The amphipod Caprella mutica is one of the most rapidly invading species in Europe and has extendedits range throughout North Sea and Celtic Sea coasts and the English Channel in less than fourteen years. It was first described from sub-boreal areas of north-east Asia in 1935 and has since spread to both northern and southern hemispheres. The first European record was from The Netherlands in 1994. Since then it has spread within the North Sea and later to the west coast of Scotland and to Ireland. C. mutica is frequently associated with man-made structures and is found in abundance on boat hulls, navigation/offshore buoys, floating pontoons and aquaculture infrastructure. It is highly likely that its dispersal is associated with vessel movements whilst attached to hull fouling. This species is expected to colonise the west coasts of France and Spain and offshore islands in the north-east Atlantic.