Anatomy of finfish and shellfish

Unit 13 - Mollusca

13.2.1. Habits and Habitats
The freshwater mussels are found in ponds, lakes, rivers and streams, some in quite and others in flowing waters. They occur more abundantly in waters containing lime as this material is necessary for the production of their shell. They live nearly buried in the mud or sand at the bottom, with only the posterior tips of their shell valves exposed. They may also occur wedged in between the rocks and stones, with the valves slightly spread, and the two siphons exposed. They burrow and crawl slowly by extending their large muscular and ploughshare like foot between the two valves, or through the gape of the shell, and larvae a furrow to mark the path they have followed. They may migrate to shallow places by night and retire to deeper places by day, and may change the habitats with the seasons.