The Japanese sea squirt (Styela clava) is an invasive marine species in the British Isles, first recorded in the 1950s. Native to East Asia, it has spread globally through hull fouling and aquaculture activites. This solitary sea squirt attaches to hard surfaces such as rocks, piers, and artificial structures in harbours and coastal areas. Its presence can impact native marine communities by competing for space and altering habitat structure, as well as positing a nuisance for aquaculture operations by fouling equipment.