Old World Camels, New World Camels
Camels and their relatives, the llamas, are longlegged, hoofed mammals in the family Camelidae in order Artiodactyla, whose members have an even number of toes. All camels have a cleft in their upper lip, and all have the ability to withstand great heat and great cold.
Camels evolved in North America and spread into South America, Asia, and Africa. Camels in Asia and Africa today have been domesticated for up to 3,500 years. The two smaller South American species of camel have been bred to develop two purely domestic species, the llama and the alpaca.
Like cattle, camels are cud-chewing animals, or ruminants. However, unlike other ruminants, which have four chambers to their stomachs, camels have only three. Both male and female camels have the same number of teeth for feeding, but the front incisor teeth of the males are large and sharp, making them useful for fighting. Camels have oval shaped red blood cells, whereas all other mammals have round red blood cells.
Both New World and Old World camels communicate in a variety of ways, including whistling, humming, and spitting. In zoos, camels have been known to spit the contents of their first stomach at annoying visitors.