quill

in mammals

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July 13, 2026

Quick Summary

Quills are modified hairs made of keratin, a structural protein. They form a protective covering for porcupines, which are large, herbivorous rodents. Quills grow in clumps or are interspersed with other hairs, depending on whether the porcupine is from the Old World or New World.12

When a porcupine feels threatened, its quills stand on end and can detach easily if they prick another animal. These quills can cause injuries ranging from minor to fatal.1

Porcupines do not suffer from losing quills, as new ones begin to grow within days. The rate of growth is about 1 mm every two days, and quills can regrow fully within months.1

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Are Porcupines Aggressive?
…turn their rear, where their quills are most concentrated, toward the perceived danger. These quills, which detach upon contact and embed in an attacker, are a passive defense mechanism rather than an active offensive action.
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…turn their rear, where their quills are most concentrated, toward the perceived danger. These quills, which detach upon contact and embed in an attacker, are a passive defense mechanism rather than an active offensive action.
Read More

Do Porcupine Quills Grow Back?
Quills are modified hairs composed of keratin, a fibrous structural protein, and consist of an inner spongy core surrounded by a tough, hollow, shaftlike, pointed shell. They grow in clumps in porcupines found in Asia, Africa, and Europe, collectively known as Old World porcupines
Read More
Quills are modified hairs composed of keratin, a fibrous structural protein, and consist of an inner spongy core surrounded by a tough, hollow, shaftlike, pointed shell. They grow in clumps in porcupines found in Asia, Africa, and Europe, collectively known as Old World porcupines
Read More