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{{Taxobox
| name = Komodo dragon<ref name="itis">{{ITIS|ID=202168|taxon=Varanus komodoensis|year=2007|date=19 June}}</ref>
| status = VU
| status_system = iucn3.1
| image = Komodo dragon Varanus komodoensis Ragunan Zoo 2.JPG
| image_width = 256px
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Reptile|Reptilia]]
| ordo = [[Squamata]]
| subordo = Scleroglossa
| familia = [[Varanidae]]
| genus = ''[[Varanus]]''
| range_map=Komodo_dragon_distribution.gif
| range_map_caption=Komodo dragon distribution
| species = '''''V. komodoensis'''''
| binomial = ''Varanus komodoensis''
| binomial_authority = [[Peter Ouwens|Ouwens]], 1912<ref name="ouwens">{{cite journal|last=Ouwens|first=P.A.|year=1912|title=On a large Varanus species from the island of Komodo|journal=Bull. Jard. Bot. Buit.|volume=2|issue=6|pages=1–3}}</ref>
}}

The '''Komodo dragon''' (''Varanus komodoensis'') is a species of [[lizard]] that inhabits the islands of [[Komodo (island)|Komodo]], [[Rinca]], [[Flores]], [[Gili Motang]], and Gili Dasami, in central [[Indonesia]].<ref name="komo">{{cite book |author=Trooper Walsh; Murphy, James Jerome; Claudio Ciofi; Colomba De LA Panouse |title=Komodo Dragons: Biology and Conservation (Zoo and Aquarium Biology and Conservation Series) |publisher=Smithsonian Books|location=[[Washington, D.C.]]|isbn=1-58834-073-2}}</ref> A member of the [[monitor lizard]] family ([[Varanidae]]), it is the [[Largest organisms#Reptiles (Reptilia)|largest living species of lizard]], growing to an average length of {{convert|2|to|3|m|ft}} and weighing around {{convert|70|kg|lb}}. Their unusual size is attributed to [[island gigantism]], since there are no other carnivorous animals to fill the [[Ecological niche|niche]] on the islands where they live, and also to the Komodo dragon's low metabolic rate.<ref name="world">{{cite book |author=Chris Mattison, |title=Lizards of the World |publisher=Facts on File |location=New York |year=1989 & 1992 |pages= pp. 16, 57, 99, 175 |isbn=0-8160-5716-8 |oclc= |doi=}}</ref><ref>{{cite journal |author=Burness G, Diamond J, Flannery T |title=Dinosaurs, dragons, and dwarfs: the evolution of maximal body size |journal=Proc Natl Acad Sci U S A |volume=98 |issue=25 |pages=14518–23 |year=2001 |pmid=11724953 | doi = 10.1073/pnas.251548698 <!--Retrieved from CrossRef by DOI bot-->}}</ref> As a result of their size, these lizards, along with symbiotic bacteria, dominate the [[ecosystem]]s in which they live.<ref name="firefly">{{cite book |author=Tim Halliday (Editor), Kraig Adler (Editor) |title=Firefly Encyclopedia of Reptiles and Amphibians |publisher=Firefly Books Ltd |location=Hove |year= |pages=112, 113, 144, 147, 168, 169 |isbn=1-55297-613-0 |oclc= |doi=}}</ref> Although Komodo dragons eat mostly [[carrion]], they will also hunt and ambush prey including [[invertebrates]], [[birds]], and [[mammals]].

Mating begins between May and August, and the eggs are laid in September. About twenty eggs are deposited in abandoned [[megapode]] nests and incubated for seven to eight months, hatching in April, when insects are most plentiful. Young Komodo dragons are vulnerable and therefore dwell in trees, safe from predators and [[Cannibalism (zoology)|cannibalistic]] adults. They take around three to five years to mature, and may live as long as fifty years. They are among the rare vertebrates capable of [[parthenogenesis]], in which females may lay viable eggs if males are absent.<ref>This article in [[Nature (magazine)]] reports a female who reproduced parthenogenetically for one batch of eggs, and subsequently was impregnated by a male in a normal process. http://www.nature.com/nature/journal/v444/n7122/abs/4441021a.html</ref>

Komodo dragons were discovered by Western scientists in 1910. Their large size and fearsome reputation make them popular zoo exhibits. In the wild their range has contracted due to human activities and they are listed as [[Vulnerable species|vulnerable]] by the [[IUCN]]. They are protected under Indonesian law, and a [[national park]], [[Komodo National Park]], was founded to aid protection efforts.

==Etymology==
The Komodo dragon is also known as the '''Komodo monitor''' or the '''Komodo Island monitor''' in scientific literature, although this is not very common.<ref name="itis"/> To the natives of [[Komodo (island)|Komodo Island]], it is referred to as '''ora''', '''buaja darat''' ("land crocodile") or '''biawak raksasa''' ("giant monitor").<ref name="amnh">{{cite web|publisher=[[American Museum of Natural History]]|url=http://www.amnh.org/nationalcenter/Endangered/ora/ora.html|title=Endangered! Ora|accessdate=2007-01-15}}</ref><ref name="sciam"/>

==Evolutionary development==
The evolutionary development of the Komodo dragon started with the ''[[Varanus]]'' genus, which originated in Asia about 40 million years ago and migrated to [[Australia]]. Around 15 million years ago, a collision between Australia and Southeast Asia allowed the varanids to move into what is now the Indonesian archipelago. The Komodo dragon is believed to have differentiated from its Australian ancestors 4 million years ago, extending their range to as far east as the island of [[Timor]]. Dramatic lowering of sea level during the [[last glacial period]] uncovered extensive stretches of continental shelf that the Komodo dragon colonized, becoming isolated in their present island range as sea levels rose afterwards.<ref name="sciam"/>

==Description==
[[Image:Komodo dragon skin.jpg|thumb|right|Closeup of a Komodo dragon's skin.]]

In the wild, an adult Komodo dragon usually weighs around {{convert|70|kg|lb}},<ref name="animal" /> although captive specimens often weigh more. The largest verified wild specimen was {{convert|3.13|m|ft}} long and weighed {{convert|166|kg|lb}}, including undigested food.<ref name="sciam">{{cite web |author=Ciofi, Claudio |publisher=[[Scientific American]] |url=http://www.sciam.com/article.cfm?id=the-komodo-dragon |title=The Komodo Dragon|accessdate=2006-12-21 |format= |work=}}</ref> The Komodo dragon has a tail as long as its body, as well as about 60 frequently-replaced serrated teeth that can measure up to 2.5 centimeters (1&nbsp;inch) in length. Its saliva is frequently blood-tinged, because its teeth are almost completely covered by [[gingiva|gingival tissue]] that is naturally lacerated during feeding.<ref name="location"/> This creates an ideal culture for the virulent [[bacteria]] that live in its mouth.<ref name="docent">{{cite web |publisher=[[Singapore Zoological Gardens]] |url=http://szgdocent.org/resource/rr/c-komodo.htm |title= Komodo Dragon|accessdate=2006-12-21 |format= |work=|archiveurl=http://web.archive.org/web/20061127173608/http://www.szgdocent.org/resource/rr/c-komodo.htm
|archivedate=2006-11-27 }}</ref> It also has a long, yellow, deeply-forked tongue.<ref name="sciam"/>

===Senses===
The Komodo dragon does not have a particularly acute sense of hearing, despite its visible earholes, and is only able to hear sounds between 400 and 2000 [[hertz]].<ref name="bbc">{{cite web |publisher=[[bbc.co.uk]] |url=http://www.bbc.co.uk/nature/animals/features/336feature1.shtml |archiveurl=http://web.archive.org/web/20061116030327/http://www.bbc.co.uk/nature/animals/features/336feature1.shtml |archivedate=2006-11-16 |title=Komodo Conundrum |accessdate=2007-11-25 |format= |work=}}</ref><ref name="sciam"/> It is able to see as far away as {{convert|300|m|ft}}, but because its retinas only contain [[cone cells|cones]], it is thought to have poor night vision. The Komodo dragon is able to see in color, but has poor visual discrimination of stationary objects.<ref name="nzpfactsheet">{{cite web |publisher=[[National Zoo]] |url=http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Komododragon.cfm |title=Komodo Dragon Fact Sheet |accessdate=2007-11-25 |format= |work=}}</ref>

[[Image:Komodo dragons video.wmv.OGG|Komodo dragon on Komodo Island uses his tongue to sample the air.|thumb|180px|left]]

The Komodo dragon uses its tongue to detect taste and smell [[stimuli]], as with many other reptiles, with the [[vomeronasal]] sense using a [[Jacobson's organ]], a sense that aids navigation in the dark.<ref name="docent"/> With the help of a favorable wind and its habit of swinging its head from side to side as it walks, Komodo dragons may be able to detect carrion from 4–9.5&nbsp;kilometres (2.5–6&nbsp;mi) away.<ref name="location"/><ref name="nzpfactsheet"/> The dragon's nostrils are not of great use for smelling, as the animal does not have a [[Thoracic diaphragm|diaphragm]].<ref name="location"/><ref name="zipcode">{{cite web |publisher=BayScience Foundation, Inc. |url=http://zipcodezoo.com/animals/v/varanus_komodoensis.asp |archiveurl=http://web.archive.org/web/20070927190225/http://zipcodezoo.com/animals/v/varanus_komodoensis.asp |archivedate=2007-09-27 |title=Zipcodezoo: Varanus komodoensis (Komodo Dragon, Komodo Island Monitor, Komodo Monitor) |accessdate=2007-02-01 |format= |work=}}</ref> It only has a few [[taste bud]]s in the back of its throat.<ref name="docent"/> Its scales, some of which are reinforced with bone, have sensory plaques connected to nerves that facilitate its sense of touch. The scales around the ears, lips, chin, and soles of the feet may have three or more sensory plaques.<ref name="location"/>

The Komodo dragon was formerly thought to be deaf when a study reported no agitation in wild Komodo dragons in response to whispers, raised voices, or shouts. This was disputed when [[ZSL London Zoo|London Zoological Garden]] employee Joan Proctor trained a captive specimen to come out to feed at the sound of her voice, even when she could not be seen.<ref name="liz">{{cite book |author=text by David Badger; photography by John Netherton |title=Lizards: A Natural History of Some Uncommon Creatures, Extraordinary Chameleons, Iguanas, Geckos, and More |publisher=Voyageur Press |location=Stillwater, MN |year=2002 |pages=32, 52, 78, 81, 84, 140–145, 151 |isbn=0-89658-520-4 |oclc= |doi=}}</ref>
{{clear}}

==Ecology==
[[Image:KDragon1mj.jpg|thumb|right|Close-up of a Komodo dragon's foot and tail.]]
The Komodo dragon prefers hot and dry places, and typically lives in dry open grassland, savanna, and tropical forest at low elevations. As an [[Cold-blooded|ectotherm]], it is most active in the day, although it exhibits some [[nocturnal]] activity. Komodo dragons are largely solitary, coming together only to breed and eat. They are capable of running rapidly in brief sprints up to 20 kilometres per hour (12.4 mph), diving up to 4.5 metres (15 ft), and climbing trees proficiently when young through use of their strong claws.<ref name="animal">{{cite book | last = Burnie | first = David | coauthors = Don E. Wilson | title = Animal | publisher = DK Publishing, Inc. | year = 2001 | location = New York, New York | pages = 417, 420 | id = ISBN 0-7894-7764-5}}</ref> To catch prey that is out of reach, the Komodo dragon may stand on its hind legs and use its tail as a support.<ref name="liz"/> As the Komodo dragon matures, its claws are used primarily as weapons, as its great size makes climbing impractical.<ref name="location"/>

For shelter, the Komodo dragon digs holes that can measure from 1–3&nbsp;metres (3–10&nbsp;ft) wide with its powerful forelimbs and claws.<ref name="cogger"/> Because of its large size and habit of sleeping in these burrows, it is able to conserve body heat throughout the night and minimize its basking period the morning after.<ref>{{cite book |author=Eric R. Pianka and Laurie J. Vitt; with a foreword by Harry W. Greene |title=Lizards: Windows to the Evolution of Diversity |publisher=University of California Press |location=Berkeley |year=2003 |page=244 |isbn=0-520-23401-4 |oclc= |doi=}}</ref> The Komodo dragon typically hunts in the afternoon, but stays in the shade during the hottest part of the day.<ref name="gateway-faq"/> These special resting places, usually located on ridges with a cool sea breeze, are marked with droppings and are cleared of vegetation. They also serve as a strategic location from which to ambush deer.<ref name="southsea"/>

===Diet===
[[Image:KomodoDragonRinca1.jpg|thumb|upright|Komodo dragons on Rinca]]
Komodo dragons are carnivores. Although they eat mostly [[carrion]],<ref name="world" /> they will also ambush live prey with a stealthy approach. When suitable prey arrives near a dragon's ambush site, it will suddenly charge at the animal and go for the underside or the throat.<ref name="location"/> It is able to locate its prey using its keen sense of smell, which can locate a dead or dying animal from a range of up to 9.5 kilometers (6 miles).<ref name="location"/> Komodo dragons have also been observed knocking down large pigs and deer with their strong tail.<ref name="coldblood"/>

Komodo dragons eat by tearing large chunks of flesh and swallowing them whole while holding the carcass down with their forelegs. For smaller prey up to the size of a goat, their loosely articulated jaws, flexible skull, and expandable stomach allow it to swallow its prey whole. The vegetable contents of the stomach and intestines are typically avoided.<ref name="southsea"/> Copious amounts of red saliva that the Komodo dragons produce helps to lubricate the food, but swallowing is still a long process (15–20&nbsp;minutes to swallow a goat). Komodo dragons may attempt to speed up the process by ramming the carcass against a tree to force it down its throat, sometimes ramming so forcefully that the tree is knocked down.<ref name="southsea"/> To prevent itself from suffocating while swallowing, it breathes using a small tube under the tongue that connects to the lungs.<ref name="location"/> After eating up to 80&nbsp;[[percent]] of its body weight in one meal,<ref name="firefly" /> it drags itself to a sunny location to speed digestion, as the food could rot and poison the dragon if left undigested for too long. Because of their slow metabolism, large dragons can survive on as little as 12 meals a year.<ref name="location"/> After digestion, the Komodo dragon regurgitates a mass of horns, hair, and teeth known as the gastric pellet, which is covered in malodorous mucus. After regurgitating the gastric pellet, it rubs its face in the dirt or on bushes to get rid of the mucus, suggesting that it, like humans, does not relish the scent of its own excretions.<ref name="location"/>

[[Image:Komodo Dragon Eating Rinca.jpg|thumb|left|Young Komodo dragon photographed on Rinca feeding on a water buffalo carcass]]

The largest animals generally eat first, while the smaller ones follow a hierarchy. The largest male asserts his dominance and the smaller males show their submission by use of body language and rumbling hisses. Dragons of equal size may resort to "wrestling." Losers usually retreat, though have been known to be killed and eaten by victors.<ref name="location"/>

The Komodo dragon's diet is wide-ranging, and includes [[invertebrate]]s, other reptiles (including smaller Komodo dragons), [[bird]]s, bird eggs, small mammals, monkeys, wild boar, goats, deer, horses, and water buffalo.<ref name="waterbuf">{{cite web |publisher=[[guardian.co.uk]] |url=http://www.guardian.co.uk/world/2008/jun/12/indonesia |title=The terrifying truth about Komodo dragons |accessdate=2008-06-19 |format= |work=}}</ref> Young Komodos will eat insects, eggs, [[gecko]]s, and small mammals.<ref name="world"/> Occasionally they have been known to consume [[human]]s and human corpses, digging up bodies from shallow graves to do so.<ref name="liz"/> This habit of raiding graves caused the villagers of Komodo to move their graves from sandy to clay ground and pile rocks on top of them to deter the lizards.<ref name="southsea">{{cite book |author=Alison Ballance; Morris, Rod |title=South Sea Islands: A Natural History |publisher=Firefly Books Ltd |location=Hove |year= |pages= |isbn=1-55297-609-2 |oclc= |doi=}}</ref> The Komodo dragon may have evolved to feed on the extinct [[dwarf elephant]] ''[[Stegodon]]'' that once lived on Flores, according to evolutionary biologist [[Jared Diamond]].<ref name = "Diamond">{{cite journal |last=Diamond |first=Jared M. |authorlink= |coauthors= |year=1987 |month= |title=Did Komodo dragons evolve to eat pygmy elephants? |journal=[[Nature (journal)|Nature]] |volume=326 |issue=6116 |pages=832 |doi=10.1038/326832a0}}</ref> The Komodo dragon has also been observed intentionally startling a pregnant deer in the hopes of a miscarriage whose remains they can eat, a technique that has also been observed in large African predators.<ref name="Diamond"/>

Because the Komodo dragon does not have a [[Thoracic diaphragm|diaphragm]], it cannot suck water when drinking, nor can it lap water with its tongue. Instead, it drinks by taking a mouthful of water, lifting its head, and letting the water run down its throat.<ref name="location"/>

===Venom and bacteria===
[[Image:KomodoDragon.jpg|thumb|A sleeping Komodo dragon. Notice the large, curved claws used in fighting and eating.]]
In late 2005, [[University of Melbourne]] researchers concluded that the [[perentie]] (''Varanus giganteus''), other species of monitor, and [[agamids]] may be somewhat venomous. The research team showed that the immediate effects of bites from these lizards were caused by mild envenomation. Bites on human digits by a [[lace monitor]] (''V. varius''), a Komodo dragon, and a spotted tree monitor (''V. scalaris'') were observed, and all produced similar results in humans: rapid swelling within minutes, localized disruption of blood clotting, shooting pain up to the elbow, with some symptoms lasting for several hours.<ref name="Fry2006"/> It has been proposed that all venomous lizards, together with their nonvenomous relatives and all snakes, share a [[Toxicofera|common venomous ancestor]].<ref name="Fry2006">
{{cite journal
|author = Fry, B. et al
|year= 2006 |month= February
|title= Early evolution of the venom system in lizards and snakes
|journal= Nature
|volume= 439
|pages= 584–588
|url= http://www.nature.com/nature/journal/v439/n7076/abs/nature04328.html
|doi = 10.1038/nature04328
|format = [http://www.naherpetology.org/pdf_files/467.pdf PDF]
}}</ref>

Komodo dragons also possess virulent bacteria in their saliva, of which more than 28 [[Gram-negative bacteria|Gram-negative]] and 29 [[Gram-positive bacteria|Gram-positive]] strains have been isolated.<ref>{{cite journal |author=Montgomery JM, Gillespie D, Sastrawan P, Fredeking TM, Stewart GL |title=Aerobic salivary bacteria in wild and captive Komodo dragons |journal=J. Wildl. Dis. |volume=38 |issue=3 |pages=545–51 |year=2002 |pmid=12238371 |doi=}}</ref> These bacteria cause [[Sepsis|septicemia]] in their victim; if an initial bite does not kill the prey animal and it escapes, it will commonly succumb within a week to the resulting [[infection]]. The most harmful bacterium in Komodo dragon saliva appears to be a deadly strain of ''[[Pasteurella multocida]]'', from studies performed with laboratory mice.<ref>{{cite journal |last=Feldman |first=Ruth Tenzer |title=Dragon Drool! |journal=Odyssey |volume=16.2 |year=2007 |month=February |pages=49}}</ref> There is no specific antidote to the bite of a Komodo dragon, but it can usually be treated by cleansing the wounded area and giving the patient large doses of antibiotics. If not treated promptly, [[gangrene]] can quickly develop around the bite, which may require amputation of the affected area. Because the Komodo dragon appears immune to its own microbes, much research has been done searching for the antibacterial molecule(s) in the hopes of human medicinal use.<ref name="nwf"/>

===Reproduction===
[[Mating]] occurs between May and August, with the eggs laid in September.<ref name="sciam"/> During this period, males fight over females and territory by grappling with one another upon their hind legs with the loser eventually being pinned to the ground. These males may vomit or defecate when preparing for the fight.<ref name="liz"/> The winner of the fight will then flick his long tongue at the female to gain information about her receptivity.<ref name="firefly" /> Females are [[antagonistic]] and resist with their claws and teeth during the early phases of courtship. Therefore, the male must fully restrain the female during coitus to avoid being hurt. Other courtship displays include males rubbing their chins on the female, hard scratches to the back, and licking.<ref name="library">{{cite web |publisher=[[San Diego Zoo]] |url=http://library.sandiegozoo.org/Fact%20Sheets/komodo_dragon/Komodo.htm |title=Komodo Dragon |accessdate=2008-01-24 |format= |work= |archiveurl=http://web.archive.org/web/20051216073115/http://library.sandiegozoo.org/Fact+Sheets/komodo_dragon/Komodo.htm |archivedate=2005-12-16 }}</ref> Copulation occurs when the male inserts one of his [[hemipenes]] into the female's [[cloaca]].<ref name="nzpfactsheet"/> Komodo dragons may be monogamous and form "pair bonds", a rare behavior for lizards.<ref name="liz"/>

[[Image:Varanus komodoensis.JPG|thumb|right|250px|In this image, the long tail and claws are fully visible.]]

The female lays her eggs in burrows cut into the side of a hill or in the abandoned nesting mounds of the [[Orange-footed Scrubfowl]] (a moundbuilder or [[megapode]]), with a preference for the abandoned mounds.<ref>{{cite web |publisher=[[Elsevier]] |author=Jessop, Tim S., et al. |url=http://www.komododragon.biz/uploads/downloads/jessop+et+al+2004e.pdf |archiveurl=http://web.archive.org/web/20070829154723/http://www.komododragon.biz/uploads/downloads/jessop+et+al+2004e.pdf |archivedate=2007-08-29 |title=Distribution, Use and Selection of Nest Type by Komodo Dragons |accessdate=2008-03-13 |format=PDF |work=}}</ref> Clutches contain an average of 20 eggs which have an incubation period of 7–8&nbsp;months.<ref name="liz"/> The female lies on the eggs to incubate and protect them until they hatch around April, at the end of the rainy season when insects are plentiful. Hatching is an exhausting effort for the pups, who break out of their eggshells with an [[egg tooth]] that falls off soon after. After cutting out the hatchlings may lie in their eggshells for hours before starting to dig out of the nest. They are born quite defenseless, and many are eaten by predators.<ref name="location"/>

Young Komodo dragons spend much of their first few years in trees, where they are relatively safe from predators, including cannibalistic adults, who make juvenile dragons 10% of their diet.<ref name="liz"/> According to [[David Attenborough]], the habit of cannibalism may be advantageous in sustaining the large size of adults, as medium-sized prey on the islands is rare.<ref name="coldblood">{{cite book |author=Attenborough, David |authorlink=David Attenborough|title=Life in Cold Blood |publisher=Princeton University Press |location=Princeton, N.J |year=2008 |pages= |isbn=0-691-13718-8 |oclc= |doi= |accessdate=}}</ref> When the young must approach a kill, they roll around in fecal matter and rest in the intestines of eviscerated animals to deter these hungry adults.<ref name="liz"/> Komodo dragons take about three to five years to mature, and may live for up to 50 years.<ref name="cogger">{{cite book |author=consultant editors, Harold G. Cogger & Richard G. Zweifel; illustrations by David Kirshner |title=Encyclopedia of Reptiles & Amphibians |publisher=Academic Press |location=Boston |year=1998 |pages=132, 157–8 |isbn=0-12-178560-2 |oclc= |doi=}}</ref>

===Parthenogenesis===
{{main|Parthenogenesis}}

A Komodo dragon at London Zoo named Sungai laid a clutch of eggs in late 2005 after being separated from male company for more than two years. Scientists initially assumed that she had been able to store [[spermatozoon|sperm]] from her earlier encounter with a male, an [[adaptation]] known as [[superfecundation]].<ref>{{cite web |author=Morales, Alex |publisher=[[Bloomberg Television]] |url=http://www.bloomberg.com/apps/news?pid=20601082&sid=apLYpeppu8ag&refer=canada |title=Komodo Dragons, World's Largest Lizards, Have Virgin Births |accessdate=2008-03-28 |format= |work=}}</ref> On [[December 20]], [[2006]], it was reported that Flora, a captive Komodo dragon living in the [[Chester Zoo]] in [[England]], was the second known Komodo dragon to have laid unfertilized eggs: she laid 11 eggs, and 7 of them hatched, all of them male.<ref>Notice by her cage in [[Chester Zoo]] in [[England]]</ref> Scientists at [[Liverpool University]] in England performed genetic tests on three eggs that collapsed after being moved to an incubator, and verified that Flora had had no physical contact with a male dragon. After Flora's eggs' condition had been discovered, testing showed that Sungai's eggs were also produced without outside fertilization.<ref>{{cite web |publisher=[[The Times]] |url=http://www.timesonline.co.uk/tol/news/uk/article759338.ece |title=Wise men testify to Dragon's virgin birth |accessdate=2007-11-26 |format= |work=}}</ref>

[[Image:Parthkomodo.jpg|thumb|right|[[Parthenogenetic]] baby Komodo dragon, [[Chester Zoo]], [[England]]]]

Komodo dragons have the [[ZW sex-determination system|ZW]] chromosomal [[sex-determination system]], as opposed to the [[XY sex-determination system|mammalian XY system]]. Male progeny prove that Flora's unfertilized eggs were [[haploid]] (n) and doubled their chromosomes later to become [[diploid]] (2n) (by being fertilized by a [[polar body]], or by chromosome duplication without [[cell division]]), rather than by her laying diploid eggs by one of the [[meiosis]] reduction-divisions in her [[ovaries]] failing). When a female Komodo dragon (with ZW sex chromosomes) reproduces in this manner, she provides her progeny with only one chromosome from each of her pairs of chromosomes, including only one of her two sex chromosomes. This single set of chromosomes is duplicated in the egg, which develops parthenogenetically. Eggs receiving a Z [[chromosome]] become ZZ (male); those receiving a W chromosome become WW and fail to develop.<ref name="ZW">{{cite web |publisher=BBC News |url=http://news.bbc.co.uk/2/hi/science/nature/6196225.stm |title='Virgin births' for giant lizards |accessdate=2008-03-13 |format= |work=}}</ref><ref>{{cite web |publisher=[[Scientific American]] |url=http://www.sciam.com/article.cfm?id=strange-but-true-komodo-d |title=Strange but True: Komodo Dragons Show that "Virgin Births" Are Possible: Scientific American |accessdate=2008-03-24 |format= |work=}}</ref>

It has been hypothesized that this reproductive adaptation allows a single female to enter an isolated [[ecological niche]] (such as an island) and by parthenogenesis produce male offspring, thereby establishing a sexually reproducing population (via reproduction with her offspring that can result in both male and female young).<ref name="ZW" /> Despite the advantages of such an adaptation, zoos are cautioned that parthenogenesis may be detrimental to genetic diversity.<ref name="pmid">{{cite journal |author=Watts PC, Buley KR, Sanderson S, Boardman W, Ciofi C, Gibson R |title=Parthenogenesis in Komodo Dragons |journal=Nature |volume=444 |issue=7122 |pages=1021–2 |year=2006 |pmid=17183308 |doi=10.1038/4441021a}}</ref>

On January 31, 2008, the [[Sedgwick County Zoo]] in [[Wichita, Kansas]] became the first zoo in the Americas to document parthenogenesis in Komodo dragons. The zoo has two adult female Komodo dragons, one of which laid about 17 eggs on May 19–20, 2007. Only two eggs were incubated and hatched due to space issues; the first hatched on January 31, 2008 while the second hatched on [[February 1]]. Both hatchlings were males.<ref>{{cite web |publisher=[[Sedgwick County Zoo]] |url=http://www.scz.org/n_recent.html |archiveurl=http://web.archive.org/web/20080211184900/http://www.scz.org/n_recent.html |archivedate=2008-02-11 |title=Recent News - Sedgwick County Zoo |accessdate=2008-02-12 |format= |work=}}</ref><ref>{{cite web |publisher=[[MSNBC]] |url=http://www.msnbc.msn.com/id/23058689/ |title=Komodo dragons hatch with no male involved |accessdate=2008-02-12 |format= |work=}}</ref>

==History==
===Discovery by the Western world===
[[Image:Komodo coin, Indonesia Dscn0057.jpg|thumb|Komodo dragon coin, issued by Indonesia]]
Komodo dragons were first documented by [[Europe]]ans in 1910, when rumors of a "land crocodile" reached Lieutenant van Steyn van Hensbroek of the Dutch colonial administration.<ref>[http://www.dailymail.co.uk/news/worldnews/article-1025349/The-dragons--bigger-man-deadly-bite-But-stranded-divers-fight-Kimodo-really-fear-prehistoric-relics.html Daily Mail] - Should we really be scared of the Komodo dragon?</ref> Widespread notoriety came after 1912, when Peter Ouwens, the director of the Zoological Museum at [[Bogor]], [[Java (island)|Java]], published a paper on the topic after receiving a photo and a skin from the lieutenant, as well as two other specimens from a collector.<ref name="ouwens"/> Later, the Komodo dragon was the driving factor for an expedition to [[Komodo (island)|Komodo Island]] by W. Douglas Burden in 1926. After returning with 12 preserved specimens and 2 live ones, this expedition provided the inspiration for the 1933 movie [[King Kong (1933 film)|''King Kong'']].<ref>{{cite book |author=Rony, Fatimah Tobing |title=The third eye: race, cinema, and ethnographic spectacle |publisher=Duke University Press |location=Durham, N.C |year=1996 |page=164 |isbn=0-8223-1840-7 |oclc= |doi=}}</ref> It was also Burden who coined the common name "Komodo dragon."<ref name="gateway-faq">{{cite web |publisher=Komodo Foundation |url=http://www.komodo-gateway.org/faq1.html |title=Komodo National Park | Komodo Island | Frequently Asked Questions |accessdate=2007-10-25 |format= |work=}}</ref> Three of his specimens were stuffed and are still on display in the [[American Museum of Natural History]].<ref>{{cite web |publisher=[[American Museum of Natural History]] |url=http://www.amnh.org/exhibitions/expeditions/treasure_fossil/Treasures/Komodo_Dragons/komodo.html?aa |title=American Museum of Natural History: Komodo Dragons |accessdate=2007-06-07 |format= |work=}}</ref>

===Studies===
The Dutch, realizing the limited number of individuals in the wild, outlawed sport hunting and heavily limited the number of individuals taken for scientific study. Collecting expeditions ground to a halt with the occurrence of World War II, not resuming until the 1950s and 1960s, when studies examined the Komodo dragon's feeding behavior, reproduction, and body temperature. At around this time, an expedition was planned in which a long-term study of the Komodo dragon would be undertaken. This task was given to the Auffenberg family, who stayed on Komodo Island for 11 months in 1969. During their stay, Walter Auffenberg and his assistant Putra Sastrawan captured and tagged more than 50 Komodo dragons.<ref name="nwf">{{cite journal |first=Mark |last=Cheater |title=Chasing the Magic Dragon |journal=National Wildlife Magazine |volume=41 |issue=5 |year=2003 |month=August/September |publisher=[[National Wildlife Federation]] |url=http://www.nwf.org/nationalwildlife/article.cfm?articleId=810&issueId=63 }}</ref> The research from the Auffenberg expedition would prove to be enormously influential in raising Komodo dragons in captivity.<ref name="komo" /> Research after the Auffenberg family has shed more light on the nature of the Komodo dragon, with biologists such as Claudio Ciofi continuing to study the creatures.<ref name="natgeo"/>

==Conservation==
[[Image:Varanus komodoensis3.jpg|thumb|left|150px|A basking Komodo dragon photographed at [[Disney's Animal Kingdom]].]]

The Komodo dragon is a vulnerable species and is found on the [[IUCN Red List]].<ref>{{IUCN2006|assessors=World Conservation Monitoring Centre|year=1996|id=22884|title=Varanus komodoensis|downloaded=11 May 2006}}</ref> There are approximately 4,000–5,000 living Komodo dragons in the wild. Their populations are restricted to the islands of Gili Motang (100), Gili Dasami (100), Rinca (1,300), Komodo (1,700), and Flores (perhaps 2,000).<ref name="komo"/> However, there are concerns that there may presently be only 350 breeding females.<ref name="amnh" /> To address these concerns, the [[Komodo National Park]] was founded in 1980 to protect Komodo dragon populations on islands including Komodo, Rinca, and Padar.<ref name="knp">{{cite web |publisher=[[Komodo National Park]] |url=http://www.komodonationalpark.org/ |title=The official website of Komodo National Park, Indonesia. |accessdate=2007-02-02 |format= |work=}}</ref> Later, the Wae Wuul and Wolo Tado Reserves were opened on Flores to aid with Komodo dragon conservation.<ref name="natgeo"/> There is evidence that Komodo dragons are becoming accustomed to human presence, as they are often fed animal carcasses at several feeding stations by tourists.<ref name="world"/>

Volcanic activity, earthquakes, loss of habitat, fire (the population at Padar was almost destroyed because of a wildfire, and has since mysteriously disappeared),<ref name="natgeo">{{cite web |publisher=[[National Geographic]]|url=http://news.nationalgeographic.com/news/2003/01/0129_030129_komodo.html |title=Trapping Komodo Dragons for Conservation |accessdate=2007-11-08 |format= |work=}}</ref><ref name="location">{{cite book |author=Tara Darling (Illustrator) |title=Komodo Dragon: On Location (Darling, Kathy. on Location.) |publisher=Lothrop, Lee and Shepard Books |location= |year= |pages= |isbn=0-688-13777-6 |oclc= |doi=}}</ref> loss of prey, tourism, and poaching have all contributed to the vulnerable status of the Komodo dragon. Under Appendix I of [[CITES]] (the Convention on International Trade in Endangered Species), commercial trade of skins or specimens is illegal.<ref name="zipcode"/><ref>{{cite web |publisher=[[CITES]] |url=http://www.cites.org/eng/app/appendices.shtml |title=Appendices I, II and III |accessdate=2008-03-24 |format= |work=}}</ref>

The Australian biologist [[Tim Flannery]] has suggested that the Australian ecosystem may benefit from the introduction of Komodo dragons, as it could partially occupy the large-carnivore [[ecological niche|niche]] left vacant following the extinction of the giant varanid ''[[Megalania]]''. However, he argues for great caution and gradualness in these acclimatisation experiments, especially as "the problem of predation of large varanids upon humans should not be understated". He uses the example of the successful coexistence with [[saltwater crocodile]]s as evidence that Australians could successfully adjust.<ref>{{cite book |author=Flannery, Tim |title=The Future Eaters: An Ecological History of the Australian Lands and People |publisher=Grove Press |location=New York |year=2002 |pages=384–385 |isbn=0-8021-3943-4 |oclc= |doi= |accessdate=}}</ref>

Although attacks are very rare, Komodo dragons have been known to kill humans. On June 4, 2007, a Komodo dragon attacked an eight year old boy on Komodo Island. He later died of massive bleeding from his wounds. It was the first recorded fatal attack in 33 years.<ref>{{cite web |publisher=[[MSNBC]] |url=http://www.msnbc.msn.com/id/19026658/ |title=Komodo dragon kills boy in Indonesia |accessdate=2007-06-07 |format= |work=}}</ref> Natives blamed the attack on environmentalists who don't live on the island prohibiting goat sacrifices, causing the Komodo dragons to be denied their expected food source, causing them to wander into human territories in search of food. To the natives of Komodo Island, Komodo dragons are actually the reincarnation of fellow kinspeople, and are thus treated with reverence.<ref>{{cite news|publisher=Wall Street Journal|title=When Good Lizards Go Bad: Komodo Dragons Take Violent Turn |url=http://online.wsj.com/article/SB121963304805268235.html?mod=djemBestOfTheWeb|accessdate=2008-08-29}}</ref>

===In captivity===
[[Image:Komododragon2.jpg|thumb|right|Komodo dragon at [[Smithsonian National Zoological Park]]. Despite the visible earholes, Komodo dragons cannot hear very well.]]
Komodo dragons have long been great zoo attractions, where their size and reputation make them popular exhibits. They are, however, rare in zoos because they are susceptible to infection and parasitic disease if captured from the wild, and do not readily reproduce.<ref name="amnh" />

The first Komodo dragon was exhibited in 1934 at the [[Smithsonian National Zoological Park]], but it lived for only two years. More attempts to exhibit Komodo dragons were made, but the lifespan of these creatures was very short, averaging five years in the National Zoological Park. Studies done by Walter Auffenberg, which were documented in his book ''The Behavioral Ecology of the Komodo Monitor'', eventually allowed for more successful managing and reproducing of the dragons in captivity.<ref name="komo" />

It has been observed in captive dragons that many individuals display relatively tame behavior within a short period of time in captivity. Many occurrences are reported where keepers have brought the animals out of their enclosures to interact with zoo visitors, including young children, to no harmful effect.<ref name="procter">{{cite journal |last=Procter |first=J.B. |year=1928 |month=October |title=On a living Komodo Dragon ''Varanus komodoensis'' Ouwens, exhibited at the Scientific Meeting |journal=Proc. Zool. Soc. London |volume= |issue= |pages=1017–1019}}</ref><ref name="lederer">{{cite journal |last=Lederer |first=G. |year=1931 |month= |title=Erkennen wechselwarme Tiere ihren Pfleger? |journal=Wochenschr. Aquar.-Terrarienkunde |volume=28 |issue= |pages=636–638}}</ref> Dragons are also capable of recognizing individual humans. Ruston Hartdegen of the [[Dallas Zoo]] reported that their Komodo dragons reacted differently when presented with their regular keeper, a less familiar keeper, or a completely unfamiliar keeper.<ref name="dragons">{{cite journal |last=Murphy |first=J. |authorlink= |coauthors=T. Walsh |year=2006 |month= |title=Dragons and Humans |journal=Herpetological Review |volume=37 |issue= |pages=269–275}}</ref>

Research with captive Komodo dragons has also provided evidence that they engage in play. One study concerned an individual who would push a shovel left by its keeper, apparently attracted to the sound of it scraping across the rocky surface. A young female dragon at the [[National Zoo]] in Washington, D.C. would grab and shake various objects including statues, beverage cans, plastic rings and blankets. She would also insert her head into boxes, shoes, and other objects. She did not confuse these objects with food, as she would only swallow them if they were covered in rat blood. This social play has led to a striking comparison with mammalian play.<ref name="firefly" />

[[Image:KdragonT.zoo.jpg|thumb|left|Komodo dragons at [[Toronto Zoo]]. Komodo dragons in captivity often grow fat, especially in their tails, due to regular feeding.]]

Another documentation of play in Komodo dragons comes from the [[University of Tennessee]], where a young Komodo dragon named "Kraken" interacted with plastic rings, a shoe, a bucket, and a tin can by nudging them with her snout, swiping at them, and carrying them around in her mouth. She treated all of them differently than her food, prompting leading researcher Gordon Burghardt to conclude that they disprove the view of object play being "food-motivated predatory behavior." Kraken was the first Komodo dragon hatched in captivity outside of Indonesia, born in the [[National Zoo]] on [[September 13]], [[1992]].<ref>{{cite journal |title=Such jokers, those Komodo dragons |journal=Science News | volume =78 |issue =1 |pages=78 |year=2002 |month=August |quote= }}</ref><ref name="sciam"/>

Even seemingly docile dragons may become aggressive unpredictably, especially when the animal's territory is invaded by someone unfamiliar. In June 2001, a Komodo dragon seriously injured [[Phil Bronstein]]—executive editor of the ''[[San Francisco Chronicle]]''—when he entered its enclosure at the [[Los Angeles Zoo]] after being invited in by its keeper. Bronstein was bitten on his bare foot, as the keeper had told him to take off his white shoes, which could have potentially excited the Komodo dragon.<ref>{{cite web |publisher=[[Time (magazine)|Time]] |url=http://www.time.com/time/sampler/article/0,8599,133163,00.html |title=Transcript: Sharon Stone vs. the Komodo Dragon |accessdate=2008-03-20 |format= |work=}}</ref><ref>{{cite book |author=Phillip T. Robinson |title=Life at the Zoo: Behind the Scenes with the Animal Doctors |publisher=Columbia University Press |location=New York |year=2004 |page=79 |isbn=0-231-13248-4 |oclc= |doi=}}</ref> Although he escaped, he needed to have several tendons in his foot reattached surgically.<ref>{{cite web |publisher=[[San Francisco Chronicle]] |url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2001/06/11/MN204069.DTL |title=Editor stable after attack by Komodo dragon / Surgeons reattach foot tendons of Chronicle's Bronstein in L.A. |accessdate=2008-03-23 |format= |work=}}</ref>

==See also==
{{portal|Indonesia}}
{{portal|Amphibians and Reptiles}}
* [[Dragon]]
* ''[[Megalania|Varanus priscus]]'' (formerly known as ''Megalania prisca'') – A huge extinct varanid lizard of [[Pleistocene]] Australia
* [[Papua monitor]] (''Varanus salvadorii'') – A monitor lizard often asserted to be the longest lizard
* [[Toxicofera]] – A hypothetical [[clade]] encompassing all venomous reptiles, including the Komodo dragon
* [[Cnemidophorus|Whiptail lizards]] – Lizards widely studied for their parthenogenesis

==References==
{{reflist|colwidth=30em}}

==Further reading==
{{commons|Varanus komodoensis}}
{{wikispecies|Varanus komodoensis}}
*{{cite book |author=Attenborough, David |title=Zoo Quest for a Dragon|publisher=Lutterworth Press|location=London |year=1957 |pages= |isbn= |oclc= |doi=}}
*{{cite book |author=Auffenberg, Walter |title=The Behavioral Ecology of the Komodo Monitor |publisher=University Presses of Florida |location=Gainesville |year=1981 |pages= |isbn=0-8130-0621-X |oclc= |doi=}}
*{{cite book |author=Burden, W. Douglas |title=Dragon Lizards of Komodo: An Expedition to the Lost World of the Dutch East Indies |publisher=Kessinger Publishing |location= |year=1927 |pages= |isbn=0-7661-6579-5 |oclc= |doi=}}
*{{cite book |author=Eberhard, Jo; King, Dennis; Green, Brian; Knight, Frank; Keith Newgrain |title=Monitors: The Biology of Varanid Lizards |publisher=Krieger Publishing Company |location=Malabar, Fla |year=1999 |pages= |isbn=1-57524-112-9 |oclc= |doi=}}
*{{cite book |author=Lutz, Richard L; Lutz, Judy Marie |title=Komodo: The Living Dragon |publisher=DiMI Press |location=Salem, Or |year=1997 |pages= |isbn=0-931625-27-0 |oclc= |doi=}}

{{featured article}}
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[[Category:Monitor lizards]]
[[Category:Reptiles of Indonesia]]
[[Category:Vertebrate parthenogenesis]]
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[[Category:Megafauna of Eurasia]]
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[[ar:تنين كومودو]]
[[bg:Комодски варан]]
[[bs:Komodski varan]]
[[ca:Dragó de Komodo]]
[[cs:Varan komodský]]
[[da:Komodovaran]]
[[de:Komodowaran]]
[[es:Varanus komodoensis]]
[[eo:Komoda varano]]
[[eu:Komodoko dragoi]]
[[fr:Dragon de Komodo]]
[[ko:코모도왕도마뱀]]
[[hr:Komodski varan]]
[[id:Biawak Komodo]]
[[it:Varanus komodoensis]]
[[he:דרקון קומודו]]
[[lv:Komodo varāns]]
[[lt:Komodo varanas]]
[[hu:Komodói sárkány]]
[[ml:കൊമോഡോ ഡ്രാഗണ്‍]]
[[ms:Biawak komodo]]
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[[ja:コモドオオトカゲ]]
[[no:Komodovaran]]
[[pl:Waran z Komodo]]
[[pt:Dragão-de-komodo]]
[[ru:Комодский варан]]
[[simple:Komodo dragon]]
[[sk:Varan komodský]]
[[sl:Komodoški varan]]
[[sr:Komodo zmaj]]
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[[sv:Komodovaran]]
[[vi:Komodo]]
[[tg:Калтакалос]]
[[zh-yue:科莫多巨蜥]]
[[zh:科莫多龍]]

Revision as of 18:02, 14 November 2008

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