Papuina pulcherrima
(Rensch 1931 )

Class: Gastropoda

Family: Camaenidae

Species: Papuina pulcherrima Rensch 1931

English Name: Manus Green Snail

Locality:  Manus Island, Admiralty Islands.

Images: Left: poached from elsewhere on Man and Mollusc
Right: appears several times on the web - origin undetermined.

All over this little ark of life we call "home", the world is currently experiencing the beginnings of a wave of extinctions which could, in the opinions of many concerned scientists, result in as many as half of all the life forms now living on our precious Earth vanishing from the "biosphere" - the living web of life which supports us, but which is under attack on a variety of fronts, by a Rogue Species by the name of Homo sapiens sapiens L. - the "sapiens" part ironically meaning "wise". Lest the reader think this an "alarmist" way to begin this brief article, let me assure you that it is no fantasy cooked up by "pinko environmentalists" for political purposes, but a well established fact that the current rate of species extinctions and estripations (when a species, subspecies or major "race" or species variant vanishes completely from the face of the earth, it is said to have become "extinct".

When a local population similarly suffers the mortality of its last member, the species or variant it represents is "extirpated" or eradicated from the area or region which the population formerly inhabited. These are the most widely known ways which the earth's "bio-diversity" is diminished - bio meaning life or living, and diversity meaning the variation present within that life.

All of the estimated 100 million species of life on our planet, and the countless genetic variations present within them, serve a variety of purposes in the incredibly complex web of life blanketing the earth which we call the "biosphere" (and which has been deified in Greek and popular mythology as "Gaia" - mother Earth).

In "normal times", when the earth's biota is in approximate or rough equilibrium, when a species is extirpated from an area or goes extinct globally, or when biodiversity is otherwise reduced - which occurs when a given population is reduced in numbers to the point where genetic variation is proportionately reduced, this variation is replaced by other life forms, either in the short or the long run, by adaptation, migration or (at the risk of offending any Creationists reading this......) evolution. However, each such reduction DOES have its consequences - for example, if a population of wild wheat was reduced to only a few plants just before it was domesticated by people in that region, and a genetic variant critical to say, rust resistance was lost in the process, then a major food source could have been lost to that region due to a major rust outbreak which the biodiversity-impoverished wheat would have had no defense for.

When the rate of biodiversity reduction becomes greater than a particular portion of the biosphere can collectively adapt to, the results can be drastic and are referred to as "ecosystem collapse" which is characterized by an often dramatic reduction in overall complexity (hence diversity): something which has been observed on at least a few occasions to date, such as the near shore marine ecosystem of the Aleutian Islands. It doesn't take a genius to realize that if enough strands in the complex, very poorly understood matrix of life of the biosphere are either weakened or destroyed, the results could be QUITE dramatic.

Currently, the major threats to the diversity of life on the only planet known to support life in the universe, and the only truly hospitable home our species is likely to have, no matter how many other heavenly bodies may eventually be found which might support us to some extent, are:

1) pollution in general - I won't tire you with a litany of facts here, but even the vast oceans of Earth have been contaminated to an astounding extent, by the millions of chemicals we have invented and poured into our environment at ever-increasing rates. The bodies of top predators such as killer whales and sharks, often contain so much mercury, PCBs, pesticide residue, etc. that their flesh would be classified as "toxic waste" in many countries, and would have to be disposed of in special incinerators or stored in sealed containers.

2) Habitat destruction and degradation: this is most concentrated in precisely the regions where life is at is most varied and lush - such as tropical, subtropical and temperate forests, which are being felled at nearly unbelievable rates to make things like toilet paper and almost 400 million Victoria's Secret catalogues each year. It must be noted in this context, that second-growth forests are nowhere NEAR as diverse as the mature ecosystems they replace: it takes hundreds or even thousands of years for nature to completely repair the damage done by monoculture or clear cutting,

3) Invasive "introduced" species - species which are (in the overwhelming majority of cases) brought to place where they were not formerly known, which are able to multiple out of control because their competitors, predators and the other parameters which would normally control them in their home territory are lacking in their new home. In the process, they either out-compete or kill via predation, local species and generally throw local ecosystems out of whack. (molluscan examples include the Giant African Landsnail (Achatina fulica Bowdich), which can grow to 10 inches and eat almost everything in sight, and the voracious predator landsnial whose name I have forgotten, but which was largely responsible for the extinction of many native Hawaiian landsnails in the 1960s. The infamous "zebra mussel" (Dreissena polymorpha (Pallas)),which has caused so much trouble for humans and many other species in the North American Great Lakes and other aquatic watersheds they have invaded) and

4) Climate change - believe it or don't, the earth IS warming up: the arctic has already seen huge changes such as a dramatic reduction in sea ice and the melting of permafrost, and many "feedback loops" are already hard at work, such as that involved with the reduction of ice cover via the melting of glaciers worldwide (90% of the world's glaciers are in "full retreat" mode, and many are expected to vanish within a few generations of our species or less), and the melting of the arctic ice-pack, which uncover either dark water or dark earth, which in turn absorbs far more of the sun's heat than the ice did - ice being highly reflective. Before our species multiplied exponentially "upon the face of the earth", species simply migrated when climactic conditions changed where they lived, with little net loss of diversity on the large scale. However, humans have altered the landscape vastly (see "habitat loss and degradation"), and placed many barriers to this kind of mass migration in the way of life-forms attempting to shift their place of habitation to climes which they can survive in. As a result, and also because of the effects of pollution of all kinds, which lessens the adaptive abilities of most affected organisms, and also because the RATE of climate change, much of which is likely due to the increased amount of heat retained or "trapped" by the "greenhouse gases" released by our society's immense use of fossil fuels, is far swifter than natural life-systems are able to adapt to, many species are quite likely to become either extinct or expatriated all over the planet - and I personally am not counting on the second coming of Christ, whenever that may be, to renew the earth and rescue us from the consequences of our folly and greed.

The Manus Green Snail is a species which has been identified by the Convention on Internatioanal Trade in Threatened and Endangered Species (CITES for short) process as an "endangered" species - that is, one which is in danger of becoming esxtinct unless protected from human exploitation. Because of its beautiful color and elegant form, it has become an endangered species "poster child" - much like the Panda Bear or the great whales.

However, most of the 16,000 species currently officially recognized as being endangered, in virtually every case by human activity, are nowhere near as cute, colorful or magnficient, hence they tend to garner correspondingly little attention or "sympathy" - and in any case it is almost universally recognized that they comprise merely the tiniest tip of the iceburg - not only is the status of most local populations of most species very poorly known, but only a small fraction of the total number of species of life, as discussed above, are known to our species.

To return to the topic at hand and back away from my prediliction for ranting (correctly or not..... i do my best to get the facts straight.), landsnails are considerably more diverse than the more popular marine species - of the 50,000 or so described species of shell-bearing molluscs, about 30,000 of them are landsnails!! This is most likely because it is far more difficult for landsnail species to travel to new localities - hence local populations, instead of being able to freely exchange genetic material with nearby populations that they are capable of interbreeding with, become effectively isolated. Over time, specieation tends to occur via simple "genetic drift" - the original Darwinian concept of speciation via successive adaptation to specific local conditions.

In many parts of the world, very similar species of landsnail can be found occupying nearly identical ecological "niches" in neighbouring valleys, separated only by higher ground which they cannot cross. Landsails can be found in nearly all terestrial ecosystems, from high in the tops of the trees in the rainforest, to deserts, arctic tundra and tallus slopes high in the mountains. There are probably several species to be found in your back yard or garden, provided you haven't killed them all with pesticiides.......

The family Camaenidae is the largest and most diverse pulmonoate (air breathing) family, containing nearly 3,000 described species and 90 of the 600 recognized genera of landsnails. It is found in tropical regions all over the planet except Africa, but especially in the Carribean and the Western Pacific. The genera Amphidromou and Papuina are very popular with collectors because of its attractive colors and patterns. They are all herbivores, munching placidly on often relatively speialized selections of vegetation.

The Manus Island tree-snail lives only on Manus island, a relatively sparsely inhabited isle in the Admiralty Island group. It eats mainly detritus or fungi and lichens growing on the trees they live in. The snail' "niche" high in the trees is ideal: its food and water are plentiful and it is safe from being drowned, washed away during heavy rain or eaten by ground-foraging animals.

The bright green tree-snail blends with the tree leaves and shelters in humid places-on foliage or in crevices in bark. If the humidity drops it can retreat into its shell to conserve moisture.

The constant high humidity of the tropical rainforest allows breeding several times a year. Individuals have both male and female sexual parts but cannot self-fertilise. The eggs are larger and fewer in number than other species of snail because they are in a reliable environment where most young will survive.

This snail, which is highly adapted to the rainforest environment, has a restricted distribution and could easily be exterminated if its habitat is destroyed. Locals did not collect or use the snails until tourists and shell collectors [to be fair, mainly tourists, to whom the bright green P. pulcerrima (Rensch) was just a "pretty shell" to take home and put in a box with other bricky-bracky souvenirs] came to buy them, endangering the population. Introduced carnivorous snails (such as the giant African snail Achatina fulica) brought into Papua New Guinea to control other pests quickly destroy native populations and are a threat to the tree-snail.

There are three stories as to why the species was listed as "endangered":

1. The most popular is the "official" version above: overcollection + invasive species and habitat destruction, combined with a highly limited distribution = endangerment.

2. Another version has scientists coming at the wrong time of year: the dry season, when most land snails are in what is called an "aestivation" phase - they essentially shut themselves down and seal off their apertures to prevent moisture loss when conditions become too dry for comfort.

3. Yet a third possibility mentioned, is that since the Green Snail lives high in the trees, the natives were cutting down many trees in order to obtain the favorite souvenir of tourists - so in order to protect the trees, the snail was placed on the endangered list.

This is an illustration of how easy it is for modern-day myths to become established: it is highly unlikely that that all the stories are components of the truth. THAT SAID, it is NOT a myth that the still largely modifiable activities of our species are severely and critically endangering a very large number of the other species which we share the planet with.

Betraying my age, I quote the immortal Pogo, "We have seen the enemy and he is us.".