Star Ascidian, Botryllus schlosseri

The Star Ascidian (Botryllus schlosseri), also known as the Golden Star Tunicate, is a species of invasive ascidian tunicate which can be found almost throughout the world’s oceans. Its native range is within the Atlantic Ocean from the Bay of Fundy to North Carolina, and is the most common colonial tunicate in North America. It grows on slow-moving, submerged objects, plants, and animals in near shore environments.

This invasive colonial zooid grows to less than 0.25 inches in size. Colonies of zooids can reach up to 2 inches long. Colonies tend to have between 5 and 8 zooids in the cluster. This species can be found in many different color variations, ranging from shades of orange to blues and grays. A colony can be easily separated from the main body and will form a new independent colony typically referred to as a sub-clone. Two separate colonies may also fuse together to share common alleles.

When sexually productive, this species is known to produce yellowish-white or pale orange tadpole larvae exhibiting an oval outline.

Image Caption: Botryllus schlosseri. Credit: Massimiliano DE MARTINO/Wikipedia(CC BY-SA 3.0)