There are two extant species of camels: the one-humped Arabian (which includes the Dromedary breed) and the two-humped Bactrian. The former is widely used as a domesticated beast of burden in Africa and Asia, and it is feral in the Australian outback. Bactrian camels have a critically small wild population in China and Mongolia, mainly in the Gobi Desert.

Mouth Gear

All camelids---members of an ungulate (hoofed mammal) family including the two camels and also llamas, alpacas, guanacos and vicunas---have a split, mobile upper lip, an adaptation for feasting on tough vegetation.

Natural Diet

Bactrians typically graze and browse on shrubs, leaves and grasses. Arabians target similar fare, apparently preferring shrubs and forbs; they'll tackle thorn bushes, saltbush and other plants of limited palatability.

Foraging Schedule

Arabians may spend eight to 12 hours a day foraging (and an equal proportion in rumination, part of the digestive process), and they do so over a broad area.

Outback Outlaws

In Australia, at least 300,000 non-native, feral Arabians mostly target succulent herbs; some 20 to 40 percent of their diet may be grasses. They also feed on shrubs and, being taller than other Australian terrestrial herbivores, destructively browse such indigenous trees as the quandong.

The Hump

The humps of both camel species are composed of fat stores that can sustain them when food is scarce, one of the prime reasons they are so successful in arid regions.

Source:

UltimateUngulate.com: Family Camelidae--Camels

UltimateUngulate.com: Camelus bactrianus--Bactrian camel

University of Michigan Museum of Zoology-Animal Diversity Web: Camelus dromedarius--dromedary

Resource:

Government of Western Australia, Department of Agriculture and Food: Feral camel