The process of evolution is incredible, offering different species unique traits that allow them to survive and thrive. One of those traits, the ability to produce and inject venom into its prey, is one that may have skipped humans, but that doesn’t mean we’re immune to the effects of other species’ venoms. In fact, there are some animals whose venom is so potent it could kill a human within just a few minutes. If you want to round up 12 of the most dangerous venom-making species in the animal kingdom, all of which have the ability to kill you distressingly quickly, then look no further. Keep reading to break down how fast they can cause a fatality to an adult and the way their venom works in our bodies once introduced. Prepare to be a little amazed, a little terrified, and a little more cautious about where you step when out in the wilderness, as these animals are no joke.
Australian box jellyfish (Chironex fleckeri)
Despite looking like a massive clump of vermicelli, Australian box jellyfish (Chironex fleckeri) are chock full of venomous booby traps. Their tentacles are covered in nematocysts, which are essentially poison-tipped darts. If stung by an envenomated nematocyst, a human adult could be dead by cardiac arrest within only five minutes, the fastest-acting venom scientists have discovered.
There are currently around 50 species of box jellyfish that have been identified, and only a few have lethal venom. C. fleckeri is the largest of the box jellies, reaching its tentacles as far as 10 feet from its 1-foot-wide body. It’s also one of the few jellyfish that actively hunt prey, spotting shrimp and small fish with its clusters of eyes on all sides of its box body. While most other jellyfish have adapted to lead more passive lives, floating along with the current, the box jellyfish will swim at a speed of up to four knots — just under the average swim speed of a human adult male.
Sydney funnel-web spider (Atrax robustus)
The 2-inch-long Sydney funnel-web spider (Atrax robustus) is the scariest of all the 40 funnel-web spider species and is considered the deadliest spider in the world. Their fangs are powerful, piercing fingernails and soft-toed shoes like paper and can inject enough venom to kill a human child within 15 minutes or a healthy adult within a few days. Their venom acts as a paralyzing agent in humans that may eventually lead to respiratory failure and cardiac arrest if not treated quickly.
Thankfully, antivenom has been created for the A. robustus, knocking down the number of human fatalities to just one since its creation in 1981. Also, the majority of funnel-web spider bites end up being dry, as we’re typically not on their list of tasty prey. That said, every bite from a dangerous spider should be treated as one that delivered venom, as going without medical care can result in death.
Black and green mambas (Dendroaspis spp.)
Mambas have a face that we think just screams “cranky — stay away,” and with good reason. Both mambas live near the upper region of South Africa and are considered shy, elusive snakes that would rather escape than fight. But if they do stand their ground, watch out. Not only will they deliver multiple bites, but their venom is neurotoxic and considered 100% fatal if untreated. Black mambas (Dendroaspis polylepis) are considered the deadliest snake in Africa, bringing an adult human down within only 45 minutes and turning fatal within two hours. Meanwhile, its cousin the Green mamba (Dendroaspis angusticeps), isn’t as widespread across the area but can pack just as deadly a punch, killing a human within only 30 minutes.
Black mambas have a larger native region, spanning most of the width of South Africa while green mambas tend to stick to the eastern coast. If envenomated by either, you’ll need to act quickly; their venom can begin to affect the respiratory system within 20 minutes after a bite. Antivenom is available and considered effective for both mambas but will require large quantities, especially if bitten multiple times.
Eastern brown snake (Pseudonaja textilis)
The Eastern brown snake (Pseudonaja textilis) is another angry-looking dude that you’d be wise to stay away from. Unfortunately, that’s a problem for people who live in rural areas of eastern Australia, as these snakes are drawn to places that were cleared out for agricultural purposes, leaving few places for rodents to hide. Its fangs are tiny, averaging around 3 millimeters, to the point that some people didn’t realize they were bitten. Unfortunately, those tiny fangs still deliver a potent venom that can kill a human within 15 minutesdue to its neurotoxins, cardiotoxins, and nephrotoxins that result in uncontrollable bleeding, paralysis, and eventually, death.
Eastern brown snakes hold the title of “Responsible for the Most Human Deaths,” which is a competitive fight in Australia. Still, these snakes would rather they and you left each other alone, preferring to flee rather than fight. A significant majority of bites were the result of the snake defending itself from being killed by humans, so it’s probably best you don’t try to do that. Eastern browns are considered nervous and may strike without hesitation, so avoid surprising one and try to keep as much distance between you and the snake as possible.
King cobra (Ophiophagus hanna)
The king cobra (Ophiophagus hanna) is a sight to behold. These massive snakes can get up to 18 feet long and raise almost a third of their body off the ground and maintain it there while chasing prey or if provoked. While they’d much prefer to be left alone and would rather flee than fight, a king cobra won’t hesitate to defend themselves or their nests. Their fangs can reach up to 10 millimeters long and deliver enough venom to kill an adult human in only 15 minutes by shutting down the respiratory system.
King cobras have some of the best eyesight of all snakes, able to clock a human’s movement 330 feet away. Another king cobra fact is that they’re considered extremely intelligent, which is why they’ve become part of the venomous keeper trade and are a sought-after species for enthusiasts. Thanks to their intelligence, keen senses, and preference for using their venom on prey instead of humans, king cobra bites are rarely seen in the wild, averaging less than five deaths per year. For all of its terrifying effects, cobra venom isn’t all bad, though; it’s led to the creation of medications that act as powerful pain relievers and nerve blockers.
Common krait (Bungarus caeruleus)
The Common krait (Bungarus caeruleus) isn’t as mean-looking as its other family members on this list, but don’t let its kinda cute face fool you — this snake is a killer. It’s capable of delivering some of the most lethal venom in its native Asian territories, killing up to 77% of its bite victims before an antivenom was created. But don’t get complacent if you’re bitten, because its neurotoxic venom can begin affecting muscle control within minutes. Some sources estimate death can be as early as 45 minutes post-bite while others say it can take up to 10 hours for symptoms to appear and 18 hours for death. Regardless, this is not a bite that’s considered a “wait and see”; seek immediate attention whether or not symptoms have begun to appear.
Common kraits, sometimes called “Indian kraits” are mostly nocturnal and will hunt around human dwellings. Unfortunately, not many realize they’re bitten thanks to subtle onsets of symptoms and the fact that its dark-colored body is hard to see at night, all contributing to why it’s so fatal. Respiratory failure will occur in approximately 50% of bites thanks to its venom’s muscle-paralyzing properties. Antivenom is available for krait venom but may require multiple doses, especially if the victim has received multiple bites.
Coastal taipan (Oxyuranus scutellatus)
One of the issues with the coastal taipan (Oxyuranus scutellatus) is that it looks like so many other snakes, including the Eastern brown and Mulga snakes. But once you see that white snout, you know you’re in for a world of hurt because the coastal taipan is not afraid of a fight. While it doesn’t hold the record for most human deaths like the Eastern brown, it’s still considered to be Australia’s most dangerous snake. Its 12-millimeter-long fangs deliver enough venom to kill an adult human within 30 minutes.
Coastal taipans tend to live around the coastal regions of northern Australia, though they’ve also been spotted further inland, in sugar plantations and forests. They’ll typically average around 6 feet in length, though records show some specimens clocking in at a whopping 11 feet long. Not only are these snakes incredibly agile and aggressive, they also don’t seem to back down their quantity of venom delivery. Records of previous envenomations show that O. scutellatus will inject as much during the second or third bites as they did in the first, making it an extremely urgent situation that will require significant doses of antivenom.
Inland taipan (Oxyuranus microlepidotus)
The inland taipan (Oxyuranus microlepidotus) may not be as big of a bully as its cousin, the Coastal taipan, but don’t mistake its placid behavior as weak; it’ll attack if it has to and deliver enough venom in one bite to kill 100 adult men. Since you’re (most likely) one person, that venom will do a number on your body, paralyzing and eventually killing you in as little as 45 minutes. Before an antivenom was created, an inland taipan bite was considered to be 100% fatal, and it is still considered the most venomous terrestrial snake we’ve found.
Inland taipans typically average around 6 feet in length and are very elusive, only coming out of its home made from cracks or crevices in the Australian desert soil during the early morning before the temperatures get too hot. Most likely, you’ll never encounter one as they’re very shy and prefer to stick to their desert habitats instead of denser populated areas. Should you stumble on one, watch its body language; raising its head and body in an S-like shape means that this is your final warning to leave it alone. If the warning isn’t heeded, the inland taipan will strike, delivering one or multiple bites. Its venom contains an enzyme that helps it spread throughout the body quickly, so even one bite is an urgent problem requiring medical care.
Gila monster (Heloderma suspectum)
Now, let’s take a break from the terrors of Australia and look elsewhere. The Gila monster (Heloderma suspectum) is from the USA and is one of only very few venomous lizards we know of, delivering its toxic venom by chewing on its victims rather than striking like a snake. Gila monster bites aren’t normally considered potentially fatal, but one case proves that they, like Siths, do not deal in absolutes and have the potential to deliver a fatal dose to adult humans in an excruciating way.
The case involves 34-year-old Colorado resident Christopher Ward who kept a Gila monster as a pet. His Gila ended up biting his hand, holding on for four minutes as it chewed its venom into his body. Normally, this wouldn’t have been much of an issue besides extremely painful, but researchers found that this Gila delivered 10 times the normal amount of venom, resulting in a horror show that probably led Ward to die in agonizing pain. A 1986 report in the Annals of Emergency Medicine found the venom attacked the cardiovascular system and created a response similar to anaphylactic shock that can start causing symptoms as quickly as 15 minutes after the lizard lets go. Interestingly, researchers found that peptides in Gila monster venom acted similarly to one of the peptides that can improve your body (GLP-1) currently being used as a weight-management treatment. Since bites are rare and fatalities even rarer, there is currently no known antivenin to Gila monster venom.
Blue-ringed octopus (Hapalochlaena)
Some creatures are so cool to look at that it feels like a shame we can’t be friends. The blue-ringed octopus (Hapalochlaena) is a perfect example, with its tiny body and bright, electric blue circles that cover its body. However, those circles are like a warning light because they only show up when you’re getting too close. Once you see those rings form, it’s time to head for dry land because catching a blue-ringed octopus bite can result in respiratory failure within 10 minutes and death within 30.
Blue-ringed octopuses are not a single animal, but a type of octopus genus that may have up to 10 separate species — we currently have only catalogued and named four. You’re most likely to encounter the greater blue-ringed octopus (Hapalochlaena lunulata) since it likes to hang out in the shallow waters around Southeast Asia and Melanesia. Within its salivary glands, a toxin is stored that’s considered 1,000 times more toxic than cyanide. Being bitten by a blue-ringed octopus is rare, but once it happens, medical intervention is immediately required. Almost instantly, the body’s muscles will paralyze, including the lungs, causing respiratory failure. There is no known antidote for blue-ringed octopus venom, but emergency care may help stabilize the body until the effects wear off.
Gaboon viper (Bitis gabonica)
Native to the forest floors of Central Africa, the Gaboon viper (Bitis gabonica) should be the official mascot for the saying “looks can be deceiving.” Gaboon vipers stay relatively small as compared to their venomous cousins, only maxing out an average of 4 to 6 feet, but will become absolute units that can weigh up to 45 pounds. They get this heavy because they don’t need to be agile; they’ll camouflage themselves in leaf litter and wait for the perfect time to ambush their prey. And once they do, there’s little chance of going back. B. gabonica have the largest fangs and will deliver up the highest venom yield of any snake – up to 2 grams of venom per bite, which can kill a human adult within one to two hours.
Thankfully, even though they’re capable of taking down larger animals, they usually stick to rodents and lizards; humans aren’t on the menu. Despite being so deadly, they’re considered to be very chill snakes that can tolerate a lot of abuse before striking out at humans. They’re even fun to watch trundle along, looking more like a wind-up toy than the elegant glide of a cobra. Though they move that bulky body slowly, they can surprise you when they want and are considered one of the fastest-striking snakes in the world, so don’t take their complacency for granted. Should you be one of the rare people to get envenomated, you’re going to be in for a bad time. Gaboon viper venom is cardiotoxic and can start affecting mammalian heart functions within only 15 minutes.
Cape cobra (Naja nivea)
The Cape cobra (Naja nivea) and black mamba are neck and neck for causing the most human fatalities in Africa, and both bites are horrifying ways to go. But what makes the Cape cobra so scary is that they are highly aggressive snakes with a bite that can cause almost instant respiratory paralysis. It’s estimated they’re responsible for anywhere from 12 to 24 deaths per year with a venom so potent it only takes 30 minutes to cause a fatal outcome.
Cape cobras live in the southern tip of Africa and can resemble the Black spitting cobra (Naja nigricincta woodi) or Mole snake (Pseudaspis cana). It seemingly does not have a fear of humans and will often live around South African suburbs, searching for rodents. It’s not as shy as its other African relatives and is known to hood and attack quickly in a very “bite first and ask questions later” sort of way. While there is an antivenom that treats N. nivea bites, patients may still be unresponsive for up to two days after medical intervention.
