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This webinar will outline what freshwater sponges are, their biology and life cycle, and the difficulties of identification. It will also discuss the distribution and biology of obligate feeders, particularly the spongeflies and sponge-feeding caddisflies.

Britain’s freshwater sponges are hugely under-recorded. They are true sponges from the phylum Porifera which, though mostly marine, does have about 250 freshwater species worldwide. We have six of these, in the family Spongillidae, in a wide variety of freshwater habitats; rivers, streams, lakes and canals. Their under-recording is due, in part, to the difficulty in identifying them to species, which requires microscopic examination of their spicules. The under-recording means that their true distribution is unknown.

However a general picture can be given by looking at distribution of sponge-dependent feeders, most notably the Spongeflies, a worldwide family (Sisyridae) of lacewings whose larvae specialise in feeding on freshwater sponges. We have three species, all in the genus Sisyra, and all have a much wider distribution than simple sponge data suggest. Other sponge specialists include some species of Ceraclea caddisflies (Leptoceridae) whose larvae feed on sponges and even make their cases from sponges. Like the spongeflies these also have a wide distribution.

Our speaker: Jonathan Briggs is an independent ecologist with 40 years experience working in freshwater and terrestrial environments. He has a particular interest in unusual species and man-made habitats. He spent 20 years working on canals, a habitat where sponges are often easily found, particularly under bridges and on lock structures.

This session will run on Zoom. If you are new to Zoom you will need to create a Zoom account and download their software. This is all free and you can do so here.

You can use a laptop/desktop computer, smartphone or tablet and it isn’t necessary to have a webcam or microphone to participate.

Further info on how to join a zoom meeting can be found here.