Australasian Science: Australia's authority on science since 1938

Komodo Dragon Myth Slain

By Stephen Luntz

One of the best-known stories about Komodo dragons has been proven false, yet it has been surprisingly hard to gain acceptance for the new evidence.

For many years it has been believed that Komodo dragons, the world’s largest lizard, kill their larger prey through a unique mechanism. The story goes that the dragons have mouths full of bacteria, and that when they bite an animal too large to bring down, such as a water buffalo, the bacteria turn the wound septic, allowing the dragon its feed.

When University of Queensland biologist A/Prof Bryan Fry came to the dragon’s habitat to determine whether it had venom (AS, Jan/Feb 2006, p.6), he noticed water buffalo standing in waterholes black with their own sewage. “My first thought was: I wouldn’t want to go into that with a cut leg,” says Fry.

This caused Fry to wonder: were the bacteria that kill the buffalo coming from the dragon’s mouth, or the water in which they were standing? Fry says there had only been two studies of the dragon’s mouth bacteria. “They were by the same group, none of whom were microbiologists. You find the same sort of bacteria in the mouth of a Tassie devil or lion.”

The buffalo are used to living in large freshwater marshes with ecosystem cleaning mechanisms. Since being imported to islands like Komodo 300 years ago, the buffalo have followed their instincts when attacked by a dragon, which is to go and stand in water. Unfortunately the only water bodies are small ponds filled with the faeces of other buffalo. “It is when the water buffalo go stand in the toxic water with gaping wounds that they get infected,” Fry reported in the Journal of Zoo and Wildlife Medicine.

The dragons largely feed on smaller game such as pig and deer, which they are capable of killing through a combination of mechanical force, vicious teeth and venom that causes even those animals that initially escape to bleed profusely. “They have a 90% kill rate,” says Fry. “It’s better than a lion or a great white shark.”

Buffalo are a different matter, and represent only a small part of the dragon’s diet. Even then, since it takes a week for a buffalo to die of its wounds, the dragon that eventually feeds on the carcass is unlikely to be the one that made the attack in the first place. “There’s not a single recorded case of a dragon stalking a buffalo until it dies,” Fry says.

Nevertheless the story is so appealing it has been propagated by such master communicators as Douglas Adams and David Attenborough. Adams added the claim that the oral bacteria gave the dragon the world’s worst-smelling breath, but Fry says Adams must not have got close enough to test. “Their breath smells better than my two staffies at home,” says Fry. “After they are done feeding, they will spend 10–15 minutes lip-licking and rubbing their head in the leaves to clean their mouth.”

So powerful has the story become that when Fry set out to challenge it some zookeepers refused to let him study their animals. “We even had zookeepers calling up other zoos lobbying them to not let me do the research.”

The journal sat on Fry’s paper for a year, even after it was cleared for peer review, but Fry says those who disagree with him have not been able to come up with a stronger response than “but, but, but…”

The death of the bacterial myth hardly makes dragons less interesting, and Fry says the venom he found in 2009 shows great promise as an anticoagulant and blood pressure reducer. “It is targeted at large prey,” says Fry, “so these are species much closer to us than those that the venom of most smaller snakes and lizards are targeted at.”