the free living state. So, S. roscoffensis could be a major nitrate interceptor. In the tissues of the animal, the micro-algae produces a sulfur compound, DMSP (dimethylsulfoniopropionate), which also diffuses into the environment. This compound is generally degraded enzymatically by DMSP-lyases to acrylic acid and DMS (Dimethyl sulfide). However, no DMSP-lyase activity was measured in cultures of Tetraselmsis convolutae alone. Bacterial DMSP-lyase activity has been hypothesized to explain the presence of DMS and acrylic acid in colonies of S. roscoffensis. It is likely that S. roscoffensis mucus (such as the mucus of other photosymbiotic animals such as corals) harbor specific bacterial populations expressing DMSP-lyases. DMSP is a sulfur compound that exhibit, among other things, a repellent property that could confer a chemical barrier explaining the absence of known or observed predators and as a consequence the abundance of worms within colonies. Notes and references See also Climate change Marine biodiversity Acoelomorphs Animal models Animal developmental biology Animals described in 1891 Fauna of the Atlantic Ocean