Compass sea squirt (Asterocarpa humilis)
The compass sea squirt is a solitary ascidian native to the S Hemisphere. First recorded in the UK in 2009 in SW England it is spreading rapidly around the UK. It is orange-red with a tough outer tunic, can be up to 4cm across and has distinctive compass-like markings around the siphons. It is a potential fouler of aquaculture equipment, clumps could clog pipes, and is a potential competitor for food and space with cultured bivalves. In the Tamar Estuaries area it is now entering natural habitats.
Environmental risk: LOW
Economic risk: MEDIUM
Image: J. Bishop © MBA