The black tip of each quill features backward-facing barbs. These barbs are tiny: a row of two hundred of them would be short of an inch long. The barbs help a quill penetrate flesh more easily than a hypodermic needle of about the same diameter, and using only half the force required to push a barb-free quill through tissue. Once the quill is in, the barbs then greatly increase what force would be needed to pull it back out again.

 

The researchers think understanding porcupine quill properties can help them make less painful needles, because of the lower force needed for penetration. Also stickier adhesives, because of the greater force needed for removal. And the study reminds us that you really, really don't want to mess with a porcupine.