Structure and Deformation of Dragline and Capture Threads of Orb-Web in Nephila Clavate

摘要

In the previous papers it was shown that the mechanical properties of spider threads taken from Nephila clavata called Jorougumo in Japan were excellent and thus the threads were expected to be one of the most useful materials in future, if produced in large quantities. In this paper, the analyses of composition and crystalline structure of dragline silk and the deformation behavior of dragline and capture thread were investigated. The results are as follows: (1) glycine and alanine are the most abundant amino acids and occupy about 70 percent of the total amino acids, (2) the crystalline structure is orthorhombic and the dimensions of the unit cell are about a =1 nm, b=0.9 nm and c=0.7 nm, (3) the load-strain curve for the capture thread is J-shaped and its fracture strain is more than 200 percent, and (4) a wonderful mechanism for the capture thread named as "windlass system" is reconfirmed.