  "These unusual elapids are the fastest striking snakes in the world. Their venom is also a fast killer." ~ Donald Schultz, Host of WILD RECON
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VENOM THAT BITES: The Death Adder Lives Up to Its Name
In a world filled with hyperbole and overstatement, the death adder might seem like just another example of overselling. But in Australia and Papua New Guinea, the snake from the genus
Acanthophis truly lives up to its formidable name. In fact, in Papua New Guinea, death adders are one of six venomous snakes that contribute to a serious public health problem.
How serious? Consider this: The incidence of snake bite in the rural and agricultural areas lying far outside Port Moresby, the national capital, exceeds 1,300 victims per 100,000 people — one of the highest rates of snake bite in the world, according to the Global Snakebite Initiative. Almost 8 people per 100,000 die, a figure that may be far too low when you consider how many victims never make it to a health center.
Don't Step There
The behavior of death adders can explain why they are particularly dangerous. As ambush predators, they conceal themselves in leaf litter and twitch their short, ratlike tails. The rustling sound attracts prey, mostly small lizards, mammals, birds and frogs. Unfortunately for humans, this hunting strategy makes death adders practically invisible. Combine this with the fact that they hunt mostly at night, and it's easy to understand how someone might step unknowingly on this concealed foe. And unlike other snakes that slither away at the first sign of danger, death adders stay and fight. When touched, they strike rapidly and effectively.
Nerve-wracking Venom
The bites would be bad enough, but the venom is worse. Death adder venom boasts an LD
50 of between 0.4 and 0.5 milligrams per kilogram. LD refers to "lethal dose." The number indicates a percentage. So, the LD
50 is the dose of venom that kills 50 percent of animals, usually mice, used in a test that involves injecting the chemical beneath the skin. The lower the number, the more toxic the venom. Death adders don't have the lowest LD
50 of venomous snakes (that honor goes to the inland taipan), but they certainly hold their own. A 10-milligram dose of death adder venom is enough to kill an adult human, which wouldn't be so bad if the typical attack only delivered a couple of milligrams. Unfortunately for its victims, a full-grown death adder can inject 180 milligrams of venom in a single bite!
Once inside a person's body, death adder venom decimates the peripheral nervous system. It contains powerful neurotoxins that lead to a condition known as flaccid paralysis, in which the body's muscles become extremely weak. This occurs because the toxins in the venom interfere with the function of acetylcholine, a neurotransmitter that communicates signals from the brain to muscles via receptors on the muscle fibers. Death adder neurotoxins block these receptors, making it impossible for muscles to contract properly. Eventually, the diaphragm shuts down and respiratory failure ensues.
For years, scientists didn't think death adder venom contained other kinds of toxins. Recent research, however, suggests otherwise. In a study published in 2003, a team of Australian scientists demonstrated that the venom of three death adder species contains myotoxins in addition to neurotoxins. Myotoxins act rapidly in skeletal muscles, causing paralysis of the limbs and the diaphragm.
That's One Brave Toad
Given the lethal cocktail of toxins in their venom and their fighting spirit, you might think that death adders have few enemies. But in Australia, that's not the case. Cane toads, which were brought to Australia in 1935 to help control insect pests, are giving death adders a taste of their own medicine. When a snake attacks one of these amphibians, it receives a jolt of powerful venom that acts quickly to shut down the snake's heart. In fact, death adders have been found with cane toads locked in their jaws, both animals dead.
None of this diminishes the death adder's fierceness, of course. In Papua New Guinea and Indonesia, this reptile still strikes fear in the hearts of natives and lives up to its reputation as one of the most dangerous snakes in the world.
Recommended HSW links: Don't let those pesky death adders frighten you off. Sink your fangs into more snake content at HowStuffWorks.com.
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