- It feeds on small organic particles.
- It requires stable cobble and gravel substrates with little fine material.
- Growth rings can be seen on the shells.
- Maturity is reached after 10-15 years.
- After maturity, it can have a reproductive life span of about 75 years.
- It has two sexes. Females can become self-fertile hermaphrodites.
- It is a Holarctic species, found in North America and Europe.
- The hosts of its parasitic larvae are salmonids. In Europe, these are the brown trout and Atlantic salmon.
- Population declined over 90 % in Europe in the last 90 years.
- The loss of habitats and host fish contributed to its population decline.
- It is assessed as Endangered globally and Critically Endangered in Europe on the IUCN Red List.
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