Deserts--areas that receive less than 10 inches of rain in a year--cover more than one-fifth of the land on Earth and are characterised by extreme temperatures, either hot or cold. Though each desert has a unique set of fauna and flora, what all desert plants and animals have in common are adaptations that allow them to survive in their habitat's harsh conditions.
The range of the chuckwalla, a large, stocky member of the iguana family, extends throughout the Sonora and Mojave deserts of North America. Chuckwallas are herbivores that feed on flowers, leaves and fruits. In this species of lizards, the sexes can be distinguished by colour. The heads, shoulders and limbs of the territorial male chuckwallas are black and their bodies can be yellow, orange, red or grey. Females, on the other hand, have bodies characterised by spots or contrasting bands of colour. If caught by one of their predators, which include hawks, coyotes and snakes, the tail of the chuckwalla detaches and later regenerates.
There are two species of camels: the dromedary and the Bactrian. The former have only one hump for storing fat while the latter have two. Dromedary camels were once populous throughout Northern Africa and Middle East but today there are none left in the wild. They exist only in captivity as domesticated animals. The Bactrian camel is native to China's Gobi desert and parts of Mongolia. Camels can grow to be up to 11.3 feet in length and have adaptations that allow them to thrive in the desert. Relying on the fat stored in their humps, camels can survive without food for months and can last a week or more without drinking water. They have a third eyelid known as a nictitating membrane and two rows of long eyelashes on each eye which help keep desert sand out. Camels can also avoid inhaling sand by closing their nostrils.
The succulent saguaro cactus is endemic to the Sonora desert. They can have up to 25 branches that bend upward. Saguaro cacti can grow to be 40 to 60 feet tall, but their growth is very slow and they can live to be two centuries old. They have one deep root that in some plants can be over 2 feet deep and shallower roots that are between 4 and 6 inches long. Cacti's ability to store water via these roots makes them appealing to thirsty animals therefore the saguaro, like all cacti species, is covered in spines that ward off would-be consumers.
Quiver trees, also known as kokerbooms, are a member of the aloe family. They are indigenous to Namibia and South Africa and are one of few varieties of tree-like vegetation in that region. These succulent plants propagate via seeds and begin producing yellow blossoms when they are between 20 and 30 years old. They can grow to be between 10 and 15 feet tall, and, according to the Quivertree Forest Rest Camp in Namibia, some of the oldest quiver trees are approximately three centuries old.