Jacky Dragon
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The jacky dragon (''Amphibolurus muricatus'') is a type of
lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
native to southeastern
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
. It was one of the first Australian
reptiles Reptiles, as most commonly defined are the animals in the Class (biology), class Reptilia ( ), a paraphyletic grouping comprising all sauropsid, sauropsids except birds. Living reptiles comprise turtles, crocodilians, Squamata, squamates (lizar ...
to be named by Europeans, originally described by English zoologist
George Shaw George Shaw may refer to: * George Shaw (biologist) (1751–1813), English botanist and zoologist * George B. Shaw (1854–1894), U.S. Representative from Wisconsin * George Bernard Shaw (1856–1950), Irish playwright * George C. Shaw (1866–196 ...
in Surgeon-General John White's ''Journal of a Voyage to New South Wales'', , also a
Project Gutenberg Australia
which was published in
London London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...
in 1790. It is well known for its bright yellow mouth and well-developed
vertebral The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordates ...
crest, as well as the
temperature-dependent sex determination Temperature-dependent sex determination (TSD) is a type of environmental sex determination in which the temperatures experienced during embryonic/larval development determine the sex of the offspring. It is only observed in reptiles and teleost fish ...
of its offspring. Other common names include blood-sucker, stonewalker, and tree dragon. The
Wergaia The Wergaia or Werrigia people are an Aboriginal Australian group in the Mallee and Wimmera regions of north-Western Victoria, made up of a number of clans. The people were also known as the Maligundidj (in the Wotjobaluk language) which mea ...
people of the
Wimmera The Wimmera is a region of the Australian state of Victoria. The district is located within parts of the Loddon Mallee and the Grampians regions; and covers the dryland farming area south of the range of Mallee scrub, east of the South Aust ...
region of north-western Victoria call it ''nganurganity''. In 2017, the star Sigma Canis Majoris was officially named "Unurgunite" (a 19th-century transcription of ''nganurganity'') due to its identification with the jacky dragon in Wergaia traditions.


Taxonomy

The jacky dragon, one of the 70 species of dragons (Agamidae) found in Australia, is generally diurnal and tends to run in an upright posture when pursued. Common morphological characteristics include rough, nonglossy
scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number w ...
; broad, thick, and fleshy
tongue The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...
s; 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 (from the Greek language, Greek ''auto-'', "self-" and ''tome'', "severing", wikt:αὐτοτομία, αὐτοτομία) or self-amputation, is the behaviour whereby an animal sheds or discards one or more of its own appendages, usual ...
and the presence of femoral and/or preanal pores. Agamidae dragons are also oviparous and tend to deposit their eggs in burrows.


Morphology

The coloration of the jacky dragon is pale
grey Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...
to dark
brown Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing or painting, brown is usually made by combining the colors orange and black. In the RGB color model us ...
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. A dark brown bar is present between the eye and the
ear An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of ...
, but no dark stripe is present between the nostril and the eye as in many other dragons. The lips and lower
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 serv ...
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 The nape is the back of the neck. In technical anatomical/medical terminology, the nape is also called the nucha (from the Medieval Latin rendering of the Arabic , "spinal marrow"). The corresponding adjective is ''nuchal'', as in the term ''n ...
crest continuous with a
vertebral The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordates ...
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 dorsolateral 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 in (22.86 cm) including the tail, though they have been recorded at lengths up to 17.5 in (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 g. The largest dragons, however, have been recorded at around 67 g. The size of the dragons' heads can be used to differentiate between sexes, with males usually having conspicuously larger heads.


Reproduction and life cycle

Gravid In biology and human medicine, gravidity and parity are the number of times a woman is or has been pregnant (gravidity) and carried the pregnancies to a viable gestational age (parity). These terms are usually coupled, sometimes with additional t ...
females are found from October until February. Females lay up to eight eggs.
Clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...
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 The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...
when the mother still has considerable control over the temperature of the nest. This may falsify the
hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...
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 Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked tu ...
s,
tuatara Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...
s, and
crocodile Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to inclu ...
s. In fact, recent research suggests 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.


Ecology


Distribution

Jacky dragons are found along the southeastern coast of Australia. They have been found as far north as central
Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...
, in
New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...
,
Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...
, and in the southeastern portion of
South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
.


Habitat

The jacky dragon is usually found in dry
sclerophyll Sclerophyll is a type of vegetation that is adapted to long periods of dryness and heat. The plants feature hard leaves, short internodes (the distance between leaves along the stem) and leaf orientation which is parallel or oblique to direct ...
forests and woodlands. They are present in the eastern highlands, but not in alpine areas. They are semiarboreal, and individuals are often seen perching on fallen or standing timber.


Predators and prey

Insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...
compose most of the diet of the jacky dragon. These include
flies Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
,
moths Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
,
caterpillars Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Symp ...
,
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...
s, and small
beetles Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
. Predators of young jacky dragons are numerous and can include small
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s, such as feral
cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...
s or rats, and other
reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...
s. Adults face aerial predation from
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
s such as
kookaburra Kookaburras are terrestrial tree kingfishers of the genus ''Dacelo'' native to Australia and New Guinea, which grow to between in length and weigh around . The name is a loanword from Wiradjuri ''guuguubarra'', onomatopoeic of its call. The ...
s, ravens, black-shouldered kites, and
Nankeen kestrel The nankeen kestrel (''Falco cenchroides''), also known as the Australian kestrel, is a raptor native to Australia and New Guinea. It is one of the smallest falcons, and unlike many, does not rely on speed to catch its prey. Instead, it simply pe ...
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), will sometimes run in an almost upright position on their hind legs when pursued. In cool, wet weather, they bury themselves in the sand or shelter under a bush. They rarely enter the water, but do 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 Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...
. 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. 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
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually 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 ...
. The abundance of the jacky dragon and other common
reptiles Reptiles, as most commonly defined are the animals in the Class (biology), class Reptilia ( ), a paraphyletic grouping comprising all sauropsid, sauropsids except birds. Living reptiles comprise turtles, crocodilians, Squamata, squamates (lizar ...
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.


References


Pet Lizards: All You Need To Know
{{Taxonbar, from=Q281038 Amphibolurus Reptiles of Victoria (Australia) Reptiles of Queensland Reptiles of New South Wales Reptiles of South Australia Reptiles described in 1790 Taxa named by John White (surgeon) Agamid lizards of Australia