Scavenging fauna plays an integral role in ecosystem functioning, nutrient cycling and circulating organic matter. Thus, baseline data of scavenger assemblages on the NW coast of the Iberian Peninsula that provides information on the abundance of species in different habitats is crucial to understanding the distribution of this understudied group. Two different types of baited traps, to capture scavenging megafaunal and scavenging benthopelagic macrofaunal assemblages, were deployed to compare them among rocky, pebbled and sandy bottoms at shallow subtidal on the northern coast of Portugal. Results showed significant differences in the structure of scavenger assemblages. Scavenging megafaunal assemblages differed between sandy and the other two studied habitats, whereas benthopelagic macrofaunal assemblages differed between pebbles and rocky habitats. This suggests that different drivers seem to shape the structure of benthopelagic macrofauna and megafauna. Regarding megafauna, the dominance of Tritia gastropods in sand habitats in comparison with its absence in rock and its very low abundance in pebbles was mainly responsible for the differences. However, in benthopelagic macrofauna, differences in assemblages between pebbles and rock were more related to changes in the relative abundance of crustacean species (Cirolana cranchii and Socarnes erythrophthalmus) that were less abundant in pebbles.

The family Onchidiidae comprises a group of air-breathing marine slugs that can be very abundant in the intertidal zone of temperate shores worldwide. Recently, the phylogeny of the genus Onchidella has been reassessed by means of molecular markers, but anatomical studies are still needed to support these conclusions. In the present work, the anatomy of Onchidella celtica has been studied by using X-ray micro-computed tomography (micro-CT), a non-invasive technique that allows for 2D and 3D imaging of the external and internal anatomy of specimens without irreversible damage. To date, the potential of this technique for the anatomical study of onchidiids had not been assessed yet and therefore a reconstruction of the whole internal anatomy of O. celtica is provided here. Most of the organs and structures were clearly visualized; our observations largely agree with previous descriptions also highlighting the usefulness of micro-CT for the anatomical study of onchidiids.