Komodo dragon - Varanus komodoensis
May 3, 2016 5:47:39 GMT 5
creature386, theropod, and 1 more like this
Post by Ceratodromeus on May 3, 2016 5:47:39 GMT 5
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Lacertilia
Family: Varanidae
Genus: Varanus
Subgenus: Varanus
Species: V.komodoensis
Other common names
Komodo monitor, Komodo dragon, Ora, buaya darat, biawak raksasa,
Description
This is the largest, and most recognized species of lizard in the world. The prehistoric, and intimidating appearance of adult animals aided in giving this animals its world famous common name, although to the locals in its native habitat, it is known by many. The body of adult animals is robust and low slung, with a gait akin to other members of Varanidae. They are fairly uniform in color, typically being light brown or grey. This is a stark deviation from the young animals, which possess alternating black and white/yellow banding. The legs of the adult animals are relatively short but sturdy, possessing heavy musculature. The head is large and very wide, the mouth filled with 33 highly serrated and recurved teeth{1}.
As noted above, this is the heaviest species of lizard, easily outdistancing other members of the Varanus genus in terms of body mass. Other species achieve large sizes, such as the asian water monitor(Varanus salvator), but this animal only gets as heavy as a young adult komodo dragon. The crocodile monitor(V.salvadorii) grows to similar lengths as the komodo dragon, but is much more slenderly built, an adaptation for its arboreal lifestyle. In his 1982 book of animal facts and feats, Gerard wood notes that the length & weight of adult females was around 2.28m(7.6ft) and 68-73kg(150-160lbs) on average, while adult males measure 2.59m(8.6ft), and weigh 79-91kg(175-200lbs); the heaviest recorded animal weighing a staggering 165.5kg(350lbs), and measured 3.1m(10.1ft) in total length but was a captive animal at a Missouri zoological park, and likely had a large amount of food in its stomach{2}. In private correspondences, Dr. Tim Jessop has stated what he believes the largest adult komodo dragons can weigh without supplemental food in the gut, a whopping 87kg -- though he believes this animal would be at the end of the bell curve for the species. He also notes that most adult males will weigh 65-80kg, similar to numbers presented by Gerard Wood.
Behavior
In his book, Auffenberg notes that the temperament of the species varies from individual to individual. Some of his studied animals were more calm in nature, but a few were decidedly very aggressive. They are readily approachable in nature, though it is advised that people for the most part due not, as they can turn & sprint very quickly, leaving very little time for people to get away and avoid being bitten. They become very aggressive and agitated when captured in traps by researchers, or cornered by people in general. Auffenberg notes that the adult animals were usually calm in a free roaming state, but became agitated when noosed, often advancing on a person with the mouth open, throat dilated, and tail curled in typical varanid fashion{1}. The ora seems to be rather aggressive towards conspecifics, especially when they are smaller than themselves, which they chase and on occasion kill. Many adult animals of both sexes possess many scars from intraspecific conflict. These scars are heavily concentrated on the backs and sides of the animal, the nape of the neck and near the nape of the tail.
Despite their at times unpredictable temperament, they are a fixture in many zoos, and zookeepers(as well as various researchers) have noted this animals to possess a high degree of intelligence; being able to recognize individual zookeepers.
Distribution & habitat use
Aside from its world known locality, the komodo dragon also ranges throughout four other small islands; they are
Flores, Gilli motang, Gilli Dasami, and Rinca;It is now believed that this varanid originally came from australia approximately 900,000 years ago. Komodo dragons show a very significant degree of genetic variation between these populations, with those on Komodo showing a high degree of genetic divergence from other populations{3}. This species occupies a wide range of habitats, at various stages of life. Recent study conducted in Komodo nationla park, Gilli montag, and Rinca have shown that habitat and niche use is heavily tied to the body mass of the lizard{4}. The smallest of the lizards preferred forest habitats, being found mostly in trees or otherwise off the ground whilst the subadult and adult animals preferred open habitats.
Venom
Not all that long ago it was widely believed that this lizard had a toxic bite, and that the toxins in its saliva(along with the bacteria filled waters of the islands the lizard lives in) helped it take down prey -- this was figured to be proven via the cultivation of bacteria such as e.coli found in the mouths of wild animals. However, in recent years studies have been conducted on the skull of this animal by Dr, Brian Fry, who put forward the notion that the Komodo dragon was actually venomous. This was supported by the finding of venom glands in the lower jaw{4}. In 2009, Brian Fry and other researchers showed this idea further, stating in their research that the venom of the Komodo dragon is the primary tool in dispatching prey, An animal of ~1.6m total body length was also shown to yield 10-50mg of venom{6}.
Dietary habits
Like all members of the Varanus genus, the ora is an opportunist, feeding on an array of animals, and will not hesitate to feed on an animal killed by other predators.
The diet of the smaller, younger animals is a lot more narrow than that of the adult animals, but they still take a variety of small animals, like insects(namely locusts and grasshoppers), lizards(skinks, geckos) which they find in the crevices of the trees or on the ground whilst foraging{1}. Juvenile animals were found to feed on small birds and rodents, and seem to prefer the palm civets over other mammals{4}. An ontogenic shift in prey preference was found to occur at a body mass of roughly 20kg(44lbs), in which the ora will start taking adult ungulates{4}. The preferred prey of the adult animals appears to be deer, hogs, domestic/ feral dogs, domestic/feral goats, and the occasional water buffalo; Locals also report that this species will go after horses{1}.
Prey is primarily taken by ambush, in one instance recorded in Auffenberg's book, an adult animal lay near a trail and waited for an adult pig to walk by it, it then lunged forward and grabbed the pig by the back of the leg, severing several tendons. it then quickly dispatched the unfortunate animal. This is one of the most commonly used predatory tactics of this species. In one particular fascinating account an ora was said to kill a fully grown water buffalo by ripping open its stomach. They are known to congregate at a large kill, though disputes do break out from time to time.
Reproduction
The ora attains sexual maturity at approximately 1.6m(5.2ft) in total body length, and the mating season of this species is believed to occur between June and August. Males will engage in ritualistic matches to establish dominance and mating rights, and curiously enough mounting and mating commonly occurs within aggregations of komodo dragons, not something that is common in Varanidae. At times the female is not susceptive to mating and will engage in aggressive displaying or attacking the male in question. Nonetheless courtship is brief and generally consists of the male scenting the female(generally on the snout and base of the tail) before trying to mount her. Mating is brief, and the male doesn't tend to stick around afterwards -- sometimes being attacked by the female if they do; Eggs are believed to be laid in late July or August{1}. The clutch is laid over several days, and typically numbers 18, but as many as 40 have been reported in captivity.
In recent years at least two captive females, both separated by males for some time, have produced fertile eggs that eventually hatched. This reproductive plasticity is believed to be an adaptation to ensure that a species' genetic line continues in the absence of males, seeing as how that only male offspring are produced from parthogenic animals{7}. Nests are constructed by females, typically being a large mound or a burrow.
Hatchlings measure anywhere from 253-555mm(9.9-21in) in length, typically measuring around 300mm(11.8in){1}. They are extremely arboreal in nature, and this doesn't typically change until they're a bit older -- what is classified as the juvenile size class. At this size they tend to become more terrestrial in nature, but still spend some time amongst the trees, and will resort to climbing them if chased. At these sizes they are likely to be taken by hogs, dogs, raptorial birds if they're caught in the open. However the larger they get, the less they have to worry about other predators. An adult ora has little to fear, except for man and larger conspecifics.
References
{1} Auffenberg, Walter. The behavioral ecology of the Komodo monitor. University Press of Florida, 1981.
{2} Gerald L. Wood. Guiness book of Animal Facts and Feats. 1982.
{3} Ciofi, Claudio, et al. "Genetic divergence and units for conservation in the Komodo dragon Varanus komodoensis." Proceedings of the Royal Society of London B: Biological Sciences 266.1435 (1999): 2269-2274.
{4} Purwandana, Deni, et al. "Ecological allometries and niche use dynamics across Komodo dragon ontogeny." The Science of Nature 103.3-4 (2016): 1-11.
{5} Fry, Bryan G., et al. "Early evolution of the venom system in lizards and snakes." Nature 439.7076 (2006): 584-588.
{6} Fry, Bryan G., et al. "A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus (Megalania) priscus." Proceedings of the National Academy of Sciences 106.22 (2009): 8969-8974.
{7} Watts, Phillip C., et al. "Parthenogenesis in Komodo dragons." Nature 444.7122 (2006): 1021-1022.
