Unionidae is a family of freshwater mussels commonly known as river mussels. They are found in rivers and streams across North America, Europe, and Asia. These bivalves play a crucial role in aquatic ecosystems by filtering water, which helps maintain water quality and clarity. Unionidae species have a unique life cycle that includes a parasitic larval stage, where young mussels attach to fish gills or fins to develop. They are important indicators of environmental health, as their presence and diversity reflect the quality of their habitats. Conservation efforts are vital due to habitat loss and pollution affecting their populations.