Extreme Behavioral Adjustments by an Orb-Web Spider to Restricted Spaces

Adaptive flexibility in response to environmental variation is often advantageous and occurs in many types of traits in many species. Although the basic designs of the orb webs of a given species are relatively uniform, spiders can adjust their webs to some types of environmental variation. This study of adult female Leucauge argyra tests the extremes to which they can adjust with respect to reduced area in which to build, and documents probably the most pronounced flexibility in orb design ever recorded. These adjustments revealed several behavioral rules that guide orb construction behavior. Spiders adjusted at least seven probably independent aspects of orb design when confined in tiny spaces that spanned about 7% of the maximum distance normally spanned by webs in the field and that had diameters that were only about three times the length of the spider itself. Webs in intermediate sized containers had intermediate designs, and many of the adjustments appear to result from extensions of the behavioral rules guiding orb construction in less severely restricted spaces in the field.