Figure 2.

(a) Diagrammatic representation of sticky spiral construction (arrows indicate movement) (after Eberhard 1982). (i) After attaching the sticky line to radius r_n, the spider moves inward towards the hub and towards the next radius; (ii) after reaching the next radius (r_n+1), it moves away from the hub, tapping with its extended leg I until it touches the inner loop of sticky spiral already in place; (iii) then it grasps this radius with its legs III and IV, turns its body laterally and attaches the new segment of sticky spiral line to the radius between the points gripped by tarsi III and IV. (b) Illustration of how intra-individual imprecision values were calculated. First, the absolute value of each difference between adjacent spaces between sticky spiral loops on the longest radius (r_i) was divided by the median space on that radius to give a dimensionless value a_n (upper equation), and then the median value of a was determined for this radius (med a_r(i)). The same process was repeated for the two adjacent radii, giving med a_r(n−1) and med a_r(n+1). These three median values were averaged to give a single imprecision value b for the web (lower equation).