Title: FUNCTIONAL SIMILARITIES OF SPIDER WEBS WITH DIVERSE ARCHITECTURES
Author: Brent D. Opell
Abstract: Spider orb webs are made of sticky prey capture threads supported by a scaffold of nonsticky threads. Capture threads produced by members of the family Uloboridae are formed of thousands of dry, proteinaceous silk fibrils. From measurements of the diameters and lengths of fibers that form the sticky and nonsticky threads of uloborids, this study determines the volume of silk these webs contain. It employs a transformational analysis to examine the relationship between spider size and the silk volume and total stickiness of webs produced by four orb-weaving species and four species that spin simpler webs. Despite differences in web design, web-monitoring behavior, and spider size, a web's total silk volume is directly related to spider weight. A web's prey capture potential, as determined by its total stickiness and total capture area, is also directly related to spider weight. The volume of silk fibrils responsible for a web's stickiness is related to spider weight, whereas the volume of its support elements is not but appears instead to be influenced by web orientation and architecture. Thus, a spider's energetic requirements appear to set the bounds within which the material investment, stickiness, and architectural details of its web are free to differ.