A little known fact about freshwater mussels is that they live part of their life as a parasite. The glochidia or larval stage of a mussel will attach to a host and grow for a few weeks before releasing and falling to the substrate below. The host that the glochidia parasitize is almost always a fish (there is one species of mussel that can parasitize salamanders). Each species of freshwater mussel has just a few species of fish on which its larva can attach. Because of this special and very specific mussel-host fish relationship, mussels have evolved ways to “trick” their particular fish into becoming infested with glochidia. Some mussel species lure fish in close with a modified section of their mantle tissue that resembles a tasty meal, such as minnows or tadpoles. When the fish strikes it is bombarded with thousands of glochidia, which will encyst onto the gills or other parts of the fish. The fish swims away, un-phased by the whole ordeal. The glochidia grow for 30 days or more on the fish. Another method a mom mussel uses to infest a host fish is by releasing a snot-like string containing their glochidia into the water. A fish swims through the strands and the larvae attach. Below are some examples of different mussel species using unique lures to attract their fish host.
Click the video below to view some examples of mussel lures.
Videos 1&2: Pocketbook (Lampsilis cardium) flapping its mantle tissue resembling a minnow or darter. This lure is used to attract fish such as smallmouth bass or bluegill on which the Pocketbook’s glochidia can attach.
Video 3: Ridged Pocketbook (Lampsilis ovata) displaying a similar lure as the Pocketbook mussel.
Video 4: Black Sand Shell (Ligumia recta) with its unique lure that to a fish looks and moves very much like a crayfish or crawdad. This lure could be used to attract fish such as largemouth bass. Interestingly, she usually displays the lure at night.
Video 5: Lilliput (Toxoplasma parvum) using undulating mantle flaps to lure in unsuspecting fish.
About the Author: Caitlin Byrne is Collection Manager of the Division of Molluscs.