Metabolic Transitions During Feast and Famine in Spiders

Abstract

Spiders are a diverse group of invertebrates that successfully inhabit most terrestrial ecosystems. Part of their success can be ascribed to a remarkable feeding ecology that allows spiders to tolerate prolonged periods of starvation and provide the capacity to feed on very large prey. In this chapter, we review the existing knowledge on the physiological transitions in spiders during prolonged fasting and during consumption of (large) meals. We focus on the metabolic transitions between feast and famine as well as the use and uptake of macronutrients and water. Spiders reduce energy consumption during fasting and food deprivation is primarily associated with utilization of lipid stores. Also, despite the continuous catabolism of energy stores spiders defend body mass through a relative increase in body water. Feeding causes huge stimulation of energy consumption, where metabolic rate can increase more than 20-fold. The elevated metabolism persists for hours to days during the postprandial period and digestion is likely to constitute the largest sustained increase in metabolism of spiders. Because spiders use extraoral digestion, it is easy to investigate the energy balance of prey and predator during feeding. We argue, therefore, that spiders represent a promising animal model to study energy flux during feeding and fasting and hope this review will inspire further studies on the feeding physiology and ecology of this interesting animal group.