Amphibolurus muricatus
Encyclopedia
The Jacky Dragon, Amphibolurus muricatus, is a type of lizard
native to Southeastern Australia
. It was one of the first Australian reptiles to be named, originally described by English zoologist George Shaw
in Surgeon-General White’s Journal of a Voyage to New South Wales, which was published in London
in 1790. It is well known for its bright yellow mouth and well-developed vertebral
crest as well as the temperature-dependent sex determination
of its offspring. Other common names include blood-sucker, stonewalker, and tree dragon.
class
, the Squamata
order
, the Sauria
suborder, and the family
Agamidae
. There are 70 species of dragons (Agamidae) found in Australia. They are generally diurnal lizards that tend to run in an upright posture when pursued. Common morphological characteristics include rough, non-glossy scales
; broad, thick, and fleshy tongues; and well-developed limbs, especially hind limbs which are generally longer and have five clawed digits. Most dragons are also characterized by a lack of tail autotomy
and the presence of femoral
and/or preanal pores. Agamidae dragons are also oviparous and tend to deposit their eggs in burrows.
The coloration of the Jacky Dragon is pale grey
to dark brown
with dark patches along the middle of the back. The dark patches are interrupted by pale blotches that often blend together to form a continuous stripe from above the arm to the groin. There is a dark brown bar between the eye
and the ear
, however there is no dark stripe present between the nostril and the eye as in many other dragons. The lips and lower jaw
tend to be of a lighter coloration than the rest of the head. Jacky Dragons are also characterized by a bright yellow lining in their mouths. .
Specimens have been seen with orange-red corners of the inside of their mouths, which may have given rise to the common name of blood-sucker.
The Jacky Dragon is more readily distinguishable by its five crests: a nuchal crest continuous with a vertebral series of enlarged scales; paravertebral series from the nape to the base of the tail, which is separated from the vertebral series by two or three scales; and a dorso-lateral series on each side. The hind legs are covered in large, spinose scales and small, keeled scales. Jacky dragons also have spinose scales on the sides of their necks. The tympanum
is medium-sized and fairly conspicuous.
The average size of a Jacky Dragon is 9 inches (22.86 cm) including the tail, though they have been recorded at lengths up to 17.5 inches (44.45 cm). The length of the tail is generally twice as long as that of the body. The average mass of the Jacky Dragon is 30 grams. The largest dragons, however, have been recorded at around 67 grams. The size of the dragons' heads can be used to differentiate between sexes, with male Jacky Dragons usually having conspicuously larger heads.
size tends to be positively correlated with female body size. Most adult females lay at least one clutch every summer. They tend to lay their clutches under sheets of bark or decaying vegetation over sandy deposits. The first young begin to appear at the end of December and are abundant by February. Jacky Dragons are usually about three inches in length immediately following hatching.
The sex of the hatchlings is determined by the temperature of the nest, a process known as temperature-dependent sex determination (TSD). The hatchlings are females in low and high temperature environments and males in medium temperature environments. This causes young dragons from clutches laid earlier in the season to be predominately male. Shine suggests, however, that the sex of the hatchling is determined soon after oviposition
when the mother still has considerable control over the temperature of the nest. This may falsify the hypothesis
that TSD evolved in lizards so as to match the sex of the offspring with environmental conditions that may be unpredictable when the clutch is laid, as is most likely the case for turtle
s, tuatara
s, and crocodile
s. In fact, recent research suggests that TSD has evolved in lizards so as to ensure reproductive success in the offspring.
The Jacky Dragon reaches sexual maturity rapidly. Females can lay clutches within one year of hatching. The average lifespan of the Jacky Dragon is four years, which is significantly shorter than most lizards.
, in New South Wales
, Victoria
, and in the southeastern portion of South Australia
.
forests and woodlands. They are present in the Eastern highlands but not in alpine areas. They are semi-arboreal and individuals are often seen perching on fallen or standing timber.
, moths
, caterpillars, grasshopper
s, and small beetles.
Predators of young Jacky Dragons are numerous and can include small mammal
s, such as feral cat
s or rat
s, and other reptile
s. Adult Jacky Dragons face aerial predation from bird
s such as kookaburra
s, raven
s, raptors
, black-shouldered kite
s, and Nankeen kestrel
s. The dragons use visual cues such as the changing area over time, edge length, shape, and orientation in the recognition of aerial predators.
Jacky Dragons have many different displays, or series of movements, that are used as communication between conspecifics. The push-up display, for example, begins with a series of tail flicks, backward and forward arm-waves, a push-up and a characteristic rocking of the entire body. Research suggests that these unique movements have velocity and directional characteristics that distinguish them from other environmental occurrences such as the blowing of vegetation. This is necessary because the visual system of the Jacky Dragon relies mostly on movement for information.
. Research has concluded, however, that the abundance of the Jacky Dragon and other common reptiles is a result of the heterogeneity and structural complexity of the ground and groundcover of undisturbed areas, which is an important observation in the conservation of reptiles in Australia.
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
native to Southeastern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. It was one of the first Australian reptiles to be named, originally described by English zoologist George Shaw
George Shaw
George Shaw was an English botanist and zoologist.Shaw was born at Bierton, Buckinghamshire and was educated at Magdalen Hall, Oxford, receiving his M.A. in 1772. He took up the profession of medical practitioner. In 1786 he became the assistant lecturer in botany at Oxford University...
in Surgeon-General White’s Journal of a Voyage to New South Wales, which was published in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
in 1790. It is well known for its bright yellow mouth and well-developed vertebral
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
crest as well as the temperature-dependent sex determination
Temperature-dependent sex determination
Temperature-dependent sex determination is type of environmental sex determination in which the temperatures experienced during embryonic development determine the sex of the offspring. It is most prevalent and common among amniote vertebrates that are classified under the reptile class, but is...
of its offspring. Other common names include blood-sucker, stonewalker, and tree dragon.
Taxonomy
The Jacky Dragon is a part of the ReptiliaReptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
class
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
, the Squamata
Squamata
Squamata, or the scaled reptiles, is the largest recent order of reptiles, including lizards and snakes. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the...
order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
, the Sauria
Sauria
Sauria is a clade of reptiles that includes all living diapsids, as well as their common ancestor and all its extinct descendants. The ancestral saurian was probably a small lizard-like creature living in the Permian Period...
suborder, and the family
Family
In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...
Agamidae
Agamidae
Agamids, lizards of the family Agamidae, include more than 300 species in Africa, Asia, Australia, and a few in Southern Europe. Many species are commonly called dragons or dragon lizards. Phylogenetically they may be sister to the Iguanidae, and have a similar appearance. Agamids usually have...
. There are 70 species of dragons (Agamidae) found in Australia. They are generally diurnal lizards that tend to run in an upright posture when pursued. Common morphological characteristics include rough, non-glossy scales
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
; broad, thick, and fleshy tongues; and well-developed limbs, especially hind limbs which are generally longer and have five clawed digits. Most dragons are also characterized by a lack of tail autotomy
Autotomy
Autotomy or self amputation is the act whereby an animal severs one or more of its own appendages, usually as a self-defense mechanism designed to elude a predator's grasp...
and the presence of femoral
Femoral
Femoral can refer to:* Femoral artery* Femoral vein* Femur* Femoral triangle* Femoral nerve...
and/or preanal pores. Agamidae dragons are also oviparous and tend to deposit their eggs in burrows.
Morphology
Grey
Grey or gray is an achromatic or neutral color.Complementary colors are defined to mix to grey, either additively or subtractively, and many color models place complements opposite each other in a color wheel. To produce grey in RGB displays, the R, G, and B primary light sources are combined in...
to dark brown
Brown
Brown is a color term, denoting a range of composite colors produced by a mixture of orange, red, rose, or yellow with black or gray. The term is from Old English brún, in origin for any dusky or dark shade of color....
with dark patches along the middle of the back. The dark patches are interrupted by pale blotches that often blend together to form a continuous stripe from above the arm to the groin. There is a dark brown bar between the eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
and the ear
Ear
The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....
, however there is no dark stripe present between the nostril and the eye as in many other dragons. The lips and lower jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...
tend to be of a lighter coloration than the rest of the head. Jacky Dragons are also characterized by a bright yellow lining in their mouths. .
Specimens have been seen with orange-red corners of the inside of their mouths, which may have given rise to the common name of blood-sucker.
The Jacky Dragon is more readily distinguishable by its five crests: a nuchal crest continuous with a vertebral series of enlarged scales; paravertebral series from the nape to the base of the tail, which is separated from the vertebral series by two or three scales; and a dorso-lateral series on each side. The hind legs are covered in large, spinose scales and small, keeled scales. Jacky dragons also have spinose scales on the sides of their necks. The tympanum
Tympanum (zoology)
The tympanum is an external hearing structure in animals such as frogs, toads, insects, and mammals, to name a few.-Anurans:In frogs and toads, it is located just behind the eye. It does not actually process sound waves; it simply transmits them to the amphibian's inner ear, which is protected...
is medium-sized and fairly conspicuous.
The average size of a Jacky Dragon is 9 inches (22.86 cm) including the tail, though they have been recorded at lengths up to 17.5 inches (44.45 cm). The length of the tail is generally twice as long as that of the body. The average mass of the Jacky Dragon is 30 grams. The largest dragons, however, have been recorded at around 67 grams. The size of the dragons' heads can be used to differentiate between sexes, with male Jacky Dragons usually having conspicuously larger heads.
Reproduction and life cycle
Gravid females are found from October until February. Female Jacky Dragons lay up to eight eggs. ClutchClutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
size tends to be positively correlated with female body size. Most adult females lay at least one clutch every summer. They tend to lay their clutches under sheets of bark or decaying vegetation over sandy deposits. The first young begin to appear at the end of December and are abundant by February. Jacky Dragons are usually about three inches in length immediately following hatching.
The sex of the hatchlings is determined by the temperature of the nest, a process known as temperature-dependent sex determination (TSD). The hatchlings are females in low and high temperature environments and males in medium temperature environments. This causes young dragons from clutches laid earlier in the season to be predominately male. Shine suggests, however, that the sex of the hatchling is determined soon after oviposition
Oviposition
Oviposition is the process of laying eggs by oviparous animals.Some arthropods, for example, lay their eggs with an organ called the ovipositor.Fish , amphibians, reptiles, birds and monetremata also lay eggs....
when the mother still has considerable control over the temperature of the nest. This may falsify the hypothesis
Hypothesis
A hypothesis is a proposed explanation for a phenomenon. The term derives from the Greek, ὑποτιθέναι – hypotithenai meaning "to put under" or "to suppose". For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it...
that TSD evolved in lizards so as to match the sex of the offspring with environmental conditions that may be unpredictable when the clutch is laid, as is most likely the case for turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, tuatara
Tuatara
The tuatara is a reptile endemic to New Zealand which, though it resembles most lizards, is actually part of a distinct lineage, order Sphenodontia. The two species of tuatara are the only surviving members of its order, which flourished around 200 million years ago. Their most recent common...
s, and crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s. In fact, recent research suggests that TSD has evolved in lizards so as to ensure reproductive success in the offspring.
The Jacky Dragon reaches sexual maturity rapidly. Females can lay clutches within one year of hatching. The average lifespan of the Jacky Dragon is four years, which is significantly shorter than most lizards.
Distribution
Jacky Dragons are found along the southeastern coast of Australia. They have been found as far north as central QueenslandQueensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
, and in the southeastern portion of South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
.
Habitat
The Jacky Dragon is usually found in dry sclerophyllSclerophyll
Sclerophyll is the term for a type of vegetation that has hard leaves and short internodes . The word comes from the Greek sclero and phyllon ....
forests and woodlands. They are present in the Eastern highlands but not in alpine areas. They are semi-arboreal and individuals are often seen perching on fallen or standing timber.
Predators and Prey
Insects compose most of the diet of the Jacky Dragon. These include fliesFließ
Fließ is a municipality in the Landeck district and is located5 km south of Landeck on the upper course of the Inn River. It has 9 hamlets and was already populated at the roman age; the village itself was founded around the 6th century. After a conflagration in 1933 Fließ was restored more...
, moths
Moths
Moths may refer to:* Gustav Moths , German rower* The Moths!, an English indie rock band* MOTHS, members of the Memorable Order of Tin Hats...
, caterpillars, grasshopper
Grasshopper
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...
s, and small beetles.
Predators of young Jacky Dragons are numerous and can include small mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, such as feral cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s or rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s, and other reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s. Adult Jacky Dragons face aerial predation from bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s such as kookaburra
Kookaburra
Kookaburras are terrestrial kingfishers native to Australia and New Guinea. They are large to very large, with a total length of . The name is a loanword from Wiradjuri guuguubarra, and is onomatopoeic of its call...
s, raven
Raven
Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...
s, raptors
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
, black-shouldered kite
Black-shouldered Kite
The Black-shouldered Kite or Australian Black-shouldered Kite is a small raptor found in open habitat throughout Australia and resembles similar species found in Eurasia and North America, which have in the past also been named as Black-shouldered Kites...
s, and Nankeen kestrel
Nankeen Kestrel
The Australian Kestrel or Nankeen Kestrel is one of the smallest falcons, and unlike many, does not rely on speed to catch its prey. Instead, it simply perches in an exposed position, but it also has a distinctive technique of hovering over crop and grasslands...
s. The dragons use visual cues such as the changing area over time, edge length, shape, and orientation in the recognition of aerial predators.
Behaviour
Jacky Dragons are very swift lizards and like many other dragons (Agamidae), the Jacky Dragon will sometimes run in an almost upright position on its hind legs when pursued. In cool, wet weather, it will bury itself in the sand or shelter under a bush. It rarely enters the water, but does have the ability to swim. In a fight, opponents circle each other in an upright position with their bodies laterally compressed so as to enlarge their appearance. They tend to direct their attacks towards the tails of their opponents. Various territorial displays include tail-waving, raising or lowering their bodies, head-bobbing, arm-waving, and darkening their color.Jacky Dragons have many different displays, or series of movements, that are used as communication between conspecifics. The push-up display, for example, begins with a series of tail flicks, backward and forward arm-waves, a push-up and a characteristic rocking of the entire body. Research suggests that these unique movements have velocity and directional characteristics that distinguish them from other environmental occurrences such as the blowing of vegetation. This is necessary because the visual system of the Jacky Dragon relies mostly on movement for information.
Conservation status
The Jacky Dragon is not in danger of extinctionExtinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
. Research has concluded, however, that the abundance of the Jacky Dragon and other common reptiles is a result of the heterogeneity and structural complexity of the ground and groundcover of undisturbed areas, which is an important observation in the conservation of reptiles in Australia.