Botryllus schlosseri

This colonial ascidian is difficult to spot during its juvenile stage.  Though the juvenile Botryllus schlosseri is fairly large, it is also almost completely transparent. Young juveniles of Botryllus schlosseri have a large, bulbous body surrounded by ampullae similar to Botrylloides violaceus.  However, Botryllus schlosseri lacks the bright pigmentation common to Botrylloides violaceus and also has less ampullae (5-8). 

Anatomy of Botryllus schlosseri

Oozooid- the juvenile ascidian which arises from the larva; the original zooid before asexual reproduction begins
Ampullae- finger-like projections within the tunic surrounding the site where the juvenile attaches to the substrate
Atrial/Excurrent Siphon- a tube through which water and excrement exits the body
Buccal/Incurrent Siphon- a tube through which water and food particles enters the body
Pharyngeal/Branchial basket- a large, basket or cylindrical shaped region which houses the cilia used to pump water through the ascidian body
Botryllus schlosseri oozoid anatomy

Colonial morphology of Botryllus schlosseri