Spongilla

Spongilla is a genus of freshwater sponges. They can be found on submerged objects in clean lakes, ponds, streams, and rivers. Spongilla was first publicly recognized in 1696 by Leonard Plukenet and described by Jean-Baptiste Lamarck in 1816. The type species is Spongilla lacustris, described by Carl Linnaeus. Spongilla have a leuconoid body form with a skeleton composed of siliceous spicules. They are sessile organisms, attaching themselves to hard substrate such as rocks, logs, and sometimes to ground. Using their ostia and osculum, these sponges filter the water for small aquatic organisms such as protozoans, bacteria, and other free-floating pond life. Sponges of the genus Spongilla partake in symbiotic relationships with the green algae, zoochlorellae, which gives the sponges a green appearance, and without which they would appear white. Spongilla was used by John Hogg in the 19th century to attempt to justify a fourth kingdom of life.