Worldwide, there are 29 species of porcupines, ranging from the Bahia hairy dwarf porcupine (Coendou insidiosus), which weighs less than a kilogram (2.2 lb), to the African crested porcupine (Hystrix cristata), which can grow to well over 27 kg (60 lb).

Their front teeth are orange from iron oxide in the enamel.

The only species of porcupine that lives in the United States, the North American porcupine (Erethizon dorsatum) is the largest of all porcupines and can have more than 30,000 quills on its body.

During the winter, they primarily eat evergreen needles and the inner bark of trees, often feeding heavily on a single tree. In the spring and summer, porcupines shift to eating berries, seeds, grasses, leaves, roots and stems. They will also gnaw bone to get minerals, like salt and calcium, and to sharpen their powerful incisors.

The word "porcupine" comes from Latin words porcus (pig) and spina (spine). However, porcupines have no relation to pigs. They are actually large rodents.

Some quills, like those of Africa's crested porcupine, are nearly a foot long.

Each quill has a greasy coating that contains an antibiotic material. This protects the porcupine from developing infections when it accidentally sticks itself.

Porcupines are rodents, and one characteristic of rodents is that their teeth continue to grow throughout their lives. Porcupines need to gnaw on hard objects to help keep their teeth at the proper length.

Porcupines are generally nocturnal, meaning they are most active at night, when they forage for food.

The porcupine gives off a warning when alarmed, although it could be mistaken for a strange dance. It will stomp its feet, click its teeth, growl and rattle its quills to warn the enemy away. If the perceived threat doesn't heed this warning, the porcupine will attack by running backwards into predators.