Prickly porcupine quills may hold clues for medical technology

Flickr user: Robbie's Photo Art

If you’re unlucky enough to have met the business end of a porcupine—or if you have a pesky dog that has—you probably know a thing or two about porcupine quills. Scientific research is now catching up: a new study in PNAS takes a closer look at porcupine quills. It illustrates why they penetrate skin and muscle so easily, and why they are so difficult to remove. Furthermore, it suggests the structure of these quills may have useful medical applications.

North American porcupines have as many as 30,000 quills that are ready to be deployed when a predator comes into contact with the porcupine (contrary to popular belief, the quills can't be shot through the air). Unlike the quills of hedgehogs, echidna, and even the African porcupine, the tips of the quills of North American porcupines are covered in overlapping backward-facing barbs.

To figure out how these barbs affected quill function, the researchers compared normal North American porcupine quills to quills that had been carefully sanded until they were smooth and barb-free. The smooth quills required more than fifty percent additional force to penetrate tissue than barbed quills did, and they actually caused more damage as they entered tissue. Barbs help quills enter cleanly, since they create high stress concentration points in the tissue, lessening the overall force needed for penetration. Serrated knives operate under a similar principle, helping them cut cleanly and easily through food (or skin, if you’re a surgeon or serial killer).