Suids belong to the
order Artiodactyla, and are generally regarded as the living members of that order most similar to the ancestral form. Unlike most other members of the order, they have four hooves on each foot, although they walk only on the middle two digits, with the others staying clear of the ground. They also have a simple stomach, rather than the more complex
ruminant stomach found in most other artiodactyl families. They are small to medium animals, varying in size from in length, and in weight in the case of the
pygmy hog, to and in the
giant forest hog. They have large heads and short necks, with relatively small eyes and prominent ears. Their heads have a distinctive snout, ending in a disc-shaped nose. Suids typically have a bristly coat, and a short tail ending in a tassle. The males possess a corkscrew-shaped penis, which fits into a similarly shaped groove in the female's
cervix. Suids have a well-developed sense of hearing, and are vocal animals, communicating with a series of grunts, squeals, and similar sounds. They also have an acute sense of smell. Many species are omnivorous, eating grass, leaves, roots, insects, worms, and even frogs or mice. Other species are more selective and purely herbivorous. Their teeth reflect their diet, and suids retain the upper
incisors, which are lost in most other artiodactyls. The canine teeth are enlarged to form prominent tusks, used for rooting in moist earth or undergrowth, and in fighting. They have only a short
diastema. The number of teeth varies between species, but the general
dental formula is: . ==Behavior and reproduction==