Gopher tortoises are mainly
herbivores that feed on low growing plant life. Their diet consists mostly of
grasses and
legumes but they will also feed on small
berries and
fruits. The diet of tortoises contain excess salt, sodium, chloride, and potassium that must be purged from the body, and drinking free standing water, even if only once or a few times each year, is essential for this function and for tortoise survival. Opportunities for gopher tortoises to drink water vary greatly between the species in the genus.
Gopherus agassizii live in extremely arid areas that can receive as little as 10–20 cm. per year.
Gopherus polyphemus live in
mesic habitat, where water is available and evaporative loss is less problematic. Other species live in intermediate environments where a few weeks of rain typically occur twice per year, or where relatively consistent summer rains occur. When pools of rain water or saturated soils are available tortoises will direct their heads face down and submerge their face to a level just below the eyes and drink copiously. Reptiles modify urine and plasma concentrations in their bodies with their bladder, cloaca, and colon, rather than the kidneys. The bladder plays a major function in regulating blood osmolality: permeable to ammonia, urea, water, and small ions, but not uric acid. This permeability allows tortoises that are hibernating, or living in arid environments without drinking water for months at a time to store uric acid, but resorb water from the bladder. Tortoises react to dry periods by retreating to shelters (burrows, caves etc.) with more humid
microhabitats, and remaining inactive. Gopher tortoises can survive a year of drought through both behavior and physiological adaptations, two years of drought can result in deteriorating body conditions, and extended years of drought will produce high mortalities of gopher tortoises. There are many observations of
Gopherus eating non-vegetation food items. Documented examples include a variety of bones, snail shells, soil at mineral licks, charcoal, sand, stones, human trash, carrion, raptor pellets and various animals feces.
Gopherus polyphemus studies observed specimens moving bones into their burrows and found the fourth most common matter in their scats was insect material. The exact reasons are not entirely understood, some cases might simply be due to accidentally ingesting materials near food items or sampling potential foods. Hypotheses concerning the consumption of animal matter by
Gopherus include supplements for the low levels of calcium, phosphorus, or protein in their diet, and a need for
calcium carbonate in bones, the production of eggshells in females, and growing young. Hypotheses on the consumption of nonfood items such as soil or rocks include
mastication or
vermifuge for the removal of parasites. ==Conservation==