Given the many problems caused by humans to the various species living on Pacific Islands, their rapid decline seems inevitable, but to a degree this process was happening naturally, long before we showed up. Such losses and gains were, and still are, dependent upon many factors, but as a general rule, smaller islands exhibit a greater turn over than do larger islands; and the arrival of man has now pushed the losses to the level of a major extinction event, with both New Zealand and Hawaii exhibiting clear examples of the problem.
I mentioned Hawaii’s carnivorous caterpillars in a previous article, and do so again because they are such a great example of the unusual directions that evolution can take on islands largely isolated by distance. So far as we know, meat eating caterpillars occur only on the islands of Hawaii.
How plants and animals get to be on a remote island in the first place depends on several things: the size and topography of the island, and its position in relation to other nearby islands is important; as is the distance these islands are from major land areas that might act as starting points for new arrivals, and this is critical both to what will arrive and how frequently; any organism capable of parthenogenesis (the development of embryos without the need for fertilisation) will have a better chance of getting started than will animals that require both males and females for reproduction.
Each and every island has a unique story held in its geology. Consider Australasia – around a 100 million years ago this huge land mass separated from Godwana (which was at the time a supercontinent). The split from Antartica happened between 37 and 35 million years ago as it moved northward. The land that would eventually be New Zealand started moving away from the larger mass we now call Australia between 60 to 85 million years ago.
It is possible thatNZ once formed part of a drowned continent, but for the millions of years the two main islands have remained above water in one form or another, extensive changes have occurred — including climatic extremes which will have eliminated many life forms.
Initially, when New Zealand sat alongside Australia, both were set in the same sub-tropical waters and in consequence had similar floras, but as the two separated, the sea flooded into the rift between them and formed the Tasman Sea. In consequence the New Zealand flora became isolated and new species began to evolve.
For the last 55 million years N.Z. has held its current position at around 2,000 kilometres to the south-east of Australia and experiences a much cooler climate than it once did, but ironically it now appears to be moving slowly back.
Apart from a few marine mammals and a couple of bat species, no other mammals have survived on these islands;
and none managed to colonise successfully until the arrival of Polynesian settlers less than a thousand years ago; this was followed by a second wave of mammalian competitors that came along with Europeans when they began settling little more than 250 years ago, with dire consequences to the established native species.
Prior to the arrival of humans and their entourage of plants and animals, New Zealand had been populated by a very distinctive flora and fauna that developed in isolation of the many mammalian predators evolved elsewhere. A European botanist arriving for the first time might initially consider that they had landed on another planet, because the invertebrates, amphibians, reptiles and birds that fill the niches taken up by mammals elsewhere, are so extraordinary.
New Zealand has been around for some time, but the Hawaiian Islands were formed far more recently and exclusively by volcanic activity — they quite literally erupted from the depths of the mid-Pacific and are about as remote from any other land area as it is possible to be. The first island, Kaui, started to push above water around 5 to 6 million years ago and is now the most westerly island in the chain. To the east at the opposite end is the Big Island (Hawai’i), and at less than a million years of age is still volcanically active.
Hawai’i is not huge, but nevertheless, it is big in comparison with the other islands in the chain. At around 10,500 square kilometres it is larger than the rest of the Hawaiian Islands put together, making up more than 60% of their total landmass.
Once the islands were formed, the possibility of a new plant or animal arriving on these tiny specks in the Pacific Ocean became a lottery. Miss the islands by only one mile or by a thousand, and the result would be the same — oblivion. Small organisms produced in large numbers will have had the best chance of arriving, with spores, seeds and tiny creatures the most likely candidates to be carried successfully on mid-altitude air currents to land against the odds on distant islands, although most of course will have perished.
Some species might have arrived carried across the surface of the ocean on any material that could stay afloat long enough to make landfall, but again the attrition rate would have been high and the chances of success slim.
It was a long shot that birds would arrive on Hawaiian Islands at all, given the distances involved, but when it did happen they would most likely have been carried on mid-altitude air currents. It is quite possible that only one or a small number of finch species arrived to become the honey creepers that radiated out across the Islands filling different habitats as they evolved into the 56 species that have been recorded, 18 of which are now extinct.
Long before humans developed the brains they have today, a great many other animals had already evolved co-ordinated nerve centres completely effective in directing their everyday lives.
In ‘Before We Had Brains 1’, I considered what might have been our earliest vertebrate ancestor – probably a worm-like creature that lived in the sea; and before that we must have passed through a variety of preceding invertebrate stages – it’s been a long road. Almost as extraordinary is that while we were on the evolutionary march from comparative simplicity to our present complexity, many other animals hardly changed at all.
Once a species has adapted through the evolutionary process to an environment that remains fairly constant, there is no advantage to making further dramatic changes. What is certain is that while animals on our branch of the tree were evolving more complex nervous systems, many invertebrates were sticking with something quite different.
The model for a brain-like structure at the front end – common to all vertebrates – was laid down in invertebrates millions of years ago, but many also evolved multiple masses of ganglia to control body functions in a manner very much different from our own.
The well developed nerve ganglia at the head end is close to organs such as ears, eyes and antennae that have developed to receive incoming information. But other masses of nerve ganglia have also developed along the main nerve that runs the length of the body – additional mini-brains if you like – that co-ordinate different parts of the body. Sensory information is also picked up in ways that we would consider unusual – grasshoppers for example can hear through their knees and pollinating insects see patterns on flowers in the ultraviolet range. These are inputs that we have no direct experience of and in consequence sometimes find difficult to comprehend.
The large and varied Phylum Arthropoda contains animals with external skeletons and segmented bodies with jointed limbs paired in keeping with their bilateral symmetry; they include the Arachnids (spiders and scorpions), Myriapods (centipedes and millipedes), Crustaceans (crabs, lobsters and woodlice) and last but not least – Insects; and all have a very different arrangement of their nervous systems than we do.
Arthropods have become extremely successful, forming a major part of life on Earth, and it is a surprise that we so often view them as aliens – the templates for creatures formed in our wildest imaginings; the sort of things that regularly crop up in our sci-fi stories, and usually portrayed as agressive invaders from another world.
With the millions of nervous systems available, it seems a poor effort to display only one, but I have chosen an example that in general form covers many other insects – it belongs to a grasshopper, and I also have a story to tell.
As a zoology student I frequently glimpsed the internal structure of the grasshopper’s big brother – the locust, and this provided at least a rudimentary understanding of the insects behaviour in relation to its nervous system – or at least as good an understanding as is possible for one who has only one brain.
Way back when I was a zoology student, our college expected everybody to work hard for a degree, but on occasions I didn’t feel inclined to fill every waking hour with study, and having finished a series of experiments on how insects see, didn’t feel inclined to attend through a Friday afternoon. As an impetuous ‘know it all’, I felt every aspect of the subject had been adequately covered; as did my co-worker, another student, who just like me, wanted to broaden his educations beyond grasshopper behaviour.
Our university was in London and not too far from The British Museum where a Tutankhamun exhibition was about to end. It would probably never leave the Cairo Museum again and as the world shouldn’t revolve around insect brains (although judging by their numbers, it probably does), we decided to take the afternoon off and visit the exhibition.
Once out of the lab we’d simply make up a thought experiment like a couple of Victorian armchair naturalists. Our experiments had already shown us that if the image of a sharp edged object – such as a blade of grass – passed rapidly across the compound eye of a grasshopper, the insect would react by jumping. We knew that the hopper would react to a sharp curved edge because that’s the way grass leaves are, but we took it a stage further bytheorising that evolution would first and foremost select for a sharp straight edge over a curved one because the former would provide a stronger stimulus when it moved across an insects compound eye, firing off neurons more effectively.
The experimental set up we’d been using all week was a simple one – a bit like a super sized hampster wheel on its side with regular grass shaped incisions cut into its rotating surface. The wheel could be spun around at various speeds with the hopper sat at the centre. But of course we had no plans to actually test our theory using it. We would instead set off for the museum and write the thing down on a scrap of paper as we travelled on the underground. Rather unsurprisingly… our theory turned out to be spot on, with a 15% increase in the grasshopper’s reaction to a straight edge over a curved edge. It was then a simple process to work our figures backwards and even devise a statistical test to make sure our results were significant, rather than a matter of chance. Clearly something new and quite fictitious had been added to the pantheon of scientific discovery; satisfied with our work, we went on to join the queue outside of the Museum, and once inside, had a great afternoon in what seemed a fantasy world almost as impressive as the one we had just invented.
The experiment was written up a few days later and submitted. We thought no more about our harmless deception, until a couple of weeks later our supervisor stopped us in a corridor to congratulate us on our work and insisted that we must submit the findings to a major scientific journal….. Now, if our brains had been working as efficiently as our make believe grasshopper then we might have seen this coming. Terrific we said, but of course we’d have to repeat the experiment to be absolutely certain. I’ve always been hopeless with repeats, all my experiments seemed to invalidate earlier results, usually because I didn’t stop when I was ahead – even though one might expect a pretty clear result with an insect brain, my own brain was less well organised. We never repeated anything of course. Utilising the same thought experiment, we quickly discovered that we couldn’t repeat the results, much to the disappointment of our supervisor. For us, it was a great relief to get off the hook, because nobody wants to start their scientific careers as fraudsters – any scientist so inclined probably needs to work up to it.
The important thing about our non-existent laboratory experiment was that the details were convincing because we had a fair idea of how a grasshopper’s brain might interpret what it’s eyes saw, because the hopper wasn’t thinking about very much, it was simply reacting to a visual stimulus.
It is usually possible to gauge how good an animals eyesight is by simply looking at the eyes – size is always important even with a compound eye, which sees things very much differently from a vertebrate eyes, even though there are similarities in the neural process. For any who have looked inside a grasshoppers head, it is clear from the amount of nerve material dedicated to the eyes and brain in this region, that this must be true.
But what about those other nerve ganglia along the body. For any who have undertaken experiments more thoroughly than I have, it is clear these centres co-ordinate a variety of bodily functions without reference to an anterior brain. I don’t advocate nasty experiments, but a cockroach without a head, and with the rest of the body sealed off with a blob of wax, will run around for several days… and it is noteworthy that you didn’t get that so much with Anne Boleyn.
Success then, is not always about the complexity of a system, it is about appropriateness to a situation; despite millions of years of appearing to show very little change, most insect nervous systems have had plenty of time to fine tune to specific environmental circumstances.
Arthropods may appear rather odd looking, but there is no doubt their bodies are fit for purpose, even though we might consider an insect’s level of complexity no match for our own. Sadly, the truth is they might well survive some environmental disasters that we cannot.
It is presently too soon to judge ‘us’ a major success because our tenure has been short in comparison with many simpler forms that have existed for many millions of years; and stood the test of time.
So, which of the vast number of present invertebrate survivors display the most sophisticated nervous systems. Certainly Crustacea such as crabs and Arachnids such as spiders show interesting refinements in behaviour, and this often includes impressive courtship displays, none of which can occur without a finely tuned nervous system.
The forelimbs of many also become more developed and used as pincers for defence and males sometimes wave them about during complex courtship displays to impress females; all of which requires a refined nervous system even within certain limitations. A lot of what a crab does is automatic and not a lot of neural activity is devoted to thinking. Crabs exist without philosophical thought. Rene Descartes said, ‘I think therefore I am’, but crabs are not well equipped to think about uses very much; their modi operandi makes them look like creatures with attitude, but b.s.ing is beyond them – sometimes neurological limitations are not such a bad thing.
Perhaps the most impressive invertebrate nervous system belongs to the octopuses. They are Cephalopods and part of the Mollusc family. It is difficult to watch a slow moving snail and consider this as a relative of such a fast moving intelligent creature. By any standards an octupus is a clever animal able to solve complicated problems. Some species have phenomenal eyesight, equipped as they are with eyes similar in structure to our own, these are often as big, or even bigger than their ‘brains’. Octopuses are exceptional at co-ordination and can change colour rapidly to match their surroundings. None of which could be done without a complex nervous system.
The octopus nervous system contains as many as 500 million neurons with three fifths of this neural mass distributed in the tentacles. The brain is a lobed and compex in structure with substantial computing ability – and this is a creature that also has a good memory.
The question is; with this well organised neural arrangement, does an octopus watch its own arms and wonder what they are up to as they go about doing their own thing, or is the main brain informed of every movement? Because our nervous system is ordered with a single brain doing all of the thinking, it is difficult for us to understand an animal with it’s thinking power distributed so widely throughout the body.
When it comes down to it, there is no need to invent strange alien like creatures, because we have plenty of extraordinary looking animals on Earth already, and many of which analyse their surroundings very much differently from the way that we do, using ultraviolet, sonar, magnetic and other sensory processes and many catch aspects of the world that we cannot. The strangest of creatures are already here – it is just a question of paying attention to them because in the grand scheme of things, we probably can’t do without them.
We should take photographs of all of the life that Planet Earth has to offer – even the small and seemingly insignificant forms because all have gone through a great many trials to survive millions of years of evolution. We owe it to them and to ourselves to pay more attention to the life that is around us; to notice and photograph as many species as we can, especially the ones that don’t immediately grab our sympathy or attention. All are fundamental to the success of natural environments and world ecosystems will ultimately suffer if they are lost. We need to record as many as we can, because species are now disappearing from the world at an alarming rate, many of them unknown to science. This is a sad state of affairs. So, ‘Take a picture and Save the Planet’, or at the very least, help to make a record of what might soon be lost to us.
Next time: The Human Brain – Are We Too Stupid to Save the Planet?
On a recent visit to Hawaii, I hardly saw any native wildlife, a stark reminder that things haven’t improved since I first came to film for the B.B.C. back in the early 1980s.
Thirty five years ago I made my first visit to Hawaii at a time when travelling to distant tropical islands from the U.K. was considered exotic. In those days, you’d emerge from a plane into the shimmering light and once down the gangway steps walk to the terminal building with the heat of the sun bouncing beneath your feet like a playful pet; and just as you were beginning to appreciate that life was all the better for being here, smiling girls in traditional dress would come out to greet you and place flower leis around your neck.
But things have changed… the sun still shines, but on more recent visits I couldn’t fail to notice that the girls were no longer present – the Honolulu Airport terminal is bigger now, reflecting that there are many more travellers coming to Hawaii and if every visitor was still receiving a traditional floral greeting, the islands would pretty soon be clean out of flowers.
People still smile though, and the pace of life is slower than many of us are used to; pretty soon you feel relaxed because it’s difficult to find these islands anything other than enchanting, but my first couple of visits were not the magical encounters with paradise that I had imagined – mostly I was filming ten hours a day in a laboratory at the University of Hawaii. I’d been sent by the B.B.C. to film a variety of tiny creatures and two oddities in particular – both spectacularly unusual carnivorous moth caterpillars.
Anything that has a sensory rear end that alerts to an approaching fly and then flips its front end over backwards to grab the unwitting insect in its jaws in a mere fraction of a second is a real attention grabber, but the little critters are just so small and well camouflaged, that if you didn’t know they were there, they’d might just as easily be another twig on the tree.
Where else but in Hawaii could you find an insect so clearly associated with feeding on leaves that has switched to eating insects? And not just any insects, in this case Hawaiian fruit flies that have evolved to become spectacularly large, but nevertheless will go down twitching as they are eaten alive.
Hawaii is an extended chain of islands which has formed over a mid-Pacific hot spot of volcanic activity, roughly equidistant between Eurasia and the Americas; and to get to either requires an approximate two and a half thousand mile journey either east or west across the Pacific Ocean. It was this creation of land by fire combined with a perfect storm of circumstances that allowed for the evolution of so many unique and unusual lifeforms.
These Islands might be regarded as a natural laboratory for the study of evolution, and if Charles Darwin had landed here rather than on the Galapagos Islands he would have come to similar conclusions about how species evolve when separated from their relatives on distant mainlands, and even from those isolated on different islands… but Darwin would have needed to be paying attention (clearly one of his strengths), because many of the animals concerned are small invertebrates, such as spiders, insects, crustaceans and molluscs.
Certainly limited numbers of creatures would have made it to the islands to start the evolutionary ball rolling and no large animals were amongst them – other than those that could swim here – turtles for example, and they never get further than the beach. Consequently no native reptiles, amphibians or mammals ever made it to the islands until their arrival alongside man, either as stowaways or transported intentionally, with frequently disastrous consequences to the native flora and fauna.
Small arthropods such as insects, spiders and crustaceans will most likely have arrived on floating vegetation, the lucky winners hitting this narrow window of opportunity, whilst the majority missed the jackpot and drifted on across the world’s largest ocean to become lost at sea.
The initial arrivals had the advantage of making landfall on uninhabited islands which provided a variety of empty niches ready to move into – and those that managed to adapt to their new circumstances would have radiated out into different habitats to eventually form species that were unique.
The habitats available for life in Hawaii were varied, and included not only forest, grass and wetlands, but also larvae flows, deserts, beaches and caves – all of these would become populated by invertebrates; there is even an small creature (the wekiu bug) that lives at altitude, sucking the juices of insects that have been caught up and preserved in snow and ice to be released many years later as frozen dinners along the thaw line of Mauna Kea, a dormant volcano and the highest point in Hawaii.
One species peculiar to the Islands is the happy-face spider, which derives its name from an apparently smiling face on the upper side of its abdomen; this tiny spider mostly lives and hunts on the underside of leaves and despite its size is visuality impressive.
The morph shown below is the one most commonly seen, but there are a variety of others that have extraordinary clown faces on their rear ends and you might want to Google ‘ happy face spider images’ to see more impressive examples. The spiders have made it onto four Hawaiian islands but are not yet on Lanai, nor have they managed to get as far west as Kauai.
It appears that almost everything that arrived in Hawaii evolved into something special… but then man arrived and the party was over, which is a sad but familiar story!
The islands by dint of their remoteness have undergone extraordinary speciation in the absence of too many predators or competitors, but once these were brought in from elsewhere, many native species were immediately threatened. Indigenous plants and animals have become well adapted to their circumstances but they have not evolved appropriate defences against the onslaught of the new invaders. And so it was, that species in existence for millions of years, were snuffed out by the newcomers like candles in the wind.
Many of the new arrivals were so closely associated with man and his agriculture that with the additional advantage of a perfect climate they thrived in their own little paradises within paradise – and from there ventured out to invade other places on the Islands.
The first aliens will have come in with the Polynesians between 300 and 500 A.D. Then the Europeans showed up; it is possible that the Spanish arrived a couple of hundred years before Captain Cook made landfall in 1778, but it is Cook that we remember because he claimed the Islands as British territory, which now counts for little more than the hoisting of an interesting union flag colonial combo.
The islands were named after Cook’s sponsor, the 4th Earl of Sandwich – the very same Earl who found himself disinclined to leave a gambling table and suggested to staff that they bring him food conveniently held between two pieces of bread… the rest of course is history… as is the case for the naming of the Sandwich Islands which later reverted to their more appropriate Polynesian name – or at least a close approximation to it.
Colonisation would be instrumental in the devastation of many indigenous species causing the rapid degradation and destruction of habitats; this combined with alien introductions became the driving force for many island extinctions.
It was decided that I would film snails to illustrate the troubles caused by introduced species and I was pleased to be filming at least some of them out of doors. There are many valid reasons for filming animals in their natural environments, but invertebrates are often the exception, usually their behaviour is not much affected as long as their living conditions are adequately simulated.
Prior to the early 1980s film stocks were limiting and a lot of light was required to capture the activity of any small creature in movies. This was just before cold light using fibre optics became widely available, and I had to devise my own water cooling system bolted to the front of lights which required a constant flow of cold water to substantially reduce temperatures. In the years to come I would replace my cumbersome system with cool fibre optic lights; this was really helpful because invertebrates can’t cope with excessive heat, but rarely are they bothered by extra light, and for the best results good lighting was essential.
There is also a moral question as to whether this is truly wildlife photography, but imagine carting all of this gear into the big outdoors to capture perhaps fifty different creatures in various locations across the islands – setting up on steep slopes for example – because hardly any fertile natural environments have escaped cultivation on the flat – and then there are the cave habitats which are a nightmare to get equipment into. Time and budget constraints required everything to be done in a few weeks (and today these constraints are even tighter). There was then little option other than to bring many of the smaller creatures to one place in order to get the job done.
Taking a still flash photo on location is one thing, but filming the very tiny with plenty of light without any vibration has always been a wind up, and there is the additional problem that when visiting delicate environments trampling has to be avoided, along with the possibility of losing invasive species to the wild. Back then, despite all the disadvantages that the real world presented to macro-photography, I still had to establish some environments on wider lenses and in the process was determined to film at least some of the native snails in the big outdoors.
I was once embarrassed to lose a large tortoise whilst filming in Africa – it made off (across its natural habitat) when I left for a short while to fetch a lens – I had assumed that it wouldn’t get too far, but of course, tortoises run at breakneck speeds when you stop watching them.
I learnt a valuable lesson… but even at my most inattentive, I thought it unlikely that I could misplace a snail, not even a well camouflaged individual, but the truth is, it’s easy to lose sight of almost any snail by simply looking away… and given half a chance they’ll dash off and hide under a leaf when you do. Living in a small world – your perspective on life changes and when you’re not worrying about snails rushing off to hide, you’re worrying about the fact that some move so slowly they won’t register as moving at all in real time. But of course, things could have been worse… ants are always in such a rush, so it was great to discover that there are thought to be no native ants living on the Islands at all.
Until recently Hawaii held the most diverse representation of land snails anywhere in the world, but since the arrival of humans it is likely that around 75% have become extinct. Habitat loss will have played a part, but many have been eaten out by introduced predators, in particular predatory snails.
After the African land snail Achatina fulica was introduced – it’s a monster and ends up elsewhere either as a food source or as a pet – it soon became clear that the newcomer was munching its way through the Hawaiian natives, and so another predator was introduced from Florida – the rosy wolfsnail (Euglandina rosea) to control it – and there wouldn’t be much of a story unless the new arrival had set about the native snails even more ferociously than the problem snail it had been brought in to eliminate, which of course it did, reducing native species even further, and pushing some to extinction… This was without doubt a ‘doh!’ of Homer Simpson proportions.
It is clear that when humans get environmental issues wrong, they make a really great job of it, and often eliminate species that have evolved to become spectacularly different from anything else on the Planet. The problem is, that when this happens to invertebrates… hardly anybody notices.
It is the larger cuter animals that usually grab our attention, but when it comes to extinction we need to consider the smaller things in life, because if we include them, the losses that are presently occurring on a worldwide scale indicate that we may be entering a mass extinction event. Long term, this makes no difference to the Planet, but species diversity remains the best measure of the prevailing conditions for life on Earth and that is an important consideration for all of us.
Our own well being can be gauged by what is disappearing around us, and it is possible that any who travel might at one time or another hit the jackpot, and take a picture of some small creature that is unknown to science. Seeing the bigger picture means looking out for the small stuff, which is one of the best ways to save the Planet… or more precisely… the life upon it.
Next: HAWAII: JUST ANOTHER DAY IN PARADISE. PART 2 – INVASIVE SPECIES.
With thanks to former BBC Natural history producers Richard Brock and Roger Jones who gave me my first opportunity to film the natural history of Hawaii, Ken Kaneshiro for fruit flies and lab space, Frank Howarth for his cave critters and Steve Montgomery who collected many of the specimens for filming; he has been foremost in discovering many new species on the Hawaiian Islands and continues to do great work bringing the uniqueness of island biodiversity to the rest of us.