Freshwater Shells -- The Excitement of Discovery

by Brian L. McElaney
Even more than twenty years after the fact, I still remember the day my particular interest in freshwater shells began. At age 15, I had just returned from a family trip to the Bahamas with a suitcase full of shells. Always fascinated by the sea, I had just succumbed to the singular lure of shelling on the white sand beaches of the Abacos. No sooner had my parents started complaining about the odor emanating from dozens of unwashed beach shells than I was out prowling the Boston area shell shops. A small shop in Newton Centre displayed a mouth watering variety of exotic specimens in a large display case. Among the large and brilliantly colored Cowries and Volutes lay two smaller gastropods which were not for sale.

Slightly less than two inches long, they appeared rather modest at first glance. Upon closer inspection, however, the olive-colored shells appeared uniquely shaped, with high spires, striking diamond-shaped apertures, and rows of strong spines. The true fascination of the specimens was, however, produced by reading the label. They were identified as Io fluvialis, a river snail from Tennessee. Suddenly, these "modest" gastropods became powerfully exotic.

I was astonished that such a remarkable animal existed not on some remote reef or sea bottom, but virtually in my own backyard. Up to that point, my impression of freshwater shells was of the tiny, drab colored snails I had disinterestedly observed during a science project at the local reservoir years before. It was almost inconceivable that the relatively large and sculptured creatures now before me could possibly belong in fresh water. My enthusiasm was, however, dashed by the last word appearing on the label. I had learned in school about the Tennessee Valley Authority and its damming of the Tennessee and other rivers, and now realized that this engineering miracle had produced more than electricity for the southeast. It was perhaps my first lesson in shell conservationism. The last word on the label was "extinct".

Despite my close encounter with the Newton Centre Io's, my collecting pursuits went in a different direction for the next three years. Less than three months after my interest in shells exploded on a small Bahamian Cay, I became certified in SCUBA and plunged into the frigid waters of New England. Not long thereafter, I joined a collecting expedition to the Florida Keys with the New England Aquarium. Following my freshman year in college, I dove with an Earthwatch team studying nudibranchs in Hawaii. My love of diving led me over an over again to the oceans and I was acquiring a large number of marine specimens. The image of the Io's, however, was implanted firmly in my mind.

I spent one semester of my junior college year in England. It was while backpacking through Europe during spring break that I first reached into fresh water to collect a shell. The shell was Lymnaea pereger and I plucked it out of a tiny, cold stream near my youth hostel in Schaan, Liechtenstein It was no Io, but it was an interesting shell nonetheless. As I had been interested in the marine nerites I had collected, I was quite enthusiastic to discover that not only did freshwater nerites exist, but that one species lived in European rivers. Shortly after finding the Lymnaea, I engaged in a relatively fierce but unsuccessful search for this species, going so far as to free dive in the muddy Avon River in Bath. As it turns out, the little Lymnaea was the only freshwater shell I was to collect in Europe for it was there that I acquired a brief but intense enthusiasm for land shells that took me into the forests and away from the streams.

Upon my return home, my attention again turned to fresh water and I decided to see just what those little reservoir snails were all about. Returning to the scene of my science project, I discovered Physa heterostropha. This sinistral snail was of some initial interest. Little did I know that it was also ubiquitous and that I would see more Physa in the coming years than I cared to. I expanded my search to the nearby golf course where I discovered Lymnaea humilis and Lymnaea columella. After a couple of golf balls whistled past disturbingly close to my head, I decided that water-trap collecting left something to be desired. I moved on to nearby rivers and streams, finding a variety of tiny gastropods. It was in the inauspiciously named Mud Pond in Dublin, New Hampshire that I began to discover just how diverse freshwater shells could be. Here I not only found my first freshwater pelecypod (Sphaerium partumeium) but also discovered freshwater limpets (Ferrissia parallela). I also discovered leeches, but was not deterred. Within a few weeks, I had found about two dozen freshwater species within a fifty mile radius of my hometown.

But it was the beginning of my stint in the Army that led to my freshwater epiphany. In the summer of 1982, I was sent for six weeks of officer basic training in Ft. Sill, Oklahoma. The first thing I did after getting to Ft. Sill, besides learning to salute, was to purchase a map of the post. Without any real idea of what I was looking for, I struck out on foot in 105 degree heat, heading for the closest stream I could find on the map. An hour later, and in the advanced stages of dehydration, I arrived at a tank bridge over Cache Creek and immediately spotted a large mussel valve on the bank. I was nearly as astonished with the appearance of this creature as I was with the Io. The shell was heavy, strong and strikingly sculptured with beads and ridges. I had never expected anything so striking to appear in this little stream. For the next few weeks, I collected a dazzling variety of mussels in the Ft. Sill streams. I had no guide book and so had little idea of what I was finding.

Back in my new home of St. Louis, Missouri, I immediately acquired what books I could find on freshwater shells. A Missouri Department of Conservation publication proved to be an outstanding resource for freshwater mussels. The Ft. Sill shell that had spurred my fascination with the naiades was Tritogonia verrucosa and it was one of thirteen different mussels I had found on post that summer.

I immediately began exploring the waterways of Missouri's Meramec River Basin and again discovered an amazing array of mussels which virtually covered the riverbed in some areas. But gastropods were much less abundant, which only made another book I had acquired more tantalizing. J.B Burch's North American Freshwater Snails contained page after page of freshwater gastropods; some plain and some exquisite. Among the pages was Io fluvialis. From this book, I determined that Alabama and Tennessee would be particularly appealing places to visit. This opportunity came in the form of a significantly rerouted drive between Missouri and Massachusetts and a weekend trip from a temporary assignment in Washington, D.C.

The rivers of the southeast yielded, in a relatively short time, an excellent assortment of snails, although not nearly the variety promised by Burch's book. I pulled an interesting Pleurocera species out of the Coosa River in the midst of an Alabama ice storm. Smaller streams in Alabama and Tennessee yielded species of Elimia and Leptoxis as well as the somewhat more commonplace Lymnaea and Campeloma.

It was a relatively fine day in the southeast when I was exploring some of the back roads in theTennessee River Valley. I had stepped onto the bank of one of the larger tributaries of the Tennessee and noted a large number of small forms in the mud. What was perhaps my best moment in freshwater collecting came when I reached down and picked up a handful of Io fluvialis. Some of the shells were long-dead and chalky-white but others were clearly freshly dead, still bearing their periostracum. It was then that I realized that this species' "extinction", of which I had learned in a Massachusetts shell shop fourteen years previously, was perhaps somewhat exaggerated. What followed was about two hours of wading and stone-turning along miles of riverbank. Finally, I reached down into two feet of water, picked a dark form off the side of a large rock and laid eyes upon my first live Io fluvialis. I would estimate that there were about fifteen specimens of this snail on or near that large rock. I never found a single live Io in any other part of this river or in any other river that I explored.

I thought it was perhaps unfortunate in a way that I had essentially discovered my "holy grail" so early in my freshwater collecting. But I soon discovered that none of the lure of freshwater was lost. I soon fell into the pattern that every freshwater collector knows. There was no body of water too small or too ugly to be explored. I have taken shells from an irrigation canal in Nepal, from a Chinese garden pool in Bali, and from a stagnant fountain on the front lawn of India's Rambaugh Palace. My wife soon learned to keep a book in the car during drives. In this manner she keeps herself entertained while I poke around in every stream, pond, and puddle in sight.

Many of the shells that I have found have been small and somewhat plain but others have been exciting and unexpected: the spiny Theodoxus corona from Thailand, a striking Thiara species from New Guinea, the smooth, sinistral Lanistes boltenianus from a roadside ditch in Giza, Egypt.

And there have been other grails. While stationed in Hawaii, I searched nearly four years for the "common" endemic Neritina granosa, leaving barely a stream on Oahu unexplored. Shortly before being transferred, I finally found this snail (in great abundance) in a large river on the island of Hawaii. While stationed in Europe, I reinitiated my search (begun over a decade earlier) for that continent's freshwater nerites, finally discovering Theodoxus fluviatilis on a dike in northern Holland.

It is for this reason that, to this day, all my freshwater shells are self-collected. There is no way to match, through purchase or trade, the excitement of discovery. But there is concern as well. Although the erroneous label on the specimens of Io fluvialis that I saw long ago may have been my first lesson in conservationism, I have since learned others. A section of Missouri's Bourbeuse River which I found to be exceedingly rich in mussels just twelve years ago now yields little more than broken valves. An Oahu streambed filled with Thiara granifera and Neritina tahitensis in 1984 seemed devoid of molluscs when I rechecked it just a month ago. Perhaps most disconcerting was my return to the Tennessee River Valley in 1995. In the same spot I had found over a dozen individuals of Io fluvialis in 1988, I found only a single immature specimen. Even the dead Io's were gone.