Variation in Scototaxis and Orientation Adaptation ofTalitrus saltatorPopulations Subjected to Different Ecological Constraints

This study focuses on the wayTalitrus saltator, a common inhabitant of the eulittoral zone of sandy shores, responds to landscape features, and highlights behavioural variations among natural populations from shores subject to different ecological constraints. Mediterranean and Atlantic talitrid populations show differences in orientation, zonation and spontaneous migration on the beach, all of which are related to differences in tidal amplitude. In particular, Mediterranean sandhoppers migrate towards the dune for feeding, whereas Atlantic sandhoppers feed downshore on fresh wrack. In constant experimental conditions, a black stripe covering a sector of the horizon produced scototaxis with rhythmic changes in the sign and intensity, which are related to variations in migratory behaviour in the field. When the scototaxis of laboratory-born juveniles is compared to the behaviour of sandhoppers in the field, it can be inferred that the species-specific responses, as well as the talitridsʹ adaptation to their natural situation, derive from both individual experience and evolution.