Tiny barbs on porcupine quills are what help the quill spenetrate flesh.
The barbs are similar to the edge of a serrated knife, allowing the quill to slide easily into skin. Once there, the barbs prevent the quill being removed by hooking into the flesh they’re attached to.
The discovery could have implications for the medical field, particularly the design of needles that easily penetrate the skin.
Read more at Brigham and Women's Hospital