Adaptive flexibility in cues guiding spider web construction and its possible implications for spider cognition

摘要

Orb web construction was originally thought to be highly stereotyped, but adaptive flexibility is now well established in several aspects. This study reviews published data on one behavioural cue and presents new data on flexibility in experimentally modified and control webs of Zosis geniculata and Uloborus diversus. By occasionally ignoring this cue temporarily, spiders gained access to otherwise inaccessible portions of their webs. I discuss three hypotheses concerning the mechanism that resulted in this flexibility. Several types of evidence argue against the hypothesis that the adjustments were pre-programmed: substantial variation in the contexts when adjustments occurred; substantial variation in details of the adjustments; and rarity of the contexts that require adjustments in nature. Lack of plausible links between behavioural decisions and payoffs from prey capture argue against a second, learning hypothesis. By elimination, this flexibility may require a third type of explanation that includes more elaborate cognitive processes.