Desert
Think hot and dry. Sandy, rocky soil. Cacti, shrub and small trees. Mountains and mesas. It’s not difficult to picture the features of deserts, which cover about one-fifth of the earth’s surface. Most of us are familiar with them from the hundreds of times they’ve been depicted in movies like American westerns and African adventures.

It’s quite possible you’ve visited or driven across the Chihuahuan Desert, which runs through parts of Arizona, New Mexico, Texas and north-central Mexico. Sometimes what little rain the desert gets (less than 10 inches a year) evaporates before it hits the ground. No wonder most animals come out only at night, when the temperature drops into the 40s from less-blistering afternoon highs well in excess of 100 degrees.

The animals you are most likely to see in the desert are non-mammalian vertebrates, such as reptiles and birds. Mammals are usually small, like North American kangaroo mice.

One denizen of the desert, the Texas tortoise (Gopherus berlandieri), has been around for some 10 million years. While it managed to survive on its own most of that time, in 1977 it was given protected status because of a severe decline in number due largely to exploitation by pet suppliers. Texas tortoises are forbidden from being taken from the desert, possessed, transported, exported, sold or offered for sale.

“The zoo’s only Texas tortoise, Nagodoches, came here in January 1995,” says Area Supervisor Lisa Scanlon. “It was confiscated from a pet-shop owner by U.S. Fish & Wildlife Services. “He was full grown when we got him, so it’s difficult to tell his age. Tortoises can live to be 50 or 60 years old.” Nagodoches is part of the zoo’s program-animals population, a variety of species taken on visits to schools and adult-care centers.

There are only a few species of tortoise in North America. The Texas brand is distinguished by its yellowish-orange horned scutes (plates) on the carapace (upper shell) and the elongated, notched gular (throat) scute on the plastron (lower shell). The hind legs are cylindrical and columnar with flat feet, like those of an elephant. The front legs are flipperlike and when drawn in to the shell form a nearly impenetrable armor.

Halfway around the world in the African desert is the naked mole rat (Heterocephalus glaber), which lives underground in colonies of 20 to 300 individuals that are ruled by queens. They have no eyes, just vestigial eye openings, so they are blind, depending on their sense of smell to find food. “They live mostly in Ethiopia, Somalia and Kenya,” says Dan Boehm, area supervisor at the Regenstein Small Mammal-Reptile House. “We have 39 naked mole rats here, in two colonies, one on-exhibit and one off. Since their native habitat is the desert, we try to keep the temperature of their exhibit at a constant 84 degrees. In the wild, the elaborate tunnels they excavate can cover an area the size of a football field.

“It’s the only species of mammal that is a true colony, with a single queen, and all the other members being soldiers or workers, similar to bee and ant colonies.”

Naked mole rats (so named because they have very little hair, except for bristly sprouts around the mouth that keep out dirt as they chew and dig tunnels) spend virtually their entire lives underground. They would be susceptible to sunburn if they emerged from their tunnels for any length of time. What water they need they get from the roots and tubers they eat.

In their exhibit at the zoo, the naked mole rats move about a series of dim chambers connected by tunnels. “The exhibit is located directly beneath the dwarf mongooses,” says Boehm, “so some people mistakenly think the naked mole rats are baby mongooses.”