Sixteen species of pigs and hogs in eight genera make up the modern family Suidae. Suids originally occurred across Eurasia south of 48° N, on islands as far away as the Phillipines and Sulawesi, and throughout Africa. Humans have introduced Sus scrofa, from which the domesticated pigs are derived, in a variety of places around the world, including North America, New Zealand and New Guinea. Fossil suids are known from the Oligocene of Europe and Asia and the Miocene of Africa.
These medium-sized animals are typically stocky with a barrel-like body. The skin is usually thick and sparsely haired. Head and body length ranges from 500-1900 mm, tail length ranges from 35-40 mm and adult body weight can be as high as 350 kg. The eyes are usually small and located high on the skull, and the ears are small and pointed. The skull is usually long and has a flat dorsal profile. One of the most notable characteristics of suids is the mobile snout, which has a cartilaginous disk at its tip and terminal nostrils. It is supported by a prenasal bone located below the nasals. The skull has a prominent occipital crest that is formed from the supraoccipital and parietal bones. The metapodials are not fused, and the first digit is missing from both forefeet and hindfeet. All four digit have hooves, but these are only functional in locomotion on the middle digits (the third and fourth), as the smaller lateral digits are located higher on the limb ( paraxonic). The dental formula varies among the genera; a general formula for the family is: 1-3/3, 1/1, 2-4/2 or 4, 3/3 = 34-44. The upper incisors decrease in size laterally; the lower incisors are long, narrow and set at a low angle in the jaw so that they are almost horizontal. The upper canines grow out and backward into large, curved tusks; wear between the upper and lower canines produces sharp edges. The upper canines are ever-growing. The molars are bunodont or cuspidate.
Pigs are omnivores, and the diet includes fungi, leaves, roots, bulbs, tubers, fruit, snails, earthworms, small vertebrates, eggs and carrion. They use their muscular, mobile snout and forefeet to root and scratch for food. They have a two-chambered stomach and do not ruminate.
Most species are gregarious. One common image of pigs, that they overeat, is not commonly true. However, it is true that most pigs are fond of mud baths!
Suids, especially hogs (Sus scrofa) have been introduced to a number of places, usually as a game species. Unfortunately, in some areas they have caused significant environmental damage by their foraging, and they carry several diseases that can be transmitted to domestic swine or people.
References and literature cited:
Feldhamer, G. A., L. C. Drickamer, S. H. Vessey, and J. F. Merritt. 1999. Mammalogy. Adaptation, Diversity, and Ecology. WCB McGraw-Hill, Boston. xii+563pp.
Nowak, R.M. and J.L. Paradiso. 1983. Walker's Mammals of the World, 4th edition . John Hopkins University Press, Baltimore, MD.
Savage, R. J. G. and M. R. Long. 1986. Mammal Evolution: An Illustrated Guide. Facts on File Publications, UK. 251 pp.
Simpson, C. D. 1984. Artiodactyls. Pp. 563-587 in Anderson, S. and J. K. Jones, Jr. (eds). Orders and Families of Recent Mammals of the World. John Wiley and Sons, N.Y. xii+686 pp.
Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, N.Y. vii+576 pp.
Vaughan, T. A., J. M. Ryan, N. J. Czaplewski. 2000. Mammalogy. Fourth Edition. Saunders College Publishing, Philadelphia. vii+565pp.
Wilson, D. E., and D. M. Reeder. 1993. Mammal Species of the World, A Taxonomic and Geographic Reference. 2nd edition. Smithsonian Institution Press, Washington. xviii+1206 pp.
David L. Fox (author), University of Michigan-Ann Arbor, Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
having the capacity to move from one place to another.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate