Description: As with other dendronotid nudibranchs, the anus is on the right side of the body instead of dorsal or posterior (photo). The clavus of the rhinophores can be withdrawn into the sheath (photo). There are bushy or paddle-like cerata or gills on the dorsum, usually in longitudinal rows (photo). Tritonia diomedia has a massive body, longer than wide and wider than high, and a longitudinal row of gills along a definite dorsolateral margin on each side of the smooth dorsum. The 20-30 gill tufts in each row are separated from one another by spaces. The oral veil has about 18 (10-30) short, simple (unbranched) white papillae. Color is salmon or rose without a pattern of white lines, except that there is a narrow white line along the margin of the dorsum, the margin of the foot, and the edge of the rhinophore sheath. The edge of the rhinophere sheath is smooth but the white-tipped clavus of the rhinophore is surrounded by about 20 yellow to brownish processes (photo). Length up to 22 cm.
How to Distinguish from Similar Species:Tochuina tetraquetra, which also eats sea pens, has unbroken rows of white gill tufts along the margins of the dorsum. Tritonia festiva is smaller and has a pink dorsum, often with a pattern of white lines. Tritonia exsulans is difficult to distinguish but it is smaller, has a body about as wide as high and several differences in internal anatomy
Geographical Range: In the north Pacific from Japan through Alaska down to Panama. Also in Florida.
Depth Range: Intertidal to 656 m (mostly subtidal)
Habitat: On sandy bottoms, especially near sea pens.
on sea pens such as Ptilosarcus
Kozloff, 1987, 1996
General Notes and Observations: Locations, abundances, unusual behaviors:
Authors and Editors of
Salish Sea Invertebrates web site provided courtesy of Walla