March 21, 2008
From: Scott Johnson
Attached is an interesting species of Elysia from the Marshall Islands. So far we have seen only one specimen. Jeanette spotted it on the common alga Halimeda cuneata f. undulata (id from Littler & Littler, 2003). She noticed it because it stood out in the middle of a white, dead patch on the algae clump. The Elysia's large parapodia and color make it look a lot like a flake of the living algae, so I presume this is what it is eating. We've looked a bit for more specimens with no luck so far. I'll send some additional photos in a second message [#21081 ].
Locality: Kwajalein Atoll, 10m, Marshall Islands, Pacific, 9 July 2007, On Halimeda algae. Length: 21mm. Photographer: Jeanette Johnson.
Littler, D. S. & M. M. Littler. 1983. South Pacific Reef Plants. Offshore Graphics, Inc. Washington, DC. 331pp.
firstname.lastname@example.orgJohnson, S., 2008 (Mar 21) Elysia from the Marshall Islands. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21080
This is certainly an interesting find, and it certainly looks as though it is coloured to hide on the Halimeda. Apart from its colour, the branching papillae on the outside of the parapodia seem to be an interesting character. The only species I know with such branching papillae is Elysia mercieri and it doesnt seem to match that species in colour or size. We don't seem to know what E. mercieri feeds on so it is, I suppose, possible that you animal is the first adult E. mercieri to be recorded, but it is equally likely you have found an unnamed species. I guess looking for smaller animals should be added to your 'to do' list.