Did you know? Lake Geneva is home to freshwater sponges, real living aquatic creatures far removed from kitchen utensils. Known by the scientific name Spongillida, there is an impressive variety of 10,000 species. Soft, fragile, slimy and irregularly shaped, they are not part of the plant kingdom, but of the animal kingdom, and play a crucial role in the ecosystem. Their porous surfaces act as filters, contributing to water quality by eliminating suspended particles.
Although they belong to the Sponges family, only a few species live in freshwater. For a long time, it was thought that these colonies lived fixed and immobile. But this is not true. Sponges are capable of moving several centimetres per month on the substrate.
Spongilla lacutris is the only species found in Lake Geneva. Described as eurybionte, it is capable of surviving in a variety of freshwater environments, regardless of current or temperature. Its only requirement is the presence of nutritious particles in the water in order to feed.
These sponges nest at depths of less than two metres, inhabiting various waterways in Europe, North America, Asia, Africa and even the north-west Atlantic. Their appearance, ranging from off-white to brown, varies according to their age and habitat. Found in lakes and rivers, they attach themselves to various objects such as plastic buoys, roots, rocks or tree trunks.
A new dimension of the richness of Lake Geneva to discover and preserve.
📷 : © Kirt L. Onthank / Wikimedia Commons
