Can Porcupines Shoot Their Quills? The Myth Explained

How porcupine quills really work

A North American porcupine carries about 30,000 quills. Each one is a modified hair: hollow, stiff and sharp, usually around 7.5 cm (3 in) long on the rump and shorter on the head. Normally the quills lie flat beneath the softer fur, pointing backward, and a porcupine can be handled gently from head to tail by an expert without trouble.

When the animal feels threatened, small muscles in the skin pull the quills upright. The porcupine turns its back toward the danger, tucks its head and fans out the quills into a spiky shield. In that position the quills come away very easily, because each sits in the skin with only a narrow, weak base.

The porcupine does not need to shoot anything. Any predator that bites, paws or pushes against it collects a mouthful or faceful of quills. You can see the North American porcupine profile for more on its body and life.

The tail swat: the closest thing to shooting

The tail is the porcupine’s most active weapon. It is thick, muscular and densely covered in quills. If an attacker comes close, the porcupine swings the tail sideways with surprising speed, driving quills into a nose, mouth or paw.

Because the strike is quick and the quills stay behind, an observer may think the quills flew through the air. Occasionally a loose quill does drop out or travels a short distance as the tail lashes, but this is accidental. A porcupine cannot aim, fire or throw its quills at a target, and quills never travel any real distance.

Why porcupine quills are so hard to remove

The tip of every quill is covered in hundreds of microscopic barbs that point backward, like the barbs on a fish hook. A study published in 2012 in the journal PNAS found that these barbs actually help the quill slide in more easily, by concentrating force along the tip, and then make it much harder to pull out.

Once a quill is in, normal muscle movements of the victim can draw it deeper. Animal Diversity Web notes that quills can travel several millimeters a day inside tissue. Predators have died from quills lodged in the mouth or throat, or from infections that followed.

For people, the rule is simple: never touch a porcupine. Quill injuries need professional care. Anyone hurt by quills should seek medical help, and in an emergency call 911 (US), 112 (EU) or 999 (UK).

Warning signs before the quills

Porcupines prefer to avoid a fight, and they give plenty of warning. A threatened porcupine:

• chatters or clicks its teeth loudly;
• raises its quills and shows the black-and-white pattern on its back and tail;
• releases a strong, sour smell from a patch of skin on its lower back;
• turns its rump toward the threat and shuffles backward.

Most predators learn to read these signals. Only an animal that ignores them gets quilled. This layered defense is why the porcupine can move slowly and live alone while many other plant-eaters need speed or a herd.

Do quills grow back?

Yes. Quills are hairs, so the skin grows new ones to replace those that are lost. A porcupine that has just defended itself may have bare patches for a while, but it keeps most of its armor, and the gaps fill in over time.

Quills also have a fatty coating that slows the growth of some bacteria. Porcupine researcher Uldis Roze suggested this helps porcupines themselves, since they often fall out of trees and can be stabbed by their own quills.

Where did the myth come from?

The idea is ancient. Roman writers, including Pliny the Elder in his Natural History, described porcupines shooting their spines at hunters’ dogs, and the story was repeated in medieval books of beasts and in folklore for centuries. The Old World porcupines those writers knew have much longer quills than the North American species, and they rattle them loudly when alarmed.

Several things make the myth believable. Quills appear suddenly in a dog or predator that barely touched the porcupine. A fast tail swat is easy to miss. And loose quills do sometimes fall out when the animal shakes. But no porcupine, in the Americas or anywhere else, can launch its quills.

Porcupines vs other spiny animals

Hedgehogs are not related to porcupines, even though both have spines. Hedgehog spines do not detach easily and have no barbs, so the hedgehog relies on curling up instead. Learn about one of the porcupine’s main enemies in What eats porcupines?.