Responses to Starvation in the Spiders Lycosa Lenta Hentz and Filistata Hibernalis (Hentz)

Abstract

Effects of starvation were investigated in two specices of spiders to gain insight on how these predators deal with an unpredictable food supply. Comparison of weights and body dimensions of individuals from field populations with those of known nutritional status showed that lack of food is a problem for field populations of both species. Adult survival times under starvation conditions averaged 208 days for the wolf spider, Lycosa lenta, and 276 days for the cribellate web—builder, Filistata hibernalis. Potential adult life spans for fed individuals were estimated to be 305 days for L. lenta and several years for F. hibernalis. Both spiders have metabolic rates significantly lower than those of other poikilotherms of similar size, and when starving revude their metabolic rates by 30% to 40% without any apparent decrease in their normal capabilities. The difference in urvival times under starvation conditions of the two species was found to be inversely related to metabolic rate. This suggests that the relative low metabolic rates characteristic of spiders as well as their capacity to reduce these rates when starving are adaptive in survival where prey are scarce. That starved individuals have the capacity to double their body weight through ingestion of large amounts of food when available may be an adaptation to their predation.