(Nat-Geo): Komodo Dragons Kill With Venom, Researchers Find

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http://news.nationalgeographic.com/news/2009/05/090518-komodo-dragon-venom.html

Komodo Dragons Kill With Venom, Researchers Find

 

Carolyn Barry

for National Geographic News <http://news.nationalgeographic.com/>

May 18, 2009

 

Komodo dragons kill using a one-two punch of sharp teeth and a venomous

bite, scientists have confirmed for the first time.

 

The find dispels the common belief that toxic bacteria in the Komodos'

mouths are responsible for ultimately killing the dragons' prey.

 

An animal that escapes a Komodo's initial attack soon weakens and dies. The

fierce carnivore tracks the wounded creature and dines at its leisure once

the prey collapses.

 

Researchers have long thought that the Komodo dragon, native to Indonesia,

kills via blood poisoning caused by the multiple strains of bacteria in the

dragon's saliva.

 

But " that whole bacteria stuff has been a scientific fairy tale, " said Bryan

Fry, a venom researcher at the University of Melbourne in Australia.

 

Fry and colleagues studied the biochemistry of Komodo venom after they had

the rare opportunity to examine two dragons from zoos that both had to be

put down due to terminal illnesses.

 

The team found that the dragon's venom rapidly decreases blood pressure,

expedites blood loss, and sends a victim into shock, rendering it too weak

to fight.

 

In the venom, some compounds that reduce blood pressure are as potent as

those found in the word's most venomous snake, western Australia's inland

Taipan.

 

*Komodo Combo Attack*

 

While his colleagues expressed surprise at the findings, Fry said he wasn't

so shocked.

 

His earlier research had shown that other lizard species—such as iguanas,

legless lizards, and monitor lizards—are also venomous.

 

In fact, Fry estimates that close to a hundred of the more than 5,000 known

lizard species use venom.

 

What is surprising, Fry said, is Komodo dragons' elaborate venom-delivery

system.

 

" It's the most complex duct system described in reptiles to date, " he said.

 

Snakes typically have a single venom duct that leads to their fangs. But

Komodos have multiple ducts located between their teeth.

 

However, this means Komodo dragons don't deliver their venom as efficiently

as snakes, Fry said.

 

Rather than injecting venom directly via a forceful bite, the dragons use a

specialized bite-and-pull motion to ooze the toxin into wounds during a

sustained, frenzied attack.

 

(Related: " Komodo Dragon's Bite Is 'Weaker Than a House

Cat's.' " <http://news.nationalgeographic.com/news/2008/04/080418-komodo-dragons.h\

tml>

)

 

The combination of venom and multiple lacerations from the lizards' sharp,

serrated teeth is what makes the dragons so deadly.

 

" They're not like the cobra, where venom is the only game in town. Komodos

have a combined arsenal, " Fry said.

 

The findings suggest that the Komodo's ancient relative, the *Megalania,* used

a similar venom-plus-wounding approach.

 

The giant lizard, which roamed Australia about 40,000 years ago, measured

about 13 feet (4 meters) long.

 

Fry's work, published in this week's issue of the *Proceedings of the

National Academy of Sciences,* could mean that the *Megalania* was the

largest venomous animal to have ever lived.

 

 

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