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Life Cycle of a Freshwater Mussel

Written by Jeff and Elizabeth Janvrin


Students are guided through the life cycle of a freshwater mussel. Each phase is introduced by a student reading an excerpt from The Story of My Life by Billie Button. Then the students view that stage or anatomical part by looking at handouts of the mussel or its life cycle. Additionally, two demonstrations involving students role playing mussels are performed:

    1. Genetic Contribution Demonstration
    2. Host and Substrate Demonstration


A generalized life cycle of a mussel
mussel life cycle
Click here for larger scale

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.

Being host specific can make a mussel extremely sensitive to human impacts. For example, the construction of Lock and Dam 19 near Keokuk, Iowa, blocked the migration of skipjack herring up the Mississippi River. The skipjack herring is the only host for the ebony shell and elephant ear mussels. These two mussels are no longer found in the Mississippi River watershed above Keokuk, Iowa, since their host, the skipjack herring, can no longer migrate above Lock and Dam 19.

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.


Overheads or copies of:
mussel life cycle
  mussel internal anatomy
  mussel external anatomy
  Chapters I - III of the Billie Button Story

Genetic Contribution Demonstration
fish host cards
confetti substrate cards

Species Identification and LocationThreatened and Endangered MusselsLife HistoryEcology Mussel Harvest on the RiverCurrent ThreatsMussel Conservation ActivitiesOngoing Studies and ProjectsMultimediaTeacher ResourcesFrequently Asked QuestionsGlossaryReferencesLinks to Other Mussel Sites


Department of the InteriorU.S. Fish & Wildlife ServiceU.S. Geological Survey
Last updated on October 16, 2003