Gastropteron pacificum - locomotion

November 22, 2007
From: Lily McLean

Dear Bill,

We have recently collected several individuals of Gastropteron pacificum, from a dredge in Barkley Sound on the west coast of Vancouver Island, Canada. We have been working on a project examining the biomechanics of their locomotion, and we have had trouble finding information. We were hoping you could tell us anything you know about locomotion in Gastropteron, or any similar cephalaspids.

Locality: Bamfield, ?, British Columbia, Canada, Pacific Ocean, 13 November 2007, Dredged. Length: 1 - 2 cm

Thanks alot,
Lily Mclean and Erika Simonson
Bamfield Marine Sciences Center

PS. We love your sea slug forum!

McLean, L., 2007 (Nov 22) Gastropteron pacificum - locomotion. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Lily & Erika,

I have a Fact Sheet on swimming but I am afraid at present it just contains a list of references - although it does have a composite photo of Sagaminopteron ornatum swimming. Haefelfinger & Kress (1967) analysed the swimming behaviour of the Mediterranean Gasteropteron rubrum by meticulously studying a film of it swimming, frame by frame. Wes Farmer's summary swimming in gastropods (1970) may be more accessible to you as it was published in The Veliger.

The name Gastropteron, which basically means 'stomach on wings' is quite appropriate. Quite a few unrelated opisthobranchs have evolved wing-like extensions on the sides of their foot - which we call parapodia - and quite a few of them have adapted them for swimming, including many species of Aplysia [see A. fasciata, A. brasiliana], Akera [see Akera bullata] as well as species of the Gastropteridae. We don't know what the function of swimming is in various species. Perhaps it is just an escape mechanism when they are disturbed, or perhaps in some species it is an important means of locomotion.

If by chance you have photos of this species swimming, they would be a nice addition to the Forum

  • Farmer, W. M. (1970) Swimming gastropods (Opisthobranchia and Prosobranchia). The Veliger 13(1): 73-89.
  • Haefelfinger, H-R. & Kress, A. (1967) Der Schwimmvorgang bei Gasteropteron rubrum (Rafinesque 1814) (Gastropoda, Opisthobranchiata). Revue Suisse de Zoologie, 74: 547-554.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Nov 22). Comment on Gastropteron pacificum - locomotion by Lily McLean. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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