Mother Nature's Kings of Pain What it's like to have a nail in your heel while walking on hot coals, and more.

Feb. 26, 2008  -- Certain members of the animal kingdom have a talent for torture, as those of us who have been unlucky enough to experience it can attest.

Maybe you're swimming at the beach, hiking in the wilderness, or just cleaning out your basement — suddenly you're on fire, dancing or doubled over, staring at an almost invisible wound and wondering how something so small could hurt so horribly.

We have compiled a Top 10 list (in no particular order) of some of the most excruciating stings and bites nature has on offer. Some are potentially deadly, some are not. All are absolutely worth avoiding.

Bullet Ant

These inch-long insects are named after their sting; the pain is likened to being shot. Most scientists claim the creature has the most excruciating sting of all insects.

"I have had some of the most painful experiences I've ever had from bullet ant stings," said Randy Morgan, curator of invertebrates, reptiles and amphibians at the Cincinnati Zoo. "For two or three hours, it felt like people had just hauled off and whacked me with a baseball bat. It's a deep, aching pain."

The bullet ant sting scores highest on the Schmidt Sting Pain Index, a rating created by entomologist Justin Schmidt, director of the Southwestern Biological Institute, which compares the ouch factors of different insects.

How does he know how much these insects' stings hurt? He's willingly endured each of them himself.

Schmidt's rating gives a poetic description of the bullet ant's sting: "Pure, intense, brilliant pain. Like fire-walking over flaming charcoal with a three-inch rusty nail in your heel."

An indigenous tribe in the South America (the bullet ant's home territory) requires their young men to pass a harrowing trial with bullet ants — the boys must wear special mitts that have been lined with hundreds of the angry insects. Not only must the youths endure the stinging treatment for 10 minutes at a time, they must repeat the process 20 times over again.

Luckily for them, as painful as the sting is, it does no permanent damage.

Box Jellyfish

These diaphanous sea creatures are the bane of tropical beaches. Considered to be one of the more dangerous critters in the animal kingdom, their tentacles contain extremely powerful venom that can kill humans.

Along with the poison comes extraordinary, burning pain. The creature's tentacles discharge tiny needles into the victim's skin; each needle contains a cocktail of pain-inducing ingredients that make it "the most painful sting. There is no question about it," according to Dr. Joseph Burnett, past chairman of dermatology at the University of Maryland School of Medicine. "The bullet ant is nothing compared to this."

What makes the animal so painfully effective are the 10-foot-long, stinging tentacles. Unfortunate swimmers can become draped and entangled in these drifting strands, and the intense doses of venom can induce shock and eventual drowning.

While it may seem like nothing but an instrument of torture, "the box jelly didn't develop its horrible toxic venom just to torture people at the beach," said Don Boyer, curator of reptiles and amphibians at the San Diego Zoo. The jellyfish requires its powerful poison to catch and eat its preferred prey, shrimp. Since a struggling shrimp can easily damage the delicate creature, the jellies need to kill their meal as quickly as possible.

Rattlesnakes and Their Relations

If there's a family of snakes you don't want to anger, it would be the vipers.

While these snakes don't always have the most deadly bites, they have the most painful ones.

Van Wallach of the Harvard Museum of Comparative Zoology has had several viper bites; the worst one, he said, "came from an African bush viper. It felt like somebody had a blowtorch and was burning you inside your arm. … It went on for three straight days before I had any relief."

Kelly Zamudio, a biologist at Cornell University, described a similar sensation when she was bitten by another member of the viper family — the rattlesnake.

"It feels like burning, like you're being branded, but the brand never lifts," she said.

The key to the excruciating pain of the viper's bite is its tissue-destroying venom, which dissolves cell walls and causes internal bleeding. As the venom works its way through the body, so does the pain.

Vipers' tissue-eating venom isn't designed to hurt humans, but rather, to get a jump on digesting their food. When the snake strikes a rodent, bird or another type of prey, the toxins work quickly to help breaking down the tissue and get the meal ready for eating.

Stingrays

Although these animals gained a bad rep after the tragic Steve Irwin incident, stingrays are not aggressive or (usually) lethal animals. However, they have a sting, and on the rare occasion they choose to use it, "it's very excruciating," said Edward DeMartini, a research biologist at the National Oceanic and Atmospheric Administration fisheries.

When these gentle animals are stepped on or threatened, they will strike out with a sharp, serrated barb — about the thickness of a golf pencil — located at the base of the tail.

"The physical wound can be pretty intense," said Jon Hoech, director of husbandry operations at the Monterey Bay Aquarium. "It's extremely painful, like getting punctured with an eight-penny nail. Also, it's like a cat scratch, it can carry a lot of bacteria."

On top of the sizeable puncture wound comes a dose of toxins that cause instantaneous pain.

Stingrays only use their venomous barbs as a defense, not for hunting or attacking. As many marine biologists, scuba divers and snorkelers know, the animals are the ocean's pussycats.

"I work with rays on a regular basis," said Hoech. "I swim with them, I feed them by hand, and they're very benign." Just be sure to look where you step.

Scorpions

There are thousands of scorpion species, all of them equipped with stings. Many species' stings aren't much worse than a bee or hornet; but a select few can be a serious source of suffering.

"There are scorpions in the Old World that have extremely painful stings," said Don Boyer. "It gets worse and worse and worse."

These types of scorpions — found in Africa and Asia — can be dangerous as well as painful. However, in the Southwestern United States, the Arizona Bark Scorpion doesn't pose much of a threat to healthy adults. It just means extreme pain.

"If you're an adult and you get the poison in your finger, it just stays, and fires your pain nerve," said Dr. Leslie Boyer — no relation to Don Boyer. "It locks the nerve in the on position."

Leslie Boyer, who is medical director of the Arizona Poison and Drug Information Center, said that the tiny sting will "send shooting sensations up your arm." If you're clumsy enough to tap or bump that finger on anything, the pain instantly amplifies.

"You just give it a tap and you're screaming in pain," said Leslie Boyer. "Just that one little spot hurts like heck, it radiates up to your arm pit with this throbbing pain — but there's nothing to see."

Boyer says that since her practice sees so many painful stings and bites, "I tend to give out morphine like it's candy."

Spitting Cobra

While this reptile has a poisonous bite, it doesn't actually induce much pain. Sure, it stops you from breathing, but for the venom to really make you scream, it needs to get into your eyes.

Spitting cobras have perfected the art of defense by shooting venom into an attacker's eyes, which creates a blinding, burning pain. Like many other pain-inducing animals, the reason for the agony is to keep attackers away, rather than to stage an offensive.

Van Wallach was unfortunate enough to get the spitting treatment from a cobra in the Philippines.

"It is excruciating," he said. "The only way I could relieve it was to pour milk into my eye about every 15 minutes. I was blind for about four to six hours."

The cobra's venom contains a mix of nerve poisons, tissue-destroying chemicals and other nasty compounds designed to elicit severe stinging. In worst case scenarios, it can lead to permanent blindness.

Should you ever encounter a spitting cobra — which is unlikely as they are fairly rare — make sure to keep a good 10-foot distance away from it. Their venom can shoot about four to eight feet.

Tarantula Hawk Wasp

This colorful, solitary wasp uses its stinging power to paralyze large tarantulas as food for its young. While the insect is not aggressive and rarely stings humans — "you really have to force them to sting you," said Leslie Boyer — the experience is fabled to be one of the top most painful stings out there.

According to sting expert Schmidt, the tarantula hawk rates just below the agonizing bullet ant.

"When that one when it hits you, it almost feels like you've been hit by a lightning bolt," said Schmidt. "You'll be screaming and writhing in agony. … It feels like every gland in your body is purged of all its hormones, you'll feel absolutely drained from the experience."

Unlike other animals on this Top 10 list, the tarantula hawk's venom is not for defense, but for paralyzing its much larger prey, tarantulas. The mother wasp lays a single egg on the comatose spider, dooming it to a horrific death. The egg hatches into a hungry larva, which then literally eats the tarantula alive, using it as a food source as it grows.

Stonefish

In terms of a perfect combo of pain and lethality, the homely stonefish's sting may take first prize.

The stonefish, found in the rocky, shallow waters of tropical oceans, has several extremely sharp spines along its back. Hapless waders can easily mistake the well-camouflaged fish for a rock or hunk of coral — and if they step on the animal, the spines will puncture the skin and inject a complex and deadly venom.

The pain from the sting is described as instant and intense. One victim described the experience on an online aquarium enthusiasts' forum:

"I got spiked on the finger by a stonefish in Australia … never mind a bee sting. … Imagine having each knuckle, then the wrist, elbow and shoulder being hit in turn with a sledgehammer over the course of about an hour. Then about an hour later imagine taking a real kicking to both kidneys for about 45 minutes so that you couldn't stand or straighten up. I was late 20s, pretty fit physically and this was the tiniest of nicks. Got sensation back in my finger after a few days but had recurrent kidney pains periodically for several years afterwards."

Other stories describe sting victims wanting to have their stung limb amputated from their body.

Hoech of the Monterey Bay Aquarium has worked closely with the stonefish, and he agreed that the animal "is definitely at the top of the list" of the most pain-producing creatures.

Black Widow Spider

"I never want a bad black widow bite," said Leslie Boyer, referring to the poisonous spider found all over the southern United States.

Although 95 percent of the spiders' bites are trivial, if you're unlucky enough to get nipped by a large, healthy black widow where your skin is thin, the experience can be excruciating.

Leslie Boyer described the time when a rural doctor called her up about an athletic 20-something man who had been bitten.

"The patient had looked at him and said 'It hurts too much to breathe,' and then he just stopped," she said. "To be awake enough to say that, and then willingly stop breathing — that's got to be intense pain."

The black widow bite doesn't hurt initially, as the fangs are small. But an hour and a half later, the venom, which contains a toxic ingredient that interacts with the body's muscles, causes extreme cramping throughout the body.

"Imagine every muscle in a spasm at the same time, and they won't relax for days," said Leslie Boyer.

But people shouldn't revile the black widow, she stressed. "I have them on my porch and in my house," she said. "They never leave their webs, you always know where they are — they're better than a bug zapper."

Gila Monster

This slow-moving lizard from the Southwest United States packs a surprisingly painful bite.

Cecil Schwalbe, ecologist with the U.S. geological survey, was bit by a Gila monster while handling one in an outreach demonstration in front of 200 people. He lists it as the most painful bite in his experience.

"My finger was on fire, the wave of fire moved slowly up my body," Schwalbe said. Within five minutes I turned pasty green and went into shock. … I had pain in my kidneys, blood in my urine. … All of my sphincters in my body were trying to relax. It was on my finger for two minutes and it bit me five times — every bite went right to the bone."

The reasons for the pain are twofold. First, the Gila monster has very sharp teeth, each about a quarter of an inch long. When the animal bites, it chomps down hard — and doesn't let go. Stories are told of bite victims rushing to the hospital with the lizard still attached.

Second, Gila monsters are equipped with specialized venom, full of compounds that break down collagen and vein membranes, a cocktail that is "built to cause inflammation, and just cause pain — it's all about pain," said Beck. On top of the pain, the venom's chemicals cause sweating, diarrhea, vomiting and a drop in blood pressure.

The goal of all this misery is to make predators and enemies stay away. The slow-moving Gila monster can become easy prey, and it relies on its knack for a nasty bite to defend itself.

While the Gila monster's venom might have caused misery in a few people, it has ended up helping many others; it's now the source of a new drug, called Byetta, which treats type Type II Diabetes. Researchers believe that this drug is just scratching the surface of the potential that venomous species have — each creature in this list produces complex, potentially lifesaving compounds.

Something to keep in mind next time you curse the existence of that pesky bee or sneaky snake.