing the unmistakeable cry of the morepork, New Zealand's only native owl, but have yet to see one.

Talking of owls, birds are the obvious favourite to attract to your property, since it's easy for them to get around and escape from predators such as domestic cats. According to the RSPB over half of UK adults have fed garden birds. In recent years organisations have started to take advantage of all this previously unrecorded observational data by encouraging the public to submit sighting reports for collation. These projects range from observing familiar creatures such as butterflies and ladybirds, to tracking the growth of invasive species such as New Zealand stick insects in the UK's South West. The RSPB, which is a veteran of collecting such data, utilised a weekend in January this year for their Big Garden Birdwatch, the world's largest wildlife survey.

Following the State of Nature report released in May this year, it sounds like this sort of project hasn't come a moment too soon. The new assessment was compiled by twenty-five British wildlife organisations including the RSPB and makes for a sobering conclusion. It found that 60% of the 3,148 UK species under assessment have declined over the last half century, with slightly over 10% deemed under threat of extinction in the UK. It's impossible to know if the situation is similar in other nations, but such worrying statistics suggest that any help given by the public to aid biodiversity can only be for the better. But as per the hedgehogs and milk example, what other pitfalls are there to befriending fauna?

It is fairly widely known that common foodstuffs such as salted peanuts and desiccated coconut should not be given to birds, but how many people remember to soak white bread before putting it out so that it doesn't swell inside the animals' stomachs? Although you can buy purpose-made bird seed mixtures it is cheaper - and frequently better - if possible to grow a bird-friendly garden yourself. It depends on what species live locally, but some birds like open lawn for insect feeding, others prefer overgrown areas (the goldfinches in my garden are very keen on the latter) whilst other species prefer fruit or nectar direct from the tree or bush.

Silvereyes eating apple

It isn't just birds either: as a child I remember a buddleia bush that attracted at least four species of butterfly whilst here in New Zealand a swan plant (a type of milkweed) plays host to dozens of monarch butterfly caterpillars over the summer. In addition, praying mantises lay their egg sacks on just about any vertical surface in our garden, masonry or timber, so spring sees a profusion of baby mantises heading for undergrowth. The trick is to keep them away from the swan plant; otherwise the caterpillars tend to disappear in their early stages at the expense of the mantises...

In contrast to planting your own, commercial ready-made food mixtures may have large carbon footprints or be grown in developing nations that could better use the land and effort for growing their own food. In addition, messy eaters will cause seeds to drop onto the ground where sterilised seeds can choke native growth and the non-sterilised ones germinate: we once even had a hemp plant that grew several metres in a month or so from some spilt seed!

Therefore having plants or garden layouts that provide food for birds can be as good as leaving out scraps or purpose-bought food. I suppose the main difference with the latter two is that you can place them where you like for ease of viewing. After all, watching birds eat is the primary attraction. Although you can buy bird feeders I prefer to make my own, with a variety of success rates depending on the design. The most popular to date has proved to be table hung from a cherry tree, with half apples spiked on nails attracting a regular stream of silvereyes. Here in New Zealand you can even feed nectar eaters such as tuis via an old wine bottle containing sugar solution.

Bird nectar feeder

One important issue is when you should feed wildlife. The best time of year is obviously winter, when natural foodstuffs are least available. As a general rule, it's probably best to stop feeding once chicks arrive, so that both they and their parents don't start relying on human support. However, in addition to providing food you can also create habitats suitable for assorted wildlife from mammals to invertebrates. As a boy I made a nesting box for a Cub Scout badge, but it was never inhabited, probably being located in too low and too busy a position for birds to consider safe. Today you can buy all sorts of homes and feeders suitable for different species and climates so there's no shortage of easy options. The RSPB recently started supplying a free guide to building animal homes in your garden, ranging from bird box to hedgehog shelter. I can even claim success with my homemade weta motel (current resident: one female tree weta), although it took some time to gain any inhabitants other than numerous, small cockroaches. Note the weta legs poking out of the hole below!

Weta motel

Most of these are generally great aids to wildlife and observing wildlife, although I find the idea of building small ponds not particularly attractive since any standing water in my gardens usually attracts biting insects to lay their eggs in it. When I lived in East London any empty plant pot that collected rainwater swarmed with wriggling mosquito larvae in next to no time. Not nice!

The one thing about this sort of amateur interaction with biology is that you can do as much or little as you like as quickly or slowly as you like, but you are bound to get some form of success. Having said that, there are still plenty of species I'd like to spot in my garden. I have a large pile of volcanic stone that would look good in a far corner of the back garden as a potential lizard home; friends down the road are lucky enough to have skinks and geckos around their grounds. I'm also ever hopeful of various sections of rotting timber serving as home to peripatus -  a.k.a. velvet worm - an ancient form of life that lies somewhere between worms and arthropods. Although I've definitely seen some small white things that might just possibly be very young ones...

Tree weta