KOMODO DRAGONS

KOMODO DRAGONS

Komodo dragons are the world's largest lizard. They can weigh up to 100 kilograms and reach a length of three meters and take prey as large as a water buffalo. They are giant versions of monitor lizards, a reptile that resides all over southern Asia and Africa and are related to goannas found in Australia. Monitors in Malaysia can reach lengths two meters. [Source: Eric Wikramanayake, Smithsonian; The Behavioral Ecology of the Komodo Monitor by Walter Affenberg; James Kern, National Geographic, December 1968]

The name Komodo dragon is kind of nickname. The animals are properly known as Komodo lizards or Komodo monitors. Their scientific name is Varanus komodoensis. They were long thought to related to monitor lizards found elsewhere in Southeast Asia but now it is believed they are the last representative of a relic population of large lizards that once lived across Indonesia and Australia.

Henry Allen of the Washington Post described the Komodo dragons as the "baddest reptiles of them all, real prizes, the crepuscular glamour of meat-seeking missiles with tongues...that flick like foot-long pieces of meat paranoia...They don't move a lot, but when they do it's with sullen self-assurance, their legs rotating forward like the arms of a fat man putting on an overcoat. The tongue flicks. The eyes have all the soul of mirror sunglasses." "They are also the pit bull, the chopped Harley, the Darth Vader, the .44 Magnum of lizards... They are not left over dinosaurs, they are monitor lizards—pro--active, self-propelled chain saws with legs."

Komodo dragons live in tropical savannahs, stream side thickets and coastal regions. There are between 4,000 and 6,000 of them left in the world today, with about half of them on the island of Komodo. The range of the Komodo dragon is smaller than any other large carnivore in the world. Komodo dragons reside only on four largely deforested islands in Indonesia— Komodo, Padar, Rintja, and Gili Motang—and parts of Flores. All of these islands are east of Java and Bali in a chain called the Lesser Sundas. Local islanders call the Komodo dragons "ora." Komodo dragons are good swimmers. It is not known why they don’t live in other places.

Jerome Rivet of Reuters wrote: “Three metres (10 feet) long and weighing up to 70 kilograms (150 pounds), Komodo dragons are lethargic, lumbering creatures but they have a fearsome reputation for devouring anything they can, including their own. They prefer to scavenge for rotting carcasses, but can kill if the opportunity arises. Scientists used to believe their abundant drool was laced with bacteria that served to weaken and paralyse their prey, which they stalk slowly but relentlessly until it dies or is unable to defend itself. But new research has found the lizards are equipped with toxic glands of their own. One bite from a dragon won't kill you, but it may make you very sick and, eventually, defenceless. About 2,500 dragons live on the island named after them ("komodo" means dragon in Indonesian). Along with neighbouring Rinca island, it is the main dragon habitat in the Komodo National Park, created in 1980 to preserve the ancient species. [Source: Jerome Rivet, Reuters, December 22, 2010 >>>]

Book: Zoo Quest for a Dragon by David Attenborough

Origin of Komodo Dragons

Komodo dragons are monitor lizards that became unusually large as result of a plentiful source of meat and carrion. It is believed that they were once regular monitor lizards that fed on insects, carrion and small animals. They are were able to grow because they had no competition from other predators for the meat sources on the islands where they lived. As they grew they eventually became big enough to bring down and kill large mammals.

Relatively recent studies indicate that Komodo dragons originated in Australia. Greg Laden, wrote on smithsonian.com: “The Komodo dragon (Varanus komodoensis), a type of "varanid" lizard. Despite the fact that Komodo dragons are very interesting and widely known, there is a lot missing in our understanding of their natural history. Now a study of fossil evidence from Australia, Timor, Flores, Java and India shows that Komodo Dragons most likely evolved in Australia and dispersed westward to Indonesia. Some of the fossils that have been studied are newly described, including a species from Timor, and some are material known for a long time. [Source: Greg Laden, smithsonian.com, September 30, 2009 ^\^]

“Here's the most important finding: The two main hypotheses for the origin of the Komodo dragon have been brought into question and replaced with a new and better hypothesis. It was previously thought that one of the best explanations for the large size of the Komodo dragon was the "island effect." On islands, some animals may get bigger because of an increasing reliance on lower quality food found on island—the larger body size accommodates a gut that can process the food. In other cases, animals get smaller for a variety of reasons. But mostly, islands have strange effects on many species because evolution in the small population can proceed very rapidly. The animals that are confined to islands for long periods of time may simply evolve into food niches (which often relate to body size) that their sister species on the mainland did not experience. A second hypothesis for the large size of Komodo dragons is that they were once specialists in the hunting of the pygmy Stegodon (a small elephant). This is a sort of indirect island effect. The Stegodons got small because they lived on islands, and the lizards evolved to be large enough to eat them. ^\^

“Both of these hypotheses—island effects and specialist Stegodon hunter—now seem unlikely. The new research indicates that Komodo dragons were really part of a distribution of related species of really large lizards across the region, including Australia. In fact, in comparison to some of these other lizards, Komodo dragons are kind of small.” ^\^

Scott Hocknull, Senior Curator of Geosciences at the Queensland Museum and author of the paper, says that Australia was is a hub for lizard evolution: “The fossil record shows that over the last four million years Australia has been home to the world's largest lizards, including a five meter giant called Megalania (Varanus prisca). Now we can say Australia was also the birthplace of the three-meter Komodo dragon (Varanus komodoensis), dispelling the long-held scientific hypothesis that it evolved from a smaller ancestor in isolation on the Indonesian islands. Over the past three years, we've unearthed numerous fossils from eastern Australia dated from 300,000 years ago to approximately four million years ago that we now know to be the Komodo dragon. When we compared these fossils to the bones of present-day Komodo dragons, they were identical. This research also confirms that both giant lizards, Megalania (Varanus priscus) and the Komodo dragon (Varanus komodoensis), existed in Australia at the same time.” This research was published Tuesday in the Open Access journal PLoS ONE. ^\^

Early History of Komodo Dragon and Humans

The origin of the Komodo dragon's name is not known. Perhaps it was a Chinese fisherman who named them after the important Chinese symbol in culture and mythology. Some think that perhaps the mythical dragon was inspired by a Komodo dragon though that seems highly unlikely.

Komodo dragons were “discovered” by Europeans in 1912. Stories by pearl divers and fishermen circulated about fearsome creatures with large teeth, fearsome claws and fiery yellow tongues. After hearing stories about six-meter-long "dragons" and "land crocodiles" known to locals as "ora," a Dutch civil servant named Lieut. Van Steyn Hensbroke decided to travel to Komodo and see what the fuss was about. There he encountered some Komodo dragons that were about two and half meters long.

Hensbroke killed one and the skin was sent to a museum in Buitenzorg (present-day Bogor), where the animal was described and given the scientific name Varanus komodoensis. Not long after that local rulers and colonial administrators, realizing the uniqueness and rareness of the animal, made it illegal to capture or hunt Komodo dragons.

Komodo Dragon Characteristics

Komodo dragons range is length from one to three meters and vary in weight from 20 to 100 kilograms. Adult males average 2.26 meters (7 feet 5 inches) in length and 59 kilograms (130 pounds). According to the Guinness Book of Records, one specimen displayed at the St. Louis zoo in 1937 measured 3.1 meters (10 feet 2 inches) and weighed 165.5 kilograms (365 pounds).

Komodo dragons can run, swim and climb trees. Half its length is taken up its tail. By contrast the tail of most monitor lizards is about two thirds its body length. They can run 15mph and good swimmers. They can climb trees when they are young. The body of a Komodo dragon is covered by non-overlapping scales. Some are spiny. Other are raised and bony. Their long powerful tails can be used for propulsion when the lizard is swimming or swatting at potential prey. When Komodo dragons sprint they do so with their tails lifted off the ground.

Komodo dragons can raise and lower their body temperatures in accordance with their activity level. This enables them to survive on about a tenth of the energy needed by a mammal of their size. This way Komodo dragons need to eat much less than their mammalian counterparts. An adult Komodo dragon needs one pound of meat a day, compared to 12 pounds for a tiger and 6 for a wild dog.

Komodo dragons have a keen sense of smell. They can sense carrion from seven miles away. They have been observed climbing to ridge tops so they can sniff the wind to for carrion odors. They have a yellow forked tongues that operates like the forked tongued of snakes. Their terrible breath is said to be caused by rotted carrion left between their teeth.

Lizards and snakes are both very good at sensing and analyzing smells and message-carrying chemicals. Many have a vomeronasal organ embedded in the roof of their mouth that detects heavy non-airborne molecules taken in through the mouth. It supplements olfaction which is the ability to smell airborne molecules that enter the nostrils and is distinct from taste, which analyzes chemicals that come into contact with taste buds on the tongue. These senses help reptiles locate prey and help warn them or potential prey that might be toxic. It also frees up the eyes to locate prey and find mates.

The vomeronasal organ is sometimes called the Jacobsen's organs. Lizards and snakes with forked tongues have these on either side of the roof of their mouth. Chemicals are picked up from the environment with their forked tongues then transfered to these organs. Lizards and snakes with forked tongues constantly flick their tongues in and out of their mouths, bringing in new samples of chemicals on either side of the tongue through the chemical equivalent of stereoscopic vision. Not only can they determine the presence of chemicals they can also determine the direction which they are coming from and detect edges and dimensions of the sources.

Lizards and snakes use their forked tongues and sense organs in their mouth to locate food, enemies and mates. And this they can do without even opening their mouths. Predators rely on smells and message-carrying chemicals to locate their prey and use their eyes to determine the location of the prey for the final lunge.

Komodo Dragon Sex and Behavior

Komodo dragons hang out at the transition between forests and savannahs. They generally don't move around much at night and wait to be heated by the sun before moving around in the day. They usually got to sleep around sunset and sleep in brush, a cave or a burrow.

Komodo dragons showing aggression react to the threat with their eyes and puff out their throats. When fighting Komodo dragons stand on their hind legs, lock arms and chests and push each other around like a couple of sumo wrestlers. Komodo dragons are good swimmers. They are regularly seen swimming between the narrow straits of their home islands and offshore islets to search for food. In zoos, Komodo dragons recognize their keepers. One scientist said Komodo dragons have "an intelligence and a ability to communicate beyond anything I've seen in a reptile."

Komodo dragons mate during the middle of the dry season, which lasts from May through November. Little is known about Komodo dragon mating behavior. They probably reproduce when they are five to seven years old. It is very difficult to tell the difference between a male and a female monitor lizard. Males out number females by a ratio of 3.4 to 1.

Male Komodo dragons have a finger-length forked penis. Describing why the huge lizard is "hemipedal," Dale Marcellini, the chief herpetologist at the National Zoo in Washington told Henry Allen of the Washington Post, "The female's tail is in the way. The male has to approach from one side or the other, and depending on which side he chooses, he’s at an angle, and that's the fork he uses.”

Komodo Dragon Young

The female Komodo dragon lays and buries 15 to 30 eggs. The eggs incubate through the wet season, from December to April, and hatch at the beginning of the dry season. Newly hatched Komodo dragons head for trees, where they are safe from attacks by adult Komodo dragons and stay in the trees until they are about four fee long. They feed mostly on insects and small lizards, many of which they find in the trees, and try to limit their trips on the ground.

Young Komodo dragons have orange, yellow an black markings on their bodies. These markings are perfect for camouflage in the trees. It was originally thought that there were fewer juveniles than there actually were because scientists could not spot them in the trees.

Young Komodo dragons usually sleep on branches or in tree cavities. Sometimes they sleep on rock outcrops that the adults can’t get at. As they get older they spend more time on the ground and seek safety among nooks among boulders. At this stage in their lives they feed on rats, mice and birds.

Hunting and Scavenging Komodo Dragons

Komodo dragons have been observed feeding on wild pigs, goats, deer, poisonous snakes, birds, small mammals, water buffalo, and other Komodo dragons. Mostly they fed on carrion. They are often seen on beaches looking for dead fish or birds and have been seen digging up nests of birds. Adult Komodo dragons will feed on small juveniles if given the chance. Remains of young dragons have been found in the droppings of adults. Most young animals escape the large lizards by scrambling up trees. The large lizards, with their bulk, can not climb the trees.

Richard C. Paddock wrote in the Los Angeles Times, “The Komodo, which shares a common ancestor with dinosaurs, hunts such creatures as deer, pigs, goats and other dragons. It can run quickly in short bursts but often lies in wait until an animal comes within a few feet, then attacks it. Komodos have poor hearing but an extraordinary sense of smell. The lizards use the tips of their long, pale, forked tongues to gather air samples and then brings those to odor receptors on the roof of its mouth. The tongue continually flick in and out as the animals plod along, swaying from side to side. [Source: Richard C. Paddock, Los Angeles Times, July 5, 2006]

Komodo dragons use their keen sense of smell and their long darting forked tongue to locate prey or carrion. They are rather dim-witted animals and are not regarded as clever hunters. Mostly it is believed they wait along game trails, camouflaged in the bush, and then leap and knock down prey with their long tails or wound it and track it down later.

Komodo dragons slash with the teeth, spread infection and pursue their weakened victims. Komodo dragon’s thick, sticky saliva reportedly contains 17 different kinds of bacteria. It was thought that prey died from infection from the saliva or loss of blood not a killing bite. Tour guides tell visitors that there is no known antidote for the bacteria-filled saliva. Researchers have studyied Komodo dragon to see how they protect themselves from germs to develop a new way to fight antibiotic -resistant bacteria.

Komodo dragons can be active hunters They have been observed killing water buffalo, ambushing deer and pigs by leaping from a thicket and following pregnant goats and seizing newborn kids when they drop to the ground. In some attacks they grab the leg of their prey with their jaws , throw it to the ground and rip open its belly. They have also been observed driving large mammals it into the surf and slashing the tendons of their hind legs. Komodo dragons can be very dangerous if cornered and have been known to rise up on their hind legs before making a lunging attack. Their sharp claws and teeth can inflict severe wounds.

Komodo Dragon Feeding Behavior

Komodo dragons can smell blood and the scent of death from nearly 10 kilometers away. Male lizards can eat up to 80 percent of their own body weight in one sitting. Komodo dragons have curved, serrated teeth enabling them to bite off large chunks of meat and bone and swallow them whole. They often eat so fast, sometimes consuming large quantities of dirt along with their prey. One scientist saw a 92-pound female eat a 66-pound wild boar in 17 minutes. He also saw another one swallow a month-old fawn whole. There are stories of dragons waiting for pregnant goats to give birth and devouring both the exhausted mother and disoriented kid.

Describing how a Komodo dragon feeds on its victims, Walter Affenberg wrote in "The Behavioral Ecology of the Komodo Monitor," it begins by "ripping open the body wall and pulling out the intestines...followed by the lungs and heart, which are obtained by thrusting the head deep within the chest cavity...The viscera are bolted down rapidly accompanied by a hollow clapping sound produced by the snapping jaws."

Describing Komodo dragons eating in a pit where tourists gather, David Attenborough wrote, “A large one is fully able to pick up a goat’s carcass with its jaws and drag its body away. If two large ones are feeding on it, they each fasten their jaws on it and rip it apart with backward jerks of their head and shoulders. If younger ones are rash enough to dispute the food with their elders, they are driven away with a lunging rush.”

Komodo dragons will eat their own dead and can expand their mouth cavity considerably allowing them swallow large prey or chunks of meat and whatever else enters their mouth. According to Reuters: “Komodo dragons have appalling table manners but at least they finish their dinners -- bones, hoofs and all.”

Dispelling Myths About Komodo Dragons Hunting and Killing

Previously it was thought the Komodo's mouth harboured virulent bacteria that quickly infected and subdued prey. But in 2009 analysis by researchers of Komodo specimens showed a well-developed venom gland with ducts that lead to their large teeth. Brendan Borrell wrote in Smithsonian Magazine, “In 2006, Scott Hocknull, a paleontologist at the Queensland Museum, discovered some puzzling fossils in a cave in northeastern Australia, and later confirmed that they were the remains of Komodo dragons that lived 3.8 million years ago. Rather than being the specialized product of island evolution, Hocknull argues, the dragon is really a “generalist carnivore” that feeds on multiple types of prey in a variety of environments. Relatives of the Komodo—monitor lizards that can grow five to six feet long—still live in Australia. [Source: Brendan Borrell, Smithsonian Magazine, February 2013 <=>]

“One of the biggest misconceptions about the Komodo is that its mouth is full of nasty bacteria that cause deadly lesions in bite wounds, enabling it to take down large prey, including water buffalo. He based the idea on bacteria he’d found in Komodo saliva and the infected wounds he’d observed in horses and water buffalo in western Flores. “An enchanting fairy tale,” says Bryan Fry, a herpetologist at the University of Queensland. “It makes no evolutionary sense.” One problem is that water buffalo were introduced to the region by humans and have never been the dragon’s natural prey. Moreover, the dragons seldom succeed in killing such large animals. Fry says water buffaloes attacked by dragons develop infected wounds from wallowing in filthy water; if they die and become a dragon’s meal, that’s more of a lucky break (for the dragon, not the buffalo) than an evolutionary adaptation. <=>

“Reptiles aren’t known for brains, but Komodo dragons create dummy chambers with dead ends, thwarting wild pigs and perhaps other, now-extinct scavengers—“the ghost of predation past,” says Tim Jessop, a University of Melbourne ecologist. When the dragons finally hatch, they take to the trees to avoid being eaten by larger dragons. At one point we spotted a tiny dragon that had risked a visit to the ground and was hunting for insects in the leaf litter.” <=>

Komodo Dragons Kill With Venom Rather Than Bacteria

Previously it was thought the Komodo's mouth harboured virulent bacteria that quickly infected and subdued prey. But in 2009 analysis by researchers of Komodo specimens showed a well-developed venom gland with ducts that lead to their large teeth. Brendan Borrell wrote in Smithsonian Magazine, “There’s no denying the dragons are effective when they strike smaller prey, such as deer and pigs. Tim Jessop, a University of Melbourne ecologist, who has spent more time studying dragons in the field than anyone since Auffenberg, observed that 70 percent of the prey die within minutes, 20 percent die of blood loss within four hours and only 10 percent survive. [Source: Brendan Borrell, Smithsonian Magazine, February 2013 <=>]

“Why so lethal? Fry has discovered the secret is the mouth after all—dragons are venomous. When he scanned a dragon’s head with an MRI device, he found in its gums a series of glands that produce venom. It is secreted into the saliva and enters the wound created by the dragon’s sawlike teeth. This venom, Fry has shown, prevents blood clotting and causes muscles around blood vessels to relax, hastening blood loss and leading to a dangerous drop in blood pressure. “This is a sustained march toward unconsciousness,” says Fry. <=>

“At first glance, the discovery presents an evolutionary enigma. We usually think of venom, whether deployed by a rattlesnake or a scorpion, as a weapon that a small animal uses to kill larger prey, or to protect itself from becoming someone else’s meal. But the dragons aren’t exactly small. The answer, Fry realized after designing a computer model of the dragon’s jaw, was that the animal doesn’t have a strong bite. A saltwater crocodile, whose skull is about the same size, produces 6.5 times more bite force than a dragon. Komodos can barely hold onto prey, preferring to wound, release—and wait. “They grab whatever they can and slice it,” Fry says. <=>

“Previously, there were only two known venomous lizards: the Gila monster of the American Southwest and the Mexican beaded lizard. Their venoms lower blood pressure and impair coagulation, but also attack muscle tissue and disrupt the nervous system. Fry, having documented vestiges of venom glands in dozens of species, from Chinese crocodile lizards to seasnakes, concludes that the ability to produce venom emerged just once in the evolution of lizards and snakes 170 million years ago. If a species evolved another, perhaps more efficient means of subduing prey—like a rat snake’s constricting embrace—its venom glands atrophied over time, a phenomenon that biologists call a trait loss. The dragon evolved a slimmer skull—a precision cutting instrument—while retaining the venom. The result is a lethal dual-weapons system.” <=>

Image Sources:

Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, Lonely Planet Guides, Library of Congress, Compton’s Encyclopedia, The Guardian, National Geographic, Smithsonian magazine, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Wall Street Journal, The Atlantic Monthly, The Economist, Global Viewpoint (Christian Science Monitor), Foreign Policy, Wikipedia, BBC, CNN, and various books, websites and other publications.

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© 2008 Jeffrey Hays

Last updated June 2015

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