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The Komodo dragon (Varanus komodoensis), also known as the Komodo monitor, is a large reptile of the monitor lizard family Varanidae that is endemic to the Indonesian islands of Komodo, Rinca, Flores, Gili Dasami, and Gili Motang. The largest extant population lives within the Komodo National Park in Eastern Indonesia.<ref>Template:Cite journal</ref> It is the largest extant species of lizard, with the males growing to a maximum length of Template:Cvt and weighing up to Template:Cvt.
As a result of their size, Komodo dragons are apex predators, and dominate the ecosystems in which they live. Komodo dragons hunt and ambush prey including invertebrates, birds, and mammals. Komodo dragons' group behavior in hunting is exceptional in the reptile world. The diet of Komodo dragons mainly consists of Javan rusa (Rusa timorensis), though they also eat considerable amounts of carrion. Komodo dragons also occasionally attack humans.
Mating begins between May and August, and the eggs are laid in September; as many as 20 eggs are deposited at a time in an abandoned megapode nest or in a self-dug nesting hole. The eggs are incubated for seven to eight months, hatching in April, when insects are most plentiful. Young Komodo dragons are vulnerable and dwell in trees to avoid predators, such as cannibalistic adults, which young Komodo dragons also try to repel by rolling in feces. They take 8 to 9 years to mature and are estimated to live up to 30 years.
Komodo dragons were first recorded by Western scientists in 1910. Their large size and fearsome reputation make them popular zoo exhibits. In the wild, their range has been reduced by human encroachment and is likely to contract further from the effects of climate change; hence, they are listed as Endangered by the IUCN Red List. They are protected under Indonesian law, and Komodo National Park was founded in 1980 to aid protection efforts.
TaxonomyEdit
Komodo dragons were first documented by Europeans in 1910, when rumors of a "land crocodile" reached Lieutenant van Steyn van Hensbroek of the Dutch colonial administration.<ref name="sciam"/> Widespread notoriety came after 1912, when Peter Ouwens, the director of the Zoological Museum of Bogor, 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="Ouwens1912"/>
The first two live Komodo dragons to arrive in Europe were exhibited in the Reptile House at London Zoo when it opened in 1927.<ref>Template:Cite news</ref> Joan Beauchamp Procter made some of the earliest observations of these animals in captivity and she demonstrated their behaviour at a scientific meeting of the Zoological Society of London in 1928.<ref>Template:Cite journal</ref>
The Komodo dragon was the driving factor for an expedition to Komodo Island by W. Douglas Burden in 1926. After returning with 12 preserved specimens and two live ones, this expedition provided the inspiration for the 1933 movie King Kong.<ref>Template:Cite book</ref> It was also Burden who coined the common name "Komodo dragon".<ref name="gateway-faq">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Three of his specimens were stuffed and are still on display in the American Museum of Natural History.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The Dutch island administration, realizing the limited number of individuals in the wild, soon 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">Template:Cite journal</ref>
Research from the Auffenberg expedition proved enormously influential in raising Komodo dragons in captivity.<ref name="komo">Template:Cite book</ref> Research after that of 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"/>
EtymologyEdit
The Komodo dragon is also sometimes known as the Komodo monitor or the Komodo Island monitor in scientific literature,<ref name="itis">{{#if:202168 | {{#invoke:template wrapper|wrap|_template=cite web|_exclude=id,ID,taxon
| url = https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=202168 | title = Varanus komodoensis | publisher = Integrated Taxonomic Information System }}
| Template:Citation error }}</ref> although these names are uncommon. To the natives of Komodo Island, it is referred to as ora, buaya darat ('land crocodile'), or biawak raksasa ('giant monitor').<ref name="amnh">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="sciam"/>
Evolutionary historyEdit
Genetic analysis of mitochondrial DNA shows the Komodo dragon to be the closest relative (sister taxon) of the Australian lace monitor (V. varius), with their common ancestor diverging from a lineage that gave rise to the crocodile monitor (Varanus salvadorii) of New Guinea.<ref>Template:Cite journal</ref><ref name="fitchetal2006">Template:Cite journal</ref><ref>Template:Cite journal; Template:Cite journal</ref> A 2021 study showed that during the late Miocene, the ancestors of Komodo dragons had hybridized with the common ancestor of Australian sand monitors (V. spenceri, V. gouldii, V. rosenbergi and V. panoptes).<ref>Template:Cite journal</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Fossils from across Queensland demonstrate that the Komodo dragon was once present in Australia, with fossils spanning from the Early Pliocene (~3.8 million years ago) to the Middle Pleistocene,<ref name="aust">Template:Cite journal</ref> with the youngest confirmed records of the species in Australia dating to at latest 330,000 years ago. In Australia, it coexisted with the even larger monitor species Varanus priscus also known as megalania, the largest terrestrial lizard ever.<ref>Template:Cite journal</ref> The oldest records of the Komodo dragon on Flores date to around 1.4 million years ago, during the Early Pleistocene.<ref>Template:Cite journal</ref> Additionally, Pleistocene fossils of Varanus found in Java and Timor may belong to the Komodo dragon.<ref>Template:Cite journal</ref>
DescriptionEdit
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In the wild, adult Komodo dragons usually weigh around Template:Cvt, although captive specimens often weigh more.<ref name="animal" /> According to Guinness World Records, an average adult male will weigh Template:Cvt and measure Template:Cvt, while an average female will weigh Template:Cvt and measure Template:Cvt.<ref name = "Wood">Template:Cite book</ref> The largest verified specimen in captivity was Template:Cvt long and weighed Template:Cvt, including its undigested food.<ref name="sciam">Template:Cite journal</ref> The largest wild specimen had a length Template:Cvt, a snout-vent length (SVL) Template:Cvt and a mass of Template:Cvt excluding stomach contents.<ref name="″IDiPSSACPUEATCIFKD″">Template:Cite journal</ref><ref name="TLMl">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The heaviest reached a mass of Template:Cvt.<ref name="″IDiPSSACPUEATCIFKD″" /> The study noted that weights greater than Template:Cvt were possible but only after the animal had consumed a large meal.<ref name="″IDiPSSACPUEATCIFKD″" /><ref name="TLMl" />
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 Template:Cvt in length. Its saliva is frequently blood-tinged because its teeth are almost completely covered by gingival tissue that is naturally lacerated during feeding.<ref name="location"/> It also has a long, yellow, deeply forked tongue.<ref name="sciam"/> Komodo dragon skin is reinforced by armoured scales, which contain tiny bones called osteoderms that function as a sort of natural chain-mail.<ref> Komodo Dragons Template:Webarchive . London Zoo </ref><ref> Komodo Dragon, Varanus komodoensis 1998. Physical Characteristics Template:Webarchive . San Diego Zoo Global Zoo (1998). </ref> The only areas lacking osteoderms on the head of the adult Komodo dragon are around the eyes, nostrils, mouth margins, and parietal eye, a light-sensing organ on the top of the head. Where lizards typically have one or two varying patterns or shapes of osteoderms, komodos have four: rosette, platy, dendritic, and vermiform.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> This rugged hide makes Komodo dragon skin a poor source of leather. Additionally, these osteoderms become more extensive and variable in shape as the Komodo dragon ages, ossifying more extensively as the lizard grows. These osteoderms are absent in hatchlings and juveniles, indicating that the natural armor develops as a product of age and competition between adults for protection in intraspecific combat over food and mates.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
MorphologyEdit
DentitionEdit
Komodo dragons have ziphodont teeth, which are defined as teeth that are laterally flattened, recurved, and with serrated tooth crowns where the serrations have a dentine core and a very thin enamel outer layer. This is the same type of dentition observed in many extinct theropod dinosaurs.<ref>D’Amore, D. C., Moreno, K., McHenry, C. R., & Wroe, S. (2011). The effects of biting and pulling on the forces generated during feeding in the Komodo dragon (Varanus komodoensis). PloS One, 6(10), e26226–e26226. https://doi.org/10.1371/journal.pone.0026226</ref><ref name=":0" /> The teeth of the insectivorous juveniles in contrast are barely recurved, with fewer and less well-developed serrations that lack dentine cores.<ref name=":1">Template:Cite journal</ref>
A 2024 study published in Nature Ecology & Evolution found that Komodo dragons have orange, iron-enriched coatings on their tooth serrations and tips, as an adaptation for maintaining the sharp cutting edges. This feature is also observed to a lesser degree in a few other Australasian to Asian monitor species, though notably absent in a few other species from that range.<ref name=":0">Template:Cite journal</ref>
Teeth are quickly replaced every 40 days, while maintaining up to 5 replacement teeth for each tooth position at any given time. This high rate of replacement and large number of replacement teeth is similar to that of the crocodile monitor. Many other monitor species as well as Chinese crocodile lizards and beaded lizards only have 1-2 replacement teeth behind each tooth position.<ref name=":1" />
SensesEdit
As with other varanids, Komodo dragons have only a single ear bone, the stapes, for transferring vibrations from the tympanic membrane to the cochlea. This arrangement means they are likely restricted to sounds in the 400 to 2,000 hertz range, compared to humans who hear between 20 and 20,000 hertz.<ref name="sciam"/><ref name="bbc">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> They were 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 London Zoo employee Joan Procter 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">Template:Cite book</ref>Template:Rp
The Komodo dragon can see objects as far away as Template:Cvt, but because its retinas only contain cones, it is thought to have poor night vision. It can distinguish colours, but has poor visual discrimination of stationary objects.<ref name="nzpfactsheet">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
As with many other reptiles, the Komodo dragon primarily relies on its tongue to detect, taste, and smell stimuli, with the vomeronasal sense using the Jacobson's organ, rather than using the nostrils.<ref name="docent">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> With the help of a favorable wind and its habit of swinging its head from side to side as it walks, a Komodo dragon may be able to detect carrion from Template:Cvt away.<ref name="nzpfactsheet"/> Their tongue-flicking behavior is similar to that of snakes.<ref>Template:Cite journal</ref> It only has a few taste buds in the back of its throat.<ref name="docent"/> Its scales, some of which are reinforced with bone, have sensory plaques connected to nerves to 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"/>
Behaviour and ecologyEdit
The Komodo dragon prefers hot and dry places and typically lives in dry, open grassland, savanna, and tropical forest at low elevations. As an ectotherm, it is most active in the day, although it exhibits some nocturnal activity. Komodo dragons are solitary, coming together only to breed and eat. There are some "personality" differences among the species, where some present as more "shy", particularly females.<ref> Laver RJ, Purwandana D, Ariefiandy A, Imansyah J, Forsyth D, et al. (2012) Life-History and Spatial Determinants of Somatic Growth Dynamics in Komodo Dragon Populations. PLOS ONE 7(9): e45398. https://doi.org/10.1371/journal.pone.0045398</ref> They are capable of running rapidly in brief sprints up to Template:Cvt, diving up to Template:Cvt, and climbing trees proficiently when young through use of their strong claws.<ref name="animal">Template:Cite book</ref> To catch out-of-reach prey, the Komodo dragon may stand on its hind legs and use its tail as a support.<ref name="liz"/>Template:Rp As it matures, its claws are used primarily as weapons, as its great size makes climbing impractical.<ref name="location"/> Template:Multiple image For shelter, the Komodo dragon digs holes that can measure from Template:Cvt wide with its powerful forelimbs and claws.<ref name="cogger">Template:Cite book</ref> Because of its large size and habit of sleeping in these burrows, it is able to conserve body heat throughout the night and minimise its basking period the morning after.<ref>Template:Cite book</ref> The Komodo dragon stays in the shade during the hottest part of the day and hunts in the afternoon.<ref name="gateway-faq"/> These special resting places, usually located on ridges with cool sea breezes, are marked with droppings and are cleared of vegetation. They serve as strategic locations from which to ambush deer.<ref name="southsea"/>
DietEdit
Komodo dragons are apex predators.<ref name="firefly" /> They are carnivores; although they have been considered as eating mostly carrion,<ref name="world">Template:Cite book</ref> they will frequently ambush live prey with a stealthy approach. When suitable prey arrives near a dragon's ambush site, it will suddenly charge at the animal at high speeds and go for the underside or the throat.<ref name="location" /> The majority of the extant Komodo dragon population's diet is made up of introduced ungulates, such as deer, pigs, and buffalo. <ref>Shine, Richard; Somaweera, Ruchira (April 2019). "Last lizard standing: The enigmatic persistence of the Komodo dragon". Global Ecology and Conservation. 18: e00624. Bibcode:2019GEcoC..1800624S. doi:10.1016/j.gecco.2019.e00624.</ref>
Komodo dragons do not deliberately allow the prey to escape with fatal injuries but try to kill prey outright using a combination of lacerating damage and blood loss. They have been recorded as killing wild pigs within seconds,<ref name=auffenberg1>Template:Cite book</ref> and observations of Komodo dragons tracking prey for long distances are likely misinterpreted cases of prey escaping an attack before succumbing to infection. Most prey attacked by a Komodo dragon reputedly suffer from said sepsis and will later be eaten by the same or other lizards.<ref>Template:Cite journal</ref>
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 skulls, and expandable stomachs allow them to swallow prey whole. The undigested vegetable contents of a prey animal's stomach and intestines are typically avoided.<ref name="southsea"/> Copious amounts of red saliva the Komodo dragons produce help to lubricate the food, but swallowing is still a long process (15–20 minutes to swallow a goat). A Komodo dragon 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"/> A small tube under the tongue that connects to the lungs allows it to breathe while swallowing.<ref name="location"/>
After eating up to 80% of its body mass in one meal,<ref name="firefly">Template:Cite book</ref> it drags itself to a sunny location to speed digestion, as the food could rot and poison the dragon if left undigested in its stomach for too long. Because of their slow metabolism, large dragons can survive on as few 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.<ref name="location"/>
The eating habits of Komodo dragons follow a hierarchy, with the larger animals generally eating before the smaller ones. The largest male typically 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 they have been known to be killed and eaten by victors.<ref name=auffenberg/><ref>Template:Cite book</ref>
The Komodo dragon's diet varies depending on stage of growth. Young Komodo dragons will eat insects, birds and bird's eggs and small reptiles, while larger Komodo dragons (typically over Template:Cvt) prefer large ungulate prey, such as Javan rusa deer, wild pigs and water buffalo.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> Occasionally, they attack and bite humans. Sometimes they consume human corpses, digging up bodies from shallow graves.<ref name="liz"/>Template:Rp 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">Template:Cite book</ref> Dwarf species of Stegodon (a proboscidean related to living elephants) are suggested to have been a primary prey item of the Komodo dragon during the Pleistocene, prior to the introduction of their modern ungulate prey, which were only introduced to the islands in the Holocene, around 10-7,000 years ago.<ref name="Diamond2">Template:Cite journal</ref><ref>Template:Cite journal</ref>
The Komodo dragon drinks by sucking water into its mouth via buccal pumping (a process also used for respiration), lifting its head, and letting the water run down its throat.<ref name=auffenberg1/>
SalivaEdit
Although previous studies proposed that Komodo dragon saliva contains a variety of highly septic bacteria that would help to bring down prey,<ref name="auffenberg">Template:Cite book</ref><ref name="Aerobic">Template:Cite journal</ref> research in 2013 suggested that the bacteria in the mouths of Komodo dragons are ordinary and similar to those found in other carnivores. Komodo dragons have good mouth hygiene. To quote Bryan Fry: "After they are done feeding, they will spend 10 to 15 minutes lip-licking and rubbing their head in the leaves to clean their mouth ... Unlike people have been led to believe, they do not have chunks of rotting flesh from their meals on their teeth, cultivating bacteria." They do have a slashing bite, which normally includes a dose of their neurotoxic venom and anticoagulant saliva.<ref>D’Amore, D. C., Moreno, K., McHenry, C. R., & Wroe, S. (2011). The effects of biting and pulling on the forces generated during feeding in the Komodo dragon (Varanus komodoensis). PloS One, 6(10), e26226–e26226. https://doi.org/10.1371/journal.pone.0026226</ref> Komodo dragons do not wait for prey to die and track it at a distance, as vipers do; observations of them hunting deer, boar and in some cases buffalo reveal that they kill prey in less than half an hour.<ref name="Goldstein paper">Template:Cite journal</ref>
The observation of prey dying of sepsis would then be explained by the natural instinct of water buffalos, which are not native to the islands where the Komodo dragon lives, to run into water after escaping an attack. The warm, faeces-filled water would then cause the infections. The study used samples from 16 captive dragons (10 adults and six neonates) from three US zoos.<ref name="Goldstein paper"/>
Antibacterial immune factorEdit
Researchers have isolated a powerful antibacterial peptide, VK25, from the blood plasma of Komodo dragons. Based on their analysis of this peptide, they have synthesized a short peptide dubbed DRGN-1 and tested it against multidrug-resistant (MDR) pathogens. Preliminary results of these tests show that DRGN-1 is effective in killing drug-resistant bacterial strains and even some fungi. It has the added observed benefit of significantly promoting wound healing in both uninfected and mixed biofilm infected wounds.<ref>Template:Cite journal</ref>
Disputed claims of venomEdit
In late 2005, researchers at the University of Melbourne speculated that the perentie (Varanus giganteus), other species of monitors, and agamids may be somewhat venomous. The team believes 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. timorensis) all produced similar effects: rapid swelling, localised disruption of blood clotting, and shooting pain up to the elbow, with some symptoms lasting for several hours.<ref name="Fry2006">Template:Cite journal</ref>
In 2009, the same researchers published further evidence demonstrating that Komodo dragons possess a venomous bite. MRI scans of a preserved skull showed the presence of two glands in the lower jaw. The researchers extracted one of these glands from the head of a terminally ill dragon in the Singapore Zoological Gardens, and found it secreted several different toxic proteins. The known functions of these proteins include inhibition of blood clotting, lowering of blood pressure, muscle paralysis, and the induction of hypothermia, leading to shock and loss of consciousness in envenomated prey.<ref>Scientists discover deadly secret of Komodo's bite, AFP, 19 May 2009</ref><ref name=fry>Template:Cite journal</ref> As a result of the discovery, the previous theory that bacteria were responsible for the deaths of Komodo victims was disputed.<ref>Staff. "Komodo dragons kill with venom, not bacteria, study says". CNN. 20 May 2009. Retrieved on 25 May 2009.</ref>
Other scientists have stated that this allegation of venom glands "has had the effect of underestimating the variety of complex roles played by oral secretions in the biology of reptiles, produced a very narrow view of oral secretions and resulted in misinterpretation of reptilian evolution." According to these scientists "reptilian oral secretions contribute to many biological roles other than to quickly dispatch prey." These researchers concluded, "Calling all in this clade venomous implies an overall potential danger that does not exist, misleads in the assessment of medical risks, and confuses the biological assessment of squamate biochemical systems."<ref name="Mackessy2009">Template:Cite book</ref> Evolutionary biologist Schwenk says that even if the lizards have venom-like proteins in their mouths they may be using them for a different function, and he doubts venom is necessary to explain the effect of a Komodo dragon bite, arguing that shock and blood loss are the primary factors.<ref name="Schwenk">Template:Cite news</ref><ref>Template:Cite news</ref> As of 2023, no clear unambiguous evidence of Komodo dragon bites being venomous has been presented.<ref>Template:Cite journal</ref>
ReproductionEdit
Mating occurs between May and August, with the eggs laid in September.<ref name="sciam"/><ref name="ciofi2004"/> 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">{{#invoke:citation/CS1|citation |CitationClass=web }}</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"/> In order to avoid inbreeding, females actively select distantly related male sperm.<ref>M. Olsson, R. Shine, A. Gullberg, T. Madsen, H. TegelströmFemale lizards control paternity of their offspring by selective use of sperm. Nature, 383 (1996), p. 585 </ref>
Female Komodos lay their eggs from August to September and may use several types of locality; in one study, 60% laid their eggs in the nests of orange-footed scrubfowl (a moundbuilder or megapode), 20% on ground level and 20% in hilly areas.<ref name="Jakarta" /> The females make many camouflage nests/holes to prevent other dragons from eating the eggs.<ref>Template:Cite journal</ref> Nests typically house one female, however a study found evidence of two females occasionally occupying the same den.<ref>Template:Cite journal</ref> Clutches contain an average of 20 eggs, which have an incubation period of 7–8 months.<ref name="liz"/> Hatching is an exhausting effort for the neonates, which break out of their eggshells with an egg tooth that falls off before long. After cutting themselves out, the hatchlings may lie in their eggshells for hours before starting to dig out of the nest. They are born quite defenseless and are vulnerable to predation.<ref name=auffenberg/> Sixteen youngsters from a single nest were on average 46.5 cm long and weighed 105.1 grams.<ref name="Jakarta">Template:Cite news</ref>
Young Komodo dragons spend much of their first few years in trees, where they are relatively safe from predators, including cannibalistic adults, as juvenile dragons make up 10% of their diets.<ref name="liz"/> 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">Template:Cite book</ref> When the young approach a kill, they roll around in faecal matter and rest in the intestines of eviscerated animals to deter these hungry adults.<ref name="liz"/> Komodo dragons take approximately 8 to 9 years to mature, and may live for up to 30 years.<ref name="ciofi2004">Template:Cite book</ref>
ParthenogenesisEdit
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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 she had been able to store sperm from her earlier encounter with a male, an adaptation known as superfecundation.<ref>Template:Cite news</ref> On 20 December 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 unfertilised eggs: she laid 11 eggs, and seven 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 Flora had never been in physical contact with a male dragon. After Flora's eggs' condition had been discovered, testing showed Sungai's eggs were also produced without outside fertilization.<ref>Template:Cite news</ref> On 31 January 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 19–20 May 2007. Only two eggs were incubated and hatched due to space issues; the first hatched on 31 January 2008, while the second hatched on 1 February. Both hatchlings were males.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Komodo dragons have the ZW chromosomal sex-determination system, as opposed to the mammalian XY system. Male progeny prove 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">Template:Cite news</ref><ref>Template:Cite magazine</ref> meaning that only males are produced by parthenogenesis in this species.
It has been hypothesised 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">Template:Cite journal</ref>
Encounters with humansEdit
Attacks on humans are rare, but Komodo dragons have been responsible for several human fatalities, both in the wild and in captivity. According to data from Komodo National Park spanning a 38-year period between 1974 and 2012, there were 24 reported attacks on humans, five of them fatal. Most of the victims were local villagers living around the national park.<ref>Template:Cite news</ref>
ConservationEdit
The Komodo dragon is classified by the IUCN as Endangered and is listed on the IUCN Red List.<ref name="IUCN" /> The species' sensitivity to natural and human-made threats has long been recognized by conservationists, zoological societies, and the Indonesian government. Komodo National Park was founded in 1980 to protect Komodo dragon populations on islands including Komodo, Rinca, and Padar.<ref name="knp">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Later, the Wae Wuul and Wolo Tado Reserves were opened on Flores to aid Komodo dragon conservation.<ref name="natgeo"/>
Komodo dragons generally avoid encounters with humans. Juveniles are very shy and will flee quickly into a hideout if a human comes closer than about Template:Convert. Older animals will also retreat from humans from a shorter distance away. If cornered, they may react aggressively by gaping their mouth, hissing, and swinging their tail. If they are disturbed further, they may attack and bite. Although there are anecdotes of unprovoked Komodo dragons attacking or preying on humans, most of these reports are either not reputable or have subsequently been interpreted as defensive bites. Only very few cases are truly the result of unprovoked attacks by atypical individuals who lost their fear of humans.<ref name="auffenberg"/>
Volcanic activity, earthquakes, loss of habitat, fire,<ref name="location">Template:Cite book</ref><ref name="natgeo">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> tourism, loss of prey due to poaching, and illegal poaching of the dragons themselves have all contributed to the vulnerable status of the Komodo dragon. A major future threat to the species is climate change via both aridification and sea level rise, which can affect the low-lying habitats and valleys that the Komodo dragon depends on, as Komodo dragons do not range into the higher-altitude regions of the islands they inhabit. Based on projections, climate change will lead to a decline in suitable habitat of 8.4%, 30.2%, or 71% by 2050 depending on the climate change scenario. Without effective conservation actions, populations on Flores are extirpated in all scenarios, while in the more extreme scenarios, only the populations on Komodo and Rinca persist in highly reduced numbers. Rapid climate change mitigation is crucial for conserving the species in the wild.<ref name="IUCN"/><ref>Template:Cite journal</ref> Other scientists have disputed the conclusions about the effects of climate change on Komodo dragon populations.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Under Appendix I of CITES (the Convention on International Trade in Endangered Species), commercial international trade of Komodo dragon skins or specimens is prohibited.<ref name="zipcode">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Despite this, there are occasional reports of illegal attempts to trade in live Komodo dragons. The most recent attempt was in March 2019, when Indonesian police in the East Java city of Surabaya reported that a criminal network had been caught trying to smuggle 41 young Komodo dragons out of Indonesia. The plan was said to include shipping the animals to several other countries in Southeast Asia through Singapore. It was hoped that the animals could be sold for up to 500 million rupiah (around US$35,000) each.<ref>'Police foil attempt to export Komodo dragons for Rp 500 million apiece', The Jakarta Post, 28 March 2019.</ref> It was believed that the Komodo dragons had been smuggled out of East Nusa Tenggara province through the port at Ende in central Flores.<ref>Markus Makur, 'Lax security at Flores ports allows Komodo dragon smuggling', The Jakarta Post, 9 April 2019.</ref>
In 2013, the total population of Komodo dragons in the wild was assessed as 3,222 individuals, declining to 3,092 in 2014 and 3,014 in 2015. Populations remained relatively stable on the bigger islands (Komodo and Rinca), but decreased on smaller islands, such as Nusa Kode and Gili Motang, likely due to diminishing prey availability.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> On Padar, a former population of Komodo dragons has recently become extirpated, of which the last individuals were seen in 1975.<ref name=Lilley1995>Template:Cite thesis</ref> It is widely assumed that the Komodo dragon died out on Padar following a major decline of populations of large ungulate prey, for which poaching was most likely responsible.<ref name=SDZ>Template:Cite report</ref>
Since the species is only found in remnant populations in the Wallacean Island, studies have examined the traits and factors that led to these certain populations’ surprising persistence. A comprehensive examination of the species survival suggested that rather than being a single attribute, but the a combination including ectotherm traits, varanid biology, habitat, and anthropogenic factors.<ref>Shine, Richard; Somaweera, Ruchira (April 2019). "Last lizard standing: The enigmatic persistence of the Komodo dragon". Global Ecology and Conservation. 18: e00624. Bibcode:2019GEcoC..1800624S.</ref>
In captivityEdit
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Komodo dragons have long been sought-after 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 in captivity.<ref name="amnh" /> A pair of Komodo dragons was displayed at the Bronx Zoo in New York in September 1926, but they only lasted a couple of months, dying in October and November 1926.<ref name="barnard">Template:Cite journal</ref> The first Komodo dragons were displayed at London Zoo in 1927. A Komodo dragon was exhibited in 1934 in the United States at the National Zoo in Washington, D.C., but it lived for only two years. More attempts to exhibit Komodo dragons were made, but the lifespan of the animals in captivity at the time proved very short, averaging five years in the National Zoological Park. Studies were done by Walter Auffenberg, which were documented in his book The Behavioral Ecology of the Komodo Monitor, eventually allowing for more successful management and breeding of the dragons in captivity.<ref name="komo" /> Surabaya Zoo in Indonesia has been breeding Komodo dragons since 1990 and had 134 dragons in 2022, the largest collection outside its natural habitat.<ref>Template:Cite news</ref> As of May 2009, there were 35 North American, 13 European, one Singaporean, two African, and two Australian institutions which housed captive Komodo dragons.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In 2016, four Komodo dragons were transferred from Bronx zoo to Madras Crocodile Bank Trust in India.<ref>Template:Cite news</ref>
A variety of behaviors have been observed from captive specimens. Most individuals become relatively tame within a short time,<ref name="procter">Template:Cite journal</ref><ref name="lederer">Template:Cite journal</ref> and are capable of recognising individual humans and discriminating between familiar and unfamiliar keepers.<ref name="dragons">Template:Cite journal</ref> Komodo dragons have also been observed to engage in play with a variety of objects, including shovels, cans, plastic rings, and shoes. This behavior does not seem to be "food-motivated predatory behavior".<ref name="firefly" /><ref name="sciam"/><ref>Template:Cite journal</ref>
Even seemingly docile dragons may become unpredictably aggressive, especially when the animal's territory is invaded by someone unfamiliar. In June 2001, a Komodo dragon seriously injured Phil Bronstein, the then-husband of actress Sharon Stone, 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 and socks, which the keeper stated could potentially excite the Komodo dragon as they were the same colour as the white rats the zoo fed the dragon.<ref>Template:Cite magazine</ref><ref>Template:Cite book</ref> Although he survived, Bronstein needed to have several tendons in his foot reattached surgically.<ref>Template:Cite news</ref>
See alsoEdit
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