As in pigs, peccaries have two-chambered stomachs and do not ruminate. However, peccary stomachs are a bit more complex than pigs'. The upper canines form tusk but are directed downward, not outward or upward as in pigs. They are also smaller than pig tusks. Peccaries occupy a great variety of habitats, from rainforest to woodlands to desert scrub.
Peccaries shelter in thickets or under large boulders.
Like pigs, peccaries root in the ground with their snouts in search of plant food and occasional grubs and small vertebrates. Like some pigs, they don't seem to be harmed by rattlesnake bites. Peccaries are gregarious. White-lipped peccaries are sometimes seen in herds numbering in the hundreds. Collared peccaries generally travel in groups of two to fifty, Chacoan peccaries in groups of about five.