DRAGLINE-ASSOCIATED BEHAVIOR OF THE ORB WEB SPIDER NEPHILA-CLAVIPES (ARANEOIDEA, TETRAGNATHIDAE)

Dragline use by an orb web spider (Nephila clavipes) was analysed by o bserving both intact spiders and those prevented from producing a drag line. The behaviours observed were those associated with returning to the web hub and prey capture. Upon returning to the hub, spiders resum e the resting position by rotating within the hub, producing several n ew dragline attachment points during the rotation. The importance of t he spider's use of the dragline was made clear by preventing experimen tal animals from producing the dragline. During resting, the permanent dragline-to-web attachment enabled the spider to maintain the correct posture. Prey capture behaviour was adversely affected in spiders pre vented from using the dragline: without a dragline, all relevant compo nents of the behaviour required more time to perform, and movements wi thin the web (e.g. toward prey and back toward the hub) were directed less accurately. The benefit of the dragline to the spider, in terms o f safety, time, energy and reduced exposure to predators, is likely to be significant.