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Botryllus tuberatus (Ritter & Forsyth, 1917)

Pacific Star Tunicate

Adeline Ang (2014)



Fact Sheet

Brief Summary

Physical Description

External Features

Internal Features

Slides Preparation


Life History & Behaviour

Feeding Mechanisms


Internal Transport & Movement

Asexual Reproduction

Sexual Reproduction

Anatomy & Physiology

Evolution & Systematics

Biogeographic Distribution

Biofouling Threats

References & Links

Internal Transport & Movement

Just like other chordates, ascidians like B. tuberatus posses a hemal and circulatory system to allow for internal transport.  Other than flow of nutrients within the individual, there are also test vessels that connect the zooids with one another (Kott 1985).  This allows the flow of nutrients through the entire colony, as seen from the video below.  These test vessels form a system of 3-dimensional network, with blind tubular enlargements called vascular ampullae as seen in the figure below.  These can be seen as dark pigmentations around the edges of the test (Abbott & Newberry 1980; Kott 1985).  
Video showing the translucent blood vessels of B. tuberatus with particles flowing through it, as seen under a microscope.

Image showing the vascular ampullae in B. tuberatus.  Picture is taken from the bottom-up view of a glass slides holding one of the B. tuberatus colonies.