Characteristics and Evolution of Porcupines

Porcupines

Porcupines are giant rodents with coats of sharp spines, or quills, that shield them against predators. 

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, and use an aposematic strategy of defense. Porcupines occur in various shades of brown, grey, and white. Porcupines’ spiny protection resembles that of the unrelated hedgehogs and Australian monotreme echidnas as well as tenrecid tenrecs.

Porcupines cover two species of animals: the Old World porcupines of family Hystricidae, and the New World porcupines of family Erethizontidae. Both families belong to the Infraorder Hystricognathi within the extremely diverse order Rodentia and display partially similar coats of quills: despite this, the two groups are different from each other and are not closely related to each other within the Hystricognathi.

The Old World porcupines live in southern Europe, Asia, and most of Africa. They are large, terrestrial, and strictly nocturnal. In taxonomic terms, they form the family Hystricidae.

The New World porcupines are native to North America and northern South America. They live in wooded areas and can scale trees, where some species spend their entire lives. They are less strictly nocturnal than their Old World relatives and usually smaller. In taxonomic terms, they form the family Erethizontidae.

Evolution

Porcupines can:

  1. Scale Trees like a Squirrel.
  2. Their quills are made up of the same material as Rhinos- Keratin.
  3. They have gigantic teeth (for their size) like beavers.

How did they evolve? 

Porcupines evolved from Hedgehogs. Hedgehogs have been on this planet for over 15 Million years. Porcupines, in the African wild, evolved as a result of predators trying to charge at Hedgehogs from all possible directions, and due to the lack of food. The New World porcupines evolved their quills independently (through convergent evolution) and are more closely related to several other families of rodents. So, we can conclude here that Porcupines were evolved from both rodents and Hedgehogs. 

Characteristics 

Longevity

Porcupines have comparatively high longevity and have held the record for being the longest-living rodent, with one individual living to 27 years, until the record was broken in 2002 by a naked mole-rat living to 28 years.

Diet

The North American porcupine is an herbivore; it eats leaves, herbs, soft branches, and green plants such as clover. In the cold, it may eat bark. It usually climbs trees to find food. The African porcupine is not a climber and searches on the ground. It is mostly nocturnal, but will sometimes search for food in the day, eating bark, roots, fruits, and berries, as well as farm crops. Porcupines have become a pest in Kenya and are eaten as a luxury.

Defense 

The defensive function in a porcupine depends on vision, odor, and noise. Often, these displays are shown when a porcupine becomes disturbed or angry. There are four main displays seen in a porcupine which are quill erection, teeth clattering, emitting of odor, and attack. These are ranked from least aggressive to most aggressive respectively. A porcupine’s coloring aids in part of its defense as most of the predators are nocturnal and color blind. A porcupine’s senses are black and white. The dark body and coarse hair of the porcupine are dark brown/black and when quills are raised, perform a white strip down its back mimicking the look of a skunk. This, along with the raising of the sharp quills, discourages predators. Along with the raising of the quills, porcupines clatter their teeth causing warning noise to let predators know not to come closer. The incisors vibrate against each other, the strike zone shifts back, and the cheek teeth clatter. This behavior is often paired with body shivering which is used to further display the formidable quills. The rattling of quills is aided by the hollow quills at the back end of the porcupine. The use of odor is when the sight and sound have sunk. An invasive scent is produced from the skin above the tail in times of stress and is often seen with quill erection. If the above processes fail, the porcupine will charge by running sideways or backward into predators. A porcupine’s tail is also able to swing in the course of the predator. If contact is made, the quills could be stabbed into the predator causing injury or death.

Quills

Quills grow in varying lengths and colors, depending on the animal’s age and species. Porcupines’ quills, or spines, take on different forms, depending on the species, but all are altered hairs coated with thick plates of keratin, and buried 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 pushed by contact or may drop out when the porcupine shakes its body. New quills arise to replace lost ones. Porcupines were long thought to have the ability to project their quills to a considerable distance at an enemy, but this has since been proven to be wrong. There are some possible antibiotic characteristics within the quills, specifically associated with the free fatty acids coating the quills. The antibiotic properties are assumed to aid a porcupine that has suffered from self-injury.

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