SuPerSilk is comprised of different work packages that integrate different aspects of the function and diversity of spider silk fibre materials. The different angles are reflected by our interdisciplinary team which is comprised of a comparative zoologist, a behavioural ecologist, a theoretical physicist and a polymer engineer. By jointly applying our diverse expertise and a mix of observational, experimental and theoretical techniques, we are clarifying why some spider silk materials can better resist dynamic or static loads than others – and what we can learn from them.
Because spiders have different types of silk glands, we first aimed to understand in which behavioural contexts each silk is used. As the gland number and ecology differs between different lineages of spiders, we established a comparative assay of silk use throughout different behaviours involved in locomotion, dispersal, web building and feeding. We found that silk use is surprisingly variable and in most situations multiple types of silk glands are active leading to a mixed composite structure of the produced fibre materials. We started to conduct anatomical and behavioural studies to understand how specific silk glands are activated and deactivated during spinning, which we will intensify in the coming year.
The next important goal was to build a catalogue of natural spider silk materials, which will enable us to infer the evolution of silk properties and identify ‘super-materials’ with outstanding mechanical properties. By the time of this interims report, we have conducted several field trips and started to build a large collection of natural spider silk fibre materials (1,800 samples so far). We have already characterised the structure and mechanical properties of fibres and threads from 65 spider species representing different evolutionary lineages across the spider tree of life. This work uncovered a surprisingly high variation of fibre mixture in spider silk lines with corresponding diversity in silk mechanical properties.
During these assays we discovered silk architectures with remarkable properties, and with the help of empirical measurements and theoretical models we inferred structure-function relationships that could be transferred into artificial material designs in the next step. For example, we found a silk material that can be elongated over forty times its original length before breaking, which is grounded in a hierarchical looping (loops-on-loops) structure.
In addition, we have performed a meta-analysis of available literature data, and found that silks with outstanding strength and toughness evolved multiple times independently in spiders – an important prerequisite to infer general structure-function relationships from natural systems. This work has given us a roadmap for bioprospecting and a plan for an enhanced sampling to run more informative models of property evolution and structure-function relationships in spider silk materials – which we will have accomplished within the next years.
