Marine Animal Encyclopedia
Star Sea Squirt Botryllus schlosseri
Individual star sea squirts are only about in (2 mm) long and cannot live on their own. Instead, they arrange themselves in star-shaped clusters, or colonies, embedded in a shared gelatinous casing, called a tunic or test. At the center of each star is a shared outgoing (exhalent) opening through which used water is voided. The colonies vary greatly in color and may be green, violet, brown, or yellow, with the individuals having a contrasting color to the test.