It’s 11 AM on a breezy September morning, too cool for swimming, and yet Kevin Cummings is crouched over, foraging like a raccoon in the swirling, waist-deep brown water of the Kishwaukee River. Two inches of rain fell yesterday, and the river is swollen with cold, murky water. He’s only a few feet offshore, but the river runs deep there and Cummings must struggle to stay upright in the current as he gropes along the bottom with outstretched hands.

“I might need a weight belt, Chris,” he says.

Chris Mayer has been watching from the steep, muddy bank. “Are you used to the water yet?” she asks.

“No. It’s still seeping into the wet suit. Hey–here’s one.”

“Let me guess. Pimpleback?”

“Yup.” Cummings holds up what looks like a gunky brown rock the size of an old-fashioned pocket watch.

“Good guess. How much weight do you need?”

“One should be enough.”

Mayer walks back to the van for a weight belt. Cummings explores the riverbed for another minute or two, then wades back to the bank. The place is littered with Styrofoam cups, bits of fishing line, and a variety of small plastic containers filled with rank concoctions used as catfish bait by local fishermen.

Cummings, in his mid-30s, has his long black hair tied back in a ponytail, and with his round sunglasses, black wet suit, and old white sneakers he looks like he’s ready for Outside’s fashion pages. He holds out his right hand and shows us the two mussels he’s found.

The pimpleback is the larger of the two. Viewed from the side, it’s about an inch deep at the thickest point, near the “beaks,” where the two “valves” are connected–a valve is what a lay person usually calls a shell, though it takes two valves to make a shell. These valves are primarily muddy brown, but they sport five concentric black rings that spread out from the beak like ripples across a pond. A thick band of warty pimples–“tubercles” in mussel lingo–runs from the beaks to the edge of each valve. The pimples are light tan and as smooth as a chestnut.

“See?” says Cummings, pointing at the line where the two valves meet. They’re tightly closed. “The shell is secreted here by the edge of the mantle, like a fingernail. The wide black rings show the age–one year for each ring.”

Cummings calls the other shell a pigtoe. It’s about the size of a silver dollar. Instead of tubercles it has a great number of fine concentric lines covering its shell, giving it the texture of linen. Its color is warm brown, and a wide ray of dull forest green spreads from the beak to the edge of each valve.

By now Mayer has returned from the van carrying a paperback-size diver’s weight strapped to a thick belt. She’s about the same age as Cummings and shares his stocky build, which is probably necessary for anyone who’s going to enjoy poking around in cold river water for any length of time.

Cummings wraps the belt around his wet suit and heads back into the river. Mayer measures the two mussels with a caliper and writes the information in a large notebook. She shows me how to distinguish males from females: the valves of males are more pointed. Then she places the two in a cotton mesh bag and lays it in the shallow water at the bottom of the bank.

Traffic booms by on Belt Line Road, which crosses the river on a crumbling highway bridge to our left. Across the river is an array of orange steel towers supporting landing lights, spaced every 200 feet, that guide pilots to the Greater Rockford Airport. At regular intervals two-engine private planes, corporate jets, and small airliners swoop low over our heads, swaying disconcertingly in the strong west wind as they make their final approach.

The closest structure is a framework of metal pipes perched on two towers set on thick orange pilings rising from the river. Two decades ago the Federal Aviation Administration built the whole landing array without a second thought. Ten years ago the regulations governing the distance between landing lights were loosened, and the light bar above the river became unnecessary. Now the FAA considers it a hazard–a plane coming in too low could crash into it–and wants to remove it.

But a thicket of environmental legislation has grown up in the intervening years, and the FAA found that it had taken on a surprisingly big project. “We had to go to literally eight or nine different agencies for permission,” says Frank Gualillo, regional engineer for the FAA. “We didn’t know how many hoops we’d have to jump through.” The pilings that support the towers are steel tubes sunk well into the riverbed and filled with concrete; it would take a large crane to remove them. The only way to get a crane close enough would be to build a gravel dike out into the river. Workers would then build smaller dikes around the two groups of pilings, drain out the water, and cut off the pilings below the riverbed. Then they’d remove the three dikes. The whole project would cost about $60,000.

One of the agencies whose OK was required was the Illinois Department of Conservation, which is responsible for ensuring that no undue harm comes to animal or plant populations. The DOC official in charge of aquatic construction permits asked Cummings and Mayer, the resident mussel experts at the Illinois Natural History Survey, what the effect on the river’s mussels would be.

The two biologists figured the construction work would send a slug of sediment downstream for 100 yards or so, burying any mussels that might be living quietly in the riverbed. They knew that the Kishwaukee was, by Illinois standards, a fairly high-quality river, relatively clean and biologically diverse. Within the last several years a researcher had found an ellipse–a mussel that’s on Illinois’ list of “species of special concern,” meaning that it may soon be considered for inclusion on the state list of threatened and endangered species–in a creek a mile away. A volunteer searcher had also found a creek heelsplitter, which is on the state threatened-species list, just a couple miles upstream.

Cummings and Mayer decided on a remediation project. They would remove all the mussels they could find immediately downstream from the construction site, take them to a forest preserve upstream, and replant them in the riverbed. It seems a lot of work to save a handful of obscure animals, but it’s the hallmark of Cummings and Mayer’s work to be concerned–fascinated, even–by the question of what mussels occur where. If the two of them sometimes seem a little obsessed by mussels, that’s because freshwater mussels are an almost totally obscure topic. It’s a surprise to almost everyone that freshwater mussels live in great, if greatly diminished, diversity in the waters of Illinois; it’s a bigger surprise that their harvest is an industry of some economic importance. Moreover, the rocklike, dull animals the two scientists were finding in the Kishwaukee’s murk might be, in the aggregate, the best indicators of the state’s environmental health. So when Cummings calls freshwater mussels “perhaps the most endangered class of animals in North America,” it ought to be sobering news, and not just to the scientists among us.

The mollusks commonly known as clams are also called bivalves, for the paired valves that make up their shell. The vast majority of the world’s bivalves are marine creatures. Only a relative handful live in fresh water, which generally offers a less stable environment over the long run than the sea.

Freshwater mussels feed like their marine cousins, by straining tiny food particles out of the water that flows past them. They are typically found with shells ajar, though the upright valves are often buried entirely in mud or sand. What biologists call the animal’s anterior points down, and a muscular, fleshy protrusion known as the “foot” hangs down from that end of the shell, anchoring the animal in the silt and sand.

The posterior end is nearest the surface. Two fleshy siphons point up from it, reaching into the current. The first, the “incurrent aperture,” points upstream; the animal sucks water in through it. Inside the mussel the water passes through gills that filter out tiny food particles: plankton, small algae, bits of detritus. Mussels are natural water clarifiers; the water that exits through the “excurrent aperture”–the second siphon–is cleaner than what came in.

It’s a simple life. They live quietly, filtering out their steady diet of whatever flows by, occasionally falling prey to a raccoon or muskrat if the water is shallow enough, or a predatory fish if the mussels are young and small. If water levels drop in the heat of summer, a mussel can move, slowly, by extending its foot and pulling itself along behind it, leaving a trademark trail on the riverbed. But if they don’t need to move they won’t.

The native freshwater bivalves of Illinois represent three families, of which the great majority belong to the Unionidae–hence the term “unionid,” which is often used when speaking about native mussels in general. There’s also a family of fingernail clams, the Sphaeriidae, which are small and little studied.

Freshwater mussels as a whole have historically been found in their greatest diversity in the central United States, from northern Alabama to the upper Mississippi basin, where a stable climate and diverse riverine topography enabled them to exploit a great variety of ecological niches. Seventy different species could be found at Muscle Shoals on the Tennessee River in northern Alabama until the shallow waters there were drowned by the reservoir behind Wilson Dam. The upper Mississippi valley was extraordinarily rich too; in 1906 one Natural History Survey researcher called it “the metropolis of the pearly freshwater mussels.”

Of the 285 species once found in the United States, 78 have been found at one time or another in Illinois. They lived throughout the state’s waterways–in lakes and ponds, in streams large and small, deep and shallow, fast moving and gentle. Just to list their common names is to speak a sort of vernacular poetry. The rivers of Illinois were once rife with the orange-foot pimpleback and the cracking pearlymussel; spike and Wabash riffleshell; tubercled blossom and Higgins eye; winged mapleleaf and round hickorynut; pondhorn, pink papershell, pyramid pigtoe, paper pondshell, and purple lilliput. One could pick out of a clear stream a plain pocketbook, fat pocketbook, or rock pocketbook, a spectaclecase, a snuffbox, a pistolgrip, a washboard. There were sheepnose, rabbitsfoot, catspaw, and monkeyface; elktoe and elephant-ear; butterfly and fawnsfoot and deertoe. There were bleufers, ring pinks, yellow sandshells, pink heelsplitters, white and purple wartybacks, and pink muckets. There were ellipses and rainbows and squawfoots and rayed beans. And that’s not including the multifarious tiny fingernail clams: the lake, swamp, river, pond, and rhomboid; or the ridged-beak, ubiquitous, greater eastern, ornamented, perforated, Alpine, or Adam peaclams.

The Kishwaukee River salvage project is atypical for Cummings and Mayer. Usually they spend their summers censusing rivers and creeks–generally using the same primitive gathering technique as here on the Kishwaukee, but leaving the mussels where they are. In the last few years they and a few other researchers have surveyed populations on a number of waterways in Illinois and Indiana: the Sangamon River and its tributaries, the Wabash, Little Wabash, Tippecanoe, Vermilion, Mackinaw, and Embarras. The field season runs from June, when the high water of spring abates, through September, when the air and water become too cold for comfortable work. During the cold months Cummings and Mayer write reports and curate the Natural History Survey’s mollusk, fish, and vertebrate collections.

It was curatorial work that brought Cummings into the slowly burgeoning field of malacology, as the study of mollusks is known. He began working for the Natural History Survey in 1983, shortly after finishing his master’s-degree work on nongame fish species at Southern Illinois University. Part of his job description included curating the fish collection at survey headquarters in Champaign–which includes some 650,000 specimens. But he found that the collection was well taken care of. “My boss said, ‘The fish collection’s in pretty good shape. Why don’t you do something with all those boxes that have been stored in the attic for the last 20 years?'” The boxes–215 old paint cartons–contained 26,000 mussels collected in mid-century by Max Matteson, a zoologist at the University of Illinois.

“Matteson visited about 215 sites in most of the rivers outside of the Mississippi and Illinois, which had been covered by other surveys,” says Cummings. “He surveyed primarily interior streams, the medium-sized streams like the Kankakee and the Embarras and the Little Wabash and the Rock. He had 215 boxes of shells, and one sheet of field notes that went with each one. He had the species already identified and counted, so it became a matter of taking them out, putting them into piles, and verifying the identifications as best I could. I picked up a copy of Paul Parmalee’s The Fresh-water Mussels of Illinois, which was published by the Illinois State Museum in 1967. I started trying to learn everything I could about mussels, got into the literature, and started to write numbers into the shells and catalog them into the collection. That’s how I got started. I just learned about mussels as I unboxed them.”

Most mussel experts enter the field that way. There are few trained malacologists around, so only a handful of graduate students have the opportunity to study under them. Mayer too started working with mussels by happenstance. Holder of a bachelor’s degree in environmental biology, she’d worked on various projects for the survey for four years before she participated in her first mussel project. The projects have kept coming in, and now she has been Cummings’s main research partner for five years.

Cummings estimates that there are only about 50 mussel researchers in the eastern and central United States, though a good many more biologists and officials are involved in regulating the commercial harvest of freshwater mussels. Yet in a very real sense the colleagues he and Mayer work with most frequently are long dead. Cummings and Mayer, following Max Matteson and Paul Parmalee, are the most recent links in a long chain of individual researchers who began studying the mollusks of Illinois–and the rest of the midwest–about the time the state was founded in 1818. As systematic biologists, they don’t spend much time exploring their subjects’ behavior, life-style, or biochemistry. The question that preoccupies them is, What lives where?

They are fortunate, as is anyone interested in the natural history of Illinois, that the settlement of the midwest coincided more or less with the great burgeoning of natural history as a topic of study in the early 19th century. Quite a few amateur and professional scientists began examining Illinois’ flora, fauna, geology, and water systems before they were seriously altered by agriculture, industry, and the growth of cities. From their records we can gain an idea of what the midwest looked like in its more-or-less primeval state.

One of the first of the great 19th-century naturalists–and the very first to look at mussels–was a Philadelphian, Thomas Say. The son of a pharmacist, Say failed in the family business because he preferred to ramble through woods and fields in pursuit of birds, insects, and other specimens. Fortunately, he found a supportive, nascent community of naturalists in Philadelphia. In 1819 he got his first glimpses of the continent’s interior as the official naturalist on an exploring trip down the Ohio River, up the Missouri, and across the Great Plains to Colorado.

It’s hard today to imagine the landscape as Say saw it on that trip. Indians still camped near Saint Louis, Carolina parakeets–now long extinct–chattered and swarmed in the nut trees, and the Ohio River ran clear and wide. Where the river ran shallow over rocky riffles its bed was covered with mussels, sometimes several layers deep.

Say wasn’t able to truly delve into his mollusk studies until he moved to the utopian community of New Harmony, Indiana, in 1826. New Harmony, on the banks of the lower Wabash, was founded by two wealthy British visionaries who wanted to set up an ideal community distinguished by egalitarian work and a scientific education for all. Say was only one of several respected naturalists and educators who ended up there; unlike most of the others, he remained until the end of his life.

Say was happy there; he had time to wade the Wabash and its tributaries, and to publish seven volumes of American Conchology, the first detailed look at shells of the New World. He also found time to elope with Lucy Sistaire, the illustrator who produced lovely hand-colored drawings for the books. By the time he died in 1834 he was considered the founder of the study of mollusks in North America (the term “malacology” didn’t replace “conchology” until much later, when scientists started to pay at least as much attention to the insides of mollusks as to the more durable shells).

The Natural History Survey collection that taught Cummings begins with some valves collected in the 1850s in Cook County by Robert Kennicott, who grew up on the pioneer homestead now preserved as “The Grove” in Glenview. It also includes shells donated by John Wesley Powell, the one-armed Civil War hero who went on to lead the first expedition down the Colorado River and to lay the foundation for much of modern geology; Powell collected shells and fossils during his years as a young schoolteacher in Illinois and won a $25 second prize from the Illinois Agricultural Society in 1860 for the quality of his collection.

From Powell the lineage moves through the early ecologists who founded the Natural History Survey in the late 1800s. From the early 19th century to the present only a handful of biologists have been interested in mussels, but a new collector came along every 20 years or so. “The research work almost turns over from one person to the next,” says Cummings. The historical continuity of the study of Illinois’ mussels is probably unique in the U.S. Cummings has delved extensively into the records, examining not only every shell in the Natural History Survey collection but those in major museums. He has also combed the scientific literature for any mention of Illinois mussel surveys or specimens. If a mussel was once found and recorded in the state’s waters, he knows about it.

Fieldwork methods haven’t changed much since Say’s time. Though Cummings and Mayer have benefit of scuba gear for exploring deep water and wet suits for comfort, they still spend most of their field time as he did, groping along riverbeds with their bare hands. Their familiarity with the historical record makes one thing very clear: they’re not finding nearly as many mussels as Thomas Say did.

Freshwater mussels are edible, but only barely so, by most accounts. Certainly harvesting mussels for food has never been a major occupation on the rivers of the midwest. Native Americans may have eaten mussel meat, but no one really knows. The pearls they occasionally found have become part of the archaeological record, along with the large shells used as scraping blades and smaller ones for jewelry and other ornamentation. When a few white settlers found their own river pearls, they set off the first great mussel boom.

Pearls are formed in freshwater mussels just as they are in saltwater oysters. An irritant–often a grain of sand, but it could be anything–lodges between the valves, and the animal secretes paper-thin layers of mother-of-pearl around it. It’s the same mother-of-pearl that makes up the shell, but it builds up in concentric spheres around the object. The traditional pearl of course is a perfect sphere, but many natural pearls are free-form, or baroque.

Pearls have been known about for millennia, but America’s white settlers apparently didn’t realize freshwater mussels could produce pearls as good as those from marine shells until 1857, when a New Jersey man inadvertently bit one while eating boiled mussels. The pearl rush on the creek he’d been foraging in soon uncovered $115,000 worth of pearls. Fortune seekers quickly turned to other creeks and rivers. Not until 1889 did they strike pay dirt in the upper midwest. That year pearlers found $10,000 worth of organic gems in the Pecatonica River.

The rewards of pearling could be great–the biologist and writer John Madson, in his vivid account of life on the upper Mississippi, Up on the River, says that one pearl found in Iowa in 1902 sold for $65,000. But it was always a quixotic quest. Only a tiny fraction of harvested mussels held pearls; of those, only a tiny fraction were high quality. Most pearlers did not hit the big time.

Just as the pearl boom crested another industry arose, one concerned not with what might lie in the mussels, but with their shells. In the second half of the 19th century buttons were commonly made by cutting thin discs from bone, antler, or marine shell, then drilling holes in them and polishing them to a fine luster. It was a labor-intensive, craft-oriented business. One of its practitioners was John Boepple of Ottensen, Germany. In the 1870s he received at his workshop a box of shells collected in the Illinois River. Freshwater shells had never been used much for buttons; indeed, there were button factories in Cincinnati and Saint Paul that bought marine shell for raw material, little suspecting the lodes in the Ohio and Mississippi rivers.

Boepple found that the shells from Illinois made excellent buttons. But he put them aside, and his discovery remained a mere curiosity until he emigrated to the United States in 1887. He reached the midwest, jobbed around for some time, and one warm day went for a swim in the Sangamon River at Petersburg in downstate Illinois. “While in bathing one day,” he later wrote, “my foot was cut, and upon examination of the cause I found the bottom of the river covered with mussel shells.” Boepple resolved to take advantage of his accident. During the next few years he found rich mussel beds at several locations in Illinois and Iowa, but none better than the deposits of particularly thick shells near Muscatine, Iowa. By 1891, with the backing of investors, he had opened a small button-making factory there.

His milling technique was pretty simple: take a clean shell and cut round blanks out of it with a cylindrical saw blade driven by a lathe. Grind the blanks to uniform thickness on a revolving emery wheel, then drill two to four holes. A little polishing, and you had a pearly white button that might even give off a little iridescent glimmer.

Boepple had good timing. A recent tariff on the import of marine shell had made most buttons quite expensive. The river shell, by contrast, was free to all takers. Just about anyone could harvest mussels, which belonged to no one.

Within a few years Boepple had several hundred employees. By 1897 there were 13 shell-processing plants on the Mississippi; by 1898 there were 49, as well as 12 on other midwestern waterways. Muscatine alone boasted five button factories and 28 blank-cutting works.

It was easy to collect mussels in shallow water. Many collectors used Boepple’s accidental technique–wade barefoot until you feel mussels underfoot, then gather them up in your bare hands. Others used rakes similar to those used for clams on saltwater mud flats. But the industry’s explosive growth was due at least partly to the invention of the “crowfoot bar,” an ingenious device that allowed mussels to be gathered in deep water. It was easy to make, consisting of a number of short lengths of chain attached to a metal bar between 4 and 20 feet in length. At the end of each chain was a large multiple hook made from a number of thick strands of wire twisted together.

A collector, operating from a square-cornered, flat-bottomed, wooden johnboat, had only to lower the crowfoot bar to the bottom over a rich mussel bed and drift with the current for a short distance. The chains bumped along the bottom. As soon as an open mussel felt the end of a hook against its exposed tissue, it clamped its valves tight and held on–with what literally became a death grip as it was dragged along the riverbed and lifted into the open air. By the time the musseler raised his bar, there might be dozens of mussels clinging to its hooks–in which case raising its weight was no mean feat (before too long gasoline engines were introduced to help with that chore). A team of two men could haul up nearly a ton of mussels during a long morning’s work on a productive river.

The closed mussels were ferried to shore and steamed en masse over an open fire. As the mussels died, their muscles relaxed. The collector scraped the meat from the shells–making sure to check the soggy mass for pearls–and piled the empty valves into great heaps.

Most shells were purchased by traveling buyers, either middlemen or the agents of processing plants, who showed up at the riverside camps every couple of weeks. By 1914 high-quality shell was fetching an average of $12 to $27 a ton, though fine yellow sandshell–which had a large, smooth valve ideal for the carving of knife handles, hat pins, buckles, and other large novelty items–might bring several times that. Savvy harvesters increased their profits by forming cooperatives and operating their own blank-cutting machines.

In 1899 almost 24,000 tons of shell were sold in the midwest for more than $200,000. By 1909 the average annual national harvest was around 40,000 tons. That year an estimated 2,600 mussel boats plied the Illinois River alone. The downstate town of Pearl, now a dot on the map, sported five shell-processing plants. Mussels were being harvested from eastern Ohio to eastern Oklahoma, from Louisiana to the eastern edge of the Dakotas.

Though about 40 species of mussels were used in the commercial trade, only about a dozen were of real importance. Of those, a few made up the lion’s share of trade, among them the yellow sandshell, the black sandshell, the pocketbook, and the mucket. But the premier button mussel of the Mississippi, the ebonyshell, was thick, heavy, pearly, and usually less brittle than other varieties. Its shells seemed almost meaty, perfect for carving. At some sites in the upper Mississippi it grew in enormous profusion. In 1910 harvesters collected 1,600 tons of shells, 80 percent of them ebonyshells, from a few miles of rapids above Keokuk, Iowa, and sold them for some $30,000.

The mussel frenzy bore all the hallmarks of the other great booms in American resources–lumber, gold, oil, or any other natural product that was there for the taking. Transient communities sprang up overnight as collectors thronged to the richest mussel beds. They put up with unsanitary living conditions. Many shellers lived in ad hoc riverside camps that, if the harvest was good, were swiftly plagued by a surfeit of mussel meat. Some was fed to pigs and chickens, some was used as fish bait, but much was either dumped back in the river or left to rot onshore. In the hot, humid Mississippi Valley summer the stench must have been impressive.

Out on the rivers fights broke out over access rights; one Mississippi River sheller mounted a small cannon on his johnboat, and used it. Thousands left more mundane professions for easy river pickings. When the beds at Muscatine were worked out, the collectors traveled upriver or downriver, then to the Wabash, and from there up the Illinois. “Many of the shellers are nomadic and therefore move readily with their launches from a region of poor fishery to a better locality,” wrote Robert E. Coker in a 1919 report for the U.S. Bureau of Fisheries. “It is often the case, however, that in times of low water, when the mussels are easily obtained, the farm hands, miscellaneous laborers, and others engage temporarily in shelling, using any kind of available equipment or collecting by hand. It is in such cases that good beds are often rapidly and seriously depleted.”

Automation and increased efficiency swiftly swept the processing industry. There were separate machines and operators responsible for cutting, grinding, drilling, polishing, and sorting. Reports were written on how to cut a maximum number of uniform-sized blanks out of nonuniform shells. Coker was saddened that the fashion industry dictated uniformity and prized only white buttons. “Many shells in nature have beautiful colorings of purple, salmon, or pink, but the shades are not adapted to market demands,” he wrote. “It is claimed that the colors are liable to fade unevenly.” By 1914 the manufacturing of buttons from freshwater shell was a $5-million-a-year industry.

Assembly-line production dramatically lowered the price of buttons. Consumption increased commensurately. In 1891 the average American bought 37 buttons; by 1910 that figure had risen to 106.

Boepple went bust in the boom. He was a skilled craftsman, not a savvy businessman. Unable to compete with efficient, automated button plants, he became a shell consultant to the U.S. Bureau of Fisheries. In 1911 he cut his foot again while sampling mussels in a stream; this time the cut became infected, and that winter he died of blood poisoning.

Meanwhile the mussel beds disappeared rapidly and predictably. The first harvest took most of the enormous old shells (in his early exploring days Boepple had found one washboard in Kentucky’s Salt River that measured 8 by 11 inches and after cleaning left a shell weighing three and a half pounds. The big shells were the only ones old enough to have produced large pearls, and after most of them were cleaned out pearling activity dropped precipitously. Next musselers collected the midsize mussels, which had the highest-quality shells (the larger, older shells are often eroded by years of exposure to sand and water). Then they started taking the smaller shells–and because shell was sold by weight, it took many more small ones to earn as much as they had from the large shells.

Once the young mussels were harvested, beds were depleted with startling rapidity. By 1912 there were only 400 boats on the Illinois, where there had been 2,600. By 1919 Coker could write, “It might be said . . . that there is no important stream in which the mussel resources now exist in anything like their former abundance.”

It would be too simplistic though to blame the decline of mussel populations solely on overharvesting. The ecology of many rivers was also disrupted by pollution. Before the turn of the century, for example, the Illinois was a fairly clean river. Once the flow of the Chicago River was reversed in 1900, sewage surged downstream. In 1912 the Natural History Survey’s Stephen Forbes and Robert Richardson examined the river at Morris, roughly 60 miles from Chicago. “The water here was grayish, sloppy,” they wrote with admirable scientific dispassion. “The odor was continuously foul, with a distinct privy smell in the hottest weather. Bubbles of gas were continually breaking at the surface from a soft bar of sludge. . . . On the warmest days putrescent masses of soft, grayish black, mucky matter, from the diameter of a walnut to that of a milkpan, were floating on the surface.”

In the early 1870s one researcher had found 35 species of mussels in the area near Starved Rock. In 1912 Forbes and Richardson were able to find only two species there. Most of the native fish species had also been wiped out. Even in 1966, after the adoption of modern sewage-treatment techniques, survey researcher William C. Starrett was still unable to find a single living mussel upstream of Starved Rock.

A further blow to the mussel populations came from the Army Corps of Engineers, in the form of the numerous dams built across the Mississippi, Illinois, and other major rivers in the first half of this century. The Illinois is a perfect example. The state and the corps together built seven large dams across the river between 1919 and 1939 to maintain a consistent navigation channel at least 9 feet deep and 300 wide. The dams essentially converted the Illinois into a series of lakes connected by short stretches of swifter water. Relatively few freshwater mussel species do well in water that isn’t flowing with some rapidity. The amount of suitable mussel habitat shrank precipitously. The shallow riffles, which generally supported the richest beds, were wiped out almost entirely.

The effect of the dams was insidious when combined with wasteful agricultural practices. Modern farming practices left many fields bare outside the growing season, subject to the worst sort of water and wind erosion. A fair amount of the state’s topsoil ended up in the river, whose current was too sluggish to carry the sediment far downstream. Instead it stayed in the big lakes and the backwater sloughs, burying mussels, aquatic plants, and other bottom fauna. The new silt bottom was far too flocculent to offer suitable footing for mussels.

The cumulative effect of all these changes has been devastating to mussel populations. Of the 285 species once found in the United States 13 are thought to be extinct, 39 are on the federal endangered-species list, and some 50 more should perhaps be on the list. Illinois was home to at least 78 species, of which 4 are extinct and 12 have been extirpated from the state. Many others are known from only a handful of locations. The creek heelsplitter, for example, one of the rare species found in the Kishwaukee watershed, used to be common in the northern third of the state. It even lived in the Du Page and Des Plaines rivers. In recent years biologists have been able to find it at only six or seven locations statewide, which is why it’s on the state’s threatened-species list; 27 other species are also either on that list or the endangered-species list, or are candidates for listing.

You could blame the problem partly on the mussels themselves. Most native mussels employ an intricate and still poorly understood reproductive strategy. Being largely stationary, male and female mussels never meet. The males merely release sperm into the water at some time in the spring. It’s not known how they know when to do this; nor is it known how the females–who are, we hope, downstream–identify the sperm of their species when it enters their gills along with the rest of the river’s organic detritus.

If all goes well, the female becomes pregnant, or gravid. Her gills become engorged with the minuscule young, which are known as glochidia. Now comes the complicated part. The female waits until a fish approaches. Some mussels wave a fleshy appendage that looks something like a minnow and tends to attract predatory fish. When a fish comes close enough, the female shoots out a cloud of glochidia. The lucky ones end up on the fish’s gills or fins, clasping on by means of tiny hooks. The flesh of the fish builds a cyst around them.

The glochidia are now the size of a pinhead at most, and they remain on the fish typically for one to three months, feeding on fish fluids. “The infections are usually not dense enough to harm the fish,” says Cummings, though he says he has heard of fish hosting thousands of glochidia at once. During those months the young mussels undergo a metamorphosis; their bodies change into adults while barely growing in size.

When the glochidia are fully adult, though still no bigger than grains of sand, they drop off the fish. The current carries them, and they tumble to the riverbed. Those that land on a good substrate–ideally a combination of mud, sand, and gravel that is neither too hard to dig into nor too soft to hold onto–bury themselves and settle down.

It’s not an easy youth–the vast majority of glochidia are devoured by minnows, never find a host, latch onto a fish that gets eaten, or suffer some other accident. So they must be produced in vast numbers for the species to survive. One study estimated that a single fragile papershell could produce up to 2,225,000 larvae.

Many native mussels infect only one or two species of host fish. Biologists call this coevolution and don’t entirely understand how it works. It’s not known, for example, how the females of those species distinguish their host fish from all the nonhost species. But this elaborate reproduction is a good example of an evolutionary strategy that’s very successful (until humans cause it to go awry). If native mussels just released their young into the water, the young would inevitably drift downstream. It would be next to impossible for a mussel species to colonize new areas farther upstream. A fish is infinitely more mobile than a mussel; it can swim a long way in the one-to-three-month period during which a glochidium is on its gills. By relying on a mobile host, mussels were able to colonize not just upstream reaches of one river but separate river systems.

But the strategy quickly proved precarious once we started messing with the rivers. A mussel that relies on a single host species can be wiped out if the host disappears. The ebonyshell once thrived throughout much of the Mississippi watershed. Its glochidia parasitized the skipjack herring, a fish that lived its adult life in the ocean but came upstream as far as Minnesota to spawn. But this fish was unable to pass over the 27 big dams the Army Corps of Engineers put across the big river. Today there are no ebonyshells in the Mississippi north of Saint Louis, site of the southernmost dam, save perhaps a very few very old specimens that predate the dams.

It might be argued that such species belong on the slippery slope to extinction, that it’s their problem if they can’t adapt to a changing environment. Such arguments have been heard in proposals to weaken the federal Endangered Species Act, which is now up for reauthorization. But Cummings believes endangered mussels are very much our problem, especially since they can never flee very far from poor conditions. Their abundance or absence is an excellent index of the health of rivers. “You’ve got to realize,” says Cummings, “that all these animals and plants are part of the same ecosystem–they depend on each other.”

It is known that mussels can grow quite old if their habitat is healthy. One specimen of a European clam reportedly attained the age of 116 years–an extreme example perhaps. But most authorities seem to agree that our native mussels can approach the century mark given the right conditions. “For an invertebrate, that’s an incredible amount of time,” says Cummings. “There may be some very important information there with regard to cancer prevention or longevity or disease immunity. No one’s even touched that facet of mussel biology yet, but obviously some of these things are living a hell of a long time in pretty harsh and disturbed environments. They must have some pretty damn good immune systems. Hell, there could be some AIDS research dollars well spent looking at the immune systems of mollusks. You find all sorts of strange things when you look at biological organisms–a tree, a plant. You find new disease prevention in places you’d least expect it.”

But these days research money isn’t flowing into the field of native mussel biochemistry. It’s going to study the zebra mussel, which, as boaters and public-utility workers know, is a native of Eurasia that was discovered in the Great Lakes a few years ago. It’s suspected that its young–which in their free-swimming larval state are known as “veligers”–were released in North America from an ocean-going freighter’s ballast tanks.

The zebra mussel is from a different biological family than native freshwater mussels. Its veligers do not require a fish host and can thrive in almost any body of fresh water. And thrive they have–in a few years they have spread throughout much of the eastern and central United States. They have been found in the Ohio River and in the Mississippi as far north as La Crosse.

Zebra mussels never grow much larger than two inches in length. But unlike our native species, they cement themselves to hard underwater objects–rocks, boat hulls, water-intake pipes, native mussel shells. And they do so in great numbers. Ellen Marsden, a Natural History Survey researcher who studies zebra mussels from the survey’s biological station at Zion, says she has found small aquatic snails encrusted with up to 190 mussels on the bottom of Lake Michigan. There are only a few native mussel species in the Great Lakes themselves, but until recently fingernail clams and snails were abundant and served as an important food source for fish and diving ducks. “In our trawls,” says Marsden, “we now find that the fingernail clams and snails are often entirely covered with zebra mussels.”

In midwestern lakes and rivers it’s not uncommon for native mussels to be the only hard objects on the bottom. Zebra mussels will attach to them like iron filings to a magnet. “They will prevent the freshwater mussel from siphoning and obtaining food, and also from reproducing,” says Cummings. “And in some cases, where substrates are soft, the actual weight of the zebra mussels will push the others down into the silt and sand and smother them.” Marsden adds that the encrustations of alien mussels can lock the shells of native species open or closed, or distort their growth. Zebra mussels also grow so densely and filter water so vigorously that they may leave little food for native mussels. In Lake Erie, where zebra mussels were found earlier than in Lake Michigan or the inland river systems, populations of native mussels have plummeted.

“It is my personal opinion that the zebra mussel has the potential to wreak more havoc on our rivers than anything that’s occurred in the past,” says Bill Fritz, who retired as a commercial-fisheries biologist for the Department of Conservation (DOC) in January. “That organism has the potential to ruin the freshwater-mussel population of the Mississippi River drainage.”

There’s little that can be done about the zebra-mussel invasion, short of manually scraping them from places we don’t want them–a difficult and expensive process. Researchers may eventually find a parasite or disease-causing organism that attacks only the zebra mussel, but that could take a long time. It’s likely that a natural equilibrium will take over first: the population will expand explosively for a few years, then decline as food resources are depleted and predation and disease increase.

Those looking for a silver lining find it in the increased awareness that often accompanies an ecological disaster. Suddenly mussels are being talked about, at least a little. “One of the most positive effects of this invasion is the political effect,” says Marsden. “This introduced species affects nearly everyone, so there’s suddenly a lot of political interest in introduced species.”

That bothers Cummings and Mayer, who can only look covetously at the sort of research dollars that are funneled into zebra-mussel research–as they are funneled into many areas once human activities are affected by a plant or animal. The vast majority of money available for biological research goes into studies of game animals (deer, trout, ducks), what biologists like to call charismatic megafauna (eagles, wolves, cougars), or species we want to control (zebra mussels, mosquitoes, boll weevils). There are no PBS specials about mussels; there has never been a Society for the Protection of American Mussels or an Anti-Shelling League. The great majority of those who have ever cared about mussels have been those who wanted to make a buck off them.

Cummings and Mayer fund much of their fieldwork in hand-to-mouth fashion, relying on one-time grants from state and federal agencies that usually come through only when threatened or endangered species are at stake. I interviewed them last in early October, when they were preparing for a major conference in Saint Louis they’d helped organize. They weren’t sure where they would find the money to pay for their trip there and back.

The whole pot of money for biological research is shrinking. The Natural History Survey, for example, lost almost a quarter of its staff this year, casualties of the state’s budget crisis. “Biological research work doesn’t seem to be important from a budgetary standpoint,” says Cummings, “though it always seems to rank fairly high on public-opinion polls.”

“Until they ask you to choose between paying for your kid or your favorite mollusk,” adds Mayer.

Though shell collectors had depleted many of the rich mussel beds by 1920, the button industry lingered on for several more decades, until plastic took the place of shell. Plastic buttons were easier and cheaper to make, and they didn’t break as easily. A few shell collectors eked out a sort of subsistence living, but the glory days were gone. The great mounds of punched-out shells outside the old button works on the banks of the Mississippi and Illinois slowly eroded and vanished under thickets of vines and shrubs.

But as one shell industry died, another was about to be born. Japanese researcher Kokichi Mikimoto had been experimenting for some time with the cultivation of pearls in saltwater oysters. He manually inserted irritants in their shells, then kept the oysters in cages in the ocean. After several years about 3 percent of the oysters contained valuable pearls. In the late 1930s Mikimoto discovered that spherical beads of freshwater mussel shell from the upper Mississippi drainage made ideal nuclei for pearls–their chemical composition allowed the oyster’s nacre to be layered more smoothly, without a blemish, than around any other object.

World War II intervened, and it was not until the early 1960s that the Japanese announced they were interested in buying shell. It had been a healthy hiatus. Some of the old mussel beds in areas where pollution and sedimentation had not been too serious were thick with shells again. A new generation of musselers went out on the rivers.

They had the benefit of modern diving gear–scuba or surface-supplied air hoses–so they could handpick mussel beds in deep water. Otherwise the job hadn’t changed much, and hasn’t changed much in the 30 years since. Shallow-water beds are still explored by hand, or barefoot. Those who don’t want to dive–or can’t afford the equipment–use the trusty old crowfoot bars. Shell collecting is still hard physical labor that usually pays poorly. It’s still done with one or two people, usually men who prefer the hard grind of outdoor work.

Though the final product has changed, market and harvest conditions have not. Just as it did around the turn of the century, the annual take in mussels and dollars varies wildly. Shell collectors still find it easier to deplete one bed rather than travel to a number of beds and take only a portion of the mussels from each, so the harvest figures for any given area tend to fluctuate greatly. In the Illinois River, for example, collectors took more than 1,000 tons of shell in 1966, less than 400 in 1967, and only about 100 in 1968. Three years later there was no appreciable harvest from the Illinois at all. Then it went back on the upswing: 12.4 tons in 1979, 292.5 in 1989, 540 in 1990. Rising prices accounted in part for the increased harvest. High-quality washboard mussels, which have generally made up most of the annual yield, brought collectors from 35 to 50 cents a pound in the mid-1980s. By 1991 the average price had risen to well over a dollar a pound, and Bill Fritz says a brief bidding war in Wisconsin raised prices there to $5 a pound for a short period. “A good washboard can weigh about a pound,” says Fritz, “so you could think of a big shell as a dollar bill lying there in the river.”

With the rising prices came increased applications for licenses. It costs only $25 to get one in Illinois. During the mid-1980s 200 were typically granted per year; by 1989 that number had risen to 1,075, and by 1990 to 1,500. The DOC sets no limit on the number of licenses that can be granted. It does set limits on the areas where mussels can be collected (only the Wabash, Illinois, and Mississippi are open to harvesting), on the season (spring and summer), and on the minimum size of mussels that may be taken. Washboards, for example, must be at least four inches long to be legal. A washboard probably takes 15 to 18 years to reach that length; as it typically requires 12 years to reach sexual maturity, the theory is that any mussel harvested has already had a few years to reproduce. Though 13 species may be taken, the washboard and three-ridge typically make up at least 95 percent of the harvest.

In spite of the regulations, there was grave concern that collectors, true to the old pattern, were depleting the beds. “Because we don’t have a large pot of money available for management, there’s only one person in the state gathering statistics on the harvest,” says Cummings. “These are just educated guesses as to what they should be doing to manage the harvest. No research has been done to decide whether the minimum-length limits are sufficient to make sure that these are sustainable populations. I mean, who knows if we’re taking out the most prolific females, the real base of the population? They just set sort of arbitrary limits, it seems to me, without having a lot of scientific fact to back that up. Of course that’s born from political pressure to keep the industry going.”

“Mussels are a low-visibility organism,” agrees Bill Fritz. “There has been virtually no research done to document how many pounds could be harvested from a mussel bed and still have recruitment equaling removal.”

“We all have a feeling that it might be getting overharvested,” says Ed Walsh, the new DOC commercial-fishery manager. “That’s why we have the size limit. But basically the harvest is limited by economics.” This year the mussel harvest fell off dramatically because prices were sharply reduced. Only 816 commercial licenses had been granted by the end of June, so the harvest will surely be well shy of last year’s state total of almost 1,700 tons and close to $2.9 million dollars.

Fisheries officials don’t know why the demand is down. It’s rumored that the Japanese overbought raw material in the last few years; it’s also rumored that they’ve found a new material to use as pearl nuclei. “I suspect there’s not going to be a whole lot of musselers in a few years,” says Walsh. “There’s a lot of guys that were musselers when there was money in it. But when it dies down, they’ll get into something else.”

It’s mid-afternoon on the Kishwaukee. Cummings and Mayer are both in the river now, foraging near the south bank. Periodically one calls out the name of a new species: fragile papershell, strange floater, giant floater. It has clouded over and the wind has the bite of fall.

“I just grabbed my foot,” says Cummings. “I thought it was a clam. It’s numb.”

The pair climb out onto the steep bank. They have found about 30 live mussels of seven species, as well as “dead shells” of three other species. None of them is on the list of threatened or endangered species. Their final list at the end of several days’ work will total 75 live mussels of nine species, fresh dead shells of two species, and weathered dead shells of an additional three species (finding a fresh dead shell means you probably just missed the live specimens; finding only weathered dead shells means the species may have been extirpated from the area since those old mussels died). It’s been a good haul. “Anything around ten live species at one location is what I would consider high diversity,” says Cummings.

Before she slips it into the cotton sack Mayer shows me the strange floater. It’s three inches long, one and a half wide, and fairly slim. Dull green algae fleck its posterior. From the rounded ends I guess this is a female. The valves are not fully shut. The creamy blob of flesh that is the foot barely oozes out beyond the shell. Mayer and I look into the body cavity. We can see the gills–a large, formless, whitish mass. Mayer says the size of the gills indicates this mussel is gravid.

Soon Cummings and Mayer will take all the mussels gathered today and drive them a few miles upstream to the Kishwaukee Forest Preserve. Cummings will gently place them, one by one, on the riverbed a few yards offshore.

I look at the pregnant mussel in my hand. It’s strange to think of it–of her–as an animal, so differently must she perceive the world. She has no sense organs I can recognize. With most animals you can sense some common ground in the eyes. Not here. What can she perceive right now of her situation as she is held in the open, alien air and moved around? Mussels may lead a simple life, but it’s well beyond my comprehension.

My mind goes over all the good, solid, practical reasons for protecting them. They are a prime indicator of environmental health. They can tell us a great deal about water pollution and the effects of agricultural runoff on river life. They serve as an index of sedimentation. Their populations may reflect the well-being of the fish that serve as their hosts. They provide important services to their ecosystem, cleaning water and providing food for fish and mammals.

But looking at this individual mussel I want to think of her as more than a sort of living barometer. I’m considering whether it’s possible to feel for the protection of mussels. When I look at a fox or a squirrel or a bird, it isn’t hard to feel a certain commonality with them and therefore compassion. But these mussels generally look like glorified rocks. If there’s a basis according to which we can respect them–and I think we should respect them–it must be that fact. Mussels are worth protecting because they are so immobile, so rooted–nourishing and nourished by the river to such an extent that a river without them is no river at all.

One of the fascinating things about them is that they can grow to the same age as we do, accumulating a long lifetime of experience–and we have no conception of what their experience is like. But it’s a pretty good bet that they ask no more than what the river brings them. And perhaps that’s what we can learn from them.

“They’re beautiful,” Mayer says. “They’re fascinating because they do so little. Beyond that, I have no idea why I think they’re so neat.”

Art accompanying story in printed newspaper (not available in this archive): photos/Jon Randolph.