56-607: Hydrosaurus giganteus , Gray The perentie ( Varanus giganteus ) is a species of monitor lizard . It is one of the largest living lizards on earth , after the Komodo dragon , Asian water monitor , and the Crocodile monitor . Found west of the Great Dividing Range in the arid areas of Australia, it is rarely seen, because of its shyness and the remoteness of much of its range from human habitation. The species
112-480: A top predator or superpredator , is a predator at the top of a food chain , without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics , meaning that they occupy the highest trophic levels . Food chains are often far shorter on land, usually limited to being secondary consumers – for example, wolves prey mostly upon large herbivores (primary consumers), which eat plants (primary producers). The apex predator concept
168-566: A 96.7% plant-based diet) and 2.57 (for Iceland , with 50% meat and fish, 50% plants). These values are comparable to those of non-apex predators such as the anchovy or pig . However, Peter D. Roopnarine criticized Bonhommeau's approach in 2014, arguing that humans are apex predators and that the HTL was based on terrestrial farming where indeed humans have a low trophic level, mainly eating producers (crop plants at level 1) or primary consumers (herbivores at level 2), which as expected places humans at
224-423: A burrow for shelter in only minutes. Their long claws enable them to climb trees easily. They often stand on their back legs and tails to gain a better view of the surrounding terrain. This behavior, known as " tripoding ", is quite common in monitor species. Perenties are fast sprinters and can run using either all four legs or just their hind legs. Typical of most goannas, the perentie either freezes (lying flat on
280-567: A complete picture. However, indirect evidence such as the absence of any discernible predator in an environment is suggestive. Anomalocaris was an aquatic apex predator, in the Cambrian. Its mouthparts are clearly predatory, and there were no larger animals in the seas at that time. Carnivorous theropod dinosaurs including Allosaurus and Tyrannosaurus are theorized to have been apex predators, based on their size, morphology, and dietary needs. A Permian shark, Triodus sessilis ,
336-455: A high aerobic scope that is afforded, in part, by their heart anatomy. Whereas most reptiles are considered to have three-chambered hearts, the hearts of monitor lizards – as with those of boas and pythons – have a well developed ventricular septum that completely separates the pulmonary and systemic sides of the circulatory system during systole . This allows monitor lizards to create mammalian-equivalent pressure differentials between
392-524: A large number of sea turtle eggs and hatchlings and hide under vehicles to ambush scavenging gulls. Mammalian prey includes bats, young kangaroos other small marsupials, and rodents. They have also been occasionally seen foraging for food in shallow water. They are able to kill kangaroos and dismember those too large to be swallowed whole using their powerful forelimbs and claws. Although adults feed predominantly on vertebrate prey, young perenties eat mostly arthropods, especially grasshoppers and centipedes. Prey
448-2150: A large number of slightly related local names for them. They are usually known as biawak ( Malay , including Indonesian standard variety), bayawak ( Filipino ), binjawak or minjawak or nyambik ( Javanese ), or variations thereof. Other names include hokai ( Solomon Islands ); bwo , puo , or soa ( Maluku ); halo ( Cebu ); galuf or kaluf ( Micronesia and the Caroline Islands ); batua or butaan ( Luzon ); alu ( Bali ); hora or ghora ( Komodo group of islands); phut ( Burmese ); and guibang ( Manobo ). In South Asia , they are known as hangkok in Meitei , mwpou in Boro, ghorpad घोरपड in Marathi , uḍumbu உடும்பு in Tamil and udumbu ഉടുമ്പ് in Malayalam , bilgoh in Bhojpuri , gohi (गोहि) in Maithili , in Sinhala as තලගොයා / කබරගොයා ( talagoya [land monitor] / kabaragoya [water monitor where kabara means vitiligo] ), in Telugu as uḍumu (ఉడుము), in Kannada as uḍa (ಉಡ), in Punjabi and Magahi as गोह ( goh ), in Assamese as gui xaap , in Odia as ଗୋଧି ( godhi ), and in Bengali as গোসাপ ( goshaap ) or গুইসাপ ( guishaap ), and गोह ( goh ) in Hindi and गोधा ( godhā ) in Sanskrit . The West African Nile monitor
504-628: A level slightly above 2. Roopnarine instead calculated the position of humans in two marine ecosystems, a Caribbean coral reef and the Benguela system near South Africa. In these systems, humans mainly eat predatory fish and have a fractional trophic level of 4.65 and 4.5, respectively, which in Roopnarine's view makes those humans apex predators. In 2021, Miki Ben-Dor and colleagues compared human biology to that of animals at various trophic levels. Using metrics as diverse as tool use and acidity of
560-527: A notable example of intraguild predation , as it eats an unusually large number of other monitor lizard species such as ridge-tailed monitors , black-headed monitors , Gould's monitors , and even Argus monitors . Perenties also eat smaller members of their own species; such is the case of a 2 m (6 ft 7 in) perentie killing and eating a 1.5 m (4 ft 11 in) perentie. Other lizard prey include central bearded dragons and long-nosed water dragons . Coastal and island individuals often eat
616-486: A perentie can do much damage, not only from the teeth but also because of the oral secretions. The perenties are apex predators that do not have natural predators in their range. They are highly active carnivores that feed on mostly reptiles, small mammals, and less commonly birds such as diamond doves . They hunt live prey, but also scavenge carrion. Reptilian prey includes mostly lizards (such as skinks and agamids ) and more seldom snakes, but this species also displays
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#1732798396379672-531: A reduction in the population of sperm whales , apex predators with a fractional trophic level of 4.7, by hunting has caused an increase in the population of the large squid, with trophic level over 4 (carnivores that eat other carnivores). This effect, called mesopredator release , occurs in terrestrial and marine ecosystems; for instance, in North America, the ranges of all apex carnivores have contracted whereas those of 60% of mesopredators have grown in
728-596: A staple in the reptile pet trade. The most commonly kept monitors are the savannah monitor and Ackie dwarf monitor , due to their relatively small size, low cost, and relatively calm dispositions with regular handling. Among others, black-throated , Timor , Asian water , Nile , mangrove , emerald tree , black tree , roughneck , Dumeril's , peach-throated , crocodile , and Argus monitors have been kept in captivity. Monitor lizards are poached in some South- and Southeast Asian countries, as their organs and fat are used in some traditional medicines , although there
784-652: Is Archaeovaranus from the Eocene of China, suggesting that the genus Varanus is of Asian origin. The oldest fossils of Varanus date to the early Miocene . Many of the species within the various subgenera also form species complexes with each other: Euprepriosaurus Odatria Varanus Polydaedalus Empagusia Soterosaurus The tree monitors of the V. prasinus species complex ( V. prasinus , V. beccarii , V. boehmei , V. bogerti , V. keithhornei , V. kordensis , V. macraei , V. reisingeri , V. telenesetes ) were once in
840-614: Is applied in wildlife management , conservation , and ecotourism . Apex predators have a long evolutionary history, dating at least to the Cambrian period when animals such as Anomalocaris and Timorebestia dominated the seas. Humans have for many centuries interacted with other apex predators including the wolf , birds of prey , and cormorants to hunt game animals, birds, and fish respectively. More recently, humans have started interacting with apex predators in new ways. These include interactions via ecotourism , such as with
896-603: Is banned under the Protected Species Act. Varanus is the only living genus of the family Varanidae . Varanids last shared a common ancestor with their closest living relatives, earless "monitors" , during the Late Cretaceous . The oldest known varanids are from the Late Cretaceous of Mongolia. During the Eocene , the varanid Saniwa occurred in North America. The closest known relative of Varanus
952-552: Is considered to be a least-concern species according to the International Union for Conservation of Nature . Its status in many Aboriginal cultures is evident in the totemic relationships, and part of the Ngiṉṯaka dreaming , as well as bush tucker . It was a favoured food item among desert Aboriginal tribes, and the fat was used for medicinal and ceremonial purposes. British zoologist John Edward Gray described
1008-593: Is derived from the Arabic word ورل waral [Standard Arabic] / ورر warar [colloquially] / ورن waran [colloquially], from a common Semitic root ouran , waran , warar or waral , meaning "lizard beast". In English, they are known as "monitors" or "monitor lizards". The earlier term "monitory lizard" became rare by about 1920. The name may have been suggested by the occasional habit of varanids to stand on their two hind legs and to appear to "monitor", or perhaps from their supposed habit of "warning people of
1064-563: Is diverse and complex, as a result of the diverse ecological niches monitor lizards occupy. For example, many species have anticoagulant venom, disrupting clotting through a combination of fibrinogenolysis and blocking platelet aggregation. Amongst them, arboreal species, such as the tree monitors and the banded monitor , have by far the strongest fibrinogenolytic venom. As a result, wounds from monitor lizard bites often bleed more than they would if they were simply lacerations. Venom may also cause hypotension . In some species such as
1120-609: Is known by several names in Yoruba , including awọ́nríwọ́n , awọ̀n , and àlégbà . In Wolof it is known as mbossé or bar , and is the traditional totem of the city of Kaolack . Due to confusion with the large New World lizards of the family Iguanidae , the lizards became known as " goannas " in Australia. Similarly, in South African English , they are referred to as leguaans , or likkewaans , from
1176-491: Is no scientific evidence as to their effectiveness. Monitor lizard meat, particularly the tongue and liver, is eaten in parts of India and Malaysia and is supposed to be an aphrodisiac . In parts of Pakistan and southern India, as well in Northeastern India, particularly Assam, the different parts of monitor lizards are traditionally used for treating rheumatic pain, skin infections and hemorrhoids , and
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#17327983963791232-827: Is shrinking the sea ice of the Arctic, forcing polar bears to fast on land for increasingly long periods. Dramatic changes in the Greater Yellowstone Ecosystem were recorded after the gray wolf , both an apex predator and a keystone species (one with a large effect on its ecosystem), was reintroduced to Yellowstone National Park in 1995 as a conservation measure. Elk , the wolves' primary prey, became less abundant and changed their behavior, freeing riparian zones from constant grazing and allowing willows , aspens , and cottonwoods to flourish, creating habitats for beaver , moose , and scores of other species. In addition to their effect on prey species,
1288-762: Is typically swallowed whole, but if the food item is too large, chunks are ripped off for ease of consumption. The perentie can lay its eggs in termite mounds or the soil. Monitor lizard Monitor lizards are lizards in the genus Varanus , the only extant genus in the family Varanidae . They are native to Africa, Asia, and Oceania , and one species is also found in the Americas as an invasive species . About 80 species are recognized. Monitor lizards have long necks, powerful tails and claws, and well-developed limbs. The adult length of extant species ranges from 20 cm (7.9 in) in some species such as Varanus sparnus , to over 3 m (10 ft) in
1344-553: Is used for membranes in traditional drums (called kundu ), and these lizards are referred to as kundu palai or "drum lizard" in Tok Pisin , the main Papuan trade language. Monitor lizard skins are prized in making the resonant part of serjas (Bodo folk sarangis) and dotaras (native strummed string instruments of Assam, Bengal and other eastern states). The leather is also used in making a Carnatic music percussion instrument called
1400-600: The kanjira . The meat of monitor lizards is eaten by some tribes in India, Nepal, the Philippines, Australia, South Africa and West Africa as a supplemental meat source. Both meat and eggs are also eaten in Southeast Asian countries such as Vietnam and Thailand as a delicacy. According to IUCN Red List of threatened species, most of the monitor lizards species fall in the categories of least concern, but
1456-863: The Dutch term for the Iguanidae, leguanen . The various species cover a vast area, occurring through Africa, the Indian subcontinent , to China , the Ryukyu Islands in southern Japan , south to Southeast Asia to Thailand , Malaysia , Brunei , Indonesia , the Philippines , New Guinea , Australia , and islands of the Indian Ocean and the South China Sea . They have also been introduced outside of their natural range, for instance,
1512-506: The Komodo dragon and the desert monitor , venom also induces a powerful neurotoxic effect. In the latter species for instance, envenomation causes immediate paralysis in rodents (but not birds) and lesser effects of the same nature in humans. At least some species of monitors are known to be able to count; studies feeding rock monitors varying numbers of snails showed that they can distinguish numbers up to six. Nile monitors have been observed to cooperate when foraging; one animal lures
1568-831: The West African Nile monitor is now found in South Florida . Monitor lizards also occurred widely in Europe in the Neogene , with the last known remains in the region dating to the Middle Pleistocene . Most monitor lizards are almost entirely carnivorous, consuming prey as varied as insects, crustaceans , arachnids , myriapods , molluscs , fish, amphibians , reptiles, birds, and mammals. Most species feed on invertebrates as juveniles and shift to feeding on vertebrates as adults. Deer make up about 50% of
1624-476: The tiger shark , and through rewilding efforts, such as the proposed reintroduction of the Iberian lynx . Apex predators affect prey species' population dynamics and populations of other predators, both in aquatic and terrestrial ecosystems. Non-native predatory fish, for instance, have sometimes devastated formerly dominant predators. A lake manipulation study found that when the non-native smallmouth bass
1680-603: The approach of venomous animals". But all of these explanations for the name "monitor" postdate Linnaeus giving the scientific name Lacerta monitor to the Nile monitor in 1758, which may have been based on a mistaken idea by Linnaeus that the German word Waran (borrowed from Arabic) was connected to warnen (to warn), leading him to incorrectly Latinize it as monitor ('warner', 'adviser'). Austronesian languages spoken across Southeast Asia , where varanids are common, have
1736-519: The assessment of medical risks, and confuses the biological assessment of squamate biochemical systems". Perenties are found in the arid desert areas of Western Australia, South Australia, the Northern Territory, and Queensland. Their habitats consist of rocky outcroppings and gorges, with hard-packed soil and loose stones. Perenties generally avoid human contact and often retreat before they are seen. Being able diggers, they can excavate
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1792-433: The case of the Komodo dragon , though the extinct megalania ( Varanus priscus ) may have reached lengths of more than 7 m (23 ft). Most monitor species are terrestrial , but many are also arboreal or semiaquatic. While most monitor lizards are carnivorous , eating smaller reptiles, fish , birds , insects , small mammals, and eggs, a few species also eat fruit and vegetation . The generic name Varanus
1848-596: The consequences of both controlling prey density and restricting smaller predators, and may be capable of self-regulation. They are central to the functioning of ecosystems, the regulation of disease, and the maintenance of biodiversity. When introduced to subarctic islands, for example, Arctic foxes ' predation of seabirds has been shown to turn grassland into the tundra . Such wide-ranging effects on lower levels of an ecosystem are termed trophic cascades . The removal of top-level predators, often through human agency, can cause or disrupt trophic cascades. For example,
1904-548: The counties of Norfolk , Cumbria , and Northumberland in England, and Aberdeenshire in Scotland as part of the rewilding movement. The reintroduction of large predators is controversial, in part because of concern among farmers for their livestock . Conservationists such as Paul Lister propose instead to allow wolves and bears to hunt their prey in a "managed environment" on large fenced reserves; however, this undermines
1960-411: The diet of adult Komodo dragons, the largest monitor species. In contrast, three arboreal species from the Philippines, Varanus bitatawa , mabitang , and olivaceus , are primarily fruit eaters . Monitor lizards are considered unique among animals in that its members are relatively morphologically conservative, yet show a very large size range. However, finer morphological features such as
2016-588: The female crocodile away from her nest, while the other opens the nest to feed on the eggs. The decoy then returns to also feed on the eggs. Komodo dragons at the National Zoo in Washington, DC , recognize their keepers and seem to have distinct personalities. Blue and green tree monitors in British zoos have been observed shredding leaves, apparently as a form of play. Monitor lizards have become
2072-971: The form of wolves, and in turn with domestic dogs , for 40,000 years; this collaboration may have helped modern humans to outcompete the Neanderthals . Humans still hunt with dogs , which have often been bred as gun dogs to point to , flush out , or retrieve prey . The Portuguese Water Dog was used to drive fish into nets. Several breeds of dog have been used to chase large prey such as deer and wolves. Eagles and falcons , which are apex predators, are used in falconry , hunting birds or mammals. Tethered cormorants , also top predators, have been used to catch fish . Ecotourism sometimes relies on apex predators to attract business. Tour operators may in consequence decide to intervene in ecosystems, for example by providing food to attract predators to areas that can conveniently be visited. This in turn can have effects on predator population and therefore on
2128-503: The fourth-largest extant species of lizard (exceeded in size only by the Komodo dragon , Asian water monitor and crocodile monitor ). However, perenties are very lean among large monitors, making it significantly less bulky than the rock monitor at a similar size. In late 2005, University of Melbourne researchers discovered that all monitors may be somewhat venomous . Previously, bites inflicted by monitors were thought to be prone to infection because of bacteria in their mouths, but
2184-427: The ground, and remaining very still until the danger has passed) or runs if detected. If cornered, this powerful carnivore stands its ground and uses its arsenal of claws, teeth, and whip-like tail to defend itself. It can inflate its throat and hiss as a defensive or aggressive display and can strike at opponents with its muscular tail. It may also lunge forward with an open mouth, either as a bluff or attack. The bite of
2240-409: The highest standard metabolic rates of all extant reptiles. Like snakes, monitor lizards have highly forked tongues that act as part of the "smell" sense, where the tips of the tongue carry molecules from the environment to sensory organs in the skull. The forked apparatus allows for these lizards to sense boundaries in the molecules they collect, almost smelling in "stereo". Monitor lizards have
2296-464: The oil is used as an aphrodisiac lubricant ( sande ka tel ). Consuming raw blood and flesh of monitor lizards has been reported to cause eosinophilic meningoencephalitis , as some monitors are hosts for the parasite Angiostrongylus cantonensis . "Large-scale exploitation" of monitor lizards is undertaken for their skins, which are described as being "of considerable utility" in the leather industry. In Papua New Guinea , monitor lizard leather
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2352-496: The park. Ecologists have debated whether humans are apex predators. For instance, Sylvain Bonhommeau and colleagues argued in 2013 that across the global food web, a fractional human trophic level (HTL) can be calculated as the mean trophic level of every species in the human diet, weighted by the proportion that that species forms in the diet. This analysis gives an average HTL of 2.21, varying between 2.04 (for Burundi , with
2408-466: The past two centuries. Because apex predators have powerful effects on other predators, herbivores, and plants, they can be important in nature conservation. Humans have hunted many apex predators close to extinction, but in some parts of the world, these predators are now returning. They are increasingly threatened by climate change . For example, the polar bear requires extensive areas of sea ice to hunt its prey, typically seals, but climate change
2464-698: The perentie in 1845 as Hydrosaurus giganteus , calling it the "gigantic water lizard". George Albert Boulenger moved it to the genus Varanus . Within the monitor genus Varanus , it lies within the subgenus Varanus . Its closest relatives belong to a lineage that gave rise to the sand goanna and the Argus monitor . Perenties are the largest living species of lizard in Australia . Perenties can grow to lengths of 2.5 m (8 ft 2 in) and weigh up to 20 kg (44 lb), possibly up to 3 m (9 ft 10 in) and 40 kg (88 lb), making it
2520-526: The population is decreasing globally. All but five species of monitor lizards are classified by the Convention on International Trade in Endangered Species of Wild Fauna and Flora under Appendix II, which is loosely defined as species that are not necessarily threatened with extinction but may become so unless trade in such species is subject to strict regulation to avoid use incompatible with
2576-656: The pulmonary and systemic circuits, which in turn ensure that oxygenated blood is quickly distributed to the body without also flooding the lungs with high-pressure blood. Monitor lizards are oviparous , laying from seven to 38 eggs , which they often cover with soil or protect in a hollow tree stump. Some species, including the Komodo dragon, are capable of parthenogenesis . Anatomical and molecular studies indicate that all varanids (and possibly all lizards) are venomous . Unlike snakes, monitor lizard venom glands are situated in their lower jaw. The venom of monitor lizards
2632-542: The researchers showed that the immediate effects are caused by mild envenomation. Bites on the hand by Komodo dragons ( V. komodensis) , perenties ( V. giganteus ), lace monitors ( V. varius ), and spotted tree monitors ( V. scalaris ) have been observed to cause swelling within minutes, localised disruption of blood clotting, and shooting pain up to the elbow, which can often last for several hours. University of Washington biologist Kenneth V. Kardong and toxicologists Scott A. Weinstein and Tamara L. Smith have argued that
2688-400: The shape of the skull and limbs do vary, and are strongly related to the ecology of each species. Monitor lizards maintain large territories and employ active-pursuit hunting techniques that are reminiscent of similar-sized mammals. The active nature of monitor lizards has led to numerous studies on the metabolic capacities of these lizards. The general consensus is that monitor lizards have
2744-507: The stomach, they concluded that humans evolved as apex predators, diversifying their diets in response to the disappearance of most of the megafauna that had once been their primary source of food. Apex predators are thought to have existed since at least the Cambrian period, around 500 million years ago. Extinct species cannot be directly determined to be apex predators as their behavior cannot be observed, and clues to ecological relationships, such as bite marks on bones or shells, do not form
2800-602: The subgenus Euprepriosaurus , but as of 2016, form their own subgenus Hapturosaurus . V. jobiensis was once considered to be a member of the V. indicus species complex, but is now considered to represent its own species complex. Genus Varanus Subgenus Empagusia : Subgenus Euprepiosaurus : Subgenus Hapturosaurus : Subgenus Odatria : Subgenus Papusaurus Subgenus Philippinosaurus : Subgenus Polydaedalus : Subgenus Psammosaurus : Subgenus Solomonsaurus : Apex predators An apex predator , also known as
2856-516: The suggestion 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 the scientists "... reptilian oral secretions contribute to many biological roles other than to quickly dispatch prey". They concluded, "Calling all in this clade venomous implies an overall potential danger that does not exist, misleads in
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#17327983963792912-620: The survival of the species in the wild. The remaining five species – the Bengal , yellow , desert , and clouded monitors and the Komodo Dragon– are classified under CITES Appendix I, which outlaws international commercial trade in the species. The yellow monitor is protected in all countries in its range except Bhutan, Nepal, India, Pakistan, and Bangladesh. In Kerala , Andhra Pradesh , Karnataka , Telangana and all other parts of South India, catching or killing of monitor lizards
2968-576: The wider ecosystem. As a result, provisioning of species such as the tiger shark is controversial, but its effects are not well established by empirical evidence. Other affected apex predators include big cats and crocodiles. In some densely populated areas like the British Isles , all the large native predators like the wolf, bear, wolverine and lynx have become extirpated , allowing herbivores such as deer to multiply unchecked except by hunting. In 2015, plans were made to reintroduce lynx to
3024-562: The wolves' presence also affected one of the park's vulnerable species , the grizzly bear : emerging from hibernation , having fasted for months, the bears chose to scavenge wolf kills, especially during the autumn as they prepared to hibernate once again. The grizzly bear gives birth during hibernation, so the increased food supply is expected to produce an increase in the number of cubs observed. Dozens of other species, including eagles, ravens, magpies , coyotes, and black bears have also been documented as scavenging from wolf kills within
3080-457: Was discovered containing two amphibians ( Archegosaurus decheni and Cheliderpeton latirostre ), one of which had consumed a fish, Acanthodes bronni , showing that the shark had lived at a trophic level of at least 4. Among more recent fossils, the saber-tooth cats, like Smilodon , are considered to have been apex predators in the Cenozoic . Humans hunted with apex predators in
3136-647: Was removed, lake trout , the suppressed native apex predator, diversified its prey selection and increased its trophic level . As a terrestrial example, the badger , an apex predator, preys upon and also competes with the hedgehog , a mesopredator , for food such as insects, small mammals, reptiles, amphibians, and the eggs of ground-nesting birds. Removal of badgers (in a trial investigating bovine tuberculosis ) caused hedgehog densities to more than double. Predators that exert top-down control on organisms in their community are often considered keystone species . Apex predators can have profound effects on ecosystems, as
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