The Komodo Dragon is the Largest Living Species of Lizards
The Komodo Dragon is the Largest Living Species of Lizards
The Komodo dragon (Varanus
komodoensis) is a large species of lizard found in the Indonesian
islands of Komodo, Rinca, Flores, and Gili Motang.
The evolutionary development of the Komodo dragon started with the Varanus genus, which originated in Asia about 40 million years ago and migrated to Australia.
Around 15 million years ago, a collision between Australia and Southeast Asia allowed the varanids to move into what is now the Indonesian archipelago, extending their range as far east as the island of Timor.
The Komodo dragon was believed to have differentiated from its Australian ancestors 4 million years ago.
However, recent fossil evidence from Queensland suggests that the Komodo dragon evolved in Australia before spreading to Indonesia.
Dramatic lowering of sea level during the last glacial period uncovered extensive stretches of continental shelf that the Komodo dragon colonized, becoming isolated in their present island range as sea levels rose afterwards.
A member of the monitor lizard
family (Varanidae), it is the largest living species of lizard, growing
to an average length of 2 to 3 metres (6.6 to 9.8 ft) and weighing
around 70 kilograms (150 lb).
Their unusual size has been
attributed to island gigantism, since there are no other carnivorous
animals to fill the niche on the islands where they live.
However, recent research suggests that the large size of komodo dragons
may be better understood as representative of a relic population of very
large varanid lizards that once lived across Indonesia and Australia,
most of which died out after contact with modern humans, along with
Fossils very similar to V.
komodoensis have been found in Australia dating to greater than 3.8
million years ago, and its body size remained stable on Flores, one of
the handful of Indonesian islands where it is currently found, ever
since Flores (along with neighboring islands) were isolated by rising
sea levels approximately 900,000 years ago.
a result of their size, these lizards dominate the ecosystems in which
they live. Although Komodo dragons eat mostly carrion, they will also
hunt and ambush prey including invertebrates, birds, and mammals.
Mating begins between May and
August, and the eggs are laid in September.
About twenty eggs are
deposited in abandoned megapode nests and incubated for seven to eight
months, hatching in April, when insects are most plentiful.
Young Komodo dragons are vulnerable and therefore dwell in trees, safe from predators and cannibalistic adults.
They take around three to five years to mature, and may live as long as fifty years.
They are among the rare vertebrates capable of parthenogenesis, in which
females may lay viable eggs if males are absent. Komodo dragons were
first recorded by Western scientists in 1910.
Their large size and
fearsome reputation make them popular zoo exhibits.
In the wild their range has
contracted due to human activities and they are listed as vulnerable by
the IUCN. They are protected under Indonesian law, and a national park,
Komodo National Park, was founded to aid protection efforts.
Although attacks are very rare, Komodo dragons have been known to attack humans.
|The Living Planet - Worlds Apart
Broadcast March 29th, 1984, this episode investigates remote islands and their inhabitants. Some islands are tips of volcanoes; others are coral atolls.
Those that colonize them transform into new species with comparative speed. Attenborough visits Aldabra in the Indian Ocean, which is 400 kilometers from the African coast.
It has a vast population of sooty terns, which enjoy a degree of protection from predators that is unavailable on the mainland. The giant tortoise has also proliferated, despite the inhospitable nature of the landscape.
Many island birds become flightless, including the Aldabran rail and the extinct dodo of Mauritius. Living in such isolation seems to allow some species to outgrow their mainland cousins, and Attenborough observes a group of feeding Komodo dragons at close quarters.
The volcanic islands of Hawaii have become rich in vegetation and therefore a multitude of colonists: for example, there are at least 800 species of drosophila that are unique to the area.
Polynesians reached Hawaii well over a thousand years ago, and their sea-going culture enabled them to reach many Pacific islands, including Easter Island, where they carved the Moai, and New Zealand: the ancestors of the Māori.
Attenborough highlights the kakapo as a species that was hunted to near-extinction. It is a facet of animal island dwellers that they have developed no means of self-defence, since their only predators are those that have been introduced by humans.
Kills With One Bite
Scientists are still figuring out the mysteries of the Komodo dragon. How is it capable of killing large prey with a single bite?
On June 4th, 2007 a Komodo dragon attacked
an eight-year-old boy on Komodo Island. The boy later died of massive
bleeding from his wounds.
It was the first recorded fatal attack in 33
years. Natives blamed the attack on environmentalists outside the island
prohibiting goat sacrifices.
This denied the Komodo dragons their expected food source, causing them to wander into human civilization in search of food. A belief held by many natives of Komodo Island is that Komodo dragons are actually the reincarnation of fellow kinspeople and should thus be treated with reverence.
On March 24th, 2009, two Komodo Dragons attacked and killed fisherman Muhamad Anwar on Komodo. Anwar was attacked after he fell out of a sugar-apple tree and was left bleeding badly from bites to his hands, body, legs, and neck. He was taken to a clinic on the neighboring island of Flores where he was pronounced dead on arrival.
In a bizarre incident in June 2001, Phil Bronstein, Executive Editor of the San Francisco Chronicle newspaper, was given a special tour of the Komodo dragons at the Los Angeles Zoo for a Father's Day present by his wife, the actress Sharon Stone.
Bronstein and Stone were benefactors of the zoo. While barefooted and petting one of the dragons, Bronstein's foot was seriously bitten and required extensive surgery