Orientation behavior of riparian long-jawed orb weavers (Tetragnatha elongata) after displacement over water

Abstract

Many organisms possess remarkable abilities to orient and navigate within their environment to achieve goals. We examined the orientation behavior of a riparian spider, the Long-Jawed Orb Weaver (Tetragnatha elongata), when displaced onto the surface of the water. When displaced, spiders move with alternating movements of the first three leg pairs while dragging the most posterior pair of legs behind them. In addition, spiders often perform a series of orientation behaviors consisting of concentric circles before ultimately choosing a path of travel directly toward the nearest point to land. While the number of orientation behaviors increased with increasing distance from shore, distance from shore had no effect on the direction of travel, which was significantly oriented toward the closest shoreline. These results indicate a complex ability to orient toward land when displaced onto water, possibly to decrease the amount of time on the surface of the water and thus decrease predation risk.