Box jellyfish

This famously venomous box jellyfish frequently ranks first among the world's most dangerous water animals. They are named for their body shape which has tentacles covered in biological booby traps known as nematocysts - tiny darts containing poison.

While it may not appear to be dangerous, its sting can be fatal. In less than five minutes, the sting can kill you. Its venom is dangerous enough to kill up to 60 people. People and animals who are bitten and receive this venom may endure paralysis, cardiac arrest, and even death within minutes of being stung. The box jellyfish can swim, unlike some jellyfish, which means they can hunt for prey and migrate through the ocean more quickly. However, of the 50 species of box jellyfish, which are also called sea wasps, only a few have venom that can be life-threatening to humans. Box jellyfish can be found in warm coastal waters all over the world, but the fatal types are only found in the Indo-Pacific and northern Australia.