The Effects of the Venom of 'Aipysurus laevis' on its Prey Species

Abstract

The aim of this investigation was to examine the effects of 'Aipysurus laevis' venom on its prey species. This was accomplished through LD50 studies with whole venom, and ventilation, behavioural and ultrastructural studies with both whole venom and venom fractions. LD50 studies demonstrated differences in resistance to 'A. laevis' venom among the species 'Chromis nitida', 'Chromis atripectoralis', 'Dascyllus aruanus', 'Istiblennius meleagris' and 'Istiblennius edentulus'. Further investigations with whole venom showed 'A. laevis' venom to significantly affect the ventilatory process, with ventilation and other behavioural signs proving to be similar in all fish tested ('C. nitida', 'D. aruanus' and 'I. meleagris'). An ethogram showing the hierarchy of behavioural changes, as the result of envenomation, was constructed. Ultrastructural examinations using muscle from 'D. aruanus' revealed the occurrence of muscle necrosis resulting from envenomation. This suggests the presence of myotoxic components that affect the muscle of lower vertebrates, i.e. marine fish. Venom fractions had different effects from whole venom. These differences are thought to be due to (1) the overshadowing of some components by more potent toxins, (2) cumulative effects producing stronger responses and (3) inhibition of the effects of some components by other constituents of the whole venom. Ultrastructural examinations showed evidence of muscle necrosis caused by many of the fractions, but fraction 4 proved to possess the most potent myotoxic component(s). Fraction 6 had the greatest effect on ventilation and appeared to be the most potent neurotoxic fraction.