The life cycle of a freshwater mussel is quite complex. Fertilized eggs (most species of mussels reproduce sexually) develop into larvae, called glochidia, in the marsupium of the female mussels.

Glochidia, when released from the female, must come in contact with a passing fish and attach to the gills, fins, or body of that fish. During this parasitic stage, the mussel glochidia is harmless to their fish host. The mussel-host fish relationship helps disperse a basically immobile creature (the mussel) within and between aquatic systems.

Many mussels are "host specific" in that their glochidia can only survive on a specific species of fish. If a glochidium attaches to a fish that is not the species it is looking for, it will not survive.

After a few days to several weeks, the glochidia free themselves from the host, drift to the substrate and begin their lives as juvenile mussels. Quite often, mussels are concentrated in certain areas of the river bottom called mussel beds. Mussel beds are often located in areas inhabited by a wide variety of fish species. The areas frequented by fish tend to accumulate higher number of glochidia and eventually a mussel bed develops.

It may take several years (2-9) before juveniles mature and can reproduce as an adult. Adults may live 60 - 70 years if conditions are right.

However, studies have documented that it is not uncommon for some species of mussels to successfully reproduce only once out of seven or more years.