Bulla gouldiana from San Diego

February 21, 2006
From: Mike Neubig

Here are some shots of Bulla gouldiana.

Two individuals, several cm apart, were completely on top of the sand when I came across them on an evening beach dive at La Jolla Shores. The one I settled on to photo (dual HIDs, no strobes, custom lense) seemed to quickly exude and cover itself with a mucous blanket - and proceeded to dive into the sand. The head shot [upper right] with the eye spot was taken before this reaction to the bright light (?) began. The second shot is of the same individual heading under, head to the left.  For the next few minutes, a free swimming sarcastic fringehead had my attention. When I looked back, the photo'd Bulla had vanished. The second individual was full below the level surface except for the anterior rhinophores, as in the lower photo.

The speckled patches seem similar to ones in Marli Wakeling's message about Melibe [#10999], in which the possibility of their being microscopic flatworm infestations is put forth. The erratic races on the Bulla 's shell are interesting too, especially how many seem to be half covered.

As the forum search turned up a few posts mentioning this species, but none with photos, I thought I would send these along for addition.

Locality: Valley-Sea-Toes, La Jolla Shores, 14 m, California, USA, Eastern Pacific Ocean, 16 February 2006, Gradually sloping sand bottom, 3 m from the "edge" of La Jolla Canyon. Length: 20 mm (shell). Photographer: Mike Neubig.

Mike Neubig.


Neubig, M., 2006 (Feb 21) Bulla gouldiana from San Diego. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15885

Dear Mike,
Thnaks for these interesting observations. Many of these bubble-shells have lare mucus glands at the front of the head which they use to make a mucus tube to crawl through in fine sand and mud, as you describe. The white speckled patches you mention are small galnds which can exude a white acidic secretion when the animal is disturbed. If look at the other photos of Melibe leonina on the Forum you will see that those in Marli's animal don't appear to be 'normal' for that species, so I suspected an external cause.

Concerning the lines across the shell which break up the pattern, they are growth lines, much like tree rings, which mark periods of growth and no growth on the shell. The uppermost one in your photo actually looks as though the edge of the shell was broken for awhile before regrowth occurred.

If anyone has a photo of Bulla gouldiana I could use for a Fact Sheet, it would be welcome.
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Feb 21). Comment on Bulla gouldiana from San Diego by Mike Neubig. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15885


Bulla gouldiana

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