MIGHTY MUCAL MUSSELS OF THE MUDDY MOVING MANSIONS
Lucky am I, to look after my interests. Listen to my heartbeats. Fashion my feelings.
Lucky am I, to focus on meanings. Seeing the real things. Touching with reason.
That moving within me. That living without.
Have we too easily escaped the shallows? Where we could have followed and looked even farther? As rivers are, we are alike. Like those mussel shells lying in the sun. Lives siphoning life’s rivers, drinking alone.
Three rivers. The Cumberland, Green, and Tennessee Rivers.
Like a bow untied, protecting the pride of the South in that great Civil War.
Some say. I say. General Johnston said. Not enough of a line to save. For Polk andGrant, Henry and Heiman, they were just a highway. These rivers, once damned with guns, carried men to Nashville, then Shiloh, where lives would end. And then the mussels siphoned red. General Johnston is dead.
These are the landscapes where the mussels then lived. Many still do.
The three rivers flow to you. Your middens, buttons, and pearls times two! And the water that you drink, their gills have passed through.
Time for freshwater mussel taxonomy: Kingdom, Phylum, Class, Order, Family, Genus, Species. And for the Pink Heelsplitter: Animalia, Mollusca, Bivalvia, Unionida, Unionidae, Potamilus alatus. The Spectacle Case. The Monkey Face and Washboard. The Deer Toe, the Pig Toe. The Fragile Papershell and Fatmucket. Diversity all about us.
There are approximately eight hundred and ninety freshwater mussel species worldwide. Three hundred and nine in North America. One hundred and three in Kentucky (with nineteen either extinct or extirpated). Seventy-two species were once found in Kentucky’s Green River. Maybe fifty-three remain. I can recognize more than twenty.
But mussel shells are only half of their story. Just their home. It is the life within those shells that matter. Lives just as alive as you and me, and like yours, important, too.
Some of these mussels live for 100 years. Almost as long as my father still lives. But they remain constantly in the same place, or nearly so. Living through drought and dredging, buried in sediment from agriculture and mining. Bathed in agricultural chemicals, industrial toxins, human pathogens, and your pharmaceuticals. And yet the mussels are still out there, in our streams, siphoning all that water over their gills and through their bodily systems. They have only you to protect them.
Wait a minute! Why are we drinking that water? Are they our canaries?
What’s inside those mussel shells anyway? Adductor muscle, mantle⎯that’s the membrane that secretes the shell⎯visceral mass, digestive tract, stomach, intestines, gonads, kidney, two-chambered heart, and a mouth with lips.
Kind of like you. Except their blood is white, they have no brain, and their lips are swollen like camel lips. Plus they have a small, stirring stick-like crystalline rod in their stomach called a protostyle, equipped with a hard knob-like terminus. It is spun by attached cilia to break up food particles in the stomach. Cool!
And, in reproduction, they are like us, too. Mussels have sperm and eggs, just like humans do.
Well, there is an additional stage compared to ours. A parasitic one. And that one is interesting to learn. It involves specific fish species in turn.
Sperm from male mussels are released to the stream. Fertilized with the female, mussel eggs grow into larvae⎯”glochidia”⎯and can remain protected and nurtured by the mother for many months. Then, when the timing is right, the glochidia will be released to the gills of specific fish species, to which they cling for several weeks and then fall off to the stream bottom to grow into adults. That’s where you will find them.
The glochidia are tiny⎯the size of a grain of salt. They have two shell-like clamps that have only enough energy to grab once onto a fish gill. The mother mussel uses three strategies to deliver them. Mimicry, lures, and entrapment.
Mimicry is the most famous. For here, the mussel mother’s mantle grows out an extension that looks like fish food: worms or a minnow. One darter-like disguise even has a pigmented area for an eyespot and darkened areas on its fake tail!
In comes the big Bass. It’s big mouth opens to strike, and out of the mussel blasts a cloud of concentrated glochidia into the mouth of the fish and over its gills. If successful, in a couple of weeks comma-sized juvenile mussels will begin to fall off into new stream sediment berths, delivered by a swimming ship.
Some mussels will package globs of glochidia at the end of a long mucal strand that extends out like a fishing line. The glob will bob and wriggle on the water until some fish takes the bait, only to have its gills slimed with glochidia.
And here’s a special setup. Some mussels grow an extension of mantle as a lure, but display it within the opening of their shells. Maybe it wriggles down there, like a bunch of tasty worms. In comes a small fish to take a peek inside. Bam! The shell closes, entrapping and holding the fish’s head while the mother bathes its gills with glochidia. Now, that’s incredible.
Have humans had a use for these bivalves? In the Late Archaic Period in Kentucky, say 3,000 years ago, Native Americans lived along the Green River, leaving waste piles of mussel shell “middens” from their industry and diet.
But no one now eats their tawny, tough, slimy mass. They are loaded with a chemical called “putrescine.” I will let you figure out the meaning of that word!
In the 1800s, someone found a pearl in an American freshwater mussel. And the great “Pearl Rush” began in the Mississippi Basin. There are concentrations of sorts in about one of every 100 freshwater mussels, but they are often irregular. There is a 1955 movie called “The Kentuckian,” starring Burt Lancaster, who hunted these pearls in 1820.
In the late 1890s, the United States placed tariffs on European buttons, closing down J.F. Boepple’s seashell button business in Germany. Coming to Muscatine on the Mississippi River in Iowa, he started a similar button business based on freshwater mussels. Billions of buttons were punched and carved out of our native mussel shells. Boepple later died of blood poisoning after cutting his foot on a mussel. Probably a Pink Heelsplitter.
The mussel button business played out by 1940 with the advance of plastics during World War II. The popularity of zippers didn’t help, either. And many of the mussel beds had been exhausted by over-collection.
By the 1990s, the Japanese had learned to manage beds of marine mussels to produce pearls. What they needed, however, was a starter irritant around which their oysters would grow pearls. What better material than the shiny shells of America’s freshwater mussels? “Nacre.” We call it “mother of pearl.” Take a look in your chest of drawers. Maybe one of those old pearls started its life in Kentucky!