KOMODO DRAGONS: CHARACTERISTICS, HABITAT, SENSES, MOVEMENT

KOMODO DRAGONS

Komodo dragon on Komodo

Komodo dragons (Varanus komodoensis) 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]

Indonesia currently has a population of about 3,000 Komodo dragons, according to government data. Most of them — around 1,700 — live on Komodo Island, and around 1,000 more live on Rinca. 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."

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

Komodo Dragons Habitat and Where They Are Found

Komodo dragon range

Komodo dragons is found only in the lesser Sunda region of the Indonesian archipelago on the islands of Komodo, Flores, Rinca, Padar and a few small nearby island. They live in tropical areas in savanna grasslands and forests at elevations from sea level to 820 meters (2690 feet). [Source: Leanne Lawwell, Animal Diversity Web (ADW) /=]

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. The islands of Komodo, Padar, Rinca, Gili Motang and parts of Flores, where they are found, are largely deforested. All of these islands are east of Java and Bali in an island 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.

Adult Komodo dragons prefer open lowland areas with tall grasses and bushes, but are also found in other habitats, such as beaches, ridge tops, and dry riverbeds. Young Komodo dragons are arboreal (live mainly in trees), and live in forested regions until they are eight months old.

Origin and History of Komodo Dragons

Komodo dragons are monitor lizards ("varanid" lizard) 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.

Komodo dragons split off from the main monitor lizard branch maybe five million years ago, but their genus Varanus goes back some 40 million, and its dinosaur ancestor lived 200 million years ago. Relatively recent studies indicate that Komodo dragons originated in Australia. Greg Laden, wrote on smithsonian.com: “ 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 ^\^]

Komodo dragon skull

“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. ^\^

Komodo Dragon Characteristics

Komodo Dragons are the largest and heaviest lizard. 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, including the tail, and weigh 59 to 70 kilograms (130 to 155 pounds). Sometimes they reach double this size in captivity. 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). Some water monitors — a type of monitor lizard — found in Thailand and Malaysia can reach about the same length. Saltwater crocodiles are the world's biggest reptiles.

Komodo dragon on a Komodo beach

Komodo dragons have a huge capacity for food and are capable of consuming half their body weight in a single meal. Although many Komodo dragons individuals fall prey to other animals and adults of their own kind as hatchlings, ones that live to adulthood usually have a lifespan of 30 to 50 years. According to the Max Planck Institute for Demographic Research the average lifespan for females in captivity is 8.9 years. Sexual Dimorphism (differences between males and females) is present: Males are around 30 percent bigger than females but there are no obvious morphological differences between the sexes

Komodo dragons adults are relatively uniform in color, ranging from brown to grayish red. Juveniles are green with yellow and black bands. The robust bodies of adults are uniformly covered by rough, non-overlapping scales. Some are spiny. Other are raised and bony. The heads of Komodo dragons have a rounded snout and ear openings. Their skulls are flexible and have sharp, serrated teeth.

Komodo dragons have long bodies, strong limbs, well-developed legs and a deeply forked tongues that they flick in and out as they search for food. Half their length is taken up by their powerful, muscular tail. By contrast the tail of most monitor lizards is about two thirds their body Their heads are relatively small with wide jaws and skin fold around the neck. Sharp claws are used for digging burrows and unearthing food. Their tail is used as a weapon when fighting and as a prop and counterbalance when standing on its hind legs,

Komodo dragons are heterothermic (having a body temperature that fluctuates with the surrounding environment). They 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 a half kilogram (one pound) of meat a day, compared to five kilograms (12 pounds) for a tiger and two and half kilograms (six pounds) for a wild dog.

Komodo Dragons Have Chain-Mail-Like Skin Growths

In September 2019, researchers at the University of Texas at Austin announced that they had discovered that Komodo dragons grow osteoderms (bony plates or scales) in their skin that closely resembles chain mail. Not only that, they grow four different shapes of osteoderms while other lizards typically only have one or two different shapes and tend to have less osteoderm coverage than komodo dragons. In addition, scans revealed that the chain mail-like scales aren’t present in baby dragons, suggesting that that osteoderms develop when the animals reach adulthood. [Source:Daisy Hernandez, Popular Mechanics, September 29, 2019]

Daisy Hernandez wrote in Popular Mechanics: “Although scientists have long known about the osteoderms in komodo dragons, the arrangement of the tiny bones remained a mystery "since the skin is the first organ removed when making a skeleton," per UT Austin's news blog. "Most monitor lizards just have these vermiform (worm-shaped) osteoderms, but this [species] has four very distinct morphologies, which is very unusual across lizards," said Jessica A. Maisano, who led the research published in The Anatomical Record.

“UT Austin researchers scanned dragon specimens from the Fort Worth Zoo and the San Antonio Zoo, who provided the team with a 19-and-a-half year old adult komodo and a two day old komodo, respectively. A high-resolution x-ray was used to "reveal the interiors of [the] specimens in great detail."Where lizards typically have one or two varying patterns or shapes of osteoderms, komodo's have four: rosette, platy, dendritic, and vermiform. Maisano et al. report that there are a few areas where osteoderms were not present on an adult komodo, including the area surrounding "the eyes, nostrils, mouth margins and pineal eye, a light-sensing organ on the top of the head."

Komodo Dragon Mobility

Komodo dragons can run, swim and climb trees. They can nimbly clamber up trees when they are young to escape danger. When Komodo dragons sprint they do so with their tails lifted off the ground. Komodo dragons are capable of running at 11 mph (18 kph) for short bursts.Their bodies are held off the ground when walking but lie on the ground when the lizards are at rest. Their long powerful tails can be used for propulsion when the lizard is swimming or swatting at potential prey or rivals.

Komodo dragons are good swimmers and divers. They have been spotted at depths of two meters underwater and are regularly seen swimming between the narrow straits of their home islands and offshore islets to search for food.

According to the book “Beastly Behaviors”: “High atop their stubby, bowed-out legs, running komodos can keep up an 8-mile-per-hour pace for a third of a mile. Their powerful tail switches back and forth for balance, and their hind legs swing in rhythm like a double-bladed kayak paddle, Witnesses say the beat of their feet against the earth sound like the “rat-tat-that” of a muffled machine gun. At slower speeds, they can stand on their hind legs and walk upright for a while. Climbing is no problem for young monitors, which prefer to spend their early years hunting geckos and keeping out of harms way up in the trees, Their talon-like claws help them get a leg up on rough, fissured bark [Source: “Beastly Behaviors” by Mark Leigh, Mike Lepine, and Rolf Harris, 1997]

Komodo Dragon Senses

Komodo dragons sense using vision, touch, sound and chemicals usually detected with smell. They communicate with vision, touch and chemicals and employ pheromones (chemicals released into air or water that are detected by and responded to by other animals of the same species). Although Komodo dragons can see 300 meters away and can hear a restricted range of sound, their sense of smell is their primary means for locating food and the tip of its tongue is its primary scent detector. Males communicate dominance in mating and feeding order by wrestling in upright positions. Females give off a scent in their feces to communicate that they are ready to mate and the male replies by rubbing his chin on her and licking her body. [Source: Leanne Lawwell, Animal Diversity Web (ADW) /=]

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.

Image Sources: Wikimedia Commons

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.

Last updated February 2025