Are Komodo dragons' mouths deadlier than cobras' venom?

By: Julia Layton  | 

Komodo dragon on Indonesian island
A Komodo dragon patrols the beaches of Komodo Island, Indonesia.
Jose Azel/Aurora/Getty Images

In June 2008, five scuba divers were carried away from their dive boat by strong currents and stranded. When they finally made it to land after 12 hours adrift in shark-filled waters, they must have thought they were home free.

As it turns out, the land they made it to was Indonesia's Rinca island, one of the last remaining homes to wild Komodo dragons, and the divers' relief was short lived. They spent the next two days throwing rocks and screaming at a Komodo dragon that appeared on the beach. They successfully kept it at bay until they were rescued from the nearly deserted island.

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The world thought Komodo dragons were mythological until about 1911. During World War I, a plane crashed near Komodo Island, and the pilot survived to tell the world about the Komodo dragon [source: Honolulu Zoo]. He, like the divers, was very lucky.

Komodo dragons (Varanus komodoensis) live up to their fierce reputation. They will attack and devour a human being unprovoked [source: BBC News]. They're part of a group of lizards known as monitors, and they're the biggest lizards in the world. The largest Komodo ever measured was more than 10 feet (3 meters) long and weighed 366 pounds (166 kilograms) [source: UKTV]. The average size in the wild is about 8 feet (2.5 meters) long and 200 pounds (91 kilograms) [source: Honolulu Zoo]. To get a feel for how powerful this creature is, consider that when a 120-pound (54-kilogram) Komodo in the London Zoo needs a blood test, it takes two people to hold down its tail [source: BBC News].

Many scientists think the record 366-pounder may have eaten a big meal just before weighing in. A Komodo can consume about 80 percent of its body weight in 20 minutes [source: Honolulu Zoo]. It can swallow huge pieces at a time because its jaw and skull are flexible, like a snake's. Komodo prey includes chickens, wild boar, deer, goats and animals as big as water buffalo. On occasion, it'll take down a human. The Komodo is the only lizard that will attack prey bigger than itself. It also regularly attacks other Komodo dragons. About one-tenth of the Komodo diet is other Komodos [source: Honolulu Zoo].

There aren't many animals that can survive a Komodo attack. A human and another Komodo are pretty much the only ones. This endangered animal, down to about 4,000 in the wild, is at the top of the food chain in its habitat [source: Honolulu Zoo].

What is it that makes this lizard such a good predator? Find out next.

Komodo Dragon Teeth: The Deadliest Bite?

A Komodo dragon runs on Komodo Island, Indonesia.
A Komodo dragon runs on Komodo Island, Indonesia.
Jose Azel/Aurora/Getty Images

With nearly 60 teeth, serrated like a shark's and about 0.4 inches (1 centimeter) long, the Komodo dragon is a brutal predator. The real brilliance in the Komodo's system, though, lies in the guarantee of a meal.

An animal that doesn't die in the actual attack will almost always die within a few days. The Komodo waits patiently, following it for miles in a leisurely fashion, and then locates the dead animal by its smell. Like most lizards -- and snakes, for that matter -- Komodo dragons have a very good sense of smell. But it's not the kind of smell most of us are familiar with. Like a snake, a Komodo "smells" by collecting air with its forked tongue and then depositing it on receptors on the roof of its mouth. Using this method, it can detect a dead animal up to 5 miles (8 kilometers) off [source: Honolulu Zoo].

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Why, exactly, an animal dies after the fact is a subject of some debate.

Until recently, scientists were sure that it was a Komodo dragon's oral bacteria that killed the prey within days after an attack. It's a very good explanation. A Komodo dragon's saliva can contain anywhere from 50 to 80 different bacteria [sources: National Geographic, BBC News]. With that much deadly bacteria entering the bloodstream through a bite, bacterial infection and death are guaranteed. But recent research suggests there may be another possibility as well.

In 2005, scientists concluded that komodo dragons (actually all monitor lizards, as well as iguanas) produce venom, not just a deadly supply of bacteria [source: New Scientist]. Venom is a toxin that's secreted by special glands and injected into an animal by a bite or sting. The researchers started looking specifically for venom in Komodos because they believed it was unlikely a bacterial infection could kill an animal in as little as a day or two. Now that at least one study has concluded that there's venom suspended in Komodo saliva, some believe this venom, and not a powerful bacterial cocktail, is what makes Komodos so reliably lethal.

Which brings us back to the question: cobra or Komodo? The comparison is kind of like pitting Alien against Predator -- it only works in the movies. And even in the 2005 B-movie "Komodo vs. Cobra," you don't find out who wins. Which bite is more potent is fairly clear: A Komodo bite will kill an animal within several days, while an animal bitten by a cobra only lives for a few minutes [source: National Geographic]. But a Komodo dragon's mouth is still undeniably fatal.

Komodo dragons, like cobras, are immune to their own poison. Like all biological defenses, this has possible applications in medical research. If scientists can find the antibody in Komodo blood that renders it immune to its own bacterial cocktail, it could lead to a new class of hardcore antibiotics.

In 2004, scientists discovered the antibody in cobras that blocks the effects of cobra venom. They believe that understanding how the venom receptors are blocked in these animals could lead to improved treatments for heart attacks, strokes and cancer [source: National Geographic].

For more information on Komodo dragons and related topics, prowl through the links that follow.

Originally Published: Jul 8, 2008

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More Great Links

  • Cobra Venom. National Geographic. http://news.nationalgeographic.com/news/2004/02/0220_040220_TVcobra.html
  • How dangerous is a komodo dragon? BBC News. June 9, 2008. http://news.bbc.co.uk/2/hi/uk_news/magazine/7443648.stm
  • Komodo Dragon. Enchanted Learning. http://www.enchantedlearning.com/subjects/reptiles/lizard/Komodoprintout.shtml
  • Komodo Dragon. Honolulu Zoo. http://www.honoluluzoo.org/komodo_dragon.htm
  • Komodo Dragon. National Geographic. http://animals.nationalgeographic.com/animals/reptiles/komodo-dragon.html
  • Komodo Dragon. Smithsonian National Zoological Park. http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Komododragon.cfm
  • Komodo Dragon. WhoZoo. http://whozoo.org/students/amabau/komodo_dragon.htm
  • Lizards' poisonous secret is revealed. New Scientist. November 16, 2005. http://www.newscientist.com/article.ns?id=dn8331
  • Stranded scuba divers chase off Komodo dragon. AP. June 9, 2008. http://ap.google.com/article/ALeqM5h04bq1u9pLOe0j5w5Uppuc7UtzmwD916KLUO0
  • Top Ten: Komodo Dragon Facts. UKTV. http://uktv.co.uk/documentary/stepbystep/aid/588092/pageNo/1