Reptiles are cold-blooded, which means that unlike mammals, they cannot regulate and maintain a constant body temperature. This is perhaps the main reason that a limited number of reptiles are found in the limits of the Grand Teton National Park which has a cold and dry climate. Most reptiles have dry, flaky skin and they can both live on water and ground. Reptiles reproduce by laying eggs or in some cases, bearing live young. They constantly need to move in and out of the sunlight to regulate their body temperatures.

Four species of reptiles are found in the Grand Teton – three snakes including the most frequently seen Wandering Garter Snake (Scientific name: Thamnophis elegans vagrans) and the lesser common Valley Garter Snake (Scientific name: Thamnophis sirtalis fitchi) and Rubber Boa (Scientific name: Charina bottae). All of these live near water and none of these are venomous. The Northern Sagebrush Lizard (Scientific name: Sceloporus graciosus graciosus) is the only lizard species found in the dry, flatter areas of the region and was first discovered within the park boundaries in the year 1922. The knowledge of reptiles inhabiting the Grand Teton is limited and further research and study is being done by experts to discover more species in the area. Chances are that the Great Basin Gopher Snake (Scientific name: Pituophis catenifer deserticola) may also be found in the Grand Teton.