
            
            By: MIGHTYmacro
            
              Image: MIGHTYmacro
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              Subject:
              Science North
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            Uploaded: 9 Apr 2018
            Last Updated: 9 Apr 2018
          
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Porcupines' quills, or spines, take on various forms, depending on the species, but all are modified hairs coated with thick plates of keratin, and embedded in the skin musculature. Old World porcupines have quills embedded in clusters, whereas in New World porcupines, single quills are interspersed with bristles, underfur, and hair. Quills are released by contact or may drop out when the porcupine shakes its body. New quills grow to replace lost ones. Porcupines were long believed to have the ability to project their quills to a considerable distance at an enemy, but this has since been proven to be untrue. Source Wikipedia https://en.wikipedia.org/wiki/Porcupine