Top 10 Smallest Animals That Could Kill You



Top 10 Smallest Animals That Could Kill You

VOICE OVER: Rebecca Brayton WRITTEN BY: Caitlin Johnson
These tiny animals are extremely dangerous. For this list, we're looking at the tiniest animals, fish and insects on Earth that can end your life. Our countdown includes Pufferfish, Poison Dart Frog, Mosquitos, and more!

Top 10 Smallest Animals That Could Kill You

Size isn’t everything. Welcome to WatchMojo and today we’ll be counting down our picks for the top 10 smallest animals that could kill you.

For this list, we’re looking at the tiniest animals, fish and insects on Earth that can end your life.

#10: Assassin Bug

There are 7000 different species of assassin bug out there, some grosser than others. By far, the most unpleasant are those that make a habit of carrying the corpses of their enemies around on their backs - but only after they’ve sucked all their insides out. And while they’re bad news for other insects, many - including the common, “masked hunter” - are capable of giving humans a nasty bite, designed to be as painful as possible. But the real danger is that they can spread parasites through their bites, causing Chagas disease; this variety of insect, also called “kissing bug” or “vampire bugs”, is known to bite the mouths of sleeping people.

#9: Pufferfish

Stepping on a spiky pufferfish might be painful, but it probably won’t do you much damage. These fish are only deadly to those that try to eat them due to the fact their bodies contain tetrodotoxin, a neurotoxin said to be 1200 times more dangerous than cyanide, which can kill a human in minutes. The dangerous pufferfish — known as fugu and often served as a delicacy in Japan in highly specialized restaurants — contains enough toxin to kill 30 people. Any chef who wants to prepare it needs to have very special training to do so. But many wouldn’t take the risk, since ingesting even a tiny amount can be disastrous, and there’s no antidote.

#8: Glaucus Atlanticus

This remarkable species of sea slug is sure to catch your eye, but if it does, remember that you shouldn’t touch it under any circumstances. Though they may look bright and friendly, they’re a predator like no other. This is because they eat and then store the deadly nematocysts from very dangerous undersea critters – and its favorite food is the tentacles of the famously toxic Portuguese Man o’ War. This means that if you touch one of these slugs, either by accident or on purpose, you might receive a sting like you’d just bumped into a Man o’ War instead. It’s best to err on the side of caution and leave them alone.

#7: Indian Red Scorpion

Not all scorpions have venom potent enough to hurt you... but the Indian red scorpion isn’t one of them. Found primarily in India and its neighboring countries, these arachnids only grow up to a few inches long, but their toxic tails certainly pack a punch. Without treatment, the sting fatality rate can be as high as 40%, usually causing death through respiratory failure. Another frightening scorpion is the menacingly-named deathstalker, a species that lives in parts of Africa and the Middle East. The good news is that most adults won’t die from a deathstalker sting, and interestingly, its venom may be used to treat brain tumors.

#6: Blue-Ringed Octopus

At their biggest, these tiny cephalopods are only 8 inches long, but their bright, ring patterns make them easy to spot. The blue-ringed octopuses venom contains a host of deadly chemicals, including our old foe tetrodotoxin. Unlike the pufferfish, however, the octopus uses its venom as a weapon rather than purely as a defense mechanism. It flashes its rings when it feels particularly threatened, so be sure to back off if you see one performing this behavior. Even more dangerous, they like to live in shallow waters and near reefs, making you at risk of stepping one. But it’s safe to admire how cute they are... from a distance.

#5: Freshwater Snails

The snail isn’t necessarily the organism that will kill you. What’s deadly is the tiny, parasitic worms these snails harbor, which will cause a disease called “schistosomiasis”, or “snail fever.” But this is a neglected tropical disease, meaning that while it kills over 200,000 people annually and affects millions, many won’t have heard of it. It’s still the snails you need to worry about however, as they’re the ones transporting and releasing the deadly parasites into water. Even just coming into contact with infected water is enough for these parasites to burrow into your skin, causing lifelong complications if not treated.

#4: Poison Dart Frog

Some of the most colorful critters in the animal kingdom, these tiny frogs wear their bright patterns as a warning sign to stop predators – or humans – from eating them. This means that their poison is entirely defensive; the frog won’t bite or sting you, and you’re only in danger if you lick or consume it. They get their name due to some being used to make poison blow darts, though not every species of poison frog is potent enough to kill someone. But one, in particular, the golden poison frog, contains enough toxin to kill 10 adults. This is definitely a case of “look, but don’t touch.”

#3: Metasepia Pfefferi

You may know it better as the flamboyant cuttlefish, and it certainly lives up to this moniker. This vibrant cuttlefish lives in the Pacific Ocean and the smallest are just about two inches long. However, the flesh of the cuttlefish is actually acidic, and could prove just as deadly as the blue-ringed octopus, though they’re the only toxic type of cuttlefish we know of. But just because you wouldn’t want to eat one doesn’t mean they’re not at risk from overfishing; many cuttlefish habitats have been destroyed by bottom trawlers. If you want to see one of these flashy cephalopods in person, lots of aquariums have been known to host them.

#2: Irukandji Jellyfish

Whereas some species of jellyfish have survivable, if painful, stings, this particular group’s sting has an entire disease named after it. “Irukandji syndrome” is what happens to someone who gets stung by any of the potent Irukandji, a type of box jellyfish, which can cause cardiac arrest and heart failure. Making them even more dangerous is the fact that they’re also the smallest jellyfish in the world, just a third of an inch in size: this makes them incredibly hard to see, and on top of that, the stings often aren’t overtly painful. You can be stung and not even notice, making it even harder to get treatment.

Before we unveil our top pick, here are a few Honorable Mentions:

Cone Snail
There’s No Antivenom to Save You From Its Deadly Sting.

Black Widow Spider
They Bite More Than 2000 People Every Year.

Asian Giant Hornet
They Didn’t Get the Nickname “Murder Hornets” for Nothing.

Deer Mice
They Spread Hantavirus, Which Kills 40% of Humans Who Get Infected

Baby Inland Taipan
Considered the Most Toxic Snake Venom in the World.

#1: Mosquitoes

These insanely bothersome pests are so incredibly dangerous due to the fact they spread many diseases. Malaria is the deadliest, but they also spread yellow fever, Dengue fever, and Zika virus, among many more. Mosquitos do this by drinking the blood of a host who has the pathogen within them and then spreading the pathogens when they move onto their next victim. More than a million people die every single year due to mosquito-borne diseases. And that’s just in modern times. Mosquitoes aren’t just the smallest animal that can kill you, they’re also the animal most likely to kill you... full stop.