Cypris settlement and dwarf male formation in the barnacle Scalpellum scalpellum: A model for an androdioecious reproductive system

► Hermaphrodites of S. scalpellum can carry 0-13 dwarf males. ► In field populations males are invariably located in two confined receptacle areas. ► Experiments show that cyprids developing into males settle in these areas. ► Settled cyprids penetrate into the hermaphrodite tissue within 12 h after settlement. ► These events are documented by video observations.