  Living systems are built of multiscale-composites: materials formed of
components with different properties that are assembled in complex micro- and
nano-structures. Such biological multiscale-composites often show outstanding
physical properties that are unachieved by artificial materials. A major
scientific goal is thus to understand the assembly processes and the
relationship between structure and function in order to reproduce them in a new
generation of biomimetic high-performance materials. Here, we tested how the
assembly of spider silk nano-fibres (i.e. glue coated 0.5 micron thick fibres
produced by so-called piriform glands) into different micro-structures
correlates with mechanical performance by empirically and numerically exploring
the mechanical behaviour of line anchors in an orb weaver, a hunting spider and
two ancient web builders. We demonstrate that the anchors of orb weavers
exhibit outstanding mechanical robustness with minimal material use by the
indirect attachment of the silk line to the substrate through a soft domain
('bridge'). This principle can be used to design new artificial
high-performance attachment systems.
