Porcupines are rodents with a coat of sharp spines, or quills that defend them from predators. They are indigenous to the Americas, southern Asia, and Africa. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about 25–36 in (63–91 cm) long, with an 8–10 in (20–25 cm) long tail. Weighing between 12–35 lb (5.4–16 kg), they are rounded, large and slow. Porcupines come in various shades of brown, grey, and the unusual white.
Porcupines' quills, or spines, take on various forms, depending on the species, but all are modified hairs coated with thick plates of keratin, and they are embedded in the skin musculature. The average porcupine has about 30,000 quills or specialized hairs, which it uses as a defensive weapon. Quills are released by contact with them, or they may drop out when the porcupine shakes its body, but cannot be projected at attackers. New quills grow to replace lost ones. From ancient times, it was believed that porcupines could throw their quills at an enemy, but this has long been refuted.
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