Fredericellidae

Fredericellidae is a family of freshwater bryozoans within the phylum Bryozoa and class Phylactolaemata. The family is named after the type genus Fredericella, and includes several genera recognized by bryozoologists, though the exact composition has varied with revisions of bryozoan taxonomy. Members are obligate freshwater organisms that form colonies on submerged substrates such as stones, shells, and aquatic vegetation.

Colonies consist of zooids embedded in a gelatinous matrix, often forming branching, sheet-like, or encrusting structures. In Phylactolaemata, colonies produce statoblasts—seasonal, resistant propagules—that facilitate survival through winter or drought and enable dispersal when waters resume. Reproduction occurs by budding to grow colonies, supplemented by sexual reproduction that yields free-swimming larvae.

Fredericellidae taxa are distributed in temperate freshwater systems of Europe and North America, with records also in other temperate regions. They are commonly found in rivers, streams, and lakes with adequate oxygenation and suitable substrates. They play a role in aquatic ecosystems as filter feeders and can be used as bioindicators of water quality and habitat condition.

Notable species include Fredericella sultana, a well-studied representative that forms colonies on stones in streams and rivers. Taxonomic work and molecular studies continue to clarify the relationships within the family and its position among phylactolaemate bryozoans.