Komodo dragon
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| Varanus komodoensis Ouwens, 1912 |
The Komodo dragon or Komodo Monitor (Varanus komodoensis) is the largest living lizard in the world, growing to an average length of 2-3 meters (approximately 6.5-10 feet). It is a member of the monitor lizard family, Varanidae, and inhabits various islands in Indonesia.
Sightings of the Komodo dragon were first reported to Europeans in 1910. Widespread knowledge came after 1912, in which Peter Ouwens, the director of the Zoological Museum at Bogor, Java, published a paper on the topic. In 1980, the Komodo National Park was founded to help protect their population.
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[edit] Physical description
In the wild, large adults tend to weigh around 70kg (154 pounds). Captive specimens often weigh more. The largest verified wild specimen was 3.13 metres (10 feet 3 inches) long and weighed 166kg (365 pounds), including undigested food [1]. Komodo dragons also have a tail that is as long as the body, as well as 52 serrated teeth that can be 1 inch (2.5 centimeters) in length. They have red, blood-like saliva and a long yellow tongue. Males are larger than the females, and can have skin color from dark gray to brick red. Females are more olive green, and have patches of yellow at the throat. The young are more colorful by comparison, with yellow, green, and white banding on a dark background.
[edit] Ecology and behavior
Komodo dragons are found exclusively in Indonesia, on the islands of Komodo, Rinca, Flores, in the Lesser Sunda archipelago. They prefer hot and dry places, and typically live in dry open grasslands, savannas, and tropical forests at lower elevations. As an ectotherm, they are most active in the day, although they do have some activity in the night. Komodo dragons are largely solitary, coming together only to breed and eat. Komodo dragons can run in brief charges, and can also swim and climb trees proficiently through use of their large claws. As they grow older, their claws are used primarily as weapons, as their size and mass make climbing impractical for larger adults.
For shelter, dragons dig holes that can measure from 3-6 feet wide (0.9-1.8 meters wide). Its sense of hearing is not very developed, and it has trouble discerning stationary objects. It uses its tongue to detect taste and smell stimuli, like most reptiles, which helps when navigating in the dark. Komodo dragons usually live for 25-30 years. It is at the highest levels of the food chain, and is important for eliminating weak and sick animals.
New research using DNA analysis and other techniques at the University of Melbourne questioned conventional wisdom and suggests that Komodo dragons and many other lizards are indeed venomous (or have venom-producing genes) and properly belong to a "venom clade" called Toxicofera. This new research calls into question the traditional view of evolution of the Squamata, and the DNA evidence now appears to indicate that modern lizards and snakes share an evolutionary ancestry that dates back more than 200 million years. This information has therefore caused many biologists to question the current classification of species in the order Squamata.
[edit] Diet and feeding
Komodo dragons are carnivorous. Although they seem to like carrion, studies show that they also hunt live prey with a stealthy approach followed by a sudden short charge, during which they can run briefly at speeds up to 20 km/h (~13 mph). Komodo dragons have not traditionally been considered venomous, but recent research has shown that they do in fact produce venom (Fry et al., 2006). Unlike snakes, which deliver venom through hollow fangs, the venom of Komodo dragons and other Varanids pools around the teeth and is delivered when the lizard attacks. If the initial bite does not kill the prey and it escapes, the animal generally succumbs within a week to the venom or infection. Once dead, the lizard is able to locate it using its sense of smell, which can locate a dead or dying animal from a range of up to four miles.
In addition to the Komodo dragon's venom, they also have virulent bacteria in their saliva, of which more than 15 strains have been discovered. These bacteria cause septicemia and infection in their victims. Komodo dragons appear to be immune to these bacteria.
Eating is controlled by a strict hierarchy. The dominant male eats first, and others eat only when he is finished. Females, however, do not follow any hierarchy and eat together. Komodo dragons eat by tearing large chunks of flesh, and holding it down with its forelegs, and swallowing it whole. Their expandable jaws and stomachs allow them to eat 80 percent of their body weight in one meal, akin to a 200 pound man (90.7 kg) eating 160 pounds (72.6 kg) of food during one sitting.
The Komodo dragon's prey is wide ranging, and includes insects, smaller reptiles, birds, bird eggs and, small mammals, wild pigs, goats, deer, macaques, horses, and water buffaloes. In the wild they have also been observed to eat other smaller dragons. Occasionally they have been known to eat humans and human corpses. Over a dozen human deaths have been attributed to dragon bites in the last century, though there are reports of survivors of the resulting septicemia.
[edit] Conservation status
The Komodo dragon is a vulnerable species and is found on the IUCN Red List. There are approximately 6,000 living Komodo dragons. Their populations are restricted to the Lesser Sunda Islands in Indonesia, including the islands of Komodo (1,700), Rinca (1,300), Gili Motang (100) and Flores (maybe 2,000). However, scientists are concerned that there may be only 350 breeding females.
[edit] Reproduction
Mating occurs between May and August, with the eggs laid in September. During this period, males fight over females and territory by wrestling each other on their hind legs to the ground, the one being pinned down losing. During copulation, the male often scratches the female's back, sometimes even to the point of drawing blood. The female lays her eggs in the ground or in tree hollows, lending them some protection. Clutches usually contain an average of 20 eggs, and have an incubation period of 7 months. However, after the hatchlings are born, they are generally defenseless and many do not survive. Young Komodo dragons generally spend their first few years living in trees where they have a greater chance of survival. Komodo dragons take around three to five years to mature, growing to 2 metres in length, and they can live for up to 30 years.[edit] In captivity
Komodo dragons have long been desired animals for zoos, where their size and reputation makes for a popular exhibit. One particularily interesting fact that has been observed from captive dragons is the fact that most individuals readily exhibit very tame behavior within a short period of time. There are many incidents reported where keepers have brought the animals out of their enclosures to interact with zoo visitors, including young children (Procter, 1928), (Lederer 1931).
Dragons are also capable of recognizing individual humans. Ruston Hartdegen of the Dallas Zoo reported that the animals react differently when present with their standard keeper, a familiar keeper, or a completely unfamiliar keeper (Murphy and Walsh, 2006). With some individual animals aside, dragons appear to be very intelligent lizards capable of peaceful interaction with humans, warranting future behavioral studies.
Various Zoos are attempting to keep Komodo Dagons in Captivity, these include:
UK - Chester Zoo - London Zoo - Colchester Zoo
USA - Disney Animal Kingdom, Florida - Woodland Park Zoo, Seattle - Honolulu Zoo, Hawaii - San Diego Zoo, California - Fort Worth Zoo, Texas - Smithsonian National Zoo, Washigton - Sedgwick County Zoo, Kansas - Saint Louis Zoo, St. Louis - Houston Zoo, Houston
Australia - Taronga Zoo - Australia Zoo
[edit] Media
Image:KDragon1mj.jpg Videos of Varanus komodoensis at Disney's Animal Kingdom
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[edit] See also
</div>- Megalania prisca (huge extinct Varanid lizard)
- European dragon (the mythical dragon)
- Monitor lizard
[edit] References and links
- Fry, B. G., Vidal, N., and Norman, J. A., 2006. Early evolution of the venom system in lizards and snakes. Nature 439: 584-588.
- King, Dennis & Green, Brian. 1999. Goannas: The Biology of Varanid Lizards. University of New South Wales Press. ISBN 086840456X
- Lederer, G. 1931. Erkennen wechselwarme Tiere ihren Pfleger? Wochenschr. Aquar.-Terrarienkunde 28: 636-638.
- Murphy, J., and Walsh, T., 2006. Dragons and Humans. Herpetological Review, 37: 269-275.
- Procter, J. B. 1928. On a living Komodo dragon Varanus komodensis Ouwens, exhibited at the Scientific Meeting, October 23rd, 1928. Proc. Zool. Soc. London 1928:1017-1019.
- World Conservation Monitoring Centre (1996). Varanus komodoensis. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Listed as Vulnerable (VU B1+2cde v2.3)
- The Komodo Dragon by Claudio Ciofi, Scientific American (March 1999)
- Woodland Park Zoo
- Komodo Dragon Central
- Discovery of venom in monitor lizards
- Whozoo
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Two komodo dragons |
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Komodo dragon at Taronga Zoo |
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