Known only from the Pacific coast of Nth America, British Columbia, Canada - Washington State, USA.
Upper: Cowlitz Bay, Waldron Island, North Puget Sound, Washington, USA, depth of 15 m, 20 July, 1975. The substrate was a hard mud. 2 cm long. Photo: Ron Shimek. Lower: SEM photo of radula showing section of left side. Specimen 30 mm long preserved, Rose Harbor, Queen Charlotte Islands, British Columbia, Canada, 4 July 1913, CASIZ 035222. Scale = 100 µm. [Radula photo from Gosliner & Bertsch, 2004 with permission].
The animal is relatively broad, the foot extending out further on each side than the body, and forming a broad tapering 'tail' behind the gills. There are 9-10 thin tapering papillae on each side of the mantle, and approximately 20 more scattered over the dorsum. The rhinophores are proportionally, very long, twice the length of the papillae. There are approximately 12 bipinnate, sometimes tripinnate, gills forming a circle in the postero-dorsal midline. The body is a translucent brownish colour with scattered opaque white spots and a prominent median white line from the gills to the posterior tip of the foot. It has seldom been reported, but Gosliner & Bertsch (2004) report a preserved animal of 30 mm.
The radula formula of an animal, 30 mm preserved, was 32 x 184.108.40.206.1. The large inner lateral teeth are typical for the Goniodorididae, with a large hook-shaped denticulate cusp, but the outer lateral teeth are quite unique. In most species the outer lateral teeth are much smaller than the inner lateral teeth and reduced to a small triangular plate. In O. vancouverensis, the outer lateral teeth are very similar in size and shape to the inner teeth, although they lack denticulation.
Gosliner, T. M. & Bertsch, H. (2004) Systematics of Okenia from the Pacific Coast of North America (Nudibranchia: Goniodorididae) with descriptions of three new species. Proceedings of the California Academy of Sciences, 55: 412-428, figs. 1-11.
O'Donoghue, C.H. (1921) Nudibranchiate Mollusca from the Vancouver Island region. Transactions of the Royal Canadian Institute, 13(1): 147-209, pls. 7-11 [1-5].
ARCHIVE NOTE: An earlier edition of this Fact Sheet [8 February 2003] is available on request.Authorship details
Rudman, W.B., 2003 (November 23) Okenia vancouverensis O'Donoghue, 1921. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/okenvanc