Art and Science of Nature
Understanding the Beauty of the Natural WorldMake My Skin Crawl
Fringe of a dry forested hillside ringed by expansive sugar cane fields north of Kinloss, Jamaica. Photo: Richard L. Goldberg. © 2009.
While shooting a series of macro photos on a dry forested hillside in Jamaica I noticed a rather bold and brazen ant strutting his stuff on a small limestone rock. The ant seemed to match the description of Solenopsis invicta, the scientific name for the much dreaded fire ant; also referred to as RIFA, or Red Imported Fire Ants.
Possibly Solenopsis invicta, the much dreaded fire ant near Kinloss, Jamaica. Photo: Richard L. Goldberg © 2009.
Its reddish-brown head and body with a brown abdomen was the tip off that my encounter with the 5mm hymenopteran was not something to just brush-off. I immediately checked to see that I did not unearth an entire colony before kneeling down on the forest floor to photograph the ant interloper — wait a minute! Was I the intruder on the isolated hillside ringed by large expanses of sugarcane fields?
Photographing an ant species on the floor of a dry forested hillside north of Kinloss, Jamaica. Who's the intruder? Photo: Alan Gettleman.
Just mentioning the name fire ant is enough to make a person’s skin crawl. Get stung by one and you can expect intense soreness and swelling for days. Stumbling onto and getting stung by a colony of fire ants is enough to take down an able-bodied outdoors man for the count. Numerous video clips on YouTube show people succumbing to attacks by fire ants; not the type of material that you are likely to see on America’s Funniest Home Videos. There is nothing funny about being attacked by a colony of fire ants, and not just for the obvious reason.
Black ants, red ants, sugar ants, crawling ants, mad ants, biting ants, rain ants, soldier ants, and duck ants are just some of the biting ant species found in Jamaica as listed on an official notification “potential invasion of the fire ant” published by the Biodiversity Branch of the National Environment and Planning Agency of Jamaica. The introduction of Solenopsis invicta, has now been confirmed in Jamaica. The notification states that no other ant species can inflict a sting as bad as the fire ant. The South American native ant species has been introduced into a number of other West Indian islands, the U.S. mainland and as far away as Taiwan and Australia.
A close encounter with a dry limestone hillside, an ideal habitat for ants in Jamaica. Photo: Richard L. Goldberg © 2009.
Ants in Jamaica are especially abundant among the dry limestone forests of central and western Jamaica. Leaf litter, tree trunks and open limestone cliff faces are especially good habitats where ants are frequently found in large numbers; the same habitats that we hike through in search of capturing other Jamaican lifeforms on film. So it is not uncommon to have RIFA encounters. Sure, ants of any type are a nuisance to people whether the biting type or not. Yet the impact of introduced ants on indigenous species is far more troubling.
Fire ants are aggressive, especially when provoked by disruption of their colony. Though one of the best know ants to inflict painful stings, the fire ant is not the only aggressive ant species.
Anolis lizard foraging in the foliage at night in the Cockpit Country of Jamaica. Photo: Richard L. Goldberg © 2009.
The myrmicine ant Crematogaster brevispinosa, a species related to the common household ant (Myrmica molesta) is known to make unprovoked attacks on juvenile and possibly adult Anolis lineatopus, an arboreal iguanid lizard native to Jamaica. In fact, when caged with almost 40 C. brevispinosa under laboratory conditions, a juvenile A. lineatopus died within hours. It seems then that such aggressive behaviors by ants can influence the local distribution and abundance patterns of animals sensitive to it such as the Anolis. This conclusion was based on a field study in Kingston, Jamaica where there was a direct correlation between the abundance of the ant with the lack of the lizard and vice versa.
Though known to feed on other insects and invertebrates, this small Jamaican centipede species lives side-by-side without harming the pulmonate snail, Dentellaria sloaneana in a delicate balance that allows both species to survive in the same habitat. Photo: Richard L. Goldberg © 2010.
It may take many tens of thousands of years for native species to find a balance in its environment. Introducing an aggressive species like fire ants into a pristine environment will quickly and negatively put the natural balance out of kilter. The University of Mona study between ants and anolids is just one of hundreds of similar ecological investigations that have revealed that introducing non-native species can and do have significantly negative impacts on native faunas.
The Tree Frog is just one of the many native Jamaican species that can be negatively and quickly affected by the introduction of non-native species. Photo: Richard L. Goldberg © 2010.
National wildlife management agencies continually monitor the introduction of invasive species within the borders of a country. The next time you return from overseas and grumble over the numerous questions your customs card asks about bringing back living plants or animals, or spending time on a rural farm, it is because non-native species can accidentally and easily be brought back in your bags; yes, even a fire ant! More than your skin will be crawling if one of these species successfully hitches a ride in your duffel bag!
Quick! Hide!!
My recent trek through Jamaica reminded me of how animals can ably and amazingly adapt to their surroundings. Most noticeably (or maybe not so noticeable) is how an animal’s shape, form, color and pattern can completely camouflage a species into its surroundings.
Rio Grande River and the Blue Mountains of eastern Jamaica. Photo: Alan Gettleman.
As the dominant species on Earth, we {Homo sapiens} have evolved from a lineage of hominids to become anything but stealthy in our world. And, it’s not surprising.
Without any predators to speak of in our daily lives (unless a bill collector or exigent-ex is stalking you) we just envelop ourselves behind the trappings of the human world… “Quick, here they come! Hide in my BMW with the dark tinted windows!”
Animals do not always have the luxury to build a fortress to hide behind. High school science introduces us to a concept called ‘Survival of the Fittest’. Being invisible to predators is one of the best ways for a species to survive. Many examples can be found right in our own backyards. Insects, birds and butterflies are just a few classes of animals that have become seemingly one with their surroundings.
Ever wonder why Praying Mantises look like a stick with wings that mimic lanceolate green leaves? Camouflage (and in the case of mantises, more for being stealthy when preying on other insects)! Is it not just a coincidence that the colors and patterns of many animals subtlety if not completely blend into their host surroundings? And what about the peripatetic Chameleon from Madagascar that changes its appearance to suit its changing background. These animals have given themselves a better-than-average chance to survive as a species when their predators have to work harder to find them.
So what kinds of natural CAMO (my acronym for Camouflaged Animals Meandering Outdoors) did I encounter in Jamaica? Some of the animal camo I observed is almost stupefying!
Alcadia hirsuta, a 20mm Jamaican terrestrial mollusk has developed a series of hair-like structures that effectively camouflage its shell against one of its preferred host leaves. Photo: Richard L. Goldberg ©2010.
Take for instance the suitably named Alcadia hirsuta (C.B.Adams, 1856) with the species name derived from the word “hirsute” meaning covered with hair. This small arboreal species of terrestrial snail has evolved a mane of long wispy hairs spaced at close, even intervals in rows around its shell. The hairs effectively blend the shell into the hairs found on one of its preferred host leaves of a “fern-wood” (a Jamaican English word meaning “unidentified tree”).
A few weeks ago I came across this hairy snail species crawling on the forest floor at about 400 meters above sea level in the John Crow Mountains of eastern Jamaica. The dead “hairy” leaves were the pervasive ground cover of this wet forested hillside. Every time I found this snail crawling on the ground in the underbrush, it was on this type of leaf. Coincidence? I’d go out on a limb and say there’s no coincidence at all!
The shell of Pleuodonte (Dentellaria) picturata is adorned with a creamy-white cuticle of radiating streaks that darken and lighten to match the tree bark during wet and dry periods. Photo: Richard L. Goldberg © 2010.
And then there is the Jamaican snail whose shell is covered with bands of radiating cuticle that blend into the coloring of the tree bark on which it prefers to aestivate. The creamy-white cuticle of Pleurodonte (Dentellaria) picturata (C.B.Adams, 1849) mimics the striations of the dry tree bark. When wet the cuticle darkens to the same dark brown tone of the wet tree, masking the shell in the wet shadowed forest.
The 25mm (1 inch) shell of a Pleurodonte (Dentellaria) picturata as it looks when dry (top) and after becoming wet and darkened (bottom). Photo: Richard L. Goldberg.
This species inhabits the limestone forests of western Jamaica along with a few other closely related snails that have developed the same propensity for adorning its shell with a radiating pattern of cuticle.
Pleurodonte (Dentellaria) catadupae H.B.Baker, 1935 is an extreme example of a Jamaican terrestrial mollusk whose shell is naturally embellished with a zigzag cuticle.
Yet, this unusual adaptation is not unique to terrestrial mollusks of the Western Hemisphere.
Cuticle of Calocochlia - Cal. depressa globosa (Moellendorff, 1898) (top) and Cal. festiva (Donovan, 1825) (bottom) are two Philippines Helicostylids whose shells are covered with intricate cuticle patterns providing effective camouflage against the tree bark on which it lives. Photo: Richard L. Goldberg © 2010.
Almost all of the 100 or so species of Helicostylids (heliko-stylids), a group of tree-dwelling mollusks from the Philippines Archipelago have also developed an epidermis or cuticle in a myriad of patterns unique to each species that help camouflage the shell during wet and dry seasons.
Terrestrial mollusks are not alone in using trees as a background for camouflage. In a dry scrub forest of Westmoreland Parish I observed a fist-sized Sphinx moth that was seemingly one with the trunk of a rather large and exposed tree. It took a few glances to realize that there was a moth anchored to the tree. So well does this moth camouflage itself against this tree that from more than a few feet away the moth was virtually undetectable.
A fist-size Sphinx moth is virtually undetectable against a hardwood tree in Westmoreland Parish, Jamaica. Photo: Richard L. Goldberg © 2010.
There are tens-of-thousands of other examples in our world where animals have been able to blend into the background of their environments for protection and stealthiness. Yet, take away stands of trees and destroy habitats and these stealthy animals become sitting ducks. Some animals will continue to survive and adapt as long as the dominant species {us} realize that saving the environment has a greater significance than for just human survival. I will now step down off my soapbox.
Back in Jamaica 2010
I am just back from another productive trip to Jamaica. My intention was to Blog while traveling around the island. Due to poor connectivity and later, the unrest and military operations against a local drug cartel in Kingston, I have had to wait until now to post my stories.
Jamaican Fern. Photo: Richard L. Goldberg
In the coming weeks I will upload stories dealing with the flora, fauna and people of Jamaica. One Blog entry being prepared deals with Jamaican ferns and will focus on the artistic patterns of some of the island’s 500+ species, and while exploring the Cockpit Country, how we stumbled upon a Jamaican elder who guided the renowned expert on Jamaican ferns, Dr. George Proctor, during his research of the island’s ferns in extreme remote regions during the 1960′s and ’70′s.
Roasted Blue Mountain coffee beans. Photo: Richard L. Goldberg.
Jamaica’s Blue Mountain coffee is revered by coffee drinkers the world over. We’ll show you how Blue Mountain coffee is still harvested and processed the old fashion way; by hand. And we’ll explore a small patch of forest on a Jamaican hillside and take a closer look at the incredible biodiversity that can be found within a few hundred square feet.
Dentellaria picturata. Photo: Richard L. Goldberg
Lots of interesting images and a couple of short films are currently being prepared for uploading to “Art & Science of Nature”. Catch you soon.
Rich.
Photographing macro-sized flora and fauna around the rim of a ± 200 foot sink hole in the John Crow Mountains
The Significance of Snail Shell Color and Pattern
[Adapted from an article that I co-authored entitled, "Isolation of Evolution of the Amphidromus in Nusa Tenggara" in American Conchologist magazine]
The almost 2 inch endemic Manus Island Green Tree Snail, Papustyla pulcherrima, is one of only a handful of tropical land snails that have a naturally green shell color. Photo by and courtesy of Brian Parkinson from worldwideconchology.com
The tropical biosphere is inhabited by animals of far greater color than any other zoogeographical zone on Earth. The Phylum Mollusca, and in particular the terrestrial mollusks, the land snails, develop shells that have some of the greatest diversity of color and pattern among all living organisms.
The often brilliant coloration and bold patterns attracted ancient societies who used the shells for ornamentation purposes. Today, naturalists with a bent on conchology are still amassing collections of these brilliantly colored snails for aesthetic reasons, but also for scientific study.
The question of why these molluscan species have developed a multitude of colors and patterns can be best understood through the foundations of evolutionary science.
Amphidromus adamsii, an extremely varied 25mm (± 1 inch) land snail species that may exhibit the ultimate in intra-population variability. Photo: Richard L. Goldberg (copyright 2009) from BiologySource 11 by L. Sandner, et. al, published by Pearson Publishing.
Land snails can develop shells with myriad colors forms within one population (intra-population variability), or may vary from the norm only in separated populations (inter-population variability). Occasionally a species can exhibit both phenomena. The Darwinian concept of natural selection can best be used to explain why a snail species can vary locally or over its entire range.
Forms of the half inch-size Fly-Speckled Polymita, Polymita muscarum, a species that exhibits inter-population variability throughout its geographical range in Oriente Province, Cuba. Left - A color form found at Loma de Calixto; Right - shells from Port of Vita. The Port of Vita form also exhibits considerable variation within the population, or intra-population variability. Photo: Richard L. Goldberg.
The external appearance of a shell — color and pattern, for instance — are likely to be influenced by natural selection when determining the genetic make up of a snail. Extreme color polymorphism in a population perhaps indicates that looking different from your neighbor is advantageous, making it more difficult for predators to develop a search image, such as color and contrast, to locate their prey. The unique color form can then spread rapidly in a population.
Amphidromus laevus from Timor-Leste. An example of frequency dependent selection where the typical dark banded pattern is occasionally replaced with a unicolored shell. Photo: Richard L. Goldberg.
This phenomenon, known as frequency dependent selection, may explain why some intra-populations of snails in the genus Amphidromus from eastern Indonesia often have unpatterned or strikingly different colored shells mixed in among the predominantly multi-colored or strongly patterned shells. Natural selection is typically considered to favor one form over another, thereby shifting the bell curve, yet frequency dependent selection flattens that bell curve and spreads it out.
An example of genetic drift. Left - Amphidromus wetaranus from Wetar Island, Indonesia. Right - A form of the same species from a small satellite island off Wetar Island. The red central band found on all specimens of the satellite island form is never found on the Wetar Island form. Photo: Richard L. Goldberg.
One explanation for inter-population variability may be a phenomenon called genetic drift. To illustrate this, let’s say a population gets split in two, one on island A, and one on island B. Both populations might start off identical, with chances at 50/50 for a particular trait. It is unlikely that the offspring will be 50/50. They may be 47/53, and the subsequent generation may be 43/57. Over many generations, the percentages will fluctuate up and down at random, and they can end up being very different from where they started. Yet, in the real world, a new mutation doesn’t start at 50/50. It might be only 1/10,000 or 1/100,000. By chance it can have more surviving offspring than average, and slowly increase in the population. Smaller populations will drift faster than large populations. But, if by chance that first mutant does not have any surviving offspring, that trait disappears. This is a more likely scenario. So, genetic drift tends to eliminate variation within a population and increases differences between populations. Over a period of time, the populations from islands A and B will end up looking very different.
These shells of Amphidromus columellaris from the Tanimbar Islands, Maluku Region, Indonesia show little variation within the population. Could that balance be tipped by the founder effect? Photo: Richard L. Goldberg.
Inter-population variability might also be explained by the founder effect. The snails that colonize an island may represent only a small fraction of the parent population’s genetic diversity. If a rare mutant color form is mixed in among the new colony, a colony that was 1 in 1000 in the parent population, it may instantly be 1 in 10 in the new population. Given a brand new set of environmental influences, the population may evolve in whole new directions from its parent population.
Environmental factors such as the geology, climate, flora, fauna, and food are all suspected contributors to the rise of a unique shell appearance. To reduce the competition with other species which overlap in some aspect of their niches, a phenomenon called character displacement occurs. Shell, behavioral, anatomical or biochemical characters eventually deviate from the ancestral form to allow the species to survive with its neighbors. Character displacement might also manifest itself in the color, pattern, and even the form of the shell. Changes brought on by one, or a combination of, these biological concepts can eventually render an isolated population unable to interbreed with the parent population, producing a situation which makes speciation possible.
Though these concepts are often difficult to understand when evolutionary science is not your main focus, understanding that tropical snails do change and adapt to external factors and random influences is enough to appreciate just how diverse a snail species can be.
Rain at Dolphin Head
Dolphin Head in Hanover Parish is one of the most massive geological formations in western Jamaica. It is often referred to as an island within an island.
The summit of Dolphin Head
Satellite Photo of Dolphin Head, north western Jamaica. The trail to the base of the mountain is difficult to traverse. Hiking up the mountain is an extreme trip in itself!
