Gastropteron pacificum from British Columbia

February 19, 2001
From: Marli Wakeling

Here's something a bit different! This is Gastropteron pacificum, also known as a 'winged sea slug', and is found flapping it's two wing like projections to swim. The gills are on the right side of the body, and you can see the gill leaflets in the photo. It is usually a yellow colour with red markings. This specimen was found in Howe Sound, near Vancouver, British Columbia, [Canada]. It is about 2 cm. in length.

Wakeling, M., 2001 (Feb 19) Gastropteron pacificum from British Columbia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Marli,
Quite a spectacular photo of it swimming. For anyone unfamiliar with members of the Gastropteridae, have a look at the photos of Sagaminopteron ornatum. Gastropterids have very large lateral extensions of the foot, called parapodia, which can flap vigorously, enabling the animal to swim, a bit like an out-of-control butterfly. This photo is looking at the animal head on.

A literal translation of the name 'gastropteron' would be 'winged stomach', which I am glad to say has not become a widely used common name.
Bill Rudman

Rudman, W.B., 2001 (Feb 19). Comment on Gastropteron pacificum from British Columbia by Marli Wakeling. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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