Acanthodoris rhodoceras
We found these two individuals of Acanthodoris rhodoceras, a new species for me, and put them in the same container as I got out my camera. They were on each other in a flash, and as soon as I realized they weren’t trying to kill each other, I let them have at it. Adult nudibranchs are hermaphrodites, and their sex organs are always on the right side of their bodies. So in order to have sex, they line up next to each other facing opposite directions, so each slug’s right side is exposed to the other’s. Both slugs inseminate their partners, and both go on to lay eggs. How incredible is that?!

They were also exhibiting this odd behaviour I hadn’t read about. They would reach out with a rhinophore and touch their partner, often quickly recoiling after doing so. It was very, well, suggestive. The temptation to anthropomorphize was overwhelming.

A. rhodoceras laying eggs

And, as if witnessing some hot molluscan coupling wasn’t awesome enough, we saw another A. rhodoceras laying eggs in the same pool! This was the first time I’d seen a nudibranch laying eggs, so you can imagine my excitement. It wasn’t exactly laying in a perfect spiral like you see if most of the pictures, possible because it wasn’t laying in the most sheltered part of the pool.

Acanthodoris hudsoni

Another new species we saw was Acanthodoris hudsoni, a pretty little white ‘branch in the same genus as the couple. Also in attendance were Acanthodoris nanaimoensis, Dendronotus subramosus, Triopha maculata, Triopha catalinae, Doto amyra, Hermissenda crassicornis, and Cuthona abronia. Strangely, we didn’t see any Phidiana hiltoni or Acanthodoris lutea, which I would have figured were givens. Seasonality, perhaps? I’ve sean A. lutea at Fitzgerald before, and I just sort of figured P. hiltoni was as abundant there as it is at Duxbury. Weird.

Acanthodoris nanaimoensis