Two-headed Chromodoris orientalis from Japan

June 8, 2002
From: Tomohiko Kurihara


Dear Bill.
I found interesting Chromodoris orientalis at Osezaki, Suruga bay, Japan. At first,I thought that it was copulating. Because I could see two heads. But it was a deformed C.orientalis - it looks like twins, it has two heads and four rhinophores. The second head doesn't have mouth, but it can sway and expand.

Because the spots are closer to the edge of mantle (LOWER PHOTO), I think the smaller head is still growing. What do you think?

Place: Osezaki, Suruga bay, Japan
Date: 28 May 2002
Depth: 32m
Length: 30mm

Best regards,
Tomohiko Kurihara

miyamoto@info.email.ne.jp

Kurihara, T., 2002 (Jun 8) Two-headed Chromodoris orientalis from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7140

Dear Tomohiko,
Every day seems to bring a new amazing find from somewhere around the world. We have a saying in English that 'two heads are better than one'. I don't think so in this case. Can you remember whether the rhinophores in the second head were able to retract? If there is no mouth I wonder whether the rhinophores are superficial growths or whether they have nerves connecting them to the slug's 'brain'. Although it is possible that the second head is still growing, most of these faults seem to be a result of something going wrong during embryonic development. However from Nishina Masayoshi's photo of this species' eggs, it seems that it has a veliger larva stage. I guess this means the mistake occurred when the veliger larvae was metamorphosing into a slug. Very few people have studied embryonic development in opisthobranchs. Even if there were more people studying them, the chances of actually observing an embryo developing two heads like this would be very slight indeed.
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Jun 8). Comment on Two-headed Chromodoris orientalis from Japan by Tomohiko Kurihara. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7140

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