The diversity of diets in Syllidae (Annelida: Polychaeta)

Results from examination of fecal pellets and gut content of some syllid species (Polychaeta, Annelida) are reported. Specimens were collected from 0 to 20m depths along Apulian coast (Mediterranean Sea). Species collected at shallowest depth showed the presence of microalgae and macroalgae fragments in their guts and were considered herbivores A prevalence of sediment grains in species from deeper samples together with animal or vegetal detritus, suggest that these are detritivores. Finally some species, collected at different depths, appeared as a mixture of the two previous categories and were considered omnivores. In addition in the omnivores, as well as in the detritivores, spicules of sponges or ascidians (Didemnidae) and bryozoan fragments could be present. Some assumptions were inferred from correlation of feeding structures with feedings categories in syllids. This paper represents a preliminary study, but it intends to warn against broad generalizations. Previous studies of trophic guilds, based on assumptions inferred from a few and old papers relative mainly to the genus Autolytus, considered all the Syllidae as mostly carnivores. Our observations suggest that the syllids are much more various in their diet than previously assumed, and that several of them are not carnivores.