Uromastyx (Spiny-Tailed Lizard)

Far from boring, Uromastyx lizards have a lot of unique features. They have large, spiky tails with which they protect themselves, as well as different colors and patterns guaranteed to catch anyone’s eye. Lizard keepers keen on exotic animals seek spiny-tailed lizards.

Facts

• Spiny-tailed lizards have nasal glands that remove salt from the salty desert plants that they eat and they “sneeze” clear fluid out which later dries as a white powder containing salt.
• Six species of spiny-tailed lizards are sold as pets in the United States.
• Spiny-tailed lizards are cold-blooded. They bask in the sun to increase their body temperature and cool off in their shaded burrows.
• Spiny-tailed lizards brumate, which is a form of hibernation during the winter cold.
• Unlike other types of lizards, spiny-tailed lizards do not have tail autotomy. This means that they cannot detach their tails as a defense mechanism.
• Spiny-tailed lizards have spiny tails as their name alludes. They use them as weapons. When threatened, they come out swinging, hissing, and baring their teeth.
• Another use of their spiny tails is that spiny-tailed lizards use them to block the entrance of their burrows to block predators off.
• Spiny-tailed lizard hatchlings eat their mother’s feces as their very first meal.

Scientific Name

Uromastyx is a genus that contains lizards from the family Agamidae which are located on the African and Asian continents. The name Uromastyx comes from the Ancient Greek words oura meaning “tail” and mastix meaning “whip,” alluding to the spiky tails possessed by all members of the Uromastyx species.

Spiny-tailed lizards, mastigures, or dabb lizards are common names for species that belong to Uromastyx.

Uromastyx contains 15 species of lizards. Some of the more common species are:

• Saharan spiny-tailed lizard (Uromastyx geyri). 
• Ornate mastigure (Uromastyx ornata). 
• Egyptian mastigure (Uromastyx aegyptia). 
• North African spiny-tailed lizard (Uromastyx acanthinura). 
• Ocellated spiny-tail (Uromastyx ocellata)
• South Arabian spiny-tail lizard (Uromastyx yemenensis)
• Thomas’s mastigure (Uromastyx thomasi)

Appearance

The species of the genus Uromastyx are homogeneous when it comes to their physical characteristics. They all have rounded heads and big, spiky tails. The main difference between the Uromastyx species is in their color patterns.

For example, the north African spiny-tailed lizard typically has a brighter base color, such as orange, green, yellow, or red. It is bespeckled with dark brown or gray spots. As one of the more brilliantly designed members of the genus, it should make for easy identification. However, sometimes, the North African spiny-tail does have duller base colors such as brown or gray which may cause further difficulty in distinguishing them.

For some Uromastyx species, the males have a more vivid color than the females. The males may be blue, green, or red, while the females are usually duller, with grays and browns.

The lizards’ colors fluctuate with the temperature and seasons. During colder weather, they tend to get darker and their colors may fade slightly, but during warmer weather, they get lighter. This is so that they can absorb sunlight easier while basking.

True to their name, the spiny-tailed lizards have a large, powerful tails covered in spikes. They use this tail as a defensive weapon and lash it at enemies at high velocity.

The sizes of the adult Uromastyx species range from 10 inches in length to over 36 inches. Newborn lizards, or hatchlings, average around three to four inches long. The largest Uromastyx species is the Egyptian spiny-tail lizard which grows over 36 inches in length.

Evolution and History

Spiny-tailed lizards are agamids from the Asian and African lizard family Agamidae. The oldest known agamid is called Protodraco, whose fossil was found embedded in a piece of Burmese amber in Myanmar, dating all the way back to the mid-Cretaceous era about 99 million years ago.

Uromastyx species primarily live in desert regions with very little water supply so they rely on their vegetative diet to get their water needs. Because the soil in desert regions has a high concentration of salt, a lot of plants that grow there absorb it and their leaves tend to be salty. As largely herbivorous animals, the spiny-tailed lizards have found a way around this. Their nostril glands have evolved to remove the salt content without reducing the amount of water they ingest. The infamous spiky tail of this lizard genus is a defense mechanism to protect themselves against predators.

Behavior

Uromastyx lizards live in burrows, usually underneath bushes or shrubbery, or in the ground. They also find shelter in rock crevices and shield the entrance with their spiny tails to ward off predators. These burrows also serve as hiding places from predators. Spiny-tailed lizards like to live in hilly regions with enough large rocks and abundant vegetation so that they do not have to stray too far from home to find food.

Uromastyx lizards are cold-blooded, which means that they rely on their environment to regulate their body temperature. They nest in their burrows to keep cool and bask in the sun to elevate their temperature. After basking, spiny-tailed go on to feed on desert vegetation. Spiny-tailed lizards typically brumate in the winter when the weather does not rise above 70 degrees Fahrenheit. Brumation is a form of hibernation for cold-blooded animals such as reptiles who are unable to raise their body temperatures during cold weather.

Uromastyx species are territorial, particularly to members of the same sex. Male lizards guard their territory from other males. Female spiny-tails do the same thing to other females and males too. These lizards are also diurnal, which means they are most active during the day and sleep at night.

The spiny-tailed lizard’s defense system consists of its powerful, spiky tail and sharp teeth. They swing their tails out at the enemy, hiss at them, and show their teeth. They can also inflict a very painful bite. Spiny-tailed lizards should never be grasped by their tails as they do not have tail autotomy (the ability to detach their tail).

Spiny-tailed lizards are usually even-tempered creatures. While they are captured from the wild and sold as pets, some biologists advise against this because they are important to their natural ecosystem.

Diet

One might think that, being reptiles, the spiny-tailed lizard’s diet consists mostly of flesh, but that assumption couldn’t be more wrong. Surprisingly for many, the species of Uromastyx are mostly herbivorous. They mostly feast on surrounding vegetation in their wild habitats. This includes wild spinach and saltbush plants. They only occasionally eat insects like ants and beetles, and smaller animals such as other lizards. Like most other lizards, spiny-tailed lizards get most of their daily moisture requirements from the food they ingest.

Spiny-tailed lizards in captivity get fed a host of plants like ground vegetables, dried lentils, leafy greens, grasses, and dandelion greens. Their food should also be brushed with calcium supplement powder.

A weird fact about spiny-tailed lizards is that as hatchlings, their first meal is actually their mother’s feces. They gobble it right up before moving on to search for actual food.

Habitat and Population

Uromastyx are native to the African and Asian continents. They have a wide range that extends from mostly northern Africa to the Middle East. The spiny-tailed lizards occupy countries such as Morocco, Sudan, Mali, Niger, Tunisia, Egypt, Algeria, Israel, Saudi Arabia, Oman, Iraq, Iran, Syria, and Jordan.

Spiny-tailed lizards primarily inhabit desert regions, especially regions with rocky zones where they can burrow for shade. They seldom occupy open desert zones. These lizards are able to dig their own burrows if they live in areas with lush, pliable soil. If not, they make shelter under bushes or within crevices and cavities in rocks. Spiny-tailed lizards typically live in altitudes ranging from sea level to more than 3,000 feet.

Several Uromastyx species are listed as Near Threatened or Vulnerable on the IUCN Red List of Threatened Species, while others are listed as Least Concern.

Reproduction and Lifespan

The sexual dysmorphia in some Uromastyx species is very apparent. Female Uromastyx lizards are smaller than the males and they are duller in appearance while the males come in brilliant colors. Mating season for some species typically starts in March and runs through to July.

When a female is ready to breed, her aggressiveness towards other lizards of both sexes will heighten and she will not allow them into her burrow.

Depending on their ages and species, female Uromastyx usually lay about 5 to 40 eggs per litter about a month after mating. These eggs are incubated for 70 to 80 days before hatching into two- to four-inch-long baby lizards. The hatchlings weigh around 0.14 to 0.16 ounces and start growing immediately for the next few weeks. For a lot of other lizard species, the sex of the hatchlings is determined by the temperature they are incubated in. However, breeders of Uromastyx have noted that temperature isn’t a factor in sex determination for these lizards. It is believed to be determined by genetic factors instead.

The hatchlings’ first meal is their mother’s feces, after which, they move on to find food. Young lizards tend to prefer eating insects more than the adults. Uromastyx species stay in their mother’s burrow for the next few weeks up to a few months after hatching. They usually reach adulthood in three to four years of age, and up to nine years in some species.

Female Uromastyx normally birth just one litter per year.

In some lizards, the sex of offspring is dependent on incubation temperatures. Breeders of Uromastyx, though, have reportedly produced both sexes at a range of temperatures. So, it is possible that genetics determine sex in this genus.

Spiny-tailed lizards in captivity can live from 15 to 35 years, and possibly even longer.

Predators and Threats

Uromastyx species are preyed upon by much larger reptiles, raptors, carnivorous mammals such as wolves and dogs, and birds of prey in the wild. They are also frequently captured and sold as food by local people.

Several species of spiny-tailed lizards are eaten as delicacies in their native regions. Some are captured and sold off as pets or killed for their hide, while others are used for traditional medicine.

Several species of Uromastyx are considered vulnerable or near-threatened by the IUCN. Conservation efforts include legislative action and trade control and regulation.

Related Animals…

• Iguana
• Skink Lizard
• Sand Lizard