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Web-Building Flexibility Differs in Two Spatially Constrained Orb Spiders

Hesselberg, Thomas
Journal of insect behavior 2013 v.26 no.3 pp. 283-303
Araneae, animals, webs
Shelter and trap-building animals that compete for limited space and/or face costly relocations benefit from being flexible in their construction behavior. Orb spiders are good examples of this and their easily quantifiable two-dimensional webs allow us to analyze the behavioral adaptations and costs in terms of higher error levels or less precision resulting from building webs in sub-optimal conditions. Here I study behavioral flexibility in spatially constrained spiders by analyzing a wide range of web parameters including measures that indicate errors during web-building. I compare the geometry of laboratory webs of two orb spiders, Cyclosa caroli and Eustala illicita, built in differently shaped experimental frames and report two major findings. i) The two species differ in their ability to build webs in constrained spaces. ii) E. illicita adjusted a range of parameters including shape, area utilization and mesh height in response to spatial constraints, but kept other parameters constant, most notably the length of anchor threads and the shape of the auxiliary spiral. I furthermore found that constrained spiders did not make significantly more errors during web-building than when they had amble space available.