The North American porcupine is a rodent. It has black to brownish-yellow fur and strong, short legs. It has hairless soles on its feet that help it climb trees. It has a round body, small ears and a small head. The most recognizable feature of the porcupine is its quills. A porcupine may have as many as 30,000 quills. The quills are hairs with barbed tips on the ends. Quills are solid at the tip and base and hollow for most of the shaft. The porcupine has quills on all parts of its body, except for its stomach. The longest quills are on its rump. The shortest quills are on its cheeks.