Adult length: 4–7 inches
Almost statewide, except for river systems far north and northwest. The plain pocketbook mussel is found in nearly every major river system and creek in Missouri. This large, moderately thick, rounded mussel prefers gravel, sand, cobble, or nearly any substrate in a quiet current. This species was important in the button industry. In Missouri, button factories opened in Mississippi River towns, like Hannibal and Louisiana, where mussel beds were prevalent. Eventually, pollution and overharvest reduced the mussel populations and the industry came to an end.
Males release sperm directly into the water, and females downstream siphon it into the gill chamber, where eggs are fertilized. Eggs mature into larvae (called glochidia). These discharge into the water and attach to host fish, like white crappie, sauger, bluegill, yellow perch, and others. The tiny mussels eventually break away and float to the bottom of the stream, and the cycle repeats.
Feeds on algae and fine particles of decaying organic matter, and gets nutrients and oxygen from water drawn into the body through a specialized gill called the incurrent siphon.
Mussels act as nature’s “vacuum cleaners,” filtering and cleansing polluted waters. They are also an important food source for other species in the aquatic environment.
Mussels are excellent indicators of water quality because they are long-lived and relatively immobile. They accumulate contaminants from pollution.
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