Arsenic occurrence and speciation in Cyclope neritea, a gastropod inhabiting the arsenic-rich marine shallow-water hydrothermal system off Milos Island, Greece

► Cyclope neritea is studied for total arsenic and arsenic species occurrence. ► Inorganic arsenic is found at high proportions in the gut and muscle of the organism. ► TMAP is found at relatively high proportions in the organism and surrounding environment. ► TETRA is found in gut and muscle suggesting that this species is biosynthesized by the organism.