Dear Brian,
 
I'm surprised by the mortality that you report, especially given the
controlled experiment you did. Ovulids are known to be able to move from
host to another (Lasker et al. 1988; Kerstich 1994). I have seen several
specimens of various species of ovulids that have changed color in
mid-shell, apparently because of a natural switch between hosts of differing
colors. I think I've seen a published report of a transplant experiment, but
I can't find the reference at the moment.
 
You should investigate whether the two color forms of Leptogorgia virgulata
are actually the same species. I know with some Caribbean hard corals,
supposed variant morphologies have recently been shown to be different
species. I think mortality would be much more likely if you had transplanted
between different species.
 
Patton (1972) discusses symbionts of Leptogorgia virgulata. Costa (1993)
reports Simnialena uniplicata on Lophogorgia punicea in Brazil. Andrews
(1977) reports Simnialena marferula (which in my opinion is a synonym of S.
uniplicata) on Leptogorgia setacea in Texas.
 
Andrews, J. 1977. Shells and Shores of Texas. University of Texas Press:
Austin, xx + 365 pp.
 
Costa, F. H. A. 1993. O efeito indesejada das cores. Ciencia Hoje 15:60-61.
 
Kerstich, A. 1994. Two interesting egg-laying gastropods: Simnia
loebbeckeana and Janthina janthina. Festivus 26(4):49-50.
 
Lasker, H. R., M. A. Coffroth, and L. M. Fitzgerald. 1988. Foraging patterns
of Cyphoma gibbosum on Octocorals: the role of host choice and feeding
preference. Biological Bulletin 174: 254-266.
 
Patton, W. 1972. Studies on the animal symbionts of the gorgonian coral,
Leptogorgia virgulata (Lamarck). Bulletin of Marine Science 22:419-431.
 
Best wishes,
Gary
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Gary Rosenberg, Ph.D.                     [log in to unmask]
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