Hungry spiders

David H. Wise

A predator is food limited if a shortage of prey limits population density. […]

Several attributes of spiders are consistent with the hypothesis that a shortage of prey has been a major selective factor over evolutionary time. Spiders can survive long periods of starvation, primarily by waiting for prey rather than by actively searching for it, and also by lowering their basal metabolic rate in the absence of enough prey to support growth and reproduction. Foraging patterns appear to have evolved under pressure from food limitation. For example, phenologies of orb weavers often coincide with the availability of insect prey in a way that appears to maximize energy input throughout the life cycle. Within a season, spatial foraging patterns of spiders appear to have been molded by prey shortages. It has been proposed that the sit-and-wait strategy of many spiders is an adaptation to a shortage of prey. When spiders change foraging sites they often re-locate in microhabitats of higher prey abundance. […]

Food is most likely not a limiting factor for all spider populations in all years or habitats. However, accumulating evidence, both indirect and direct, makes it clear that spiders are frequently hungry, to the point of exhibiting rates of growth and reproduction considerably below what is physiologically possible.

Fonte: Wise, D. H. 1993. Spiders in ecological webs. Cambridge, CUP.