Cuthona amoena
(Alder & Hancock, 1845)

Family: Tergipedidae


Atlantic coast of Europe [Mediterranean, British Isles, Holland].


Upper: South Gortein, Loch Fyne, 15 m, Scotland, Atlantic Ocean, 30 April 2006, Rocky reef. Length: 15 mm. Photographer: Jim Anderson. Lower:The Netherlands. Photo: Peter H. van Bragt

Like many species of the genus, Cuthona amoena is a small and rather cryptic species. It aparently feeds exclusively on the hydroid Halecium halecinum on which it is usually found. It is translucent, if not transparent, with the viscera and brownish digestive gland showing through the body wall. The back of the body and the cerata are covered in scattered gold or yellowish-white pigment specks, more abundant in some animals than others. The specks are particularly concentrated at the tips of the head tentacles and cerata. There is a brown band about midway down each rhinophore, and around each oral tentacle and often there is brown pigmentation at the base of the cerata. It reaches a maximum of about 12 mm in length.

Another species, Cuthona rubescens, feeds on the same common hydroid and looks very similar in colour and shape. The most distinctive external difference is that it does not have a brown band in the middle of the oral tentacles.

Authorship details
Rudman, W.B., 2006 (May 8) Cuthona amoena (Alder & Hancock, 1845). [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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