Uromastyx acanthinura

Geographic Range

Uromastyx acanthinura inhabits the Saharan desert from the Saharan Atlas (Morocco, Tunisia) to the Sudan and from Mauritania to Algeria and Egypt. It is widespread throughout North Africa as a whole. Being a territorial species inhabiting a relatively harsh and unproductive habitat, it is fairly thinly spread over the areas it does inhabit and population densities may be low.

• Biogeographic Regions
• palearctic palearctic
  • native native

Habitat

Uromastyx acanthinura occupies desert habitats, but specifically occupies rocky areas that can support its burrows. In the desert, its most common habitats are rocky or semi-rocky sandy areas and, rarely, open sandy desert. The burrows that this species builds are often beneath bushes or in high rocky cliffs. When living in softer-soiled habitats, this species can dig to make its burrows. It is still able to live in rockier areas by using natural cracks and openings in the rock face. In general, this lizard will make use of high cliffs and banks, the banks of dry rivers, or stabilized dunes. The elevation of its habitat can be anywhere from 1,000 to 2,000 meters. The temperature in the habitat of U. acanthinura can vary from -7 degrees Celsius to 60 degrees Celsius. However, this species is able to maintain a minimum body temperature of about 20 degrees C by seeking refuge in burrows. The burrows tend to stay within a temperature range of about 20 to 25 degrees Celsius. Humidity in this habitat can have a very wide range depending on the amount of rain, though rain is rare. Uromastyx acanthinura can therefore tolerate a fairly wide range of ambient humidity and much variation in the amounts of available water.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune

Physical Description

North African spiny-tailed lizards attain a maximum total body length of 40 to 43 cm and an adult mass of 450 g. These lizards have a dorsally flattened body and the tail, as the name would suggest, is large and covered with ringed spines. Individuals may exhibit wide variation in color as the scales of adults are at times either a mottled red, orange, green, or yellow, though the basic color is gray. Juvenile individuals are almost always gray and brown. Scale colors reach their greatest intensity at about four years of age, which coincides with reaching sexual maturity. The colors also change with stress level and body temperature.

Basal metabolic rate does not seem to have been researched directly for this species. However, metabolic rate has been researched in the closely related Uromastyx microlepsis . At the optimum temperature of U. acanthinura (104 degrees Fahrenheit) and for large lizards with an average body mass, the average basal metabolic rate is approximately 41 mL/hour of oxygen.

Several subspecies of Uromastyx acanthinura have been described, but are difficult to distinguish without locality data. Some authorities ignore subspecies designations or consider some of them separate species.

Uromastyx acanthinura is not notably sexual dimorphic. Both males and females can be either dull or brightly colored in this species though on average the males are generally more colorful than most females. Overall, males and females are about the same size though males tend to grow slightly faster than females before they reach maturity. Males can have a wider vent and tail base (where the hemipenes are), a proportionally larger head, and larger, darker femoral pores. None of these features are invariable.

Many Uromastyx species can be very easily confused. They all have the same blunt head and large, spiny tails. Many also might have similar intricate patterns. Seemingly the best way to tell species apart is to observe the color patterns on the lizards. Uromastyx acanthinura usually has a bright background color such as red, orange, yellow, or green. This is then overlaid with a series of elongated, curling dark brown or gray spots. These spots become much denser on the neck of this species. Since most other species are not as brightly colored as U. acanthinura , the colors and the patterns should allow identification. This is made difficult by U. acanthinura sometimes having a basic gray or brown color, so caution is advisable.

• Other Physical Features
• heterothermic heterothermic

• Sexual Dimorphism
• sexes alike
• male more colorful

Development

The eggs of U. acanthinura have a lengthy incubation period and hatch after 8 to 10 weeks. Uromastyx acanthinura does not complete metamorphosis. The newly hatched young will often stay within the burrow for a few weeks to a few months before they will set out on their own. Newly hatched neonates are about 5 cm long when measured from the snout to vent (not including the tail), and they weigh 4 to 6 grams. The bright colors of this species will usually begin to show at about one year of age though they tend to become brightest at sexual maturity around three years later. Uromastyx acanthinura generally reaches full size at 8 to 9 years old.

In some lizards, the sex of offspring is dependent on incubation temperatures, but breeders of Uromastyx have reportedly produced both sexes at a range of temperatures so it is possible that sex is genetically determined in this species.

Reproduction

During the breeding season, Uromastyx acanthinura females tend to become particularly aggressive to burrow intruders of both sexes. When a male courts a female, he will often shake his head from side to side and make push-up motions. Once he has finally gotten close enough, the male will use his mouth to hold the female firmly by either her sides or her neck and proceed to copulate. There is little information on mating systems for this lizard and further research is needed.

Uromastyx acanthinura generally mate in April and eggs are usually laid one month after fertilization occurs. The typical mating season lasts from March to July. It is likely that this species breeds once per year. The eggs are elliptical in shape and have leathery shells. The clutch size is usually 6 to 23 eggs. The eggs take about 8 to 12 weeks to hatch, and the newly hatched lizards weigh between 4 and 6 g. The young will typically remain in their mother's burrow for another few weeks to a few months. Juvenile Uromastyx acanthinura become sexually mature at about 4 years of age.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
• oviparous oviparous

Post-oviposition parental investment in North African spiny-tailed lizards consists of the attendance and guarding of the nest by the female. Males have no parental investment beyond fertilizing the eggs. The eggs are laid in the female's burrow, and the increased aggression the females exhibit around the breeding season is attributed to guarding behavior. The female guards the eggs at least for the 8 to 12 weeks it takes for the eggs to hatch. However, it is not clear whether or not the female remains to guard the neonates during their post-hatching period in the burrow. Since Uromastyx acanthinura is a solitary and territorial species, young lizards are very likely completely independent upon leaving the burrow and must establish their own territories. It is also likely that the mother retains her own burrow.

• Parental Investment
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • female

Lifespan/Longevity

There is little information regarding the lifespan of North African spiny-tailed lizards. There is evidence that lizards in captivity have lived up to 20 years when caught in the wild. These captured individuals were sexually mature adults, thus it is reasonable to assume they would have been at least 4 or 5 years old when captured.

The presence of parasites has been recorded in this species. Therefore, parasitism and predation are likely two factors affecting life span.

Behavior

This species is often very aggressive against other members of its own species. Individuals fiercely defend territory against intruders. In captivity, even siblings hatched from the same clutch of eggs will attack one another if housed together for too long. In fights, this species tends to bite the sides of its opponents. This can leave white, colorless scar tissue in those areas.

Uromastyx acanthinura is a diurnal species, meaning it is only active during the day. They are often found basking when the temperature outside of their burrow is anywhere from 18 to 28 degrees Celsius. This species hibernates during the winter for two to five months, and will aestivate during summer months when there are drought-like conditions.

• Key Behaviors
• fossorial fossorial
• diurnal diurnal
• sedentary sedentary
• hibernation hibernation
• aestivation
• solitary solitary
• territorial territorial

Home Range

This species is highly territorial and solitary. The territory of each individual can extend from 10,000 to 50,000 meters squared. This species does live in discrete populations as well however. Populations can consist of anywhere from 10 to 100 individuals living in one square kilometer. The lizards are quite sedentary. They only ever move significantly when traveling from food plant to food plant, and usually stay within the bounds of their territory. This is thought to be behavior designed to avoid predation.

Communication and Perception

Little information exists on communication between individuals in this species. Courtship involves visual displays of head swinging and push-ups. Males also use secretions from their femoral and anal glands to mark their territories upon reaching sexual maturity.

This species likely perceives its environment predominantly with sight, based on its reliance on visual cues in courtship. It may also use tactile cues in locating preferred soil types for burrowing. There is also evidence that at least some species of the Uromastyx genus use chemical cues to find mates and the food they prefer. Studies have shown individuals prefer tiles lacking visual cues for food but smeared with favorite food items. However, studies with this specific species would be necessary to confirm that this is the case for U. acanthinura .

• Communication Channels
• visual visual
• tactile tactile
• chemical chemical

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

North African spiny tailed lizards are primarily herbivorous lizards. However, they also will consume ants (family Hymenoptera) and beetles (family Tenebrionidae). Young lizards are more willing to consume insects. Most of the desert plants it eats are highly fibrous. It is known that other Uromastyx species make use of microbial digestion and a complex digestive tract that maximizes surface area to absorb as much nutrients possible.

One of the primary food sources is plants of the genus Chenopodium which includes fat hens ( Chenopodium album ) and some types of spinach. They also commonly eat plants of the salt tolerant genus Atriplex . Since the soil in deserts tends to have a high salt content, many plants tend to also have high salt concentrations in their leaves. As a result this species has glands in its nostrils used for eliminating extra salt without eliminating water.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • frugivore frugivore

• Animal Foods
• insects

• Plant Foods
• leaves
• seeds, grains, and nuts
• fruit
• flowers

Predation

Specific predators for this species are not well known. In a closely related species, Uromastyx aegyptius , adults are often predated by raptors, wolves, and dogs. Juvenile Uromastyx aegyptius are more easily preyed upon and are often attacked by monitor lizards (genus Varanus ), shrikes (Laniidae family), and snakes.

Adults of this species will immediately hide in burrows when approached by a predator or curious human. Uromastyx acanthinura builds burrows that can be upwards from 4 meters deep in which they hide as soon as a perceived threat approaches. The burrows can also have multiple entrances and exits that are used to confuse and escape predators. If attacked while in the burrow, these lizards use their powerful limbs to cling tightly to burrow walls to avoid being dragged out. If attacked outside of the burrow, they are not hesitant in using their large spiny tails to defend themselves.

Juveniles do not build burrows, but instead tend to reside under stones or other shallow shelters. If approached, their first strategy is to freeze in place. Only after a few moments have passed will they seek shelter. Juvenile lizards likely suffer higher mortality rates because of this behavior.

Ecosystem Roles

This species acts as prey to many birds, snakes, wolves, and monitor lizards and thus these supports local populations. Uromastyx acanthinura also acts as host to several types of internal parasites including roundworms, pinworms, tapeworms, and protozoan. The nematode species Foleyella candezei has been found in the liver or under the skin of these lizards, especially in individuals living in Algeria. External parasites include various mites and ticks. Since U. acanthinura is an herbivore, it may assist in spreading the seeds of the plants it eats.

The burrowing activities of this species may also impact its ecosystem. It has been confirmed for the related species U. aegyptius that other organisms may take up residence in its burrows such as insects and snakes. Since U. acanthinura also engages in burrowing in areas that are populated by snakes and insects, the same benefit to other organisms can occur with the burrows of this species. Also, the soil in deserts is often high in salt. When burrows are dug deep underground, it can bring soil with lower salt content to the surface. This can benefit plants growing around the burrows that have lower salt tolerances.

• Ecosystem Impact
• creates habitat

Economic Importance for Humans: Positive

One benefit these animals offer to humans is through the pet trade. Their bright colors make them a desirable pet species. Uromastyx acanthinura has been traded internationally in the past and was at one time the highest traded Uromastyx species. Captive breeding has now reduced the market for wild-caught animals.

There is also exploitation of these lizards for food and medicine. Though they are listed as Near Threatened in the IUCN red list, local native people have likely eaten and used them for medicine for many years, so illegal trapping is unlikely to stop anytime soon. This species is also sold as souvenirs or live. Live specimens are apparently sold frequently by children along roadsides at only the equivalent of $1.75 to $4.70. Certain herbalists and traditional healers in the southern part of its range use this species in medicine. There do not seem to be any studies available indicating any true medicinal use of this lizard, so this use is most likely based on culture. There are also some native tribes that use the skin of this species for holding liquid, and it is apparently often used as a baby bottle.

• Positive Impacts
• pet trade pet trade
• food food
• source of medicine or drug source of medicine or drug

Economic Importance for Humans: Negative

There are no true negative effects on humans caused by this species.

Conservation Status

The international trade of Uromastyx acanthinura is currently regulated by CITIES and is listed with all other Uromastyx species in Appendix II. Successful trade regulation is difficult to enforce as many can be sold through underground markets. This species is often misidentified, therefore making regulation increasingly difficult.

Additional threats to this species includes agricultural grazing on plants that U. acanthinura commonly eats which creates competition for resources. More important factors that threaten its survival tend to come from humans through the pet trade and trapping for food and medicine. Road mortality is of great concern as the heat-absorbing roads are an attractive basking spot for these lizards.

This species has not been evaluated by the IUCN.

Other Comments

More studies of this and related species in the wild are needed to better define ecological niches and assist conservation efforts.

Additional Links

Encyclopedia of Life

Contributors

Megan Climans (author), Michigan State University, James Harding (editor), Michigan State University, Rachelle Sterling (editor), Special Projects.

References

Bartlett, R. 2003. Spiny-tailed Agamids: Uromastyx and Xenagama . Hauppauge, New York: Barron's Educational Series, Inc..

Cooper, W., A. Al-johany. 2002. Chemosensory responses to foods by an herbivorous acrodont lizard, Uromastyx aegyptius. Journal of Ethology , 20: 95-100.

Foley, W., A. Bouskila, A. Shkolnik, I. Choshniak. 1992. Microbial digestion in the herbivorous lizard Uromastyx aegyptius (Agamidae). Journal of Zoology , 226: 387-398.

Gray, R. 2001. "The Natural history, husbandry and captive propogation of the Moroccan spiny-tailed lizard (Uromastyx Acanthinurus)" (On-line). Accessed December 07, 2010 at http://www.kingsnake.com/uromastyx/caresheets/MOROCCON1.htm .

Highfield, A., T. Slimani. 2010. "The spiny-tailed lizard at home - Uromastyx acanthinurus in southern Morocco" (On-line). Tortoise Trust. Accessed December 07, 2010 at http://www.tortoisetrust.org/articles/uromastyx.html .

Nemtzov, S. 2008. Uromastyx lizards in Israel. NDF Workshop Case Studies, WG 7 - Case Study 5: 1-22.

Yildirimhan, H., S. Goldberg, C. Bursey. 2006. Helminth Parasites of the Caucasian Agama, Laudakia caucasia, and the Roughtail Rock Agama, Laudakia stellio (Squamata: Agamidae), from Turkey. Comparitive Parasitology , 75/2: 257-262. Accessed December 09, 2010 at http://www.bioone.org/doi/abs/10.1654/4205.1 .

Zari, T. 1991. The influence of body mass and temperature on the standard metabolic rate of the herbivorous desert lizard, Uromastyx Microlepsis. Journal of Thermal Biology , 16/3: 129-133.

TRAFFIC Europe. An assessment of the international trade in Spiny-Tailed Lizards Uromastyx with a focus on the role of the European Union. AC20 Inf. 13. Online: Convention on International Trade in Endangered Species. 2004. Accessed December 09, 2010 at http://www.cites.org/common/com/ac/20/E20-inf-13.pdf .

Convention on International Trade in Endangered Species. Uromastyx acanthinura. AC22 Doc. 10.2. Online: Convention on International Trade in Endangered Species. 2006. Accessed December 07, 2010 at http://www.cites.org/eng/com/ac/22/E22-10-2.pdf .