More nudibranch procreation and another record

We saw a couple of noteworthy nudibranch (or if you prefer, sea slug) events on our recent trip. Kawaihae Harbor of course.

A couple of Goniobranchus alboputulosus mating on a piling in the harbor. Like most nudibranchs, the species is hermaphroditic. Also like a lot of nudibranchs, there’s no broadly accepted common name for this species; Hoover calls it “Purple-edged Nudibranch” in the 1998 edition of Hawaii’s Sea Creatures, but changes that to the to me less useful “White-bump Nudibranch” in the 2006 edition. Neither of these helps to distinguish it from the similar Trembling Nudibranch, but that’s the way common names go. This species, while not endemic to Hawaii, has a fairly limited distribution, occurring only in Hawaiian archipelago and the remote Marshall Islands.

This is another species with no agreed-upon common name. Two,” Mourning Nudibranch” and “Funeral Nudibranch,” seem appropriate. More boring is “Polka-dot Nudibranch.” The Latin name is Jorunna funebris—I’m guessing the second term refers to funerals. Anyway, this specimen is in the process of laying eggs, that stippled ribbon to the slug’s left. A lot of nudibranchs deposit their eggs in these looped ribbons. Why loops? As Geoffrey Rush would say, “it’s a mystery.” I was with Hai and Wendy when we found these nudis—there were several of them scattered on the pilings. Hai being Hai noticed that some were kind of big, so he took a photo one with a dive knife next to it to serve as a measurement reference. Sure enough, the animal measured about 70mm compared to the 50mm maximum length posted on the authoritative seaslugsofhawaii.com. Cory Pittman, primary curator of the site, and invaluable resource for us amateurs, has since updated the site with the new maximum. Another obscure record! This species is broadly distributed in the tropical Pacific. It’s unclear if it’s native to Hawaii or introduced.

I’m far from alone in my fascination with nudibranchs—the web is full of nudi fanciers. A lot of it is the phantasmagoria of colors and color schemes, but to me it’s also the hostile, alien environment these little slugs inhabit. They go about their colorful, sluggish business in a world full of stinging hydroids and poisonous sponges (both of which the nudibranchs eat), noxious bristle-worms, and sundry other unlikely creatures. Someone please pass the mushrooms…wait, no need.