About how many quills cover the body of a North American porcupine?
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Answer
About 30,000 quills
Porcupines cannot shoot their quills. The quills simply detach on contact, and their tips carry microscopic backward-facing barbs that make them hard to pull out.
How to estimate it
Treat the porcupine as a cylinder 60 cm long and 60 cm around: 60 × 60 = 3,600 square centimetres of skin. Quills cover the back, sides and tail but not the belly or face, so about two thirds: 2,400 square centimetres. With quills spaced about 3 mm apart, there are 11 per square centimetre. 2,400 × 11 = 26,000. The usual quoted figure is about 30,000 quills.
Source: National Geographic; Smithsonian National Zoo
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