A STUDY OF THE COMPOSITION OF THE SCLERITES OF GYRODACTYLUS NORDMANN,1832 (MONOGENEA) USING X-RAY ELEMENTAL ANALYSIS

The elemental compositions of the hamuli, marginal hooks and ventral b ars were examined following their release from the opisthaptor of the monogenean parasites Gyrodactylus salaris, C. caledoniensis and G. col emanensis. Their compositions were determined using X-ray elemental an alysis on an analytical scanning electron microscope, and the variatio n between each species investigated. Hamuli and marginal hooks exhibit ed a major peak for sulphur, whilst the ventral bar had high peaks of both sulphur and calcium. The high sulphur content and structure of th e hamuli suggest they are composed of a keratin-like protein, while th e nature of the ventral bar is less clear. The hamuli of G. colemanens is were differentiated from those of G. caledoniensis by virtue of the ir calcium fraction. Low levels of several other elements, including v anadium, were also detected in some sclerites. The composition of the hooks of Gyrodactylus and their relationship to the sclerites of monop isthocotyleans and polyopisthocotyleans is commented upon.