From The Times
May 20, 2009

Venom is Komodo dragon's lethal weapon


Anne Barrowclough in Sydney

The Komodo dragon is not just the largest living lizard, but also one of the most venomous creatures on Earth, scientists have discovered.

The carnivorous animal, which can tear its prey apart, kills with venom rather than bacteria-laden bites, as scientists had always believed.

The dragons, which grow to a length of about 10ft and weigh about 130lb (60kg) are vicious predators that prey on animals as large as deer.

They attack their victim by biting and tearing at it repeatedly, then wait as it dies a lingering death.

Scientists always believed that because Komodos also fed on carrion, their mouths must teem with bacteria and that the germs infected their victims, killing them slowly.

Magnetic resonance imaging scans have shown, however, that Komodos have glands in their mouths that produce venom similar to that of many snakes.

The lizard’s sharp, serrated teeth open up wounds into which the venom flows from the gland that runs along the jawline. The venom acts as an anticoagulant, increasing the blood flow and reducing blood pressure, sending the victim into shock. The victim’s blood cannot clot and it bleeds to death.

The venom makes the animals formidable killers even though their bite is much weaker than that of a crocodile. “The teeth and the venom work in perfect harmony,” said Bryan Fry, the head of the international team whose research on the lizard’s killing powers is published in the US journal Proceedings of the National Academy of Sciences.

“It works as well as a poisoned dagger,” the venom expert from Melbourne University told The Times. “It is an amazing killing machine.”

Komodos rarely attack humans although an eight-year-old Indonesian boy was attacked and killed in a park on Komodo Island two years ago. This year a Komodo stalked a poacher for several days before killing and eating him.

Despite the dragon’s venom gland running visibly along its jawline, scientists had not realised until now that it was poisonous.

“That’s because no one bothered to look,” said Dr Fry, who noted the gland during his work with captive Komodos at Singapore zoo.

The endangered species, which is found only in the Indonesian islands of Komodo, Flores, Rinca and Gili Motang, inherits its size and venomous punch from its extinct ancestor, the megalania, a giant goanna that roamed Australia 400,000 years ago.

Research carried out by Dr Fry’s colleague, the biomechanist Stephen Wroe, found that the megalania, which grew to 23ft, was the most venomous creature to have lived.

Until recently, only two poisonous lizards were thought to exist — the Gila Monster and the Mexican Beaded Lizard. Both live in the southern United States and Mexico.

This finding actually amazes me, that the Komodo dragon actually has venom. Their saliva alone has so much bacteria in it to kill large animals.