Ciona intestinalis is a solitary ascidian which is up to 15 cm high. This upright cylindrical
sea-squirt has a smooth soft test. It is translucent and its colour varies from white to yellow. Muscular
bands, branchial sac and intestine are visible through the test. The edges of the siphons have a yellow margin.
Oral and atrial siphons are contiguous and terminal. The oral siphon has 8 lobes and the
atrial one has 6 lobes. Yellow sea-squirts often live in groups attached to rocks, piles, hulls. It can be
common in harbours because this species seems to bear polluted waters.
It is found from low water level to 50 m deep in the Atlantic Ocean, the English Channel, the North Sea, the
Baltic sea and the Mediterranean Sea.
Phylum Chordata, subphylum Tunicata, class Ascidiacea, order Phlebobranchia, family Cionidae, Ciona intestinalis (Linnaeus, 1767).
Test: or tunic: thick layer secreted by the mantel containing cellulose and protecting the animal.
Oral siphon: Opening by which water is drawn in the ascidian.
Atrial siphon: Opening through which water is expelled.
Ciona intestinalis
Close-view ot the oral tentacules
Outline of the pharynx
Photographs: © Wilfried Bay-Nouailhat. Published with author's kind permission.
Ciona intestinalis, Bay of Concarneau, South-Brittany, West of France. Depth 5 meters.
Ciona intestinalis, Bay of Concarneau, South-Brittany, West of France. Depth 4 meters.
Ciona intestinalis, Bay of Concarneau, South-Brittany, West of France. Depth 11 meters.
© William Desmartin. Published with author's kind permission.
Ciona intestinalis, detail of the oral tentacles.
Text: Anne Bay-Nouailhat © 2005-2008.
Translation: Anne Bay-Nouailhat © 2007-2008.
