Ryan Photographic - Urechidae - Innkeepers
The family Urechidae contains 4 species in one genus. They were originally placed in their own phylum because they lacked segmentation. Subsequent genetic analysis placed the echiurans in the Annelida.
They live in U-shaped burrows in muddy substrates, feeding mostly on detritus. They make a mucus net and then draw oxygenated water into their burrow through peristaltic waves. When the net is full they ingest the trapped particles and the net and then make a new one. Perhaps because the water in the burrow is always oxygenated their burrows are often home to a variety of commensals - hence their common name of "Innkeepers".
Urechis caupo Innkeeper
Urechis caupo Innkeeper, captive in artifical burrow