The orb-web: an energetic and behavioural estimator of a spider's dynamic foraging and reproductive strategies

Abstract

Abstract. This field study analyses reasons behind the changing, nightly web dimensions of the orb-weaving spider Larinioides cornutus (Araneidae), thereby providing insight into this species' dynamic foraging strategies. The investigation contrasts with earlier studies which have generally assumed web parameters of individuals to remain constant, constrained by species-specific design patterns. Three web dimensions, area of the catching spiral, total thread length, and mean mesh size, were measured for webs built before and after experimentally supplemented prey consumption and egg production. Nightly variations in web dimensions suggest that hungry spiders invest more effort into foraging, while sated spiders re-allocate energy from continued foraging to egg production. These data demonstrate that the foraging plasticity of individual orb-weavers is greater than previously presumed. More generally, the data lend support to a seldom-tested tenet of optimal foraging theory: the direct relationship between foraging success and enhanced reproductive fitness.