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Question: What are the quills of a porcupine made of?
North American porcupines inhabit forested areas in Alaska, Canada and much of the United States. They are large rodents; in our country only beavers are larger. As herbivores, their diet consists of most any type of vegetation and during winter they eat bark and wood. Because they like salty things they will eat wooden items containing human sweat, such as canoe paddles. Although porcupines live locally, they are nocturnal and therefore rarely seen. Slow on land, they are excellent climbers and prefer to spend their time in trees.
Porcupines are mammals and are covered with fur. But unlike most mammals, some of their hair has been modified into needle sharp quills. Quills are interspersed with hair and are found everywhere except the snout and belly. One porcupine can have as many as 30,000 quills! When the animal is threatened muscles under the skin make the quills stand up. Since quills are loosely attached they come out easily and are a very effective defense mechanism.
Porcupines cannot throw their quills, but may charge or swing their tail at the intended victim. If a predator is struck by the tail or grabs the porcupine quills will become lodged in its skin. The end of each quill is covered with overlapping scales which serve as barbs to hold it in the attackers' skin, and help the quill to travel deeper into the animal. If quills are not properly removed it is possible for them to end up in muscles and organs, even sometimes causing death.
Quills, hair, skin, fingernails, feathers and hooves are examples of materials made of a protein called keratin. Proteins are polyamides, a type of polymer (characterized by small molecules, or monomers, bonded together to form long chains). Strong and insoluble, polymers are flexible because the chains can stretch and bend (for instance, plastic). In the case of polyamides, the monomers are amino acids. Keratin is composed of 18 different amino acids, one of which is cysteine. Cysteine is especially important because sulfur atoms in cysteine form strong chemical bonds with each other, making keratin especially tough. The more cysteine the keratin contains the stronger it is, thus hooves contain more cysteine than hair. Keratin is a naturally occurring polyamide. Man-made polyamides include nylon and Kevlar. Kevlar is so strong that it is used in bullet-proof vests.
In addition to providing protection for porcupines, quills are used in jewelry and other crafts. Luckily for porcupines, quills are shed just like hair and can be collected without causing any harm.
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