From The Art and Popular Culture Encyclopedia
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 and short legs. 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 small animals. Pigs will scavenge and have been known to eat any kind of food, including dead insects, worms, tree bark, rotting carcasses, excreta (including their own), garbage, and other pigs. In the wild, they are foraging animals, primarily eating leaves and grasses, roots, fruits and flowers. Occasionally, in captivity, pigs may eat their own young, often if they become severely stressed.
In fiction and art pigs are displayed as greedy and/or filthy. Both aspects are due to the natural pig lifestyle (when raised on a farm rather than a feedlot)—"greedy" from the way they devour any food put in front of them, "filthy" from the fact that a pig-sty is generally a soup of mud and feces which the pigs don't seem to mind at all (this also gives rise to the saying "Happy as a pig in shit").