Spider silk has been an attractive biopolymer since ancient times. Learning from both its excellent properties and spinning process, silk provides people with inspiration to develop functional fibers. Recently, inspired by shiny water droplets on a spider's web, we revealed that the capture silk of the cribellate spider would deform to have a special periodic spindle-knots structure and hence displayed unique wettability, making it efficient at directional water-collecting. This provides insights in designing functional fibers with unique wettability, by either creating special structures on the fiber surface, or modifying it with responsive molecules. These bioinspired functional fibers may find applications in many fields, such as water collection, smart catalysis, filtration, and sensing.