spongillids

Spongillids, commonly known as freshwater sponges, are a group of sponges in the phylum Porifera that inhabit inland waters worldwide. They belong to the class Demospongiae, order Spongillida, and family Spongillidae. The group includes genera such as Spongilla and Ephydatia.

They form irregular to encrusting or branching colonies anchored to submerged substrates such as rocks, aquatic plants, or detritus. Their skeleton is composed mainly of silica spicules embedded in a gelatinous matrix, sometimes reinforced by proteinaceous fibers. A characteristic trait of spongillids is the production of gemmules, resistant resting bodies that form under adverse conditions and can give rise to new colonies when conditions improve.

Reproduction occurs both asexually and sexually. Asexual propagation includes budding and gemmule formation; sexually, they produce free-swimming larvae that settle to form new sponges.

Habitat: Spongillids are found in a range of freshwater environments, from quiet ponds and lakes to slow-moving streams, typically attached to hard substrates or aquatic vegetation. They prefer habitats with clean, well-oxygenated water but can occasionally endure seasonal fluctuations.

Ecology and significance: As filter feeders, spongillids play a role in nutrient cycling and water clarity. They also provide microhabitats for other small organisms. Because they are sensitive to pollution and changes in water chemistry, spongillids can serve as indicators of freshwater ecosystem health.

Taxonomic note: The group is often referred to as freshwater sponges and is distinct from marine sponges in many aspects of morphology and life history.