Cuthona viridis
(Forbes, 1840)

Family: Tergipedidae


Circum-boreal. Nth Atlantic [Known from Roscoff in France and the British Isles, north to Iceland and west Greenland. East coast of North America]. North Pacific [Alaska, Canada, Russia].


UPPER: Folly Cove, Gloucester, Massachusetts, USA. 10 to 12 meters, Length: 12-14 millimeters. Photo: Alan Shepard.
LOWER: Sound of Mull, Scotland, April 1977. Photo: B.E. Picton.

Body semi-translucent white. Opaque white pigment scattered on rhinophores and oral tentacles, usually more concentrated at the tips. There are also white streaks and specks on the dorsal side of the cerata and the large yellowish white cnidosac at the tip of the cerata gives it a yellowish white cap. The digestive gland duct is green with some black specks. Grows to about 15mm in length. In British Isles it is reported to feed on the hydroids Sertularella spp, especially Sertularella rugosa.

i>Cuthona viridis (from New Zealand), C. albocrustata (west coast Nth America) and C. signifera (Japan) were considered by Thompson & Brown (1984) to be possible synonyms of this species.

• Bleakney, J.S., 1996 Sea Slugs of Atlantic Canada and the Gulf of Maine
• Millen, S. V. 1989. Opisthobranch range extension in Alaska with the first records of Cuthona viridis (Forbes, 1840) from the Pacific. The Veliger, 32(1): 64-68.
• Roginskaya, I.S. 2000. Notes on Trinchesia viridis (Forbes, 1840) and its veligers. Opisthobranch Newsletter, 26(3): 13.
• Thompson, T.E. & Brown, G.H. 1984. Biology of Opisthobranch Molluscs, Volume II

Authorship details
Rudman, W.B., 2002 (June 12) Cuthona viridis (Forbes, 1840) . [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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