Rhythmical Hatching and Oncomiracidial Behaviour in the Hexabothriid MonogeneanRajonchocotyle Emarginatafrom the Gills ofRajaspp.

Abstract

In a study of the life-cycle of the hexabothriid monogeneanRajonchocotyle emarginataby Wiskin (1970), attempts to obtain newly hatched larvae were unsuccessful, and it was decided to make a new attempt to culture eggs and hatch larvae, at the same time investigating the effects of those factors found in other monogeneans to influence hatching, such as host mucus (see Kearn, 1974), shadows (see Kearn, 1982) and mechanical disturbance (see Bovet, 1967). The success of these renewed attempts to hatch the eggs ofR. emarginataprovided an opportunity to study the behaviour of the free-swimming oncomiracidium and attempts were made to relate hatching phenomena and larval behaviour to the behaviour of the host.