The Mystery of the Dorid Eggs

By the time we reached Port Townsend, my friend Stevie was picking up the rhythm of the day - scan the dock, focus eyes on likely features, contort body for closer inspection. Repeat. Although we’d not found any actual sea slugs at our earlier stops, Port Ludlow and John Wayne Marina, she’d enthusiastically pointed things out. I’d cajoled her into joining me for this dock fouling trip around the Olympic Peninsula, so I felt both relieved and pleased that she was having fun.


A bit despondent at the apparent lack of slugs, I picked up a fragment of decaying rope from the deck, turned it over, and, finally, there it was, our first sea slug of the day. A lovely thick Horned Nudibranch, crawling on the rope, oblivious to our excitement. I took a few photos and carefully replaced the rope.

Encouraged, we began a more systematic search of the marina. No more slugs, but there were numerous dorid nudibranch egg ribbons on the dock posts. Stevie went from post to post pointing them out. I kept looking for sea slugs but couldn’t find a single one. It seemed improbable that there were so many eggs but not a single slug in sight. We worked our way to the end of the marina and were about to give up when I noticed movement among the barnacles on one of the egg-covered poles. There, above and below the waterline, were a whole slew of cunningly camouflaged dorid nudibranchs. Between the size of a quarter and a silver dollar, they had disproportionately long rhinophores and anal gills. Revisiting the posts we’d previously inspected, we found there were actually hundreds of these little slugs. Quite possibly the most I have ever seen in a single place and time.

These dorid nudibranchs eat barnacles. After studying them for a while I noticed the dessicated corpses of sea slugs dotting the dock around the circumference of the post. Most likely the remains of slugs stranded by the receding tide. Once out of the water they fell to the dock where they dried out. I collected several of different shapes and sizes. Most of the barnacle nudibranchs were a mottled brown-olive-green color but some were white. They were difficult to photograph because of their tendency to be near the surface.


What had started out a rather unpromising trip, proved to be a very satisfying experience.