Water Improve Crystal Quality in Dragline of Cyrtophora Spider

摘要

The draglines of Nephila and Cyrtophora spiders have been studied by means of X-ray diffraction method in wet and drying conditions. Both spiders are commonly found in environs in Taiwan. Nephila spider is the biggest orb web spider in Taiwan and Cyrtophora is one of large spiders which build 3D web. There are two kind crystallites in spider dragline. One is highly orientated with c axis along silk direction. The other is more or less randomly distributed inside silk. Crystallite is a hard material when mix with soft protein molecules can form composite structure which believed to be responded to the strength of silk. In this study, we find that the diffraction peak profile of random distributed crystallites in Cyrtophora dragline become sharper in wet silk indicated that crystal quality become more ordering than that of dry silk. The same treatment has also employed to Nephila pilipes dragline but diffraction pattern is smear out due to its super-contraction property and high scattering background from water. The different behaviors of crystalline property to water between these two spider's dragline maybe reflect to the strategy of their utilizations of silk in nature.