Memory of distances and directions moved as cues during temporary spiral construction in the spiderLeucauge mariana (Araneae: Araneidae)

The spider Leucauge marianaprobably uses the presence of temporary spiral (TSP) lines already in place to determine sites of attachment of currently produced loops of temporary spiral, but less rigidly than has been previously supposed for orb weavers. Memory of distances and directions traveled recently to and from TSP lines is implicated by the fact that adjustments to experimental and natural discontinuities in previous TSP lines occur gradually rather than being abrupt. Distances and directions traveled along both radii and previous TSP lines correlate with relative amounts of adjustment. Body size may also be used as a reference measure, but not in the simple, inflexible way suggested by R. W. G. Hingston (A Naturalist in Himalaya,Small, Maynard, Boston, 1920). Tensions on radii are not used as cues in any simple way, and may not be used at all, since experimental changes in tensions produced effects consistent with resulting changes in thread positions but inconsistent with tension differences.