More Than Sharp: The Science of Porcupine Quills A close-up of a
porcupine quill shows the difference in texture between the tip
and the base. Credit: PNAS If youre walking through the woods
and you see what looks like a small dog clinging to a high
branch, dont investigate. Thats probably a North American
porcupine up to 3 feet long weighing 35 pounds, covered in
30,000 sharp spines. And he wont hesitate to stick you if youre
acting suspicious. Most people know to steer clear of these
spiny rodents (though some curious dogs learned it the hard
way). What you may not know is that there is more to these
quills than meets the eye. In a study out today in the
Proceedings of the National Academy of Sciences, Jeffrey Karp of
the Center for Regenerative Therapeutics at Brigham and Womans
Hospital and a team of Harvard Medical School researchers have
comprehensively described these defensive hairs. Their quills
easily penetrate the skin of a predator but are much harder to
get out. And unlike the African porcupine,