Sperm morphology of scleractinians from the Caribbean

This study compares the sperm morphology of 2 hermaphroditic (Diploria strigosa, Montastrea annularis) and 2 gonochoric (Siderastrea siderea, Dendrogyra cylindrus) Caribbean reef corals. The spermatozoa of the gonochoric species are morphologically more specialized than those of the hermaphrodites. The cytological differences are apparent in the formation of a Spitzenkorper and pro-acrosomal vesicles, a mitochondrial mass (Nebenkern) and a large lipid vesicle in the gonochorists studied. Harrison (1985) first demonstrated that sperm morphology is correlated with sexual reproductive pattern and systematic position in scleractinian corals, and this is supported by the results of this study. The possible functional and phylogenetic bases of sperm morphology are discussed and a brief outline is given of further studies required.