Photo by Jeff Corbett
Photo by Guido Zsilavecz.
This is a comparatively large nudibranch, reaching at least 6 cm in length, and is currently very regularly seen at many False Bay dive sites, especially Long Beach, but also A-Frame, Windmill and other sites, from a few meters to at least 20m depths. It preys on other nudibranchs. According to "Nudibranchs of Southern Africa", it is seasonally common in winter, which explains the frequent sightings.
In contrast to many other nudibranchs the gills are not external, but a single gill is instead found under the mantle. For an animal pointing right it is at the side facing you, and is often very visible on surgy days when the mantle is opened by the moving water.
Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T Gosliner, 1987.
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, 1994.