Though pretty small, a school of these fish can feast on larger animals like no one’s business. They swim in the rivers of the Amazon rainforest and enjoy utilizing their strong jaws and sharp teeth.
They eat other fish, insects, and pretty much anything that was unfortunate enough to fall into the water they swim in. Plentiful in their freshwater habitat, these ferocious fighters will perish in saltwater.
Ascaris (Lumbricoides) Roundworms
Common in sub-Saharan Africa and tropical climates, these worms infest your body after you drink water that's been contaminated with human feces.
They can cause a serious infection. In fact, they affect around one-sixth of the human population and are widespread mostly in tropical and subtropical climates. There’s a reason you should always drink bottled water in areas with poor sanitation!
Duck-Billed Platypus
The duck-billed platypus has deadly venom, which makes it one of only a few mammals on earth of that kind. Both males and females have ankle spurs, only the males seasonally produce the deadly substance from their hind limbs. You might mistake it for an animal you could keep on a farm, its venom can actually kill other animals and cause pain to its victims.
While the venom isn’t deadly for humans, the agonizing pain paralyzes its victims. Despite posing a danger to humans and animals alike, it is an iconic symbol of Australia and has appeared as a mascot at several events, as well as been featured on the Australian twenty-cent coin.
Gila Monster
These little monsters are one of only two poisonous lizards in the world. They kill their prey with the venomous saliva they produce while chewing. They live in the Southwest of the US and in Mexico and are the only venomous lizards native to the U.S. They are heavy and slow-moving and may reach a length of 2 feet.
They live in brush areas, lush deserts, and oak woodland, and find shelter in locations where moisture is within reach. It used to be believed that the Gila monster had toxic breath and that its bite was deadly, however, it is known now that it isn’t fatal to healthy adults.
Irukandji Jellyfish
This is the smallest jellyfish in the world but also one of the most dangerous. Their sting is 100 times stronger than a cobra and may cause the Irukandji syndrome, which involves nausea, muscle cramps, excruciating back and kidney pains, a burning sensation of the skin and face, headaches, vomiting, and a feeling of impending doom. While most jellyfish have stingers only on their tentacles, the Irukandji also has stingers on its stomach.
They live in the waters of northern Australia. Oftentimes, jellyfish nets which are meant to protect beaches, don’t catch these small jellyfish due to their size of less than a cubic centimeter. They are tiny, translucent, and difficult to spot while in the water, hence why it is also referred to as an invisible danger.