Spongilla

Spongilla is a genus of freshwater sponges in the family Spongillidae, within the phylum Porifera. Freshwater sponges are sessile, filter-feeding organisms that inhabit lakes, rivers, and ponds around the world, often attaching to submerged surfaces. Spongilla species have a soft body supported by a skeleton made largely of spongin, a fibrous protein. Some species also contain siliceous spicules embedded in the tissue, but unlike many marine sponges their skeletons are often less rigid.

A key feature of freshwater sponges is the production of gemmules, dormant, resistant clusters of archaeocytes surrounded by a protective layer. Gemmules enable survival during freezing or drought and can give rise to new colonies when conditions improve. Reproduction can also occur sexually, with hermaphroditic individuals producing eggs and sperm and fertilization leading to free-swimming larvae that settle as new individuals. In addition, asexual reproduction by budding or fragmentation can occur, contributing to colony growth.

Spongilla lacustris is the best-known species and historically has served as a model for studies of freshwater sponge biology. Other species are described from North America, Europe, and Asia. These sponges play a role in aquatic ecosystems as filter feeders, contributing to water clarity and nutrient cycling, and they can serve as indicators of water quality. Conservation concerns include habitat degradation, pollution, and sedimentation.