{ Mussel Fundamentals }

Mussels may look like motionless rocks, but they have fascinating life histories and bring incredible diversity to our waterways. Tennessee ranks 2nd place for freshwater mussel diversity in the U. S., with 269 of 297 North American species living here in our rivers and streams... meaning 30% of the world's freshwater mussel species live in Tennessee. Yet, Tennessee's freshwater mussels are a highly imperiled group of organisms with 42 of our native species endangered and more still threatened.

Anatomy

Freshwater mussels are mollusks, which are invertebrates -- meaning they have no spine or skeletal system. Instead, they have shells that provides protection and structure.

Taxonomy

Life Cycle

Did you know that mussels undergo metamorphosis? Freshwater mussels, unlike marine mussels, rely on a fish host to reproduce; without these fish*, the mussel population won't grow.

The mussel larvae, called glochidia, rely on the sustenance and safety provided in the gills of a fish to metamorphose into juvenile mussels and detach into open water. The juvenile mussels will settle into the substrate below and continue to grow as they reach maturity and reproduce on their own.

*specific mussel species rely on salamanders as hosts instead of fish!

Freshwater Mussel Lifecycle, John Megahan/University of Michigan, Public Domain, https://www.fws.gov/media/freshwater-mussel-lifecycle

Wavyrayed lampmussel, Lampsilis fasciola, exhibiting mimicry to draw in fish; GIF by Evan M. Raskin, some rights reserved (CC BY) - https://www.inaturalist.org/photos/56221328

Because mussels rely so heavily on host species, many have evolved methods of attracting hosts nearer to give their larvae a better chance of proper attachment. This image may look like a fish at the bottom of a stream bed, but it is actually the mantle of a wavyrayed lampmussel. Host fish of the mussel would predate on similarly sized fish, so the appearance and movement of the mantle would lure hosts in. The mantle lures of mussels are an excellent example of mimicry.

Habitat

Existential Threats

Human Interest

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