Porcupine, a large rodent that has sharp quills covering most of its stocky, short-legged body. Porcupines are grizzled brown or black, and are 1 to 3 feet (45 to 90 cm) long, including the tail. Some kinds have short tails, others have long tails that may be prehensile (grasping).

The porcupine defends itself by thrusting its quills into the flesh of an attacking animal. The quills are modified hairs that are mixed in with other hairs. They may be hollow or solid, and either long and flexible, or short and stiff. Usually the quills lie flat, but are raised when the porcupine becomes frightened. Porcupines cannot throw their quills, but the quills are easily detached. Some porcupines have barbed quills that continue to work their way into the enemy's flesh after penetrating it.

Porcupines are found in the Americas, Europe, Asia, and Africa. Some kinds live in forests, others in savannas. They eat shoots, leaves, fruits, grains, and the inner bark of trees. Where numerous, porcupines cause much damage to trees and crops. They usually sleep during the day, in burrows, rocky crevices, hollow logs, or trees.

The North American, or Canadian, porcupine is the only American species found north of Mexico. It is found in Alaska and most of Canada. In the West it ranges south to western Texas. It is also found from Maine to West Virginia, and in the Great Lakes region. This porcupine may be three feet (90 cm) long, including its six-inch (15-cm) tail. It has blackish underfur, yellow guard hairs, and yellowish, black-tipped, barbed quills. In winter, the quills are almost concealed by fur. In summer, the quills are more conspicuous.

A number of species of tree porcupines are found in Mexico and South America. They have long, prehensile tails. The thin-spined porcupines and the mountain porcupines are South American groups that have long, nonprehensile tails.

Old World porcupines are not tree-dwellers, and do not have prehensile tails. The crested porcupine of southern Europe and northern and eastern Africa gets its name from the long bristles on its head and neck. It is about two feet (60 cm) long. A closely related species, the brush-tailed porcupine, inhabits parts of Africa and Asia. Its scaly tail ends in a brush of quills. The long-tailed, or rat, porcupine lives in Borneo, Sumatra, and the Malay Peninsula.

How Many Quills Does a Porcupine Have?

A porcupine has about 30,000 quills on its back, sides, and tail. The quills are sharp, stiff hairs. A porcupine uses them for defense. If an enemy attacks, the porcupine strikes with its quilled tail. The quills from a porcupine’s body also stick into the skin of an attacker if it gets too close. When the attacker pulls away, the quills stay stuck to its body. This is very painful for the attacker and can even be deadly.

Quills also help a porcupine to swim. The quills have a spongelike filling that helps the porcupine float on water. Floating in a stream or pond is a great way to enjoy a meal of water plants.

American porcupines make up the family Erethizontidae. The North American porcupine is Erethizon dorsatum. The tree porcupines make up the genus Coendou; the thin-spined, Chaetomys; the mountain, Echinoprocta. Old World porcupines make up the family Hystricidae. The crested porcupine is Hystrix cristata. The brush-tailed porcupine is genus Atherurus; the long-tailed, genus Trichys.