Pronghorns are native to North America. They are considered the second fastest land mammal after the cheetah, and can run at speeds up to 55mph. Unlike deer antlers which are shed annually, pronghorn horns are permanent. Pronghorns have a special arterial network inside their skulls that is used to keep their brains cooler than their bodies. This cooling adaptation allows pronghorns to conserve water in dry environments. In fact, pronghorns may be able to cut their daily water use in half through this system. This allows them to survive with very little access to drinking water, instead taking their water directly from the plants they eat.