While the chief reptile groups represented in deserts are snakes and
lizards, tortoises also occur. Their thick shells reduce water loss
greatly as well as affording protection, and their lugubrious movement
means that panting, which gets rid of water vapor from the lungs,
occurs only exceptionally. In Africa the leopard tortoise (Geochelone
pardalis), with its high-domed sporting biotches that resemble a
leopard’s spots, dwells in savannas and on desert fringes. If the
ground is too hard, the female urinates on it so she can dig a hole for
her eggs. The African pancake tortoise (Malocochersus tornieri) has
an unusually shape, as its name suggests, and a highly flexible shell.
Instead of withdrawing into its shell when threatened, it runs—quite
fast—to a crack or crevice and inflates its body with air so that it
becomes wedged in and immovable. The gopher tortoise (Gopherus
potyphemus) of North America has wide, flattened, spadelike forefeet
to dig a burrow up to 14 meters (45 ft.) long. It basks and chomps by
day and hides by night in the chamber at the end of its tunnel, the way
blocked by its hard shell. The species of desert tortoise shown right,
eating the moist fruit of the prickly pear, is Gopherus “Xerobates”
agasszii, a tortoise found in the Sonoran Desert