Re: Caulerpa ambigua - sacoglossan food

March 27, 2002
From: Cynthia Trowbridge

Dear Nishina and Bill,
Hi. Thank you, Nishina, for all the wonderful photos of sacoglossans from Japan!! I find your messages very enjoyable and Bill's answers quite educational.

I have been reading the Japanese sacoglossan-Caulerpa literature this winter so would like to advise you of a small correction to your message.

Prof. Tadao Yoshida et al. (2000) published an update to their checklist of Japanese algae. This resource is invaluable for all the recent name changes, particularly for Caulerpa and Codium spp. because Japan is an area of incredibly wonderful diversity. For example, there are 19 spp. of Caulerpa listed and 16 spp. of Codium.

First, Caulerpa ambigua Okamura has been moved into another genus: Caulerpella ambigua (Okamura) Prud'homme van reine et Lokhorst. I will find the paper and let you know privately why it was shifted into another geuns.

Second, Caulerpa okamurae is still in Caulerpa. One confusing point is that in all the Japanese and English photo guides, the alga is called C. okamurai. But, Yoshida et al. (2000) and other Japanese phycology papers list it as okamurae. From your wonderful photos, I would guess that you have C. okamurae.

Another sacoglossan species to add to your list on this alga would be Stiliger smaragdinus. Also, I have found one Elysia setoensis on this alga but it may have been just crawling across the Caulerpa bed; the species would not eat the Caulerpa in the lab.

• Yoshida, T., Yoshinaga, K. & Nakajima, Y. (2000) Check List of Marine Algae of Japan (Revised in 2000). Jpn. J. Phycol. (Sorui), 48: 113-166.

Thank you for considering my comments and THANK YOU for the wonderful photos!


Trowbridge, C., 2002 (Mar 27) Re: Caulerpa ambigua - sacoglossan food. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Cynthia,
Identifying foods is a difficult job. We tend to think that names in other areas of biology are permanent, when in fact they are often even more unstable than in opisthobranchs. I wonder how many Caulerpa species are eaten by Stiliger smaragdinus? In Australia it is always found on a Caulerpa which has inflated 'bubbles'. In Nishina's photos the Caulerpa appears to have flattened 'bubbles'.
Best wishes,
Bill Rudman


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