The Avilés Canyons System (ACS) is located in the South of the Bay of Biscay (Northern Spain, Cantabrian Sea) and covers a total of 3,390 km2. It is composed of three canyons, reaching the abyssal plain at 4700 m depth. The mixing of diverse water masses

Echinocardium cordatum is likely the most widely distributed extant echinoid. The species status remains, however, puzzling as it includes several morphotypes that are not all geographically well delimited. It encompasses a cryptic species complex of

Echinocardium cordatum is likely the most widely distributed extant echinoid. The species status remains, however, puzzling as it includes several morphotypes that are not all geographically well delimited. It encompasses a cryptic species complex of