Colpodaspis pusilla
M. Sars, 1870

Family: Diaphanidae


Known from south-western Britain, western Ireland and southern Norway from 4-150m.


Village Bay, St. Kilda, Outer Hebrides, Scotland, United Kingdom, 1993. Photos: Daniel Geiger.

Until Greg Brown's report (1979) of this species from southern England it was known only from the original specimen dredged in 150m in Norway (1870) and a second specimen from Plymouth, England in 1894. The lightly calcified globose shell is completely enclosed by a thin mantle layer which has an exhalent siphon on the posterior right side. The head has two prominent enrolled rhinophores which lead to a groove along each side of the head. The posterior foot is very short and cannot be seen from above as it is covered by a foot-like extension of the mantle much as in the haminoeid bubble shells such as Atys semistriata. In the upper photo of colpodaspis, the animal is somewhat contracted, which shows the short foot and the posterior mantle flap or 'pseudofoot'. Its diet is unknown.

Maximum length is about 5mm, and the skin contains secretory glands which produce a milky secretion when the animal is disturbed. An accessory pedal gland on the sole of the foot, in the midline, produces a sticky secretion which apparently helps the animal stay attached to the thin stalks and growths it lives on.

• Brown, G.H. (1979) An investigation of the anatomy of Colpodaspis pusilla (Mollusca: Opisthobranchia) and a description of a new species of Colpodaspis from Tanzanian coastal waters. Journal of Zoology, London, 187: 201-221.

Authorship details
Rudman, W.B., 2000 (June 17) Colpodaspis pusilla M. Sars, 1870. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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