The environmental physiology of the scorpion 'Urodacus manicatus' (Thorell) (Scorpionidae)

Abstract

The aims of this thesis was to examine the microclimates and the physiological and behavioural responses to seasonal changes in the microhabitats of populations of 'Urodacus manicatus' that occur in different parts of the species' range. The aims were achieved by measuring resting metabolic rate (RMR), temperature selection, activity, evaporative water loss and haemolymph osmolality in field-collected specimens during different seasons. Further investigations were then conducted on captive 'U. manicatus' to discern the specific effects of biotic and abiotic factors on the scorpions' physiology and behaviour. This study shows for the first time that 'U. manicatus' can extend their distribution from cool temperate ranges to semi-arid plains by selecting shelters for home sites that differ in their thermal properties. In doing so, the upper burrow temperatures are similar between populations that differ in broader climatic conditions. 'U. manicatus' behaviourally adapts to temperature change but not physiologically so. Regulation metabolic rate and evaporative water loss after high and low temperature acclimation was achieved by the selection of higher or lower temperatures instead of metabolic compensation or alteration of culticular permeability. The cool temperature which elicited a decrease in selected temperature was the threshold temperature for foraging activity.