Box jellyfish aka Sea wasp

Box Jellyfish / Sea wasp

Scientific name: Chironex fleckeri

The box jellyfish is also known as box fish and sea wasp. It has one of the fastest working toxins and kills more people each year than any other marine animal. The box jellyfish (sea wasp) is primarily a problem in Australia. Australia is subjected to a box jellyfish season that usually lasts from October to April, and box jellyfish are also known to regularly swarm along Hawaii’s leeward shores 9-10 days after a full moon. Box jelly fish that swarm outside Hawaii do not belong to the potentially deadly species Chironex fleckeri (about which this article is written). They are the less harmful species Carybdea alata and Carybdea rastonii that can cause severe pain and anaphylactic shock in some of those that get stung. Only sever allergic reactions will cause stings from these two species to be fatal.

Sea wasps (box jellyfish) are usually found in shallow waters, and swimming and other water activities are not recommended if you can see sea wasps in the sea. A normal wetsuit is usually not safe enough and it is therefore best to use a specially designed box jellyfish safe wetsuit to prevent being stung. There is however a poor mans trick for those without a suitable suit – sea wasps can’t sting you trough nylon pantyhose’s and this is why you can see Australian lifeguards wearing with nylon stockings over their arms and legs. Don’t forget that a sea wasp can sting your head and neck if you don’t protect these areas as well.

Box jellyfish (sea wasps) have a bell or cube like form and are divided into segments. The cube like shape is what has given these jellyfish their common name box jellyfish. They have a transparent body with a pale blue color and can grow to be about 20 cm (size of each side) and weigh 2 kg/ 4.5lb. A box jellyfish can have up to 15 tentacles in each corner of the cube, and these tentacles can grow to a length of 3 m / 10 ft and are covered with stinging cells, so called nematocysts. Each tentacle on a box jellyfish can have up to 5000 of these nematocysts. The box jellyfish uses these tentacles to catch its prey, i.e. small fish and crustaceans. Box jellyfish is, unlike many other jellyfish, equipped with four eyes. It is not known how it can process what it sees since it has no brain, but it somehow manages to use its eyes without a normal brain and can by sight avoid colliding with the smallest of objects. The box jelly can move with a speed of up to four knots.

The very potent venom of the box jellyfish is stored within stinger cells which are triggered to release their venom when sensing the present of certain chemicals and not by touch. This means that you could touch a box jellyfish without being stung if your skin didn’t release these chemicals. Once activated by the right chemicals, e.g. chemicals exuded by human skin or fish scales, the stinger cells immediately inject their venom into the victim.

Sea wasp (box jellyfish) stings can cause excruciating pain in humans. The tentacles stick to the skin and should never be removed while they still are alive since this might increase the damage. The pain can remain for weeks if not treated and the sting often leaves a scar. Sea wasp stings are causing a high number of deaths each year in effected areas. The stings from a sea wasp can be threaded by pouring vinegar (never methylated spirits) on the remaining tentacles. This will kill the tentacles and make it possible to remove them safely. You should always seek professional help as soon as possible after a sea wasp sting since you need to be given proper treatment and antidote to the venom. The stings can cause cardio respiratory arrest or arrhythmias, so don’t delay seeking medical attention.

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