Facts and data on the Komodo Dragon
Source material for this fact sheet:
(Ciofi and Jessop, 1999)
(Winters, 1999) [You must be registered and logged in to see this image.]
The Komodo Dragon, Varanus Komodoensis, is a wonder of the natural world. The largest surviving lizard, a miracle of evolution and a living mythology, this site has been dedicated to the Komodo Dragon and this Data Sheet provides detailed information on all aspects of the Komodo Dragon from metrics to environment and from conservation to evolution.Names
Most of the western world knows this large monitor lizard as the Komodo Dragon, or Komodo. To the scientific world it is Varanus komodoensis, the largest of the fifty or so Varanids, or Monitor Lizards. In the Indonesia archipelago, or more specifically around the island of Komodo where the lizard calls home, it goes by the simple name Ora, or occasionally buaja durat (land crocodile) or biawak raksasa (giant monitor), which is perhaps the most appropriate name.Physical dimensions
The Komodo Dragon may not be the longest lizard in the world, that honour probably goes to the Papua Monitor, Varanus salvadorii, which is much thinner than the Komodo Dragon but regularly longer. No one however would dispute that the Komodo Dragon is the largest surviving lizard. Adult males often exceed 2.5 meters (8 feet) in length and weigh around 90 kilograms (200 pounds). The largest verified specimen was 3.13 meters and 166 kilograms. The problem with weight is that the Komodo Dragon is an impressive diner and can eat pretty much its own weight in food. This begs the question, where does the Komodo end and dinner begin. Without a full stomach the mature adult male is more likely to weigh in the 60 to 90 kilogram range.Taxonomy
Kingdom - Animalia
Phylum - Chordata
Subphylum - Vertebrata
Class - Reptilia
Order - Squamata
Suborder - Sauria
Family - Varanidae
Genus - Varanus
Species - Varanus komodoensis Evolution
The evolution of the Komodo Dragon makes for interesting reading. As with all modern reptiles, with the exception of turtles, the Komodo Dragon is a distant descendant of the subclass Diapsida that emerged some 300 million years ago. Around 250 million years ago, Diapsids divided into Archosaurs, the descendents of the Dinosaurs, and Lepidosaurs, the precursors to snakes and lizards. In somewhat of a simplification, Dinosaurs stood more upright and Archosaurs retained a sprawled posture. Snakes and Lizards are not the descendents of Dinosaurs, as many people assume, that path led in the long sweep of history to modern day birds that would emerge only some 60 million years ago. The Archosaurs evolved in to the Order Squamata which split into Snakes and Lizards. Modern Day Lizards include five main groups, Monitors, Dragons, Geckos, Legless Lizards, and Skinks. The Komodo Dragon is the king of the Monitors, not the Dragons as the name would suggest. For much more detailed evolutionary history, click here >>Senses
Based on observation and biological examination, Komodo Dragons have been determined to have relatively poor eyesight and hearing. The retina of a Komodo Dragon has only cones, not rods, and as a result although seeing colour, their sight is limited in dim light and in picking up peripheral movement. As with other Varanids, they have a single ear bone for transferring sound and are likely restricted to sounds in the 400 to 2,000 hertz range, compared to humans who hear between 20 and 20,000 hertz. This means they are unlikely to hear very deep or high pitched sounds. There range of sight and hearing may also be somewhat limited, observation has suggested their effective range of sight is limited to some 300 metres. When it comes to smell however the Komodo, like many reptiles is extremely gifted. In the right conditions, the Komodo Dragon may be able to smell prey such as carrion up to four kilometres away. This impressive sense comes not from the Komodo Dragon’s nose but from his tongue and Jacobson’s organs. After the Komodo Dragon flicks his tongue, it retreats into the roof of the mouth where it is analysed by these sensitive organs. Basically chemical analysers, the Jacobson organs can sense minute concentrations of airborne particles. Not only is the sense extremely attuned, it is also directional, helping lead the Komodo Dragon to prey. Measurements and Statistics
Length (max) - 3.13m (10.3ft)
Weight (max) - 166kg (366 pounds)
Running speed - 20kph (13mph)
Size at birth - 40cm (16in)
Weight at birth - 100gms (3.5oz)
Clutch size - 15 to 30 eggs
Incubation period - 8 to 9 mths
Longevity - 30 to 50 years
Scent range (max) - 4km (2.5 miles) Environment
The Komodo Dragon is only found within the Komodo Island National Park, a group of small islands in the Indonesian archipelago and on the larger island of Flores which falls just outside of the park. Both fossil evidence and the rate of habitat destruction indicate that the Komodo Dragon once had a broader range, possibly as far as Timor in the East.
The Komodo Dragon is the number one predator in its island domain. On an island, with reduced resources, reptiles have an advantage over other predators that comes from their cold-blooded biology. Reptiles have much lower total energy requirements than mammals and other predator groups, this allows them a relatively larger size on lower dietary requirements. In this Island environment, Komodo Dragons were able to flourish and grow to their incredible size.
The Komodo Islands are the result of ancient volcanic eruptions and have very low rainfall, only some 600 to 800mm annually, making the islands dry and hilly, with tall savannah grass a prime example of the Komodo's habitat. The Komodo Dragon lives efficiently, preying on Sunda deer (Cervus timorensis), wild boar (Sus scrofa) and a wide range of other fauna from turtle eggs through to their own young.Discovery
The Western World was unaware of the Komodo Dragon before 1912. In 1910, after hearing about "land crocodiles", Lieutenant van Steyn van Hensbroek, of the Dutch colonial administration in Indonesia, went in search of the Komodo Dragon and would send the skin of a 2.1 meter specimen, along with photographs to the Zoological Museum and Botanical Gardens at Bogor (Java, Indonesia).
The Director of the Bogor Zoological Museum, Peter Ouwens, recruited a collector to obtain further specimens. Ouwens described the Komodo scientifically and classified it as a member of the Varanidae (Monitor Lizard) family, naming it Varanus komodoensis in his scientific paper of 1912 which announced the Komodo Dragon to the world's scientific community.
Interest in the Komodo Dragon grew quickly. One particular expedition by W. Douglas Burden from the American Museum of Natural History in 1926 captured 27 Komodo Dragons and examined as many as 70 others.Ecological and Conservation Status
Officially classified as VULNERABLE by The World Conservation Union (IUCN), most Komodo Dragons remain within the Komodo National Park which is both a World Heritage Site and a Man and Biosphere Reserve. Despite this protection, the future survival of the Komodo Dragon remains threatened.
Today as few as 3,000 lizards may exist with only around 600 being females of breeding age. Although many Komodo Dragons have been born in captivity in recent years and many Zoos are involved in breeding and research projects, both the range and numbers of Komodo Dragons continues to decline.
The Komodo Dragon is at the top of a complex food chain and even with international protection and attention, offshore reefs are still damaged by dynamite blasting and cyanide fishing. More critically, is the general encroachment of humans and poaching of the Sunda deer (Cervus timorensis) which is one of the Komodo Dragons main sources of food. In fact it is the poaching of deer that is blamed for the disappearance of Komodo Dragons from the island of Padar (within the national park) in the late 1970s.
Flores, a large island just outside the Komodo National Park, is rugged and the Komodo Dragon numbers have not been effectively surveyed. What is true however is that the range and numbers found in areas around human habitation have been falling significantly in recent decades.
Within the Komodo National Park, numbers are reasonably well monitored (Komodo Island, 1,700 | Rinca, 1,300 | Gila Motang, 100 | Padar, 0 ), on Flores there may be as many as 2,000 Komodo Dragons remaining, however this number is unclear. The Komodo Dragon is certainly vulnerable, and in an area that is also geologically unstable, a volcanic or seismic event, although unlikely in the short-term could end the reign of the Komodo Dragon as the largest surviving lizard.Interesting Facts
* Small (young) Komodo Dragons are accomplished tree climbers.
* Komodo Dragons are cannibals, eating their young and occasionally their eggs.
* The Dragon's teeth are large, curved and serrated and arranged so that the maximum amount of flesh can be bitten off and swallowed whole.
* The saliva of a Komodo Dragon contains over 50 types of bacteria, seven of them highly septic.
* Under severe environmental conditions, Komodo Dragons have been know to swim between islands.
* Infant Komodo Dragons may roll themselves in entrails and faecies to prevent being eaten by mature Komodo Dragons.
* Komodo Dragon's sense of smell is powerful enough to smell carrion up to four kilometres away and sea turtle eggs up to half-a-metre under the sand.
* Other than finding cool spaces, the only mechanism a Komodo Dragon has for lowering its body temperature is panting.
* The genus Varanus (Monitor Lizards) emerged in central Asia around 40 million years ago, most of the Komodo's related species are found in Australia.
* The largest risk to the survival of the Komodo Dragon is encroachment by humans, destruction of environment and poaching of prey such as the Sunda deer. Hunting Methods and Diet
The Komodo Dragon is powerful and agile, and yet surprise is still the method of choice for capturing larger prey. The Komodo Dragon will eat almost anything from its own eggs and those of turtles, to pretty much any animal within its domain, including deer, buffalo, boar, snakes, lizards (including young Komodo Dragons), frogs, and even wild horse and the macaque monkey. Despite this broad dietary variety, human attacks are rare and usually due to 'getting in the way' rather than the Dragon's attempt to feed. The Komodo Dragon can be classified as a man-eater, and such a designation plays to our dramatic fancies, however locals move around the Komodo Dragons with the care and respect that such a powerful wild animal deserves, but certainly without the fear that prey would exhibit.
The tall savannah grass on the islands provides good cover for the Komodo Dragon, and most direct attacks on prey occur when they pass within strike range. A small adult Komodo, weighing around 40 kilograms can kill the much larger Sunda deer at around 90 kilograms. By striking quickly and knocking the deer off its feet, the Komodo Dragon begins tearing it to pieces using its powerful claws and large, serrated teeth. Animals that survive this initial attack are likely to die from infection from the bite, as the Komodo's saliva is particularly infectious, with as many as 50 strains of bacteria. On an island, and with the predators amazing sense of smell, carrion is just as good as live prey. For smaller prey, the Komodo Dragon may just strike straight for the neck and kill its target instantly.Saliva, Bacteria and Immunity
There are only two lizards considered venomous, the Beaded Lizard (Heloderma horridurn), and the Gila monster (Heloderma suspectum). Although not strictly venomous, the bite of a Komodo Dragon is not just dangerous for the physical damage the Komodo is capable of causing, it is also heavily dosed with dangerous bacteria.
Within the Komodo's saliva reside more than fifty strains of bacteria, some seven of which are highly septic and four of which have no known specific antidote. Addressed early, attacks on humans have not proven fatal when treated with broad based and powerful antibiotics. However for animals in the wild, the bite usually proves fatal as a result of infection, even if the wound itself is insufficient.
Despite the toxicity of a Komodo Dragon's bite, Komodo Dragons bitten by their own species seem unaffected by the bacteria. As a result, the Komodo makes an interesting study in terms of both the toxicity of its saliva and the impregnable nature of its immune system. Some of the zoological studies of the Komodo Dragon are focussed on this particular aspect of the Komodo Dragons make-up.Genetic Diversity
In any small surviving group, genetic diversity becomes problematic. Most Komodo Dragons born in captivity are related back to a small handful of lizards originally from Indonesia. Within the Indonesian archipelago, there are only 600 or so females of breeding age and the breadth of genetic diversity is falling, this is compounded by the falling number of geographic locations in which different colonies remain.
A large number of Komodo Dragons have been genetically sampled and micro-chipped and studies into the genetic range and maintenance of the genetic pool are part of the ongoing study of this species.Breeding and Captivity
In 1992, Kraken was born at the National Zoo in Washington, D.C., in the United States. Kraken was the first Komodo Dragon hatched in captivity outside of Indonesia. More than 50 other Komodo Dragons were hatched at the Zoo and found their way to other zoos around the world. Since 1992, other Komodo Dragons have been born in captivity in numerous locations around the world, mostly other zoos.
In the wild, mating occurs between May and August and the female lays her eggs in September. The female occasionally lays on the eggs and protects them during incubation, however once the hatchlings emerge, they are on their own, without parental care. In fact they flee to the trees to avoid become prey to a number of potential predators including their parents.Studies and Experts
There are numbers of people working directly on Komodo Dragon related projects or on other projects benefiting conservation of this species, including the care of the Komodo National Park.
Much of today's knowledge however is built on the work of Walter Auffenberg, particularly his comprehensive field study of the 1970s which looked at everything from behaviour and diet through to distribution and environment. Papers and research are still being released by scientists and researchers that worked with Auffenberg later in his life.