June 30, 2003
From: Kathe R. Jensen
Dear Bill & Oliver,
In answer to Oliver's question about zigzag marks on Halimeda - In the Caribbean, Bosellia mimetica makes the zig-zag grazing marks on Halimeda. I can't remember if Elysiella does the same. Most of the specimens I have collected have been very small and so probably have not made much in the way of visible grazing marks. The teeth of Bosellia are short and broad and thus may only penetrate the superficial utricles of Halimeda. The teeth of Elysiella are relatively longer and more slender, so probably they can penetrate to the deeper utricles, which may mean that they can empty several interconnected superficial utricles at the same time.
Elysia serca, also a Caribbean species, which feeds on seagrasses, makes the same kind of zig-zag grazing marks. It shifts the head alternately to the left and right when feeding, so it does not penetrate into cells (seagrasses are real plants and have cells, not utricles), which have already been sucked dry.
Perhaps it would help Oliver if you could tell us where your Halimeda is from?
Elysiella pusilla from the Pacific coast of Mexico
From: Kevin Lee, December 1, 2009
Elysiella pusilla from Gulf of Kutch, India
From: Vishal Bhave, November 27, 2009
Feeding on Halimeda
From: Oliver A. Gussmann, June 27, 2003
Elysiella pusilla from Kerama Is., Japan
From: Jun Imamoto, August 3, 2001
Chemical defence in Elysiella pusilla
From: Bill Rudman, May 6, 2000
Re: Elysiella pusilla
From: Eirik Eilertsen , July 28, 1999
Halimeda sea slug
From: Eirik Mack Eilertsen, July 25, 1999