Post-feeding thermophily in a scorpion is associated with rapid digestion and recovery of maximal nocturnal activity

A postprandial increase in metabolic rate is typical in all studied animal groups. The phenomenon, termed specific dynamic action (SDA), is understudied in terrestrial arthropods, and arachnids in particular. To the best of our knowledge, this is the first report of SDA properties in scorpions, which are temperature-dependent as in other poikilotherms. Metabolic rates of scorpions are low compared with similarly-sized arthropods, and as they often feed on relatively large prey the cost of digestion is expected to be notable. This prompted us to study the extent of SDA and its characteristics in scorpions at two different ecologically-relevant temperatures. We also hypothesized that post-feeding behavioral thermoregulation would reflect benefits to the scorpion energy balance. On average, fed adult Hottentotta judaicus (Buthidae) expressed a 3 °C increase in preferred surface temperature, although we did not find evidence for lower costs of digestion at higher temperatures. However, SDA duration was significantly shorter at 30 compared with 25 °C. Fast processing of their meal at 30 °C was correlated with recovery of elevated nocturnal metabolic rates, which are not digestion-related. This suggests that post-feeding choice of higher temperatures accelerates digestion and recovery of other elevated metabolic states such as locomotion and lower sensory threshold, which may enhance foraging success.