Describer (Date): P.A. Ouwens (1912) On a large Varanus species
from the island of Komodo. Bull. Jard. Bot. Buitenzorg. 2(6):1-3. Earliest
official mention by H. Zollinger (1850). Verslag van eene reis naar Bima en
Sumbawa en naar eenige plaatsen op Celebes, Saleyer en Flores gedurende de
maanden Mei tot December, 1847. Vehl. Batav. Gennotschap. 23:10-22.
Kingdom: Animalia Phylum: Chordata Class: Reptilia Subclass:
Diapsida (Crocodiles, tuataras, lizards, snakes) Order: Squamata (lizards, snakes and amphisbaenians or "worm-lizards") Suborder: Sauria (Lacertilia) Infraorder: Autarchoglossa Family: Varanidae Genus:Varanus (50+ recognized species) Species: V. komodoensis
The genus name "Varanus" was introduced in 1820 by
German professor, Blasius Merrem. It is a latinization of the Arabic
"waran," the Egyptian name for the Nile monitor. (Egyptians believed that these lizards served as "monitors,"
alerting people to the presence of crocodiles.)
70 species and subspecies of Varanus have been described but
only 50 species are currently recognized
Size is the most variable
anatomical characteristic in the family (length varies from 0.32m to
All species are similar in appearance
The family Varanidae includes the largest living lizards
First mention of Komodo dragon in scientific literature:
Peter Owens in 1912 mentions "Varanus species of an unusual size" from Komodo Island
Komodo Dragon. (Komodo is the name of one of the islands on which they
"Ora" is a local name in the Mangarrai dialect.
The Hindi name "biscobra" implies that it is twice as deadly
as the cobra.
The Malaysian name "buaja darat" means land crocodile.
Members of the Varanidae family are commonly referred to
"varanids," "monitors," or (in Australia)
The oldest varanoid fossils (95 million years ago, Cretaceous) are related to the early mososaurs and snakes; lived in Europe and Asia
Genus Varanus first recognized in the fossil record from about 34 million years ago (Late Eocene)
(Homes et al. 2010)
Fossils found in Egypt; dispersals followed into Europe, Asia, Australia
A direct ancestor of the Komodo Dragon is the gigantic Pleistocene fossil Megalania prisca from Pleistocene deposits in eastern Australia.
DISTRIBUTION & HABITAT
(Auffenberg 1981) (CBSG 1995)
(Fitch et al 2006)
Varanid lizards occur throughout Africa, the Middle East, South-East Asia, Australia (Fitch et al 2006)
Komodo dragons restricted to the islands of Komodo, Flores, Rinca and Gilli Motang in
the middle of the Lesser Sunda Islands, Republic of Indonesia. Less
than 1000 sq km of is officially protected and designated Komodo
Different methodologies have produced different population figures.
Best current estimate from the IUCN/SSC/CBSG : 5000
In Komodo National Park:
1600 on Komodo
1100 on Rinca
70 on Gilli Montang
100 on W. Flores (Wae Waul Reserve)
2000 scattered in non-protected areas
One of world's major volcanic areas. Slight tremors felt every few
weeks; volcanic ash fall occurs periodically.
Largest komodo habitat is on the island of Komodo where they occupy the
entire island. On Flores they occupy 400 sq km and on Rinca 278 sq km
Regions inhabited are arid and mountainous. Komodos are usually found
in the rocky valleys between 500-700 m. They prefer the extensive flat
savannas. The driest savanna is studded with lontar palms. Moister
grasslands have tamarind and jujube trees.Adult Komodos frequently
occupy the transition zone between tropical monsoon forest (tamarind
and kapok trees, cycads and ferns) and the savanna.
Found from sea level to 800 m.
Average temperature 26.7 C at sea level (Range: 17C - 43C)
(Auffenberg, 1981) (Ciofi 2004) (De Lisle, 1996) (King & Green, 1993) (Fry et al. 2006) (Fry et al. 2009)
Largest living lizard. (Males: 3 m, 90 kg; Females 2 m, 70 kg)
Average field weight: about 47 kg. (Heaviest 54 kg)
Average field length: Up to 260 cm
Head raised to full extent is approximately 40 cm above the ground.
When lowered the animal is less than 20 cm high (Long neck can stretch
to give the dragon a better view of its surroundings in tall grass.
Toes have sharp, recurved claws.
Teeth are specialized for a carnivorous diet. They are serrated,
compressed laterally, and curved posteriorly with a sharp tip and
broad base, (Curved teeth are better than straight teeth for catching
and holding prey). Although many varanids have one or two replacement
teeth at each position, the komodo has four or five. Longest teeth are
approximately 2 cm.
Venom toxins are now known to be present in toxin-secreting glands of monitor lizards (Fry et al. 2006; Fry et al. 2009)
Biologists hypothesize that venom systems evolved early in the evolution of both snakes and lizards
Nine toxin types are shared between lizards and snakes
In one monitor lizard, the Lace Monitor (Varanus varius), its toxin effects blood pressure and clotting ability of its prey
Short intestine is typical of carnivores (Diets high in proteins and
lipids don't require a great deal of digestive processing)
Juvenile Komodos are slender and agile. Adults are massive with flatter
bodies and proportionately shorter tails
Skin is like "chain-mail" with numerous osteoderms. Shedding
occurs in patches and lasts about 6 months each year (In the Komodo
this begins in September)
Tongue is long and narrow with a deep fork at its tip. It does not move
freely in the mouth, but retracts into a sheath. It is partially
supported by a complex structure of bone and cartilage called the
hyoid apparatus. Varanids are unique in using their tongues only as a
sensory organ for locating prey and as a socialization tool. Other
lizards use the tongue to manipulate food.
Males are bulkier and larger than females.
Most adults are uniformly gray or clay-colored. Until the age of four
they have much brighter, speckled skin. (Komodos of Flores retain
There is little sexual dimorphism. The flanks of adult females have
more red than males. Yellowish-green nose spots are more common in
The light yellow tongue is species specific. (V. salvator has a
blue tongue, V. dumerili and V. grayi have pink tongues)
Sense of smell extremely important in food detection. Komodos can
detect the scent of carrion from as far as 11 km. (Decomposition
releases volatile oils - wind and size of prey are important factors)
Each external nostril leads to a multi-chambered nasal capsule. (One of
the chambers functions to excrete excess sodium.) A pair of Jacobson's
organs open into the roof of the mouth. Scent particles are collected
by the forked tongue and delivered to these sense organs which
stimulate the brain to react.
Eyes are placed laterally and covered by two unequal lids.
Upper lid has little mobility.
Lower lid contains a cartilaginous plate which slides over surface of
The ear is important for maintaining balance as well as sound reception.
Behavior seems to be more scent than sound oriented
Varanid lungs are larger than most reptiles.
Take in relatively larger amounts of oxygen and their physiology
produces a more efficient system of air circulation.
Breathing rate is regular and low but varanids can voluntarily hold
their breath for long periods.
Varanids have a more complex heart structure and blood chemistry
than other lizards.
This allows them to achieve intense activity without becoming
Water makes up 70% of a lizard's body weight. (10% more than humans).
Varanid skin is covered with scales and contains no sweat glands.
Excess sodium is removed by a special salt-secreting glands in the
nasal capsules (many lizards have them)
Opportunistic carnivores. Feed on a wide variety of prey
Hatchlings feed exclusively on insects (beetles and grasshoppers)
Small komodos tend to be arboreal and feed on smaller lizards, insects
birds and their eggs.
Medium Komodos feed largely on rodents (rats, shrews) birds (megapodes
and various small species) geckos, skinks and small snakes.
Large Komodos feed on carrion or hunt animals along game trails: wild
boar, sunda deer, water buffalo, large snakes, occasionally smaller
About 16 scavenging dragons occupy a sq km
Large Komodos kill about one large prey ungulate (deer or boar) per
month. This is supplemented with small prey (birds, rats)
Most lizards have broad flat tongues that are used primarily for food
handling but varanids have snake-like tongues which lack tastebuds and
can be retracted into a sheath. As the lizard searches for food or
explores, the tongue is moved up and down through an arc sampling
about 7 sq cm of air. Odor molecules are then carried back to the
Jaws close rapidly (enabling capture of fast-moving prey.) Prey is held
(sometimes thrashed) until all movement ceases. Small prey is
swallowed whole, usually head first. Large prey is sliced in pieces
Tongue is partially attached to a skeletal structure called the hyoid
apparatus. All snakes and lizards have such a structure which helps in
swallowing large food items.
Swallowing is accomplished by pushing prey down the throat while the
flexible jaws move forward to engulf it. Large prey is torn apart. The
hyoid apparatus moves it back to the esophagus. Neck muscles bend from
side to side to move food through the esophagus.
Ingestion rate may be as much as 2.5 kg/min - higher than any other
predator except large snakes.
After a heavy feeding, Komodos drink from water holes produced by wild
High digestive efficiency (70-90%) Time is dependent upon temperature
(about 26 hours at normal body temperature) Cool nights can delay to
almost 5 days. Stress can slow or even stop digestion (defecation of
partially digested prey may occur)
Similar to owls, all varanids regurgitate gastric pellets of
Fecal pellets may include hair, feathers, partly digested bones,
hooves, teeth, and claws and are excreted covered with a semisolid,
white uric acid paste.
Researchers identified venom in the saliva of monitor lizards, and venom-producing glands (Fry et al. 2006; Fry etl a. 2009)
The idea that bacteria-laden saliva contributes to their success in killing their prey (Auffenberg, 1981) is discounted
A comparatively high venom yield and large gland size argue convincingly for venom being vital to monitors' predation
REPRODUCTION & DEVELOPMENT
(Auffenberg, 1981)(IUCN/SSC CBSG, 1994)(Judd & Bacon, 1977)
Sexual maturity for both males and females occurs between 5 and 7 years
(Data from captive population indicates first reproduction for females
occurs 7-10 years)
Adult sex ratio: Auffenberg's 1981 study reports 3 males to 1 female.
Lilley reports 3.4 males to 1 female in his 1994 CAMP report.
Courtship and mating in Zoos and the field have been observed from Jan
19-October 1. Successful coition from June 28 to October.
Territories are not established. Courtship and mating takes place in
small aggregations of Komodos near carrion (other lizards usually mate
Monitors (like fishes and some birds) have a very brief courtship.
Mating occurs quickly. Attacks of males upon females are common at the
time of, and immediatley after, coitus. Most female acts are agonistic
(use teeth and tails) during early phases of courtship. Males must be
able to completely restrain females in order to remain uninjured.
Visual display is not significant. Other cues: rubbing chin on top of
body and neck of female. Hard scratches to back. Tongue-licks to area
around hind legs, shoulders, neck and head
Mounting occurs several times in each courtship sequence
Nest is an excavation in soil or in nests of megapods (mound-builder birds)
1-30 eggs laid in a clutch (average is 18) Females may lay one or more
eggs several times during several, successive days. Most females lay
only one clutch per year. (July to early September)
Eggs of all varanids have a soft, leathery shell.
Incubation: 2.5 - 8 months (probably dependent on temperature and soil
220 days when in captivity
Young appear in April or May and may remain together in small groups
for several months. Hatchlings weigh about 80 grams and average length
Young are arboreal during their first year
Adults largely terrestrial and rarely climb. May construct burrows
along vertical banks of stream beds or under boulders and fallen
trees. May also spend the night sleeping in high grass or dense brush.
Female breeding ability thought to decline around age of 20 and cease
around 30 yrs
Longevity: About 25 years in captivity. (Frankfurt Zoo & Berlin
Aquarium) Auffenberg estimates a lifespan of 50 years in wild.