FLEXING YOUR MUSSELS

Freshwater mussels are a group of soft bodied invertebrates within the phylum Mollusca.  They have two shells (bivalves) that are attached at a hinge, like a folding door.  Two large muscles (adductors) are used to close the shell.  When a mussel dies, the adductors relax, and the shell opens.  This is why when you are shopping for mussels to eat, you want to avoid the ones that are open…they are dead.

The adductor muscles can also be used to open/close the shell, allowing the animal to bury itself in the substrate of streams.  They extend a hose-like structure called a siphon to bring in water.  The water gets filtered and provides food for the mussels.  The water also provides oxygen and carries away wastes. 

Because they filter water for their foods, they are considered filter feeders (nice logical name huh?).  This benefits other organisms by filtering the water and improving water quality.  Regrettably, native mussels are declining due to siltation, habitat loss, pollution, and invasive species.  The most notable, invasive species is the zebra mussel (Dreissena polymorpha).  The zebra mussel is a small mussel (1/2-1 inch) introduced from Caspian Sea.  The zebra mussel secretes byssal threads that allow it to attach to almost any surface, including other mussels.  They can outcompete our native mussels by attaining more food and by encrusting our native mussels.  You can help conserve our native mussels by NOT distributing the zebra mussel or it’s microscopic glochidia (kind of like easily transported teenage mussels).  That means, clean, drain, and dry boats and gear between visiting new water bodies and dispose of unused bait in the trash.

If you want to flex your mussels and learn more, check out this field guide at https://nature.mdc.mo.gov/discover-nature/field-guide/search?f[0]=field_fg_types%3A5583&f[1]=types%3A5675