In their own language: cues guiding sticky spiral placement by Micrathena duodecimspinosa (Araneae: Araneidae)

Orb-web construction behaviour, a classic example of ‘innate’ behaviour, is highly flexible. Determining which cues guide construction behaviour is complicated by the strong correlations between some variables, and the difficulty of manipulating of some web variables in biologically realistic ways. This study utilized a new experimental technique, adding sticky lines to webs during construction, to examine cues that guide sticky spiral spacing. Deflections and subsequent reductions in spacing produced by experiments that involved relatively long radii resembled the reduced spacing pattern on short radii in control webs; radius length was thus not the cue eliciting reduced spacing in control webs. An alternative, that smaller inter-radius distances elicited reduced spacing, was supported by experimentally removing radii to increase the distances between radii. The new technique also elicited variation in responses that suggested that spiders may use mental cues such as memories or expectations of line positions to guide sticky spiral placement.