5 Small Creatures Capable of Causing Massive Amounts of Pain


What these animals lack in size, they make up for in their ability to make you wish you were dead, thanks to their painful bites and stings. Sometimes, these tiny creatures can even kill.

1. Irukandji Box Jellyfish

Jamie Seymour

Believed to be the most venomous creature in the world, the Irukandji is roughly the size of a peanut. It thrives in warm water, making Australia’s Great Barrier Reef its preferred home. This hard-to-see creature is outfitted with tentacles and has the ability to fire its stingers into its victim. If you are hit, you will experience what is described by victims as “the worst pain of your life—pain so intense that the maximum dose of morphine barely takes the edge off.” According to the documentary Killer Jellyfish, whether you live or die from an Irukandji sting depends on your current state of health as well as “ your blood vessels' ability to handle the pressure.” There is no antidote for an Irukandji sting. Hospitals help to manage symptoms, but if you are stung, you simply must wait it out. “No single pain killer works for everyone, except for time.”

Where it Lives: While Irukandjis prefer the warm waters of Australia, they have been spotted in the British Isles, as well as in Japan and in waters of the Atlantic Ocean.

The Sting: At first, the sting from an Irukandji is not too bad. You may experience some swelling along the site of contact and some minor discomfort. Five to 45 minutes later, though, the real pain sets in. Victims will start to experience a severe backache, headache, or shooting pains in their muscles, chest, and abdomen. Additional symptoms may include nausea, restlessness, and vomiting. If left untreated, “irukandji syndrome” can lead to pulmonary edema, a build-up of fluid in the lungs that can be fatal if not properly treated.

Scary Fact: The Irukandji is only 2.5 centimeters in diameter and weighs in at less than 1 ounce. The jellyfish’s four stinging tentacles are nearly as fine as a hair and trail up to 30 centimeters behind it. According to Jamie Seymour, a professor of biology at James Cook University who has made a career out of tracking these tiny predators, the Irukandji are quick and agile swimmers. Certain species of box jellyfish can swim almost as fast as an Olympic swimmer, giving them the ability to navigate through the water at speeds of up to four and a half knots!

Do Stinger Suits Work? Australian Medical Association of Queensland president Dr. Alex Markwell points out that the Irukandij are small and transparent, which makes them very difficult to see and avoid. “Barrier protection such as Lycra sting suits or wetsuits help, but often hands, feet and face are still uncovered leaving people vulnerable to stings,” she explains.

Video: In this clip from Killer Jellyfish, Seymour and Teresa Caratte get stung and deal with the repercussions in a nearby hospital.

Seymour’s symptoms last for a reported 2 days while Caratte battles Irukandji syndrome for a whopping 2 weeks!

2. Asian Giant Hornet (Vespa mandarinia)

Takehiko Kusama

In the States, we make fun of our friends for overreacting when a winged insect flutters by, but Japanese residents have a valid excuse for panicking. The Asian giant hornet is two inches long with a wingspan of around three inches and an oversized mandible with a strong black tooth. These giants of their species have the ability to dispel venom with an enzyme so strong that it’s said to be able to dissolve human tissue. The Asian giant hornet kills more people each year than any other animal in the country of Japan. Fortunately for humans, the hornet’s preferred victim is a honeybee. Each hornet has the ability to take out around 40 European honeybees in a mere 60 seconds, and it’s been reported that just a handful of these insects can kill over 30,000 bees within hours. While they don’t tend to go after humans, a hornet will sting you if you aggravate it. In this scenario, your normal escape plan of running away will not save you as these creatures can fly at speeds of 25mph!

Where it Lives: According to Ross Piper, author of Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, these massive insects prefer to live in the mountainous region of Japan. They have also been spotted in areas of Russia, Korea, China, Taiwan, Nepal, India, and Sri Lanka.

The Sting: Dr. Masato Ono, an entomologist at Tamagawa University has stated that the sting of a Japanese hornet is exceptionally painful, describing it as “a hot nail through my leg!”

Crazy Fact: In lieu of steroids, some professional athletes are now ingesting vials of Asian hornet vomit. The larvae of these hornets are said to regurgitate a liquid which, if ingested by their parents, gives them the ability to fly over 60 miles at a speed of 25mph. A synthetic form of this hornet juice is being sold on the market and has been used by professional athletes in competition. Long distance swimmer Naoko Takahashi claimed to have had some of the juice before her record-setting gold medal swim at the 2000 Olympics in Sydney.

How To Avoid Being Stung: Piper says the best way to avoid a run-in with an Asian giant hornet is to steer clear of their homes, which are commonly found in forested areas—in abandoned animal burrows, the hollow beneath a tree, tree holes, etc. “As with all stinging insects, the key to not being stung is not to annoy or threaten them. All wasps are very protective of their nests and this is when stings are most likely, i.e. if someone gets too close to the nest or disturbs it."

Video: In this video clip from Hornets From Hell, you’ll see these creatures in action and will hear a first-hand account of a scientist who was stung in the field.

Additional Source: Hornet Venoms [PDF] 

3. Candiru

Dr. Peter Henderson

Among the strange creatures that live in the Amazon River is a parasitic eel-like fish known as the Candiru. These tiny creatures feed mainly on blood, can often be found inside the gills of other fish, and have been known to swim up a human urethra. Once they wiggle their way inside, they expand, nestle in, and send you to the emergency room in need of an invasive medical extraction. Though sometimes considered an urban legend, the Candiru is a real threat to unsuspecting swimmers. In 1877, an Amazon physician named Dr. Castro performed one of the first known extractions of a Candiru from a urethra, stating: “I have myself extracted from the urethra of a negress a little candiru which had penetrated during micturition while bathing in the river. The patient experienced cruel suffering for since I had to drag the animal out. The extraction was difficult and the mucus membrane was lacerated.”

What Makes It Even More Terrifying: Once the Candiru travels through a urethra, it spreads its gills, which are outfitted with spikes, as it gasps for oxygen. As you can imagine, the process of being “invaded” by a Candiru is quite painful. Housing a Candiru in your urethra can lead to inflammation, hemorrhage, and, in the worst-case scenario, amputation or death.

Urban Legends: Rumor has it that this fish is attracted to the smell of urine—so attracted, in fact, that it’s said to be able to jump up out of the water and into the urethra of a man peeing at the water’s edge. In actuality, Candirus are said to track down their fish victims by sight and are incapable of physically swimming up a stream of urine. They can, however, easily slide into your genitals if you are already in the water.

Where it Lives: The Candiru favors the water of the Amazon River and lives in the countries of Brazil, Peru, Ecuador, Colombia, and Bolivia.

How To Avoid a Run-in with This Creature: The obvious solution is not to swim in the Amazon. If you must do so, wear briefs or some kind of protection under your swim trunks and by all means, do not pee in the river.

Video: In this video clip from River Monsters, you’ll meet a gentleman who had a Candiru in his urethra for four days before making it into the ER in Manaus, Brazil for surgery. Watch at your own risk!

Additional Source: Candiru: Amazonian Parasitic Catfish [PDF]

4. Bullet Ant (Paraponera)

Gerald Urquhart

Known by the rainforest locals as “hormiga veinticuatro” or “24 hour ant,” the bullet ant is said to possess the most painful insect bite in the world. Their venom is a neurotoxic peptide, which is used to kill caterpillars and other small critters, but to people, a bullet ant sting is one of the most painful experiences in the world. One sting from a bullet ant will cause swelling resulting in pain for an entire day. Aggravating one of these creatures—actually the biggest ant in the world—is something you’ll regret for quite some time.

Where They Live: Bullet ants are found in tropical rainforest areas across Central and South America.

The Sting: According to the Schmidt Pain Index, a bullet ant sting ranks among the worst pain you will ever feel. If an ant feels threatened, it will use its mouth to grab onto you before it injects you with its venomous sting. Terry McGlynn, Associate Professor of Biology at California State University Dominguez Hills, was stung while working in a lab with bullet ants. He describes his experience as follows:

Imagine that you put your finger flat on the countertop and hand someone a hammer and ask them to hit your finger as hard as they can. That's what the sting itself feels like. Then, it ached just like you would expect for a few hours, throbbing and swelling enough that it was difficult to concentrate on work. Then, for several hours, I lost the muscular strength to hold on to things with my hand, so I couldn't hold my coffee mug alone in the hand that was stung. Then, it was numb for several hours, and then the next morning it felt like nothing had ever happened.

How Badly Do You Want to be a Man? In the Satere-Mawe tribe of the Amazon rain forest of Brazil, bullet ants are a part of a traditional coming-of-age ritual. A boy as young as twelve must stick his hand into a pair of hand woven gloves, which is filled with bullet ants. The boy must do this 20 times in total, ten minutes at a time. This ritual is said to test “one’s worthiness to take on adult roles.”

Tip for Avoiding Being Stung: McGlynn says it comes down to being careful as to where you put your hands. “[Bullet ants] typically nest at the base of large rainforest canopy trees and walk up the trees and other routes to forage for sugar water and prey in the canopy,” he says, adding that the way you’d typically come into contact with one is to accidentally rest your hand on a tree trunk. If you see an ant, McGlynn advises that you refrain from swatting at it, which "will only make it mad.” He also says you should keep your composure in the event one walks on you: “If you stay calm, you'll be just fine. But if it's disturbed, then it might sting you.”

Video: In this clip from National Geographic, you’ll follow the journey of Ted from the Satere-Mawe tribe as he sticks his hand into the ceremonial gloves that will transform him from a boy to a man.

5. Golden Poison Dart Frog (Phyllobates terribilis)


The Golden poison dart frog is not an animal that you would ever want to come in contact with: Phyllobates terribilis is the most poisonous vertebrate on the planet. The frog is currently on the endangered species list and organizations like the World Land Trust are fighting to keep it alive. The frogs range in size from half an inch to 2 inches long. One frog is said to house enough deadly poison to kill ten grown men or 10,000 mice. In addition, the tiny frog is so toxic that it’s said that merely touching a paper towel that has been in contact the frog can be fatal. Tribes of the rainforest have traditionally used its poison on the end of their blowgun darts during hunting ceremonies.

Where They Live: The frog makes its home in a small coastal region in southwestern Colombia, but scientists aren't sure of the actual extent of its range.

The Poison: The golden poison dart frog's skin is saturated with an alkaloid poison that contains batrachotoxins, which prevent nerves from transmitting impulses and lead to muscle paralysis. The poison is about 20 times more toxic than a typical poison dart frog; a single frog's skin contains enough poison to take down two full-grown bull elephants!

Strange Fact: According to Oswaldo Cortes, who led a study on the frogs in conjunction with the Conservation Leadership Program, The golden poison dart frog gets its toxicity from the mites that it ingests. “Traditionally scientists thought the frogs obtained their venom from ants, however, a new study in the Proceedings of the National Academy of Sciences has revealed it is in fact mites that causes them to be so dangerous.” The frog then secretes the poison through its skin glands. The toxins are used to defend the frog against a predator; it does not use its toxins to hunt for food. Since the frog gets its toxic nature from its meals, golden poison dart frogs held in captivity will not be nearly as toxic.

How to Keep Away: It’s plain and simple—don’t touch it! Avoid areas where golden poison dart frogs thrive, such as rainforests of Colombia. If you’re in their habitat, wear protective boots and long pants. In the rare occasion that you brush up against one, you’ll probably want to throw that outfit away.

Videos: You can see a golden poison dart frog in a terrarium in the video below.

Scientific Reports, Fernando Ramirez Rozzi
Stones, Bones, and Wrecks
Humans Might Have Practiced Brain Surgery on Cows 5000 Years Ago
Scientific Reports, Fernando Ramirez Rozzi
Scientific Reports, Fernando Ramirez Rozzi

In the 1970s, archaeologists discovered a site in France containing hundreds of cow skeletons dating back 5000 to 5400 years. The sheer number wasn't surprising—human agriculture in that part of the world was booming by 3000 BCE. What perplexed scientists was something uncovered there a few decades later: a cow skull bearing a thoughtfully drilled hole. Now, a team of researchers has released evidence that suggests the hole is an early example of animal brain surgery.

Fernando Ramírez Rozzi, a paleontologist with the French National Center for Scientific Research, and Alain Froment, an anthropologist at the Museum of Mankind in Paris, published their findings in the journal Nature Scientific Reports. After comparing the opening to the holes chiseled into the skulls of humans from the same era, they found the bones bore some striking similarities. They didn't show any signs of fracturing from blunt force trauma; rather, the hole in the cow skull, like those in the human skulls, seemed to have been carved out carefully using a tool made for exactly that purpose. That suggests that the hole is evidence of the earliest known veterinary surgery performed by humans.

Trepanation, or the practice of boring holes into human skulls, is one of the oldest forms of surgery. Experts are still unsure why ancient humans did this, but the level of care that went into the procedures suggests that the surgery was likely used to treat sick patients while they were still alive. Why a person would perform this same surgery on a cow, however, is harder to explain.

The authors present a few theories, the first being that these ancient brain surgeons were treating a sick cow the same way they might treat a sick human. If a cow was suffering from a neural disease like epilepsy, perhaps they though that cutting a hole in its head would relieve whatever was agitating the brain. The cow would have needed to be pretty special to warrant such an effort when there were hundreds of healthy cows living on the same plot of land, as evidenced by the skeletons it was found with.

Another possible explanation was that whoever operated on the cow did so as practice to prepare them for drilling into the heads of live humans one day. "Cranial surgery requires great manual dexterity and a complete knowledge of the anatomy of the brain and vessel distribution," the authors write in the study. "It is possible that the mastery of techniques in cranial surgery shown in the Mesolithic and Neolithic periods was acquired through experimentation on animals."

Either way, the bovine patient didn't live to see the results of the procedure: The bone around the hole hadn't healed at all, which suggests the cow either died during surgery or wasn't alive to begin with.

15 Incredible Facts About Pigeons

Though they're often described as "rats with wings" (a phrase popularized by the movie Stardust Memories), pigeons are actually pretty cool. From homing instincts to misleading rump feathers, here are 15 things you might not know about these avian adventurers.


The common city pigeon (Columba livia), also known as the rock pigeon, might be the first bird humankind ever domesticated. You can see them in art dating back as far as 4500 BCE in modern Iraq, and they've been a valuable source of food for thousands of years.


Pigeon-breeding was a common hobby in Victorian England for everyone from well-off businessmen to average Joes, leading to some fantastically weird birds. Few hobbyists had more enthusiasm for the breeding process than Charles Darwin, who owned a diverse flock, joined London pigeon clubs, and hobnobbed with famous breeders. Darwin's passion for the birds influenced his 1868 book The Variation of Animals and Plants Under Domestication, which has not one but two chapters about pigeons (dogs and cats share a single chapter).

Nikola Tesla was another great mind who enjoyed pigeons. He used to care for injured wild pigeons in his New York City hotel room. Hands down, Tesla's favorite was a white female—about whom he once said, "I loved that pigeon, I loved her as a man loves a woman and she loved me. When she was ill, I knew and understood; she came to my room and I stayed beside her for days. I nursed her back to health. That pigeon was the joy of my life. If she needed me, nothing else mattered. As long as I had her, there was a purpose in my life." Reportedly, he was inconsolable after she died.


In a 2017 Current Biology study, researchers showed captive pigeons a series of digital lines on a computer screen for either two or eight seconds. Some lines were short, measuring about 2.3 inches across; others were four times longer. The pigeons were trained to evaluate either the length of the line or how long it was displayed. They found that the more time a line was displayed, the longer in length the pigeon judged it to be. The reverse was true too: If the pigeons encountered a longer line, they thought it existed in time for a greater duration. Pigeons, the scientists concluded, understand the concepts of both time and space; the researchers noted "similar results have been found with humans and other primates."

It's thought that humans process those concepts with a brain region called the parietal cortex; pigeon brains lack that cortex, so they must have a different way of judging space and time.


A pigeon flying in front of trees.

The birds can do this even if they've been transported in isolation—with no visual, olfactory, or magnetic clues—while scientists rotate their cages so they don't know what direction they're traveling in. How they do this is a mystery, but people have been exploiting the pigeon's navigational skills since at least 3000 BCE, when ancient peoples would set caged pigeons free and follow them to nearby land.

Their navigational skills also make pigeons great long-distance messengers. Sports fans in ancient Greece are said to have used trained pigeons to carry the results of the Ancient Olympics. Further east, Genghis Khan stayed in touch with his allies and enemies alike through a pigeon-based postal network.


Pigeons' homing talents continued to shape history during the 20th century. In both World Wars, rival nations had huge flocks of pigeon messengers. (America alone had 200,000 at its disposal in WWII.) By delivering critical updates, the avians saved thousands of human lives. One racing bird named Cher Ami completed a mission that led to the rescue of 194 stranded U.S. soldiers on October 4, 1918.


In 1964, scientists in Holmdel, New Jersey, heard hissing noises from their antenna that would later prove to be signals from the Big Bang. But when they first heard the sound, they thought it might be, among other things, the poop of two pigeons that were living in the antenna. "We took the pigeons, put them in a box, and mailed them as far away as we could in the company mail to a guy who fancied pigeons," one of the scientists later recalled. "He looked at them and said these are junk pigeons and let them go and before long they were right back." But the scientists were able to clean out the antenna and determine that they had not been the cause of the noise. The trap used to catch the birds (before they had to later be, uh, permanently removed) is on view at the Smithsonian Air & Space Museum.


Japanese psychologist Shigeru Watanabe and two colleagues earned an Ig Nobel Prize in 1995 for training pigeons, in a lab setting, to recognize the paintings of Claude Monet and Pablo Picasso and to distinguish between the painters. The pigeons were even able to use their knowledge of impressionism and cubism to identify paintings of other artists in those movements. Later, Watanabe taught other pigeons to distinguish watercolor images from pastels. And in a 2009 experiment, captive pigeons he'd borrowed were shown almost two dozen paintings made by students at a Tokyo elementary school, and were taught which ones were considered "good" and which ones were considered "bad." He then presented them with 10 new paintings and the avian critics managed to correctly guess which ones had earned bad grades from the school's teacher and a panel of adults. Watanabe's findings indicate that wild pigeons naturally categorize things on the basis of color, texture, and general appearance.


In a 2016 study, scientists showed that pigeons can differentiate between strings of letters and actual words. Four of the birds built up a vocabulary of between 26 and 58 written English words, and though the birds couldn't actually read them, they could identify visual patterns and therefore tell them apart. The birds could even identify words they hadn't seen before.


A white pigeon with curly feathers and fluffy feet.

A few pigeon breeds have fuzzy legs—which hobbyists call "muffs"—rather than scaly ones. According to a 2016 study, the DNA of these fluffy-footed pigeons leads their hind legs to take on some forelimb characteristics, making muffed pigeon legs look distinctly wing-like; they're also big-boned. Not only do they have feathers, but the hindlimbs are somewhat big-boned, too. According to biologist Mike Shapiro, who led the study, "pigeons' fancy feathered feet are partially wings."


In a life-or-death situation, a pigeon's survival could depend upon its color pattern: Research has shown that wild falcons rarely go after pigeons that have a white patch of feathers just above the tail, and when the predators do target these birds, the attacks are rarely successful.

To figure out why this is, Ph.D. student Alberto Palleroni and a team tagged 5235 pigeons in the vicinity of Davis, California. Then, they monitored 1485 falcon-on-pigeon attacks over a seven-year span. The researchers found that although white-rumped pigeons comprised 20 to 25 percent of the area's pigeon population, they represented less than 2 percent of all the observed pigeons that were killed by falcons; the vast majority of the victims had blue rumps. Palleroni and his team rounded up 756 white- and blue-rumped pigeons and swapped their rump feathers by clipping and pasting white feathers on blue rumps, and vice versa. The falcons had a much easier time spotting and catching the newly blue-rumped pigeons, while the pigeons that received the white feathers saw predation rates plummet.

Close observation revealed that the white patches distract birds of prey. In the wild, falcons dive-bomb other winged animals from above at high speeds. Some pigeons respond by rolling away in midair, and on a spiraling bird, white rump feathers can be eye-catching, which means that a patch of them may divert a hungry raptor's focus long enough to make the carnivore miscalculate and zip right past its intended victim.


Two blue and green Nicobar pigeons.

Though most of this list focuses on the rock pigeon, there are 308 living species of pigeons and doves. Together, they make up an order of birds known as the columbiformes. The extinct dodo belonged to this group as well.

Flightless and (somewhat) docile, dodos once inhabited Mauritius, an island near Madagascar. The species had no natural predators, but when human sailors arrived with rats, dogs, cats, and pigs, it began to die out, and before the 17th century came to a close, the dodo had vanished altogether. DNA testing has confirmed that pigeons are closely related to the dodo, and the vibrant Nicobar pigeon (above) is its nearest genetic relative. A multi-colored bird with iridescent feathers, this near-threatened creature is found on small islands in the South Pacific and off Asia. Unlike the dodo, it can fly.


Wild/feral rock pigeons reside in all 50 states, which makes it easy to forget that they're invasive birds. Originally native to Eurasia and northern Africa, the species was (most likely) introduced to North America by French settlers in 1606. At the time, a different kind of columbiform—this one indigenous—was already thriving there: the passenger pigeon (Ectopistes migratorius). As many as 5 billion of them were living in America when England, Spain, and France first started colonizing, and they may have once represented anywhere from 25 to 40 percent of the total U.S. bird population. But by the early 20th century, they had become a rare sight, thanks to overhunting, habitat loss, and a possible genetic diversity issue. The last known passenger pigeon—a captive female named Martha—died on September 1, 1914.


According to one study, they're more efficient multitaskers than people are. Scientists at Ruhr-Universitat Bochum put together a test group of 15 humans and 12 pigeons and trained all of them to complete two simple jobs (like pressing a keyboard once a light bulb came on). They were also put in situations wherein they'd need to stop working on one job and switch over to another. In some trials, the participants had to make the change immediately. During these test runs, humans and pigeons switched between jobs at the same speed.

But in other trials, the test subjects were allowed to complete one assignment and then had to wait 300 milliseconds before moving on to the next job. Interestingly, in these runs, the pigeons were quicker to get started on that second task after the period ended. In the avian brain, nerve cells are more densely packed, which might enable our feathered friends to process information faster than we can under the right circumstances.


Only mammals produce genuine milk, but pigeons and doves (along with some other species of birds) feed their young with something similar—a whitish liquid filled with nutrients, fats, antioxidants, and healthy proteins called "crop milk." Both male and female pigeons create the milk in the crop, a section of the esophagus designed to store food temporarily. As is the case with mammal milk, the creation of crop milk is regulated by the hormone prolactin. Newly-hatched pigeons drink crop milk until they're weaned off it after four weeks or so. (And if you've ever asked yourself, "Where are all the baby pigeons?" we have the answer for you right here.)


We've already established that pigeons are excellent at differentiating between artists and words, but a 2015 study revealed they can also distinguish between malignant and benign growths in the right conditions. Researchers at University of California Davis Medical Center put 16 pigeons in a room with magnified biopsies of potential breast cancers. If the pigeons correctly identified them as either benign or malignant, they got a treat, According to Scientific American.

"Once trained, the pigeons' average diagnostic accuracy reached an impressive 85 percent. But when a "flock sourcing" approach was taken, in which the most common answer among all subjects was used, group accuracy climbed to a staggering 99 percent, or what would be expected from a pathologist. The pigeons were also able to apply their knowledge to novel images, showing the findings weren't simply a result of rote memorization."

Mammograms proved to be more of a challenge, however; the birds could memorize signs of cancer in the images they were trained on but could not identify the signs in new images.

No matter how impressive their results, "I don't anticipate that pigeons, no matter how good they become at pathology or radiology, will be playing a role in actual patient care—certainly for the foreseeable future," study co-author Richard M. Levenson told Scientific American. "There are just too many regulatory barriers—at least in the West."


More from mental floss studios