Dragon With A Deadly Bite

The Komodo dragon, like its name suggests, is a ferocious animal. It is the largest lizard in the world–as an adult it may grow to a length of ten feet and weigh over 150 pounds. In addition to its menacing size, the Komodo dragon also features super-sharp teeth and claws. If the teeth and claws don’t kill its prey, blood poisoning caused by one of the 50 bacteria species in its saliva will.

The komodo dragon is a reptile endemic to Indonesia. (Photo credit: Wolfgang Kaehler/Alamy)

Natural History

The Komodo dragon is the worlds largest living lizard. Male lizards can grow up to ten feet in length and weigh around 200 pounds. Females tend to be slightly shorter (growing to a length of eight feet) and weigh around 150 pounds. These unusual lizards live in the lower dry forest and savanna habitats of four volcanic islands (Komodo, Gila Montang, Rinca, and Flores) within Indonesias Lesser Sundra Islands. The population of komodo dragons across these four islands is estimated to be between 3000 and 4000 individual animals. Komodo dragons are considered to be an endangered species due to factors including the loss of adequate habitat, poaching, and natural disasters.

Though some female Komodo dragons have been known to reproduce asexually, that is, they are able to fertilize their own eggs, most Komodo dragons reproduce by sexual means. The lizards mate between the months of May and August. Male lizards wrestle together to gain access to females. Following a victory, a male Komodo dragon mates with a female, fertilizing her eggs. In September, the female lizard lays a clutch of between 20 and 30 eggs into a nest. The female then incubates the eggs for a period of seven to nine months. Upon hatching, the young Komodo dragons have to fend for themselves, and many do not survive to adulthood.

Ambush Predator

In addition to their formidable size, Komodo dragons also have a ferocious bite. A Komodo dragons mouth is filled with 60 serrated, shark-like teeth that are able to tear chunks of flesh out of its prey when feeding. The teeth are embedded within its gums. When it begins to feed, the lizards gums begin to bleed, meaning feeding time can be a particularly gruesome sight. In addition, the Komodo dragon has a flexible skull, which lets it swallow large hunks of food at one time.

The komodo dragon’s serrated teeth pop out of its gums when it is ready to feed. (Photo credit: Anna Yu/Getty Images)

Like crocodiles, komodo dragons are ambush predators. When ready for a meal, the lizards lie in wait, and spring upon their unsuspecting prey in a violent maelstrom of super-sharp teeth and claws. Even if a prey item is somehow able to survive the initial attack, it most likely will die soon after due to blood poisoning–a komodo dragon harbors over 50 different strains of bacteria in its mouth. Komodo dragons have a keen sense of smell and have been known to track the presence and direction of a kill as far as 2.5 miles away. These reptiles detect odors like a snake. A Komodo dragon uses its long, forked tongue to gather particles from the air. Next the lizard moves its tongue against its Jacobson’s organ, a sensory receptor located in the roof of its mouth, to identify airborne molecules.

A Komodo dragon is an indiscriminate eater–it eats nearly 90 percent of each kill it makes, including hooves, bones, and skin. It will also eat its prey’s intestines, first swinging them about to remove any fecal matter before chowing down. Komodo dragons are voracious eaters. In fact, a Komodo dragon tends to eat up to 80 percent of its body weight at one feeding. When young, Komodo dragons typically eat smaller items such as insects, birds, eggs, and small mammals. As adults, Komodo dragons have been known to eat deer, smaller pigs, water buffalo, and smaller Komodo dragons. At times, humans have also become a Komodo dragon’s prey. Though uncommon, four people have been killed by Komodo dragons since 1974, and eight people have been injured by the lizards in the previous decade.

A Venomous Bite?

Recent research indicates that there may be more than just virulent bacteria that kills a Komodo dragon’s prey. In 2006, Dr. Brian Fry and a colleague published a scientific study that indicated that some lizards may share with snakes the same gene responsible for venom production. Following an unfortunate outbreak of a deadly virus in a population of Komodo dragons held at the Singapore Zoo, Fry and his colleagues were able to collect specimens to study. The scientists discovered that Komodo dragons have a set of glands that make venomlike proteins. These proteins can cause a rapid drop in blood pressure and/or prevent blood from clotting. In a paper published recently in the Proceedings of the National Academy of Science, Fry and his fellow researchers conclude that when a Komodo dragon bites into its prey, it adds venom to the wound, which causes the prey to bleed uncontrollably and/or lose consciousness due to a rapid drop in blood pressure.

Not all scientists are convinced by this research, however, and find any compelling evidence lacking. Further research is required to determine if Komodo dragons truly pack some venom in their already deadly bite.

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An Alien Among Us!

 Truth is often at least as strange as fiction. Rita Mehta, an evolutionary biologist at the University of California, Davis, found that the moray eel uses a secret weapon to eat its prey, one that seems straight out of the movie Alien.

Moray eels are ray-finned fish, but they don’t hunt or eat like other ray-finned fish do. Most ray-finned fish, including other types of eels, feed by suction. A typical fish will get close to its prey, then swell its mouth cavity, sucking water and the hapless morsel into its mouth. Next, the fish uses a second set of jaws in the throat, called pharyngeal jaws, to grind the food and push it to the stomach.

This feeding mechanism works very well for many fish. However, moray eels live in and hunt from narrow crevices in coral a cramped environment for suction feeding. Instead, moray eels eat by biting. This, however, poses a problem: How does a moray eel get a large, slippery animal down its throat? If the moray lets go of its prey to swallow it, the meal might just escape.

Moray eels are very efficient predators that evolved an effective feeding strategy. Once the moray gets a bite on its prey, it moves a set of ferocious pharyngeal jaws out of its throat that clamp down on the prey and drag it down the eels esophagus. Much like the monster in Alien, the first set of jaws is dangerous, but the second set does the dirty work.

Oral Gymnastics

While researching moray eel feeding habits, Mehta and her colleague Peter Wainwright filmed morays eating. When Mehta and Wainwright were reviewing the film, they discovered the double bite. When we got the movies, we sat and stared in disbelief, Wainwright said.

“The pharyngeal jaws in their throat exhibit a very different architecture from the jaws of other bony fishes,” Mehta said. “[They] look like a fancy pair of forceps with large, sharp recurved teeth. They further investigated the way these pharyngeal jaws work and how they evolved.

Mehta and Wainwright recorded the moray eels while they were eating using an X-ray imaging technique and high-speed video; Mehta also carried out anatomical dissections. Through their research, they found unusually long muscles running from the second set of jaws to the morays skull. These muscles pull the pharyngeal jaws up the entire length of the skull to grab the prey.

The pharyngeal jaws rest behind the skull when they are not in use. When needed, they quickly move up and forward into the mouth to grasp the prey and yank it back into the esophagus with a gulping motion. The two sets of jaws work together until the whole animal has been swallowed.

How This Fierce Double Bite Evolved

Mehta found that moray eels evolved forceps-like pharyngeal jaws in response to their environment. There simply is no room to expand the mouth cavity with the required suction within the coral crevices in which they hunt. In fact, Mehta found that morays do not have the strong muscles and bones needed to expand the mouth cavity to suck in prey. Suction feeding also restricts the size of prey that can be drawn into the mouth. Biting allows morays to grab larger, more slippery prey such as squid and octopuses.

It is this major adaptation that may be responsible, in part, for the success of moray eels as chief predators hunting within the complex crevices of coral reefs.

According to Mark Westneat, curator of zoology at the Chicago Field Museum of Natural History who studies the feeding behavior of fish, having pharyngeal jaws is common in fish that lack teeth for grinding food. However, only morays have been found to have ones that are so highly evolved and use them so uniquely. “Having a jaw in your throat that has long, recurved, canine teeth and can actually shoot out of your throat into your mouth, grab a fish or something, and pull it down the throat is highly unusual,” he said.

Sometimes real-life can be as frightening as in the movies. When asked which set of teeth should be feared most, Mehta replied, “Oh, man, that’s tough, the front ones are really long and sharp, too. I’d be afraid of both!”

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