Exploring Rocky Shores of Southern Oregon Coast

Alabaster (Eolid)

One of our most exciting tide-pool finds last year was the Alabster Nudibranch, "Dirona albolineata".  We were tide-pooling at Sisters Rocks, 15 miles north of Gold Beach, in August during a  good low-tide (-1.4).  We spotted this white, fairy-like critter (see below).  Its cerata, the leaf-like projections, looked like translucent wings outlined in white (albolineata translates: white line).  I sent an inquiry to the Nudibranch Forum, hosted by the Australian Museum, and they identified the little guy for me. 

Since that day, we have found many more specimens (the two below were spotted 10 miles north of Gold Beach, at the base of Devil's Spine).  The Alabaster is found in rocky intertidal areas, as well as sub-tidally, from southern California to Alaska. It is an opportunistic predator that feeds on a wide variety of prey, including bryozoans, small crustaceans, small snails, and hydroids, depending upon which is the most abundant. They can grow up to 7 inches long sub-tidally, but the ones pictured in both photos were less than 2 inches long.

Hermissenda (Eolid)

The Hermissenda (Hermissenda crassicornis) is my favorite nudibranch. It only grows to 3" long, but its' translucent body, bright orange cerata, and blue markings make it a spectacular find in the tide-pools.

Hermissendas are very aggressive carnivores, preying upon small anemones, sea squirts, worms, and more.  One of the Hermissendas in the photo below was biting the other when we discovered them at Lone Ranch, just north of Brookings.  We have since read that they bite each other when defending their feeding area.

Sea Lemon (Dorid)

The Sea Lemon (Anisodoris nobilis) is one of the more common nudibranch found on the Southern Oregon Coast and one of the largest, growing to more than four inches in length.  It is bright yellow with a white gill plume around the anus (see photo below).  The two circular markings at the left end are its rhinophores, used to detect the scent of prey. 

Sea Lemons primarily feed on sponges, and can vary widely in appearance. Marine biologists have recently determined there are five separate species that had all been categorized as Sea Lemons.   They can be solid yellow, or mottled ( as the one shown in the photo below) with dark patches between its tubercles.