Botryllus schlosseri

Botryllus schlosseri, commonly known as the star ascidian or golden star tunicate, is a colonial ascidian tunicate that grows on slow-moving, submerged objects, plants, and animals in nearshore saltwater environments.

Description

Individual zooids may grow to 3 millimetres (0.12 in) in size, with colonies reaching 50 millimetres (2.0 in) long .

This species can be distinguished from Botrylloides sp. by the pattern of zooid growth. B. schlosseri zooids emanate from a center in the manner of the arms of a star. Also, there usually are fewer zooids per cluster (5–8 in B. schlosseri and 10 or more in Botrylloides). There are many colors in which this species can be found, ranging from orange, blue and grey. A colony can be easily be separated from the main body to form an independent colony usually referred to as a subclone. Two colonies may also fuse together if they share common alleles for historecognition.

Distribution

The native range of Botryllus schlosseri is the north eastern Atlantic Ocean, the Mediterranean Sea and the North Sea. Its range has spread over the last 100 years to a nearly worldwide extent. Ranging in the western Atlantic Ocean from the Bay of Fundy to North Carolina, it is regarded as an invasive species and is "the most common colonial tunicate in North America."