Angleheads, calotes, dragon lizards, and relatives

(Agamidae)

Class Reptilia

Order Squamata

Suborder Sauria

Family Agamidae

Thumbnail description
Small to large lizards

Size
1.6–13.8 in (40–350 mm) in snout-vent length

Number of genera, species
52 genera; about 420 species

Habitat
Versatile

Conservation status
Endangered: 2 species; Vulnerable: 1 species; Data Deficient: 2 species

Distribution
Europe, Africa, Asia, and Australia

Evolution and systematics

Agamids are derived descendents of ancestors of New World Iguanidae. They are Old World ecological counterparts of iguanids, with numerous highly convergent ecological equivalents, such as Phrynosoma and Moloch, Hydrosaurus and Basiliscus, Ctenosaura and Uromastyx, Pogona and Agama, and Corytophanes and Acanthosaura. A unique shared derived feature that ties Agamidae to Chamaeleonidae (chameleons are derived from within agamids) is acrodont dentition, in which teeth are fused to the top of the jawbones and are not replaced after they are formed. As a lizard grows, new teeth are added posteriorly. Agamids also have caniform (sometimes fanglike) pleurodont teeth set in sockets anteriorly, which are replaced continuously. Two subfamilies are recognized:

Agaminae

These are small to large terrestrial and arboreal lizards distributed in Africa, Asia, and Australia. There are 50 genera with more than 400 species.

Leiolepidinae

These are medium to large terrestrial lizards found in northern Africa east to Southeast Asia. There are two genera with 21 species.

Physical characteristics

Agamids range from commonplace to bizarre to spectacular. They are small, medium, and large diurnal terrestrial

lizards. (Some are arboreal or saxicolous.) None is fossorial. All agamids have movable eyelids, and all have legs. Scales are irregularly shaped and are rough, spiny, or keeled in many but not all species. Enlarged scales are scattered across the dorsal surface in many species, and some have dorsal crests of enlarged scales along their spines. Tails do not regenerate. Many agamids possess intrascalar pores. Head scales are usually smooth and are seldom enlarged. The external ear opening and tympanic membrane is conspicuous in most agamids (with the exception of some Australian Tympanocryptis and Indian and Sri Lankan Otocryptis). Many agamids exhibit striking sexual dimorphism in body size as well as dichromatism (sexual dimorphism in color patterns).

Distribution

Agamids are found in Europe, Africa, Asia, throughout Southeast Asia, including Indonesia and the Philippines, New Guinea, the Solomon Islands, and Australia. On Madagascar, they are replaced by oplurines.

Habitat

Agamids thrive in both sandy and rocky deserts. They also occur in savannas and in thornscrub and dry forest habitats.

Behavior

The low-energy, sedentary lifestyle of agamids allows them to get by on small amounts of food. Agamids rely on camouflage to escape the attention of potential predators.

Feeding ecology and diet

Agamids are visual, sit-and-wait, ambush predators, and, as a consequence, they encounter only relatively mobile prey. Most are insectivorous, but a few eat plants. Except for the few herbivorous species, agamids take prey items into their mouths using their sticky tongues.

Reproductive biology

Males of most species are territorial, defending a space that includes the home ranges or territories of several females. Under such "resource defense polygyny," a male mates with most females residing within his territory. Males typically engage in territorial displays with other males, either head bobbing or using an extendable dewlap.

All agamids lay eggs, except for a few species of high-latitude northern Eurasian Phrynocephalus, which are live-bearers. (Cophotis may also be a live-bearer, but this has not been confirmed.) Small species have small clutch sizes, but some larger species lay more than a dozen eggs. Some agamids lay several clutches of eggs during a growing season.

Conservation status

Most agamids are not threatened. The IUCN lists only five species as being in trouble: two are Endangered, one is Vulnerable, and two are listed as Data Deficient. Both the endangered species (Calotes liocephalus and Ceratophora tennentii) are endemic to Sri Lanka. Several other Sri Lankan endemic agamid species have suffered habitat loss.

Significance to humans

Agamids are major insectivores in many different habitats. Some species are kept as pets in terraria, and others are eaten by humans.

Species accounts

List of Species

Spiny agama

Agama hispida

subfamily

Agaminae

taxonomy

Agama hispida Bocage, 1896, Angola. Two subspecies are recognized.

other common names

English: Desert agama, ground agama.

physical characteristics

Spiny agamas are medium-size, usually terrestrial lizards; however, they do climb up perches, such as fence posts. Males have a blue head, a bright red nape, and yellow shoulders. Females are drab, with orange, brown, and cream splotches. These lizards possess two fanglike canine teeth large enough to draw blood, which probably are used to pierce the hard elytra of beetle prey.

distribution

The species occurs in western Cape Horn and adjacent regions of southern Africa, including most of the Namib and Kalahari Deserts in Namibia, South Africa, and southern Botswana.

habitat

They inhabit interdunal streets in arid semidesert, open sandy veld, salt pans, and coastal sand dunes.

behavior

These lizards dig short tunnels at the base of bushes. They do not live in colonies but are solitary.

feeding ecology and diet

Spiny agamas are sit-and-wait ambush predators. Their diet consists mostly of ants, beetles, and termites. Small amounts of plant foods also are eaten

reproductive biology

During the breeding season males are colorful, with blue heads, bright red napes, and yellow shoulders. Males defend territories and mate with several females that reside inside the territory. Females lay large numbers of fairly small eggs. The average size of 45 clutches was reported as 13.4 eggs.

conservation status

Not threatened.

significance to humans

Local myth has it that spiny agamas climb trees or posts to scan the horizon for rain. Locals also warn that these lizards are venomous, saying that agamas do not make their own poison but rather obtain venom by "milking" cobras. When questioned further, Afrikaaners explain that the lizards are often seen with their heads inside a cobra's mouth, extracting cobra venom. Of course, a more likely and simpler alternative explanation for such an observation is simply that cobras eat these lizards!

Brown garden lizard

Calotes versicolor

subfamily

Agaminae

taxonomy

Calotes versicolor Daudin, 1802, Pondicherry, India.

other common names

English: Beauty lizard, bloodsucker, Indian garden lizard.

physical characteristics

The brown garden lizard is a medium-size, brownish lizard with a laterally flattened body and a crest of scales on the neck and partway down the back.

distribution

The species occurs from eastern Iran to southern China and south to the Maldives and Sumatra.

habitat

They live in open habitats, such as light, sun-drenched forests.

behavior

Brown garden lizards are agile climbers and are adept at hiding behind branches. They follow humans and thrive in open parks and gardens and on date palms.

feeding ecology and diet

These sit-and-wait ambush predators feed largely on insects, but they also eat other, smaller lizards.

reproductive biology

Brown garden lizards sometimes are called "bloodsuckers," because males have bright red heads during the breeding season, just before the rainy season. They staunchly defend their territories against other males. They nod their heads and extend the gular pouch in a threat posture toward other males. Two males first watch each other from a distance and then suddenly walk straight toward each other. Fighting males stand erect on their hind legs and tails, grasping each other with their front legs and trying to bite their opponents. If one male does not back away, a serious biting fight ensues. Males court females using pushups and head-bobbing displays. Females lay from one to 25 eggs in the middle of the rainy season. Hatchlings mature at nine to 12 months.

conservation status

Not threatened.

significance to humans

These lizards have lived in close association with humans for centuries and are kept in captivity in terraria.

Leaf-horned agama

Ceratophora tennentii

subfamily

Agaminae

taxonomy

Ceratophora tennentii Gunther, 1861, Sri Lanka.

other common names

None known.

physical characteristics

These small, tropical, arboreal agamids have evolved unusual appendages on their snouts. (Ceratophora means "horn carrying.") Horns are larger in males than in females (in some other species, horns are entirely missing among females). The rostral appendage of the leaf-horned agama is covered with scales and shaped like a leaf, flattened from side to side and coming to a point.

distribution

This lizard inhabits the Knuckles Mountains, Sri Lanka.

habitat

The leaf-horned agama occurs in cloud forests between 2,950 ft (900 m) and 3,940 ft (1,200 m) in elevation.

behavior

These arboreal lizards live in forests, where they frequent the lower branches of trees. These slow-moving chameleon-like lizards rely on camouflage to evade enemies.

feeding ecology and diet

These lizards are sit-and-wait ambush predators, eating insects that move past their perches. Occasionally, they jump down to the ground to catch an insect.

reproductive biology

Males expand an erectile sail-like crest on the back of the neck and back when displaying. The snout appendage probably also is used in sexual displays.

conservation status

The leaf-horned agama has lost much of its habitat to human encroachment and logging. They have a very small geographic range and now are officially listed as Endangered by the IUCN.

significance to humans

None known.

Frilled lizard

Chlamydosaurus kingii

subfamily

Agaminae

taxonomy

Chlamydosaurus kingii Gray, 1825, Port Nelson, northwestern coast of Australia.

other common names

English: Frill-necked lizard, cloaked lizard; Australian aboriginal dialect: Bemmung.

physical characteristics

These are large, pale or dark gray lizards. Juveniles sometimes are reddish.

distribution

The species occurs in all of tropical northern Australia, down the east coast as far as Brisbane, Queensland. Cogger (1992) says that they are "extra-limital" in southern New Guinea.

habitat

The frilled lizard inhabits semihumid grassy woodlands. These arboreal lizards are seldom found very far from trees.

behavior

The species spends most of its time on tree trunks, descending to the ground after rain. When threatened, these lizards erect a large, reddish, fanlike frill around their necks. Two modified elongated hyoid bones form rods used to expand the frill. Like many long-legged lizards, frilled lizards can run bipedally.

feeding ecology and diet

This lizard feeds mostly on invertebrates but also on some small vertebrates.

reproductive biology

A clutch of 13 eggs has been recorded.

conservation status

The species is not threatened at present, but it may be devastated soon by introduced toxic cane toads.

significance to humans

Fire prevention signs along roads in the Northern Territory announce, "We like our lizards frilled, not grilled."

Central netted dragon

Ctenophorus inermis (sometimes called C. nuchalis)

subfamily

Agaminae

taxonomy

Ctenophorus inermis De Vis, 1884, Delta Station, Bogantungan, Queensland, Australia.

other common names

None known.

physical characteristics

These are medium-size yellowish brown terrestrial desert lizards with relatively short legs, a low crest along the top of the neck, a narrow vertebral stripe, and a blunt snout. Breeding males have orange to reddish heads and throats.

distribution

The species occurs in desert regions of central Australia.

habitat

They inhabit red sandy deserts with spinifex grass vegetation.

behavior

These lizards dig several shallow dead-end burrows near favored basking sites, to which they retreat when threatened. If disturbed in their burrows, they dash off and hide in another nearby burrow. Body temperatures correlate with ambient air temperatures, averaging about 96.8°F (36°C). When ambient air temperatures are high, the lizards climb up as high as 3.3 ft (1 m) above ground and face directly into the sun. Varanid monitor lizards prey upon central netted dragons.

feeding ecology and diet

These lizards are omnivorous. They eat such insects as ants, grasshoppers, beetles, and termites and are partially herbivorous, taking about 25% of their diet by volume in plant food.

reproductive biology

Males defend territories during the breeding season in the spring months. Clutch sizes range from two to six eggs, depending on the size of the female; the average is about four eggs.

conservation status

Not threatened.

significance to humans

None known.

Military dragon

Ctenophorus isolepis

subfamily

Agaminae

taxonomy

Ctenophorus isolepis Fisher, 1881, Nickol Bay, Western Australia. Three subspecies are recognized.

other common names

None known.

physical characteristics

These are small reddish or reddish brown terrestrial lizards with long hind legs. Males are more colorful than females,

with dark black patches on their sides and bellies. Males of the desert subspecies also have yellowish stripes on the sides of their heads and shoulders.

distribution

Military dragons occur in desert regions of central Australia.

habitat

The species inhabits red sand plain deserts with spinifex grass vegetation.

behavior

In the early morning, these lizards bask in the open sun, but as temperatures climb during midday, they position themselves in the dense shade offered by spinifex grass tussocks. Their active body temperature is about 100°F (37.8°C), but it is lower during winter months and higher in the summer. Lizards are active during midday in winter, but they are most active early and late in the day in the summer. When pursued, they make long, zigzag runs through the open between grass tussocks. If chased until they experience oxygen debt, they seek cover by trying to climb into spinifex tussocks, but their long legs impede their ability to move inside such grasses.

feeding ecology and diet

These sit-and-wait ambush predators feed mainly on ants, but they also eat grasshoppers, termites, beetles, and other insects.

reproductive biology

The military dragon has two clutches of three to four eggs per year, laid during spring and early summer. Hatchlings mature by the next year.

conservation status

Not threatened.

significance to humans

None known.

Flying lizard

Draco volans

subfamily

Agaminae

taxonomy

Draco volans Linnaeus, 1758, Java, Indonesia.

other common names

None known.

physical characteristics

These are slender, long-legged, small lizards with folding ribs that expand to form a winglike structure. At rest, these dermal sails are folded along the body, giving the lizards a slim appearance.

distribution

The species inhabits the Indonesian islands, including Borneo, Java, Sumatra, Sulawesi, and Timor. They also occur in Thailand, western Malaysia, and the Philippines.

habitat

Their habitat is open forests and dense rainforests of both lowlands and highlands.

behavior

With their "wings" extended, these long-tailed, lightly built agamids glide gracefully between trees, losing altitude along the way. When gliding, these delicate, slender lizards use their tails to steer and sometimes can travel as far as 55 yd (50 m). Expert hang gliders, they rise up and stall at exactly the right moment to make a gentle landing. Upon landing on an adjacent tree, with the head up, they scamper up the tree, gaining elevation in preparation for their next flight. When on the ground, flying lizards are clumsy and vulnerable to predators.

feeding ecology and diet

The species feeds almost exclusively on ants and termites.

reproductive biology

Wings of males and females are of different colors, which allows these lizards to identify the sex of another at a distance. Males defend territories, courting females by extending their brightly colored throat dewlap appendages, much like anoles do in the New World. Females lay one to four eggs. Their unusual eggs are elongated and spindle-shaped, with dense calcium carbonate "caps" at each end. The function of the caps has not been studied, but they could be deposits for developing embryos.

conservation status

Not threatened.

significance to humans

None known.

Sailfin lizard

Hydrosaurus amboinensis

subfamily

Agaminae

taxonomy

Hydrosaurus amboinensis Schlosser, 1768.

other common names

English: Soa soa.

physical characteristics

These are large, semiaquatic lizards with a pronounced crest on the neck and an enlarged sailfin down the back to the base of the tail. Both sexes have a black and dark green reticulated pattern.

distribution

The sailfin lizard occurs in Southeast Asian islands (Celebes, Moluccas, and New Guinea). Another population occurs in the Philippines.

habitat

This species is found in trees in the vicinity of water.

behavior

These lizards are expert swimmers and take refuge in the water. Using their fringed toes, juveniles can run across the surface of water. They spend most of their time in branches overhanging water.

feeding ecology and diet

These herbivorous lizards harbor intestinal endosymbiotic microbes that produce cellulases that aid in digestion of plant foods.

reproductive biology

Crests and sailfins of males are larger than those of females and may be used in courtship displays or in fighting with other males. Females lay three to nine eggs. Hatchlings are about 8 in (20 cm) long, about two-thirds of which is tail.

conservation status

Not listed by the IUCN. Owing to habitat loss and hunting, however, these lizards are now uncommon and could be threatened.

significance to humans

These large lizards are considered a delicacy.

Long-snouted dragon

Lophognathus longirostris

subfamily

Agaminae

taxonomy

Lophognathus longirostris Boulenger, 1883, Champion Bay, Western Australia.

other common names

English: Long-snouted lashtail.

physical characteristics

This species is a medium-size grayish lizard with a long snout and a very long tail, up to three times its snout-vent length,

which is used as a counterbalance in climbing. It has whitish stripes along the side.

distribution

The species occurs in central arid regions of Australia.

habitat

This lizard inhabits open savanna woodlands, riparian habitats, and red sandy deserts, usually associated with sand ridges in desert habitats.

behavior

These uncommon, large, agile, and fast agamids are never found very far from trees. They can attain speeds of 15 mph (24 km/h) running bipedally on their hind legs.

feeding ecology and diet

The species eats wasps, beetles, grasshoppers, mantids, hemipterans, and various insect larvae. Occasionally, they also eat some plant food.

reproductive biology

Seven clutches averaged 3.9 eggs. Little else is known about reproduction in this species.

conservation status

Not threatened.

significance to humans

None known.

Thorny devil

Moloch horridus

subfamily

Agaminae

taxonomy

Moloch horridus Gray, 1841, Western Australia.

other common names

English: Mountain devil.

physical characteristics

The thorny devil is a very spiny, moderately sized, reddish and yellowish lizard with a round body and a short tail, about 4–6 in (10–15 cm) long. Adult females are larger and stouter than adult males; they range from 3.1 to 4.3 in (80–110 mm) in snout-vent length and weigh 1.2–3.1 oz (33–88.7 g). Adult males are all less than 3.8 in (96 mm) in snout-vent length and never weigh more than 1.7 oz (49 g).

distribution

The species occurs in the southern section of the Northern Territory, the northern section of South Australia, and in Western Australia.

habitat

Thorny devils are found through most of arid inland Australia, particularly on sandy soils, but they seldom occur on stony soils. They prefer two quite different habitats: spinifex sandy plain and the sand ridge deserts of the interior and the mallee belt of southern South Australia and southwestern Western Australia. The geographic distribution of the species corresponds more closely to the distribution of sandy and sandy loam soils than to any climatological field.

behavior

Thorny devils display a bimodal seasonal pattern of activity. These lizards move little during the coldest winter months (June and July) or the hottest summer months (January and February). They are active for a three-month Austral autumnal period (March, April, and May) and a five-month period that spans late winter, spring, and early summer (August through December), during which mating and egg deposition take place. During hot summer days, thorny devils are inactive, retreating into shallow underground burrows that they dig for themselves.

These lizards posses a curious knoblike spiny appendage on the backs of their necks, which has been likened to a false head. When threatened, they tuck their real heads down between their forelegs, leaving this false head in the position of the real head. This makes them difficult for most predators to swallow. When disturbed, thorny devils also inflate themselves with air, puffing up like little puffer fish. They can also change color rapidly; when warm and active, they are usually a pale yellow and red. When they are alarmed or when they are cold, however, they turn dark olive drab.

feeding ecology and diet

Thorny devils are obligate ant specialists, eating virtually nothing else. They consume several species of ants but are especially partial to very small Iridomyrmex ants, especially Iridomyrmex flavipes. Large numbers of these tiny ants are eaten per meal by an individual thorny devil (estimates range from 675 to 2,500).

reproductive biology

Mating has been observed in the autumn, which suggests that thorny devils may have a mechanism of sperm storage. In contrast to the relatively sedentary summer to autumn existence, thorny devils move over much greater distances during August and September, when most mating takes place. Female thorny devils excavate nest chambers and lay clutches of eggs in September, October, and November. Eggs are laid from mid-September through late December. Only a single clutch is laid per year, and clutch size varies from three to 10, with a mode of eight eggs per clutch. Seven clutches had reported incubation times of 90–132 days.

Hatchlings emerge in January and February, weighing an average of 0.06 oz (1.8 g) and measuring 2.5–2.6 in (63–65 mm) in total length (snout to tail tip). Hatchlings may eat their own egg cases to obtain calcium and other materials to support early growth.

conservation status

Not threatened.

significance to humans

These lizards are interesting to biologists because they are independently evolved ecological equivalents of North American horned lizards and one of the best examples of convergent evolution.

Bearded dragon

Pogona minor

subfamily

Agaminae

taxonomy

Pogona minor Sternfeld, 1919, Hermannsburg, Northern Territory, Australia.

other common names

None known.

physical characteristics

The bearded dragon is a medium-size, grayish to dark gray lizard with splotches of cream.

distribution

It is distributed through the central deserts of Australia.

habitat

These lizards occur in a variety of habitats, including red sandy deserts and shrub acacia woodlands.

behavior

Bearded dragons are semiarboreal, often using perches as basking sites and vantage points. They have a distinctive throat pouch, which is extended in defensive displays, but they do not appear to defend territories.

feeding ecology and diet

These sit-and-wait ambush foragers prey on grasshoppers, beetles, termites, and insect larvae.

reproductive biology

The average clutch size of 73 females was reported as 7.6 eggs.

conservation status

Not threatened.

significance to humans

Bearded dragons are popular in the pet trade and often are kept and bred in captivity.

Earless dragon

Tympanocryptis cephalus

subfamily

Agaminae

taxonomy

Tympanocryptis cephalus Gunther, 1867, Nickol Bay, Western Australia.

other common names

None known.

physical characteristics

The earless dragon is a small, roundish lizard that mimics rocks. It may be gray or reddish. There is no external ear opening. Its head is rounded and bulbous, and its tail usually is obscurely banded.

distribution

The species is distributed in rocky, arid regions of the central portion of Western Australia and across the southern Northern Territory, with isolated populations in western Queensland.

habitat

Earless dragons are found in rocky habitats, such as the Gibber Desert.

behavior

This lizard mimics rocks, relying on camouflage to escape detection.

feeding ecology and diet

The species is an insectivorous sit-and-wait ambush predator.

reproductive biology

Nothing is known about its reproductive habits.

conservation status

Not threatened.

significance to humans

None known.

Butterfly agama

Leiolepis belliana

subfamily

Leiolepidinae

taxonomy

Leiolepis belliana Gray, 1827, Penang. Two subspecies are recognized.

other common names

None known.

physical characteristics

This is a dorsoventrally flattened, medium-size lizard with a round tail that is about twice as long as the snout-vent length. There are three yellow, dark-bordered dorsal stripes with yellowish ocelli scattered across the back and orange-red and black splotches along the sides. The long hind legs have light yellow speckling on the upper surface. The scientific name Leiolepis means "smooth scaled." The bodies of these lizards are covered with small, smooth body scales, although the scales on their tails are keeled.

distribution

The species occurs on the Malaysian peninsula and in Southeast Asia (Laos, Thailand, Vietnam, Burma [Myanmar], Sumatra, and Bangka Island) east to southern China (Hainan Island).

habitat

Butterfly agamas inhabit open coastal tropical areas with sandy soils.

behavior

These handsome, agile, active lizards dig deep burrows. They are reputed to live in colonies. They are active during midday at high temperatures. Their elongated ribs allow them to flatten their bodies; they are even reputed to be able to parachute and make gliding jumps, although this behavior requires confirmation. It may be related to the origin of their common name, butterfly agama.

feeding ecology and diet

Butterfly agamas feed on insects and small crabs in nature. They also eat some plant foods.

reproductive biology

Little is known about their reproductive biology, but they do lay eggs.

conservation status

Not threatened.

significance to humans

These lizards thrive in captivity in large terraria. In Bangkok, Thailand, the species is sold regularly as food for humans.

Toad-headed agama

Phrynocephalus mystaceus

subfamily

Leiolepidinae

taxonomy

Phrynocephalus mystaceus Pallas, 1776, "Arenosis Naryn" and "deserti Comani." Two subspecies are recognized.

other common names

English: Bearded toad head.

physical characteristics

These small, brownish terrestrial lizards have large heads and peculiar pouches, or "beards," at the corners of their mouths that are expanded in threat displays.

distribution

The species occurs in extreme western Asia and the northern Caucasus along the Caspian Sea and across northern Iran and northern Afghanistan to central Asia.

habitat

It inhabits sand dunes and semideserts with sparse vegetation and also is found on hard soils covered with small pebbles.

behavior

These lizards dig burrows in sandy areas between dunes. Fleeing individuals run long distances, up to 66 yd (60 m); pause briefly with the tail rolled up; and then, vibrating their bodies, rapidly sink into loose sand. If threatened, they adopt a defensive stance, raising up on their hind legs, opening their mouths wide, and hissing and sometimes lunging, with folds of skin spread out at both sides of their mouth. These red folds make the mouth look much wider than it actually is. They rock back and forth on their legs, whirling their tail in a spiral, and jump toward their antagonist. The entire performance is very menacing.

feeding ecology and diet

These are sit-and-wait insectivores.

reproductive biology

The species reaches sexual maturity at two years. Breeding takes place from late April to early July. Females are slightly larger than males and lay two clutches of two to three eggs. Young hatch in about 70 days.

conservation status

Not threatened.

significance to humans

The species can be maintained in terraria, where some herpetoculturists have succeeded in keeping them alive for seven to eight years.

Spiny-tailed agama

Uromastyx acanthinurus

subfamily

Leiolepidinae

taxonomy

Uromastyx acanthinurus Merrem, 1820, Egypt. Six subspecies are recognized.

other common names

English: Bell's dab lizard, dob lizard; French: Fouette-queue; German: Veranderlicher Dornschwanz.

physical characteristics

These large, flattened lizards have very spiny tails. They are gray, yellowish, or reddish.

distribution

The species is found in the Sahara Desert of northern Africa.

habitat

These lizards inhabit rocky slopes in small mountain valleys with rich vegetation.

behavior

These large lizards dig extensive burrows, into which they retreat (rock crevices are sometimes used as well) when threatened, blocking off the entrance with their very spiny, sharp, and muscular tails. If pursued, they thrash their tails vigorously from side to side; a few blows from this sharp, spiny club discourages most small enemies. These lizards sometimes are found in small colonies of about 20 individuals.

feeding ecology and diet

This lizard forages over large areas, walking a zigzag path. They are vegetarians, eating flower buds of a wide variety of plants. They are especially fond of yellow flowers. In droughts they even subsist by eating wood. The species can survive a fast of an entire year. They have powerful jaws that can shear and crush even hard grains. They also eat insects such as beetles, when they are available.

reproductive biology

Courtship takes place from April to June. A complete courtship sequence may take from two hours to an entire day. During courtship the male bites the female's neck and back and curls the base of his tail underneath hers. Females lay two clutches of about 23 eggs in a lateral chamber dug off the main tunnel at a depth of about 23.6 in (60 cm). Hatchlings appear in September or October and have a total length of about 3 in (75 mm). The young eat both insects and flowers. They grow rapidly, reaching 8 in (20 cm) in their first year of life.

conservation status

Not threatened.

significance to humans

This species is kept in captivity in terraria.

Resources

Books

Cogger, H. G. Reptiles and Amphibians of Australia. Ithaca, NY: Cornell University Press, 1992.

Daniel, J. C. The Book of Indian Reptiles. Bombay, India: Bombay Natural History Society, Oxford University Press, 1983.

Estes, R. "The Fossil Record and Early Distribution of Lizards." In Advances in Herpetology and Evolutionary Biology: Essays in Honor of Ernest E. Williams, edited by A. G. J. Rhodin and K. Miyata. Cambridge, MA: Museum of Comparative Zoology (Harvard University), 1983.

Pianka, E. R. Ecology and Natural History of Desert Lizards: Analyses of the Ecological Niche and Community Structure. Princeton, NJ: Princeton University Press, 1986.

Pianka, E. R., and L. J. Vitt. Lizards: Windows to the Evolution of Diversity. Berkeley: University of California Press, 2003.

Saville-Kent, W. The Naturalist in Australia. London, 1897.

Schleich, H. Hermann, Werner Kästle, and Klaus Kabisch. Amphibians and Reptiles of North Africa. Koenigstein, Germany: Koeltz Scientific Books, 1996.

Schmidt, K. P., and R. F. Inger. Living Reptiles of the World. Garden City, NY: Hanover House, 1957.

Witten, G. J. "Family Agamidae." In Fauna of Australia. Vol. 2A, Amphibia and Reptilia, edited by C. J. Gasby, C. J. Ross, and P. L. Beesly. Canberra: Australian Biological and Environmental Survey, 1993.

Zug, George R., Laurie J. Vitt, and Janalee P. Caldwell. Herpetology: An Introductory Biology of Amphibians and Reptiles. 2nd edition. San Diego: Academic Press, 2001.

Periodicals

Bentley, P. J., and W. F. Blumer. "Uptake of Water by the Lizard Moloch horridus." Nature 194 (1962): 699–700.

Bursey, C. R., S. R. Goldberg, and D. N. Woolery. "Oochoristica piankai sp. n. (Cestoda: Linstowiidae) and Other Helminths of Moloch horridus (Sauria: Agamidae) from Australia." Journal of the Helminthological Society of Washington 63, no. 2 (1966): 215–221.

Huey, R. B., and E. R. Pianka. "Seasonal Variation in Thermoregulatory Behavior and Body Temperature of Diurnal Kalahari Lizards." Ecology 58 (1977): 1066–1075. (With an appendix by J. A. Hoffman.)

Pianka, E. R. "Australia's Thorny Devil." Reptiles 5, no. 11 (1997): 14–23.

——. "Comparative Ecology of Two Lizards." Copeia (1971): 129–138.

——. "Ecology of the Agamid Lizard Amphibolurus isolepis in Western Australia." Copeia (1971): 527–536.

Pianka, E. R., and H. D. Pianka. "The Ecology of Moloch horridus (Lacertilia: Agamidae) in Western Australia." Copeia (1970): 90–103.

Pianka, G. A., E. R. Pianka, and G. G. Thompson. "Egg Laying by Thorny Devils (Moloch horridus) Under Natural Conditions in the Great Victoria Desert." Journal of the Royal Society of Western Australia 79 (1998): 195–197.

Sporn, C. C. "Additional Observations on the Life History of the Mountain Devil, Moloch horridus, in Captivity." Western Australian Naturalist 9 (1965): 157–159.

——. "The Breeding of the Mountain Devil in Captivity." Western Australian Naturalist 5 (1955): 1–5.

——. "Further Observations on the Mountain Devil in Captivity." Western Australian Naturalist 6 (1958): 136–137.

Eric R. Pianka, PhD