Freshwater Sponges

Freshwater sponges are non-moving organisms that live at the bottom of water bodies. They are invertebrates (have no backbone) and do not have organs, but instead have specialized cells that help them filter water for food.

Freshwater sponges grow on sturdy submerged objects in clean streams, lakes, and rivers. Because they are sensitive to water conditions, their presence indicates high water quality and low levels of pollutants. They obtain food from the fl ow of water through their bodies and from symbiotic algae. They also serve as food for ducks, crayfish, and a variety of macroinvertebrates.

Unlike marine sponges, freshwater sponges are exposed to far more adverse and variable environmental conditions, so they have developed gemmules as a means of dormancy. When exposed to excessively cold or otherwise harsh situations, the sponges form these gemmules, which are highly resistant "buds" that can live dormant after the mother sponge has died. When conditions improve, the gemmules "germinate" and a new sponge is born.