Why is spider silk stronger than steel?

The answer

Spider silk is roughly five times stronger than steel of the same diameter and can stretch up to 40% of its length without breaking, giving it a toughness (energy absorbed before failure) greater than nearly any synthetic material. This extraordinary performance comes from its molecular structure: chains of protein molecules arranged in crystalline regions connected by flexible, amorphous segments. The crystalline beta-sheet nanocrystals provide strength while the amorphous regions provide elasticity. Different spider glands produce up to seven different types of silk, each optimized for a specific purpose such as wrapping prey, building frame structures, or creating draglines.