New research being published in the next issue of Proceedings of the National Academy of Sciences gives insight into how Komodo dragons kill their prey. Komodo dragons can grow over 10 feet long and kill prey as large as deer and even humans. How they manage to do this was never empirically studied, but it was long thought that bacteria in the dragons’ mouths caused acute septicemia after a few days, and that the dragons tracked their prey until they succumbed to the blood poisoning. Science News gives the following report on that widely held notion:
“In the minds of many biologists, that just didn’t make sense,” comments Christopher Shaw, a biological chemist at Queen’s University Belfast in Northern Ireland. “If you’ve evolved to be the size of a Komodo dragon, it seems to be a waste of time.”
What’s more, rare sightings of the lizards hunting didn’t fit with this method. Victims typically died quickly and quietly after going into shock, the authors say. “No one’s actually seen a Komodo dragon track a prey for three days until it dies of septicemia,” Fry says. “It’s an absolute fairy tale.”
And though the lizards wouldn’t win any gold stars at the dentist, Komodos may have a bad rap for oral hygiene. The Komodo dragon’s mouth is no nastier than those of other predators, Fry says. “A lion has a larger bacterial load.”
MRI imaging of a Komodo dragon head showed six venom compartments and an extensive network of internal ducts and specially serrated teeth, which the authors are calling, “the most structurally complex reptile venom gland described to date.” Mass spectrometry of the venom showed many proteins similar to those found in snake venom. The toxins primarily restrict blood coagulation and induce shock in victims by lowering blood pressure. In order to immobilize prey, Komodo dragons are able to use a much smaller amount of venom than would be needed to completely kill a victim, allowing them to take their time and savor the meal, so to speak. The researchers confirmed the effects of the venom on lab mice.
Oh, look at those cute little eyes. He just can’t wait to grow up, gain 100 pounds, and use his razor-sharp serrated teeth to immobilize you and eat you alive. OM NOM NOM!
Fry et al. A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus (Megalania) priscus. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0810883106