Arachnids are perhaps the most ecologically pervasive predators on earth. Through over 125 million years of evolution, orb-web weavers have developed an arsenal of silken tools for the aerial arms race, producing up to six fibers with each fiber having the appropriate combination of mechanical properties to suit its ecological niche. This intricate multi-fiber design of the aerial orb-web has the strength to restrain a struggling insect and the proper elasticity to dissipate the energy of a prey that has the capability to jump and fly. Major ampullate silk, which is used for the frame of the web, is a high performance nanocomposite fiber with a blend of strength and elasticity unrivaled by synthetic polymers.

Despite its evolutionarily conserved molecular architecture and spinning apparatus, each individual spider generally produces single fibers with wide ranging mechanical properties. This range has been characterized for the first time using a mathematical model to more precisely define clusters of fibers based on their mechanical properties. Currently, similar clustering effects are observed among synthetic spider silk fibers. This new model should help researchers to better understand, characterize, and ultimately control the mechanical properties of synthetic major ampullate silk fibers.