Relative capture rates of orb, sheet, and tangle spider webs at the University of Michigan Biological Station, Pellston, Michigan.

Abstract

Spider webs are divided into three major architectural groups: orb, sheet and tangle. This study examined differences between these groups in distance from the ground to the web, surface area of the web, and the angle of planar webs with respect to the horizontal, and their capture success in a twenty-four hour time period. Captured prey fell into different classifications, including other spiders, crawling (wingless) prey, flying (winged) prey, small (<2mm in length) prey, medium (between 2 and 5 mm in length) prey, and large (>5 mm in length) prey. The capture rates were compared both by web type and by the spatial properties of the web. I found orb webs captured the most total prey as well as the most flying prey. Tangled webs captured the most crawling prey, but little flying prey. Sheet webs captured as much total prey as tangled webs, but were less proficient at catching crawling prey and more able to catch flying prey. Orb webs captured the most small prey, but differences in the distribution of the other two size classes were not significant. Lack of significant correlations between the spatial qualities of webs and their capture rates suggest that differences in the types of captured prey are due to the architecture of the web, not its dimensions and orientation. Previous studies suggest that the success of a web is due not to its size and shape, but to its composition. Webs with more adhesive silk and UV reflecting decorations are more successful than those without.