Porcupines are large rodents with coats of sharp spines, or quills, that protect them against predators. The term covers two families of animals, the Old World porcupines in the family Hystricidae, and the New World porcupines in the family Erethizontidae. Both families display superficially similar coats of rigid or semirigid quills, which are modified hairs composed of keratin, and belong to the infraorder Hystricognathi within the diverse order Rodentia. The two groups are distinct and are not closely related to each other within the Hystricognathi. The largest species of porcupine is the third-largest living rodent in the world, after the capybara and beaver. The Old World (Hystricidae) live in Italy, West and South Asia, and most of Africa. They are large, terrestrial, and strictly nocturnal. New World porcupines (Erethizontidae) are indigenous to North America and northern South America. They live in wooded areas and can climb trees, where some species spend their entire lives. They are generally smaller than their Old World counterparts and are less strictly nocturnal. Most porcupines are about 60–90 cm (25–36 in) long, with a 20–25 cm (8–10 in) long tail. Weighing 5–16 kg (12–35 lb), they are rounded, large, and slow. Their colouration consists of various shades of brown, grey, and white. Porcupines have various methods to defend themselves from predators, the most prominent being the use of their quills, which advertises their unsuitability for being preyed upon. This strategy is known as aposematism. To some degree, the spiny protection resembles that of the hedgehogs, echidnas, and tenrecs, none of which share any spiny ancestors; all of them, and also the Old World and New World porcupines, are products of convergent evolution. The spines of the various groups also vary markedly. Humans have a varied history with porcupines, with some cultures considering them symbols of self-defense or cautiousness. Porcupines appear in mythology in regions where the animal has economic significance, such as for food or in the production of quillwork textiles.
Terminology and etymology The word "porcupine" comes from the Latin porcus 'pig' + spina 'spine, quill', from Old Italian porcospino, 'thorn-pig'. A regional American name for the animal is "quill-pig". A baby porcupine is known as a porcupette. When born, a porcupette's quills are soft hair; they harden within a few days, forming the sharp quills of adults.
Taxonomy and evolution
Classification A porcupine is any of 29 species of rodents belonging to the families Erethizontidae (genera: Coendou, Erethizon, and Chaetomys) or Hystricidae (genera: Atherurus, Hystrix, and Trichys). The two families of porcupines are quite different, and although both belong to the Hystricognathi branch of the vast order Rodentia, they are not closely related. Porcupines are distributed into two evolutionarily independent groups within the infraorder Hystricognathi, part of the suborder Hystricomorpha of the Rodentia:
Evolution Studies on the physical characteristics of New World porcupines initially described them as being the most basal (earliest to diverge) group among the hystricognaths, and fossil records point to a common ancestor of the Erethizontidae and all other hystricognaths occurring 37.2 to 33.9 million years ago in the early Oligocene. Dorothée Huchon and Emmanuel Douzery wrote in 2001 on the diversification of the hystricognaths, reporting that molecular phylogenetic studies using nuclear genes (e.g., the von Willebrand factor gene) suggested that the Hystricidae (Old World porcupines), Phiomorpha, and Caviomorpha (which includes New World porcupines) lineages split some 63 to 43 million years ago. This supported a single colonization event of South America by hystricognaths. A 2013 study of nuclear and mitochondrial genomes supports a mid-Eocene diversification of New World hystricognaths, with family-level splits occurring in the early Miocene. Fossils belonging to the genus Hystrix date back to the late Miocene of Africa and Asia. One of the oldest known porcupine fossils is Hystrix primigenia, an Old World porcupine that lived in the late Miocene to the Pliocene; the oldest known porcupine fossil in Asia, Hystrix lufengensis, dates back 8 million years, also in the late Miocene.
Biology
Old World compared with New World species The 11 Old World porcupines tend to be fairly large and have spines grouped in clusters. The two subfamilies of New World porcupines are mostly smaller (although the North American porcupine reaches about 85 cm (33 in) in length and 18 kg (40 lb)), have their quills attached singly rather than grouped in clusters, and are excellent climbers, spending much of their time in trees. The New World porcupines evolved their spines independently (through convergent evolution) and are more closely related to several other families of rodents than they are to the Old World porcupines. The quills of New World porcupines are unique among spined rodents, being stiff with a circular cross-section that is small in proportion to their length, which allows them to penetrate further into a potential predator before breaking off near the base. In contrast, the spines of Old World porcupines are similar to those of other rodents with spiny hair, such as the bristly mouse and short-tailed spiny rat, in that they have a concave cross-section and are shorter and softer, making them break off closer to the tip.
Description Porcupines are rodents of varying fur color that are characterized by their abundance of protruding spines, or quills, found all along the head and body of the animal. Some species have quills that extend from the tail, as well. They vary in size considerably: an adult Andean porcupine weighs roughly 2 kg (4.4 lb), while the crested porcupine can grow to weigh up to 27 kg (60 lb).
Longevity Porcupines have relatively long lifespans and hold the record for being the longest-living rodent, with one individual named Cooper living over 32 years.
Diet
The North American porcupine is an herbivore and often climbs trees for food; it eats leaves, herbs, twigs, and green plants such as clover. In the winter, it may eat bark. The African porcupine is not a climber; instead, it forages on the ground. It is mostly nocturnal but sometimes forages for food during the day, eating bark, roots, fruits, berries, and farm crops. Porcupines have become a pest in Kenya and are eaten as a delicacy.
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