Invasive Seaweeds and Hull Fouling Species

Ciona spp. (C. intestinalis, & C. savignyi) - Visit ITIS for full scientific classification. 

Ciona spp. Photo by Carrie Culver © 2008 Regents, University of California.

• Solitary tunicates ("sea squirts") with cylindrical-shaped bodies that can grow to about 6 inches long.
• Soft, gelatinous bodies attach to surfaces.
• Translucent and creamy yellowish-green in color.
• Their sac-like body is filled with water being brought in through an incurrent siphon (or tubular opening).
• They filter-feed on particles brought in with the water current, and push waste water back outside the body through the excurrent siphon.

• Marine environments.
• Occurring in low intertidal to subtidal areas.
• Found attached to a variety of surfaces including rocks, woody debris, and vessel hulls in marinas. 

• Spread by attaching to vessel hulls, from which larvae swim to settle on surfaces in marinas.
• Very broad global distribution, and native ranges are difficult to determine.
• C. intestinalis appears to be native to the North Atlantic, and C. savignyi to Japan and possibly Alaska.
• Non-natives in California.
• See NEMESIS for distribution maps. 

• Pumps water through its siphons and filters food particles from the water.
• Reproduce sexually by releasing sperm and eggs into the water, where they unite to form swimming larvae.

• This fouling growth roughens the hull’s surface, creating friction or “drag” that slows sailboats and increases fuel consumption for powerboats.
• Tolerant of copper in antifouling paint.
• Filter large amounts of water, thus reducing amount of food available for native species. 

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