Clavelina dellavallei is a colonial ascidian. Each zooid is up to 3 cm high. The test
is transparent and covered by small white spots. Through the test, the pharynx with its 13 to 17 stigmata is
clearly visible, as well as the white or bluish vertical line of the endostyle. Siphons are close and prominent.
The atrial siphon may be underlined by a blue-purple margin. In the lower part of the zooid, the purple stomach
and intestine are also visible. Blue ascidians arise from a short stalk erected from a basal stolon through which
zooids are connected one another. Colonies are attached to rocks, sea-fans or seaweeds.
It is found from surface to 10 meters deep in the Atlantic Ocean and the Mediterranean Sea.
(source : European Register of Marine Species)
Zooid : Individual, single animal.
Test : or tunic: thick layer secreted by the mantel containing cellulose and protecting the animal.
Endostyle : Groove through which food particles are moved up to the oesophagus.
Atrial siphon : Opening through which water is expelled.
Stolon : Root-like element binding together the individuals of a colony.
Top photograph :
© William Desmartin. Published with author's kind permission :
Clavelina dellavallei, Pointe de Locca, Corsica, South of France. Depth 25 meters.
Text : Anne Bay-Nouailhat © 2006-2017.
Translation : Anne Bay-Nouailhat © 2007-2017.