Effects of ultra violet ray and aqueous environment on deformation behavior of spider threads
Kitagawa Masayoshi; Katsumi Seiji; Wakoh Yutaka
Abstract:As a series of the studies on the mechanical properties of spider threads, the effects of ultra violet rays (UV) and water was investigated using drag lines of Nephila clavata (Jorougumo) and capture threads of Argiope amoena (Koganegumo). It was shown for the effect of water that 1) the drag line was contracted as soon as immersed in water (super contraction), while the capture thread was not so contracted and the viscid droplets attached to it were dissolved in water, and 2) the super contracted drag line behaved like a capture thread with a J shaped load draw ratio curve. For the effect of UV, it was found that 1) the degradation due to UV irradiation with short wave length was accelerated more than that with long one and 2) the degree of degradation for each wave length was governed by the integrated irradiation energy of UV. Key Words:spider thread, viscid droplet, ultra violet rays, water, degradation