Ciona intestinalis is a solitary ascidian, commonly found in dense aggregations. It usually hangs vertically upside-down in the water column. It is cylindrical, 100-150 mm in length and ends with a cone-shaped inhalant siphon. It is pale yellow green with 5 muscle bands running lengthways down the body, clearly visible on each side. Short projections (villi) at the base anchor the ascidian to the substratum. There are 8 lobes on the inhalant (branchial) siphon and 6 on the exhalent (atrial) siphon. The siphonal openings may have yellow margins and orange/red spots. The body wall is generally soft and translucent with the internal organs visible, however, may it be hard and leathery when heavy fouled.
Ciona intestinalis is a known introduction in many parts of the world including the Pacific North America, Western Pacific, South Pacific, Hong Kong, China Sea, South Africa and Indian Ocean. Introductions appear to follow a ‘boom and Bust’ cycle with rapid population explosion on initial introduction followed by a decline, reaching a lower stable abundance equilibrium (Kott, 1990, Van Name, 1945). C. intestinalis is declared invasive in; the Gulf of St Lawrence, Canada, Chile, China, United Kingdom, Japan, Mediterranean Sea and the U.S. North Pacific.
Ciona intestinalis - NIMPIS.
Ciona intestinalis siphon - NIMPIS.
Ciona intestinalis diagram & key features. Solitary ascidian commonly found in dense, unfused aggregations. Body translucent greenish/yellow. Siphons may have yellow margins with orange/red pigment spots. Inhalant siphon has 8 lobes. Exhalant siphon has 6 lobes.
Ciona intestinalis growing on a boat anchorage in Cape Jaffa, South Australia.
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