Sandy beaches are the most widely distributed coastal systems worldwide and have several relevant ecological functions. However, in the last decades, they have been subjected to an increasing human pressure related with recreational activities, unbridled urbanization of coastal areas and tourism, which led to an environmental quality decline of these fragile ecosystems. Often dominated by Crustaceans, the macrofauna of exposed sandy beaches occupies a key-position in the food chains and plays an important ecological role in sandy shore function. Studying abundant species at the population level might be an adequate approach to the ecosystem when the aim is to assess the potential impact of induced environmental changes. The main goals of this study are: (i) to investigate the existence of macrofaunal key species on exposed sandy beaches; (ii) to study their bio-ecology and (iii) to evaluate the possibility of this bio-ecological knowledge presenting a role in global changes assessment. To accomplish this evaluation on a much wider and comprehensive scale, comparative bio-ecological studies between Atlantic and Mediterranean populations from Europe and North Africa are performed.