Distribution of species per family (abundance and percentage) for the most species-rich families in the MidMedPol dataset. Families with less than four species were combined in the category "Others". These are: Sabellariidae, Terebellidae (3 species each), Capitellidae (2 species), Amphinomidae, Aphroditidae, Chrysopetalidae, Dorvilleidae, Maldanidae, Oenonidae, Opheliidae, Orbiniidae, Pholoidae and Polynoidae (1 species each). Diagram based on the data from Suppl. material