Spider dragline silk is of practical interest because of its excellent mechanical properties. However, the structure of this material is still largely unknown. In this article, we report what we believe is a new model of the hierarchical structure of silk based on scanning electron microscope and atomic force microscope images. This hierarchical structure includes beta-sheet, polypeptide chain network, and silk fibril. It turns out that an exceptionally high strength of the spider dragline silk can be obtained by decreasing the size of the crystalline nodes in the polypeptide chain network while increasing the degree of orientation of the crystalline nodes. Based on this understanding, how the reeling speed affects mechanical properties of spider dragline silk can be understood properly. Hopefully, the understanding obtained in this study will shed light on the formation of spider silk, and consequently, on the principles for the design of ultrastrong silk.

Summary 1.We review the mechanisms behind ecosystem functions, the processes that facilitate energy transfer along food webs, and the major processes that allow the cycling of carbon, oxygen and nitrogen, and use case studies to show how these have already been, and will continue to be, altered by global warming. 2. Increased temperatures will affect the interactions between heterotrophs and autotrophs (e.g. pollination and seed dispersal), and between heterotrophs (e.g. predators-prey, parasites ⁄ pathogens-hosts), with generally negative ramifications for important ecosystem services (functions that provide direct benefit to human society such as pollination) and potential for heightened species co-extinction rates. 3. Mitigation of likely impacts of warming will require, in particular, the maintenance of species diversity as insurance for the provision of basic ecosystem services. Key to this will be long-term monitoring and focused research that seek to maintain ecosystem resilience in the face of global warming. 4. We provide guidelines for pursuing research that quantifies the nexus between ecosystem function and global warming. These include documentation of key functional species groups within systems, and understanding the principal outcomes arising from direct and indirect effects of a rapidly warming environment. Localized and targeted research and monitoring, complemented with laboratory work, will determine outcomes for resilience and guide adaptive conservation responses and long-term planning.

No animals are known to possess both ultraviolet (UV) reflectance and fluorescence that are sex-specific. We provide evidence for this separation in the jumping spider Cosmophasis umbratica, which has UV reflectance and UV-induced green fluorescence restricted to males and females, respectively. During courtship, many of the studied pairs failed to show typical display posturing when UV light was blocked. Occluding the UV component of sunlight to only one of each pair also caused atypical behavior: Females showed no interest in non-UV-reflective courting males, and males either ignored or were lackluster in courting nonfluorescing females. These results demonstrate the importance of both sex-specific hues as sexual signals for effective intraspecific communication.