A closer view revealed just how orange this nudibranch was!
In the picture above, you can also see relatively long papillae (or projections) that make the nudibranch look fuzzy, white flecks scattered across the surface, dark tips to the rhinophores (the sensory organs), and a hint of the white gill plumes — all important characteristics of an Orange-peel Dorid (Acanthodoris lutea).
The orange color is important to the nudibranch. It's an example of aposematic coloration, or "warning" coloration — a signal to potential predators that the nudibranch is unpalatable or toxic.
Here's one more image, this time from above. The water was flowing by at the time, so the rhinophores are leaning to the left. This shot includes a better view of the extended white gill plumes.
Although they're known to occur from Cape Arago, Oregon to northern Baja California, Orange-peel Dorids appear to be uncommon in the Bodega Bay area. This is the first time we've encountered this species locally.