FMCS - Freshwater Mussels

Gone Fishin’

One of the most amazing things about freshwater mussels is the use of host fish as a part of their lifecycle. To get their glochidia into a fish’s gills, they have to lure them in close. The inevitable analogies regarding human fishermen quickly surface. When mussels go fishing, it’s a challenge any angler quickly understands. Check out these amazing adaptation.

	MINNOW LURE The pocketbook mussel depends on bass for its host. Females have special flaps on its mantle that resemble a small fish. The mussel extends the flaps from the shell and waves the lure in the water. Bass cannot resist and try to strike the lure thinking it is a tasty minnow to eat. Instead, the fish gets a mouthful of pocketbook glochidia.
	CRAYFISH LURE The rainbow mussel (Villosa Iris) uses smallmouth bass for its host. The favorite food of smallmouth bass is crayfish. So this little mussel has a crayfish lure that can be walked across the bottom.
	WET FLY Fly fishermen use a dainty, sinking lure called a “wet fly” that resembles a small insect. The kidneyshells are “fly fishermen” of the mussel world. These mussels release small packages called conglutinates that resemble aquatic insects, but are filled with glochidia. When small fish like darters try to eat them, the conglutinate ruptures, releasing glochidia into the mouth and gills of the fish.
	WORMS Everyone uses worms for fishing, and mussels are no different. Fanshells release worm shaped conglutinates that are probably tasty to fish because they are made of mussel eggs and glochidia. When the host fish (darters in this case) eats the worm, some of the glochidia attach to the gills of the fish.
	LINE AND LURE The Orange nacre mussel perhaps has the most incredible mussel lure of them all. They release a conglutinate that looks like a small prey fish, but it is attached on a long, transparent mucus strand up to one meter in length. Being attached to the mussel makes the lure look like a fish swimming against the current. When bass mistake it for an easy meal, they are infested with the glochidia.
	GLOW IN THE DARK LURES These mussels display mantle flaps that are so iridescent that they almost glow in the dark. These displays probably are for attracting fish host, but exactly how they interact with their fish host is a mystery.
	CATCH AND RELEASE Mussels want to conserve good fishing too and some like these little snuffbox mussels practice catch and release. These mussels trap their fish host, force glochidia onto their gills, and then release them to fight another day.
	THE ULTIMATE SACRIFICE Some mussel mothers make the ultimate sacrifice to take advantage of some fish that like to eat mussels for dinner. When it is time, mussels like this federally endangered scaleshell lie on the top of the substrate and wait. They wait until a hungry fish swims by to eat them. While the fish chomps down on the crunchy treat, larvae the female was holding become attached to the gills. In this case, just any mussel-eating fish will not do. Scaleshell needs to be eaten by a freshwater drum as that is the only fish that will support the development of the glochidia.

Photos and Videos, courtesy of Chris Barnhart's Unio Gallery.