Most Dangerous Animals in the World

Hippos may look like giant, bumbling things, but they are often considered Africa’s most dangerous mammal. They’re territorial, unpredictable, and armed with a mouthful of teeth sharp and strong enough to do lethal damage. If their territory is encroached—whether that be by a crocodile, another hippo, or boat full of tourists—they will aggressively defend their space

The most deadly, the golden poison dart, inhabits the small range of rain forests along Colombia’s Pacific coast, and grows to around two inches long (roughly the size of a paper clip). Its poison, called batrachotoxin, is so potent that there’s enough in one frog to kill ten grown men, with only two micrograms—roughly the amount that would fit onto the head of a pin—able to kill a single individual.

Many spiders have fangs packed full of toxins but aren’t known to bite people. Unfortunately, the Brazilian wandering spider is not one of these. Even worse, this spider often lives up to its name and wanders into densely populated areas to seek shelter in dark, cozy places like the inside of shoes, clothes, log piles, cars, and other places people may stick their hands.

The most venomous fish known to humans is an easy one to miss—which is by design. Stonefish, after all, are named for their visual similarity to rocks, sitting perfectly still and blending right into the seabed where an unsuspecting foot can easily step down on their dorsal fins, primed and ready to attack with potent neurotoxins.

. Of all the species in the world, the largest—and most dangerous—is the saltwater crocodile. These ferocious killers can grow up to 23 feet in length, weigh more than a ton, and are known to kill hundreds of people each year, with crocodiles as a whole responsible for more human fatalities annually than sharks (then again, so are cars).

While the flies themselves are nasty bloodsucking bugs that usually feed during the peak warm hours of the day, their true terror lies in the protozoan parasites they spread known as Trypanosomes. These microscopic pathogens are the causative agent of African Sleeping Sickness, a disease marked by neurological and meningoencephalitic symptoms including behavioral changes, poor coordination, as well as the disturbances in sleeping cycles that give the illness its name. If untreated, the condition can be fatal.

This docile animal will attack when threatened, packing a neurotoxin 1,000 times more powerful than cyanide, with no known antidote—not that there would even be enough time to administer it before death occurs. The bite of the blue-ringed octopus is so painless, one might not even feel it happening (which makes it even more remarkable how often people share photos and videos with one in their hand).

The mosquito is the single deadliest, most dangerous animal in the world and also one of the smallest. Mosquitoes are estimated to cause between 750,000 and one million human deaths per year.