Upon appearance, one wouldn’t think these creatures were deadly. They’re gelatinous looking with long streaming tentacles. They look like you could play with them. When they float in the water, they look angelic. But beneath that innocent exterior is a creature that is ready to embrace its victim with a deadly serenade. Some are so small that a swimmer doesn’t even notice until the sting begins to turn into agonizing pain. Jellies, while beautiful, can be dangerous creatures that need to be recognized. There are 200 known species. Some only produce mild to severe stings, and discomfort, while only a few are known to be deadly.

Box Jellyfish (Chironex Fleckeri)

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Chironex fleckeri are the largest of the box jellies, and are predominant throughout Australia. They are usually transparent and bell or cubed shaped with four distinct sides. This is where they get their name box jellyfish. They can be 20cm (7.9 inches) long on each side of the bell or cube, and have as many as 15 tentacles on each side, which can be 3 meters (9.84 feet) in length. It can contain up to 5,000 nematocysts (stinging cells). Unless the sting from one of these jellies is treated immediately, survival is minimal. The pain is unbearably excruciating and most victims go into shock, and drown if swimming alone. They can have an effect on the heart due to cardio toxins, damage to the nerves from neurotoxin, and dermatonecrotic effects (skin damage). Some victims who have been entangled in more than 3 feet of the box jellyfish’s tentacles can experience cardiac arrest. The tentacles can stick to the skin and continually release venom if not treated. Severe stings can even cause necrosis of the stung area. Over 50 deaths from these jellies have been the cause of death in Australia.

Irukandji (Carukia Barnesi)

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These jellies are about the size of a thumbnail, and are highly venomous. A man by he name of Hugo Flecker began noticing that patients of his were experiencing nausea, back pain, burning sensations on the skin, headaches, vomiting, restlessness, elevated blood pressure, rapid heartbeat, and abdominal cramps. The collective symptoms were coined Irukandji (an indigenous tribe of Cairns, Australia) syndrome. He was unable to identify the jellyfish. Nearly 10 years later a physician, Jack Barnes, suspected a small box jellyfish was the culprit. He tested his theory by allowing himself, his nine-year-old son, and a lifeguard to get stung. The symptoms occurred on all three. Unlike most jellyfish, the Irukandji has stingers not only on their tentacles, but also on is bell. So far only 2 deaths have occurred from their stings, but some deaths have possibly been wrongly attributed to other ailments rather than from the sting of the Irukandji. It is possible that people who are stung by these jellyfish can suffer brain hemorrhages or heart failure.

Chiropsalmus Quadrigatus

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It is another type of box jelly, closely related to the Chironex fleckeri (a cousin if you will). In Japan it is known as the Habu-kurage (sea wasp). It’s predominant through the tropical Pacific region. It has also been responsible for three fatal cases from stings in Japan. While antivenin has been created to ward off the sting of the box jellies, in most cases, it is of no use, because the amount of time it takes to go from the site of the sting, to the hospital takes too long. By then, the attacked victim will have swatted or tried to pull off the jelly. The tentacles will have released its toxin, and if the tentacles stay on the victim, the stinging cells can still pulse venom into the victim’s body. Panic can increase the heart rate further spreading the venom, and more quickly, thus resulting in death.

Malo Kingi

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Malo kingi is one of several Irukandji jellyfish, and was named after its victim Robert King. He was an American tourist swimming off the coast of Queensland, Australia. Although he was the first, it is unknown how many other people could have been possible victims, especially in the Philippines since they don’t have death certificates. It has been noted that it isn’t unusual for there to be 20-30 deaths a year from the Irukandji in the Philippines. The Malo kingi has earned the 8th rank in the top 10 species of 2008 by the International Institute for Species Exploration.