"A rock garden. Despite the great variety of living things to be found here, most of the surface of the land, at least three-quarters of it, is sand or sandstone, naked, monolithic, austere and unadorned as the sculpture of the moon. It is undoubtedly a desert place, clean, pure."

— Edward Abbey, Desert Solitaire

The lack of water that keeps Arches "monolithic, austere and unadorned" has a profound effect on the animal population. Like plants, animals must cope with the heat, cold and aridity of this environment. Most land animals avoid the heat of the day by remaining sheltered until evening. That is when they venture out in search of food.

More than 200 species of vertebrates and hundreds of invertebrate species live within the boundaries of the park. The desert cottontail, white-tailed antelope squirrel, mule deer, jay, raven, mourning dove, golden eagle, side-blotched lizard and plateau lizard are animals that are commonly seen in the park. 

Less often spotted are the foot-long collared lizard (the largest lizard in the park and an aggressive daytime predator) and the long-nosed leopard lizard. Also occa-sionally found is the highly poisonous, but extremely shy, midget faded rattlesnake, which rarely grows to more than two feet in length. More frequently seen is the gopher snake, which may exceed four feet in length. 

Unlike mammals or birds, reptiles must find and absorb warmth in order to remain active enough to search for food at night. That is why the gopher snake can be seen frequently in the evenings, lying on the roadways, absorbing the heat of the day that has been trapped in the blacktop.

The larger mammals in the park include the coyote, gray fox and mule deer. Bighorn sheep, once native to the park, were wiped out in the early 20th century. They were reintroduced to Arches in 1985 and 1986, and appear to be thriving.

As with the animal kingdom, the diversity of plant life at Arches is impressive, but not obvious. The rare biscuitroot grows in only a few locations in Arches and nearby Canyonlands. It is found in the loose, sandy areas near Sand Dune Arch, in Fiery Furnace and in a few locations in Devils Garden.