This week we are coming back to California and discuss a more local Branch. Trapania velox is a rather rare nudibranch species along this coast. Every once in awhile someone comes across a specimen cruising out in the open and they get a great photo like this one. Trapania feeds on the white sponge seen here in Tracy's photo, above. This phanerobranch dorid is characterized by a long slender body with an extra-rhinophoral appendage set to the side of each rhinophore and a strong extra-brachial appendages flanking the gills. Rhinophores, gills, cephala tentacles, appendages and tail are all tipped with yellow, and there are a series of thin dark brown lines down the body.
The range of this uncommon species is from San Luis Obispo County at the north to Bahia Tortugas, Baja California, Mexico to the south. Population densities for given species are usually highest near the center of a species range. Interestingly, Trapania velox has been observed and collected commonly in deep holes in the coastal estuary of Morro Bay, San Luis Obispo County, California (Michael Behrens and Duke McPherson, pers. comm.). Finding this somewhat hard to believe I had my son Mike take me diving in one of these holes in Morro Bay. Although one of the worst dives I have ever experienced in my life due to near zero viz, the occurrence of dozens of specimens confirmed that apparently there is something there in the gloomy depths of Morro Bay that T. velox likes. Curious.
More recently a second species of Trapania has been added to our California fauna. Trapania goslineri was described by Sandra Millen & Hans Berstch in 2000. Some years before, webmaster Mike also featured this species as Trapania sp. in a Branch of the Week.
This beautiful little goniodorid was named in recognition of friend and opisthobranch researcher, Terrence Gosliner, Provost of the California Academy of Sciences. It differs from Trapania velox, in having large clown-like brown spots on its white body, rather than thin stripes. This latter species also occurs further south off Baja California and within the Sea of Cortez.
Nice find Tracy. Thanks for sharing this with us.
Picture was taken with a Nikon N90, Subal housing, two YS-90 strobes.
You will find Tracy at La Jolla Shores almost every weekend.
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David W. Behrens
Pacific Coast Nudibranchs
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