Dear Vincent,
Thanks for these photos. There are two species in your photos. On the left in the top photo there is Aplysia kurodai, which is also the species forming the mating ring in your second photo. The animal on the right in the top photo - and in the bottom photo - is A. oculifera.  Aplysia oculifera is easily identifiable from the white spots ringed in dark brown, which resemble eyes and give it the name oculifera [= 'carrying eyes' in Latin].

Concerning your questions, they can certainly act as both male and females when in mating chains. Have a look at the Mass Mortality page for a discussion on mass deaths after breeding.

Best wishes,
Bill Rudman

Dear Koh,
Thanks for these spectacular photos. It certainly looks quite similar to A. extraordinaria, and as I have said before, its possible that there is one large swimming Aplysia throughout the Indo-West Pacific. However at present A. extraordinaria is only known from Australia.

It is possible that this is a colour form of Aplysia kurodai. The white patches on the inside edge of the parapodia, and the white patches on the mantle covering the shell, are identical to those in a painting in Baba, 1949 (Opisthobranchia of Sagami Bay). Do you know if A. kurodai swims? I'm afraid this is one of those times when I have to say we just don't know enough about about these animals to be sure. I am almost certain that the animal from Japan in Jun Imamoto's earlier message [#9129], which is sitting uncomfortably with A. californica, is the same as your species.

Best wishes,
Bill Rudman

Dear Koh,
I think something has damaged this animal - perhaps something has tried to eat it. In the upper photo there is a large white patch on the head which looks very much like a bite. In the photo alongside the shell is cracked and the mantle on the right side (nearest the viewer) has been ripped, torn or bitten off. my feeling is that these animals are dying, or at least damaged.
Best wishes,
Bill Rudman

Thanks Ron,
This is clearly the same species as Okutani (2000) identifies as A. kurodai from Japan. It is still hard to be sure how many species of Aplysia there are in the Indo-West Pacific at present, but I have not seen this colour pattern elswhere but in the NW Pacific so it is possibly endemic to the region. I look forward to hearing of your research work.
Best wishes,
Bill Rudman

Dear Ron,
In my reply to Tony Wright's message about an Aplysia from Taiwan, I discuss two species reported by Baba (1937) from Japan (Aplysia sibogae Bergh, 1905 and Aplysia kurodai Baba, 1937) both of which I thought could be colour forms of A. juliana. Both were reported to secrete a white fluid from the opaline gland which is usually only obvious in species like A. juliana which do not secrete purple ink as well. On re-reading Baba's paper I see that although he doesn't mention purple secretions for A. kurodai, he does mention that it has a purple gland and that the parapodia are separated behind. From that I woud conclude that the animal he identified as Bergh's A. sibogae was actually A. juliana and his new species, A. kurodai, is not.

Apart from the fused posterior lobes of the parapodia and the lack of a purple gland in A. juliana, that species can also be distinguished by the way the rear part of the foot forms a sucker - the rest of the body often been held above the substrate. Aplysia juliana is very variable in colour, ranging from a uniform black to light brown with whitish patches.

In short A. kurodai is definitely distinct from A. juliana. The photo in Okutani, (if correctly identified), of A. kurodai certainly looks distinctly dfferent from other speces of Aplysia I have seen alive. However producing purple ink and having the parapodia separate posteriorly, are characters found in most species of Aplysia. Until someone is able to review the genus worldwide I cannot say whether A. kurodai is endemic to Japan and other parts of the NW Pacific, or whether it is a more widely spread species and so may have an earlier name from somewhere else. Some photos of this animal would be much appreciated, and any news on your research activities would be very welcome.

Reference:
• Baba, K., (1937) Opisthobranchia of Japan (I). Journal of the Department of Agriculture, Kyushu Imperial University, 5(4): 195-236. (Pl.4)

Best wishes,
Bill Rudman.