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Endangered Species Mural #8: Freshwater Mussels of Tennessee

July 4, 2016

The eighth of the Endangered Species Murals is now complete! I’ve just returned to Portland from Knoxville, Tennessee, after finishing up the largest mural I have ever had the pleasure to work on. I worked with artists Merrilee Challiss and Tricia Tripp and local volunteer coordinator Chris Irwin to fill nearly 2500 square feet of wall with an image of the endangered freshwater mussel diversity of the Tennessee river. You might be more familiar with saltwater mussels- that’s what you’re likely to be served in a restaurant- but freshwater mussels are much more diverse, strange, and fascinating. They live in colonies called shoals on the riverbed, spending their days endlessly filtering the water around them in search of food. North America is the world hotspot of freshwater mussel diversity- and over 70% of the mussel species found in the rivers and streams of this continent are endangered. Most of the species of animal that have gone extinct since settlers arrived have been freshwater mussels- and that’s largely to do with how settler society and industrial capitalism have transformed our rivers. Today it’s become a rare thing to find a river that isn’t dammed, or full of silt from development, dredging, or agricultural runoff, or poisoned by industrial effluent or excesses of fertilizer. Mussels are the bellwethers of river health- their decline tells us a lot about how we treat our rivers, and how we have to change.

Volunteer Shelby Kray, with the Tennessee Freshwater Coalition, painting grasses.


The mural focuses on three species of freshwater mussel from the Tennessee River basin, two of which are federally-listed endangered species. We painted the mussels in the middle of their reproductive process, which is where the really interesting and strange aspects of them come to light.

Mussels essentially parasitize certain fish, using them as hosts to raise their young. They accomplish this by using parts of their soft mantle as lures to bait the fish, and the magic of evolutionary transformation has produced some pretty astonishing lures. In one of the species (not endangered) featured in the mural, the Wavy-Rayed Lampmussel, the lure can look just like a small fish, or a worm, or a dragonfly nymph, or even a crawdad- and that’s just within the same species! The mussel twitches this lure in the current to lure down a smallmouth bass. When the bass nips at the mantle, the mussel releases it’s glochidia- a cloud of larval mussels that spray out and up into the gills of the fish, where they clamp on.

You can see the cloud of glochidia in the second mussel image in the mural- the endangered Cumberlandian Combshell. The Combshell goes one further than the Lampmussel- it has developed sharp teeth on it’s shell edge (actually just extrusions of shell matter).

When it wiggles the small wormlike lure within it’s shell, it’s trying to lure in a much smaller fish- like the endangered Blotchside Logperch, pictured here after having been enclamped by the Combshell. When the mussel has the fish in it’s “jaws” it pumps out its glochidia- and also, it’s thought, some sort of sedative compound which causes the fish to thrash less while the mussel has it by the head. Surprisingly dark!

The third mussel pictured here is the endangered Pink Mucket Pearlymussel- here shown as a dead shell housing another endangered fish, the Citico darter.

These small fish use mussel shells as shelter- and the decline in mussels has been bad news for them as well. To the right of the Mucket is an exploded view of darter fish gills with the larval glochidia clamped on to them. The larvae spend a short time drinking the blood of the host fish until they attain a particular size, and then they drop off and float slowly down through the water column to begin life as a new shoal, somewhere else on the riverbed.




Mussels have a long history of cultural use- the peoples that inhabited what is now eastern Tennessee for thousands of years before Europeans used mussel shells as decorative objects and tools, and there are archaeological images of the huge middens of shells that they used for food. In more recent times, mussel shells were used in the button-making industry- an early driver of their decline. These amazing creatures deserve our solidarity, and our activism- we need to bring these rivers back to life. Check out a TV spot from local Knoxville station WBIR here.


I didn’t know a great deal about freshwater mussel biology before I started planning this mural, but I know a lot more now, thanks in no small part to Gerry Dinkins, curator of malacology (mussel studies) at the McClung Museum in Knoxville and Kristin Irwin, graduate student at the University of Tennessee. Gerry and Kristin generously opened up their collection of shells to us for use as reference, and answered a lot of questions about our process and our images, helping us to get the biology right. Also invaluable was the enormous amount of volunteer work done by local artists and activists, coordinated by Chris Irwin, without whom this mural would not have been possible. Also huge shouts to collaborating artists Merrilee Challiss and Tricia Tripp, pictured below!


This is the eighth in a series, sponsored by the Center for Biological Diversity. Berea, Kentucky, is next with the endangered Fringeless Ghost Orchid- the first plant in the project!




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2 comments on “Endangered Species Mural #8: Freshwater Mussels of Tennessee”

I am an author with History Press writing the history of Cherokee National Forest in Tennessee. I would like to include a photo of Roger Peet’s mural of freshwater mussels in that publication. How can I get in touch with him? Great work!

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