Sweating and panting both cost water, which is the scarce resource in the Kalahari and Namib. Oryx take the alternative route of heterothermy: body temperature is permitted to drift upward through the day, sometimes by several degrees, and the accumulated heat is dumped by radiation and convection once the air cools after dark. Water that would have gone into evaporative cooling is retained.
A rising core temperature is dangerous for the brain, and oryx have a carotid rete, a network in which arterial blood bound for the brain runs alongside venous blood cooled in the nasal passages. Heat passes from artery to vein, so brain temperature can be held below body temperature. Early laboratory work on this system reported body temperatures above forty-five degrees Celsius, though field-measured values under natural conditions are generally lower.
Behaviour completes the picture. Gemsbok feed at night and in the early morning when grass moisture is highest, dig for roots and bulbs, take tsamma melons, and orient the body to present the least surface area to the sun.