Komodo dragon

The Komodo dragon (Varanus komodoensis) is the largest lizard in the world, growing to an average length of 2-3 meters (10 feet). In the wild large adults tend to weigh around 70kg (154 pounds). Captive specimens often weigh more. The largest verified specimen was 3.13 meters (10 feet 3 inches) long and weighed 166kg (365 pounds) including undigested food. [1] It is a member of themonitor lizard family, Varanidae, and inhabits various islands in indonesia . The papua monitor, Varanus salvadorii may surpass the Komodo in length but it is slimmer and weighs less. [2]

They are carnivorous and 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. Komodo Dragons are not venomous, but the serations along their teeth create an ideal niche for over 50 different strains of bacteria. If their initial bite does not kill the prey, and it escapes, the deadly infections caused by the bacteria living in the Dragons teeth kill it within a week. Then the Komodo Dragon descends upon it to feed on its dead flesh.

The Komodo dragon's prey is wide ranging, and includes wild pigs,goats,deer, and water buffaloes. In the wild they have also been observed to eat other young Komodo 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.

Mating occurs between May and August, with the eggs laid in September. The female lays her eggs in the ground or in tree hollows, which lends them 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 defenceless and many do not survive. Young Komodo dragons generally spend their first few years living in trees where they have a higher rate of survival. Komodo dragons take around five years to mature, growing to 2 metres in length, and they can live for up to 30 years.

There are approximately 6,000 living Komodo dragons, 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).

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.

Evolutionary Overview

Monitor lizards are considered to be the most highly developed lizards, possessing a relatively rapid metabolism for reptiles, several sensory adaptations that benefit the hunting of live prey, and a lower jaw that may be unhinged to facilitate eating large prey animals. Recent work also indicates that the Varanid lizards, including the Komodo dragon, produce venom. These latter two adaptations are shared with snakes, which are thought to have evolved from a sister group to the Varanidae as part of a larger venom clade.

Origin of Name

It has been said that the name of monitor lizards is derived from a superstition that the creatures would give a warning about the presence of crocodiles. However, this explanation may be apocryphal. According to Wildwatch, the name actually resulted from a mishearing of the Arabic word oaran (lizard) as the German warnen (to warn), which was subsequently Latinized into monitor.

Lizards are reptiles of the order Squamata, which they share with the snakes (Ophidians). They are usually four-legged, with external ear openings and movable eyelids. Species range in adult length from a few centimeters (some Caribbean geckos) to nearly three meters komodo dragons

Some lizard species called " glass snakes" or " glass lizards" have no functional legs, though there are some vestigial skeletal leg structures. They are distinguished from true snakes by the presence of eyelids and ears.

Many lizards can change colour in response to their environments or in times of stress. The most familiar example is the chamelonbut more subtle colour changes occur in other lizard species as well (most notably the anole, also known as the "house chameleon" or "chamele").

Lizards typically feed on insects or rodents. A few species are omnivorous or herbivorous; a familiar example of the latter is the iguana , which is unable to properly digest animal protein. Until very recently, it was thought that only two lizard species were venomous: the Mexican beaded lizard and the closely-related gila monster, both of which live in northern mexico and the southwest United States. However recent research at the University of Melbourne, Australia and Pennsylvania State University has revealed that in fact many lizards in the iguanians and monitor (lizard) families have venom-producing glands. None of these poses much danger to humans, as their poison is introduced slowly by chewing, rather than injected as with poisonous snakes. Nine toxins previously thought to only occur in snakes have been discovered, and a number of previously unseen chemicals as well.

These revelations are prompting calls for a complete overhaul of the classification system for lizard species form a venom clade. "These papers threaten to radically change our concepts of lizard and snake evolution, and particularly of venom evolution," says Harry Greene, a herpetologist at Cornell University in New York.

Most other lizard species are utterly harmless to humans (most species native to North America, for example, are incapable even of drawing blood with their bites). Only the very largest lizard species pose any threat at all; the komodo dragon , for example, has been known to attack and kill humans and their livestock. The chief impact of lizards on humans is positive; they are significant predators of pest species; numerous species are prominent in the pet trade; some are eaten as food (for example, iguanas in Central America); and lizard symbology plays important, though rarely predominant roles in some cultures (e.g. Tarrotarro in Australian mythology).

Most lizards lay eggs, though a few species are capable of live birth. Many are also capable of regeneration of lost limbs or tails.

Lizards in the Scincomorpha family, which include skinks (such as the blue-tailed skink), often have shiny, iridescent scales that appear moist. However, like all other lizards, they are dry-skinned and generally prefer to avoid water (though all lizards are able to swim if needed).