Orange Sheath Tunicate

Botrylloides violaceus

''Botrylloides violaceus'' is a colonial ascidian. It can be known by the common name 'Orange Sheath Tunicate' among others.
Its native range is in the northwest Pacific from southern China to Japan and Siberia. Colonies attach and grow on solid substrates, and consist of individuals arranged in twisting rows. Outside its native range, it is considered an invasive species and are becoming more common in coastal waters of North America and other waters around the world, likely being spread by shipping industries.

In the San Francisco Bay area, ''B. violaceus'' can be readily found on boat docks in the Richmond Marina. The ecological impact of ''B. violaceus'' in this region remains unknown.