Pig

Pig
A domestic sow and her piglet.
A domestic sow and her piglet.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Theria
Infraclass: Eutheria
Order: Artiodactyla
Family: Suidae
Subfamily: Suinae
Genus: Sus
Linnaeus, 1758
Species

Sus barbatus
Sus bucculentus
Sus cebifrons
Sus celebensis
Sus domestica
Sus falconeri
Sus hysudricus
Sus oliveri
Sus philippensis
Sus scrofa
Sus strozzi
Sus verrucosus

Pigs, also called hogs or swine, are a genus of even-toed ungulates within the family Suidae. The name pig, hog, or swine most commonly refers to the Domestic pig (Sus domestica) in everyday parlance, but technically encompasses several distinct species, including the Wild Boar. With around 2 billion on the planet, domestic pigs are also by far the most numerous pig species.[1][2] Pigs are omnivores, and despite their reputation for gluttony, they are generally social and intelligent animals.

Contents

Description and behavior

A pig has a snout for a nose, small eyes, and a small tail, which may be curly, kinked, or straight. It has a thick body, short legs, and coarse hair. There are four toes on each foot, with the two large middle toes used for walking.

Pigs are omnivores, which means that they consume both plants and animals. Pigs will scavenge and have been known to eat any kind of food, including dead insects, worms, tree bark, rotting carcasses, garbage, and even other pigs. In the wild, they are foraging animals, primarily eating leaves, grasses, roots, fruits and flowers. Occasionally while in captivity, pigs may eat their own young if they become severely stressed. A typical pig has a large head with a long snout which is strengthened by a special bone called the prenasal bone and by a disk of cartilage in the tip. The snout is used to dig into the soil to find food and is a very sensitive sense organ.

Pigs have a full set of 44 teeth. The canine teeth, called tusks, grow continually and are sharpened by the lowers and uppers rubbing against each other.

Pigs that are allowed to forage may be watched by swineherds. Because of their foraging abilities and excellent sense of smell, they are used to find truffles in many European countries. Domesticated pigs are commonly raised as livestock by farmers for meat (called pork), as well as for leather. Their bristly hairs are also used for brushes. Some breeds of pigs, such as the Asian pot-bellied pig, are kept as pets.

Breeding occurs throughout the year in the tropics, but births peak around rainy seasons. A female pig can become pregnant at around 8-18 months of age. She will then go into estrus every 21 days if not bred. Male pigs become sexually active at 8-10 months of age.[3] A litter of piglets typically contains between 6 and 12 piglets. After the young are weaned, two or more families may come together until the next mating season.

Pigs do not have functional sweat glands,[4] so pigs cool themselves using water or mud during hot weather. They also use mud as a form of sunscreen to protect their skin from sunburn. Mud also provides protection against flies and parasites.

Species

The Pygmy Hog is now in the monotypic genus Porcula again[14]

Domestic Pigs

Pigs on a farm
Main article: Domestic pig

Pigs have been domesticated since ancient times in the Old World and are known for their exceptional intelligence. Domestic Pigs are found across Europe, the Middle East and extend into Asia as far as Indonesia and Japan. They were brought to southeastern North America from Europe by De Soto and other early Spanish explorers. Pigs are particularly valued in China and on certain oceanic islands, where their self-sufficiency allows them to be turned loose, although the practice is not without its drawbacks (see below).

The Domestic Pig (Sus scrofa domesticus) is usually given the scientific name Sus scrofa, although some authors call it S. domesticus, reserving S. scrofa for the Wild boar. It was domesticated approximately 5,000 to 7,000 years ago. Their coats are coarse and bristly. They are born brownish colored and tend to turn more grayish colored with age. The upper canines form sharp distinctive tusks that curve outward and upward. Compared to other artiodactyles, their head is relatively long, pointed, and free of warts. Their head and body length ranges from 900-1,800 mm and can weigh 50-350 kg.

Pigs can be trained to perform numerous simple tasks and tricks. Recently, they have enjoyed a measure of popularity as house pets, particularly the dwarf breeds.

Cultural references to pigs

Main article: Cultural references to pigs

Pigs are frequently referenced in culture and are a popular topic for idioms and famous quotes.

Pigs in religion

Painting of Saint Anthony with pig in background by Piero di Cosimo c. 1480

Environmental impacts

Domestic pigs that have escaped from farms or were allowed to forage in the wild, and in some cases wild boars which were introduced as prey for hunting, have given rise to large populations of feral pigs in North and South America, Australia, New Zealand, Hawaii and other areas where pigs are not native. Accidental or deliberate releases of pigs into countries or environments where they are an alien species have caused extensive environmental change. Their omnivorous diet, aggressive behaviour and their feeding method of rooting in the ground all combine to severely alter ecosystems unused to pigs. Pigs will even eat small animals and destroy nests of ground nesting birds.[15] The Invasive Species Specialist Group lists feral pigs on the list of the world's 100 worst invasive species and says:[16]

Feral pigs (razorbacks) in Florida, United States
Feral pigs like other introduced mammals are major drivers of extinction and ecosystem change. They have been introduced into many parts of the world, and will damage crops and home gardens as well as potentially spreading disease. They uproot large areas of land, eliminating native vegetation and spreading weeds. This results in habitat alteration, a change in plant succession and composition and a decrease in native fauna dependent on the original habitat.

Health issues

Pigs harbour a range of parasites and diseases that can be transmitted to humans. These include trichinosis, Taenia solium, cysticercosis, and brucellosis. Pigs are also known to host large concentrations of parasitic ascarid worms in their digestive tract.[1] The presence of these diseases and parasites is one of the reasons why pork meat should always be well cooked or cured before eating. Some religious groups that consider pork unclean refer to these issues as support for their views.[2]

Pigs are susceptible to bronchitis and pneumonia. They have small lungs in relation to body size; for this reason, bronchitis or pneumonia can kill a pig quickly.

Pigs can be aggressive and pig-induced injuries are relatively common in areas where pigs are reared or where they form part of the wild or feral fauna.[3]

See also

Footnotes

  1. Production, Supply and Distribution Online Query, United States Department of Agriculture, Foreign Agricultural Service
  2. Swine Summary Selected Countries , United States Department of Agriculture, Foreign Agricultural Service, (total number is Production (Pig Crop) plus Total Beginning Stocks
  3. The solitary adult males together and fight for the right to mate with a female. A single male usually wins control over 4 females on average.ADW: Sus scrofa: Information
  4. Managing Heat Stress In Outdoor Pigs
  5. Müller, 1838
  6. Heude, 1892
  7. Heude, 1888
  8. Müller & Schlegel, 1843
  9. Groves, 1997
  10. Nehring, 1886
  11. Linnaeus, 1758
  12. Linnaeus, 1758
  13. Müller, 1840
  14. Funk et al. (2007)
  15. ADW: Sus scrofa: Information
  16. Ecology of Sus scrofa, Global Invasive Species Database, The Invasive Species Specialist Group

References

External links