Saturday, December 15, 2007

Komodo Dragon Spit-It's Aliiiiive!!!

Komodo island monitors are famous for being the world's largest lizard, they can reach three meters in length.  This may seem like reason enough not to mess with them, but you shouldn't be afraid of the dragons, just their thousands of tiny little friends...

Komodo dragons are scavengers and carnivores.  They'll eat most recently dead animals, and will hunt goats, wild boars, water buffalo and even horses and eat them.  But their hunting technique is quite unusual, they will stalk their large prey, then ambush it, not to kill it, but to bite it.  The lizard then simply follows the unfortunate prey around until it dies, either from blood loss or infection.  But what if the animal heals?  Well, this just doesn't happen.

Komodo dragon saliva contains over 50 different kinds of bacteria, once an animal is bitten it is almost guaranteed to develop a bad bacterial infection, a septic wound that will become so toxic it will end their life.

A study of the saliva of both captive and wild komodo dragons was published in the Journal of Wildlife Diseases in 2002.  In part of the study komodo dragon saliva was injected into mice.  One strain of bacteria was present in the blood of mice who died following injection, Pasturella multicoda.  The study stated that many strains of bacteria were isolated in the saliva, "54 of which were known pathogens" and "at least one species of which was highly lethal in mice".  

These findings certainly explain the hunting style of the komodo dragon, but why isn't the deadly bacteria in their saliva a problem for these animals?  Wouldn't a mere scratch to the gum be enough to introduce infection and kill them?  The really interesting finding of the study was that the plasma of komodo dragons contains an anti-Pasturella enzyme, so if the bacteria were to enter the bloodstream, it would be killed.

This fact shows that the giant lizards have evolved with their little friends, so that they can coexist without any danger of infection.  A sinister but fascinating kind of symbiosis!


Aerobic Salivary Bacteria in Wild and Captive Komodo Dragons

Animal Diversity Web

*This too was actually a post by Liz, sorry again*