Camels bear all their weight on the two middle toes of each foot like yaks, hippos, giraffes, antelopes, water buffalos and other large herbivores, including our own cosy farmyard animals: cattle, sheep, pigs and goats – cloven footed animals, as the bible would have it; even-toed ungulates for those with a taste for cladistics or Latin; artiodactyls for those with a preference for ancient Greek.
They rely so heavily on their two toes that all their other toes have atrophied and disappeared. The ankle joint is half way up the leg and the bones of the foot-arch fused into a single long bone that acts as an added limb to the leg, leaving only the toes in contact with the ground. These are cushioned underneath by a wad of fat and a wide pad of connective tissue, and shielded above by a couple of tremendous toe nails.
Evolution has not only rejigged the foot but also shortened the thigh bone and lengthened the shin bone so that a muscular swing from the hip is amplified down the long legs to produce an extended stride. Forelegs show similar adaptations, though equivalent joints bend in different directions.
When the camel couches, the whole assembly folds up like a deck chair. First the front legs buckle until the camel is kneeling, then the back legs collapse until the camel is seated, then the front legs push forward, bringing the chest to the ground where it has a calloused pad to protect it from the searing heat of the ground. To stand up, the camel reverses the process.
As a camel walks, it moves one foot at a time keeping the other three planted firmly on the ground until weight is transferred, the classic quadruped gait. As it speeds up, it starts to move two legs in tandem on one side and then on the other, giving the classic rolling camel gait. When urged on more, the camel shifts into a gallop, pushing off with its two back legs while leaping forward with its two front legs.