Also called sea wasp or marine stinger, the box jellyfish (Chironex fleckri) is a weird, wonderful but very deadly animal. In fact, it is known as one of the most dangerous marine creatures killing more people than sharks, crocodiles and stonefish combined.
Box jellies can grow up to 3 meters long and 10 inches wide and can weigh up to 2 kilograms. It is named after its box-shaped bell which can grow to about the size of a basketball. It has four clusters of 15 tentacles up to 5 meters long trailing from each of the four corners of its bell.
Just like all jellyfish, box jellies have tentacles with stingers called nematocysts. The stingers are used to acquire food. Since they are not active hunters, they rely on small fish or shrimps and other crustaceans to bump into their tentacles where they are almost immediately paralyzed and then swallowed, a death that can be seen through its pale blue and almost invisible body.
Their powerful venom is designed to instantly stun or kill prey so their struggle to get away will not damage the jelly’s delicate tentacles. But swimmers and divers who are unfortunate enough to get in touch with their tentacles will become victims of the most venomous stinging cells. The stingers are activated by pressure and as a reaction to proteinous chemicals. The frighteningly powerful toxins attack the heart, nervous system, and skin cells that no other animal toxin can. The victim will experience the most powerful pain accompanied by burning sensation that some have been known to go into shock or die of heart failure in just a few minutes.
The box jellyfish live primarily in coastal waters off Northern Australia and throughout the Indo-Pacific region. While other marine creatures stay away from them, turtles want to get near them because they eat them. The box jellies’ most venomous tag has no effect on the turtles.
In waters where jellies are known to drift, swimmers bring along vinegar as first aid should they get stung. There is also an antivenom which must be administered quickly. It is of utmost importance that hospitals must be contacted immediately if somebody becomes a victim of the the world's most venomous animal--the box jellyfish.