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Deadly Box Jellyfishes

The box jellyfish species (cubozoa) is a free-swimming cnidarian invertebrate and a carnivorous animal. It is easily distinguished from other jellies by its cuboid medusae - cube-shaped body.

Despite their infamous notoriety, not all box jellyfish species are poisonous.

Nonetheless, the deadly breathtaking toxins from Chironex fleckeri make it one of the most venomous of all creatures on earth.

They exist primarily throughout the warm ocean currents of the Indo-Pacific regions and the northern coasts of Australia.

Box jellyfishes, sometimes called sea nettles, sea wasps or marine stingers, can grow to reach more than three meters long and around 25 cm across.

They often weigh more than two kilos and generally live for about a year. They feed on small fishes and shrimps using their delicate yet powerful paralyzing stinging barbs and deadly venom for defense and to stun their prey followed soon after by death.

Their main predator is the sea turtle which is unaffected by the box jellyfish's poisonous stinging tentacles.

Box Jellyfish Venom

The venom of the box jellyfish ranks among the world's most deadly toxins which attack the victim's skin cells, the heart, and the nervous system.

Making contact with the box jellyfish's tentacles often results in severe shock symptoms, weeks of excruciating pain, skin scarring, heart failure, or death. Their box-shaped bell is usually transparent and pale blue in color.

They have up to 15 long dangling tentacles flowing from each corner which contains around 5,000 stinging cells or 'nematocysts'.

Surprisingly, the cells are fired by contact with a chemical and not by touch alone.

Despite not having a central nervous system to process what they see, their eyes have an advanced retina, cornea and iris with a sophisticated lens. The eyes are grouped in clusters located on each of the four sides of the bell.

They move and drift in water different from most pulsing jellyfishes. Box jellies can propel themselves through water jetting around seven kilometers per hour.

Chironex Fleckeri

The quantity of venom that the victim is subjected to correlates to the extent of the damage received and the seriousness of the injury. The box jellyfish species Chironex fleckeri is attributed to more than 100 known deaths.

Picture of Box Jellyfish (Cubozoa) This jellyfish has toxins so immensely poisonous, marine biologists suggest that one death-dealing animal can kill 60 adults.

In fact, biochemists have discovered exactly how the Chironex fleckeri delivers its fatal venomous sting.

The lethal blow is delivered by a proteinous chemical which makes the victim's cell walls to leak potassium directly into the bloodstream.

Excessive potassium is called hyperkalemia and causes almost immediate death.

Within three minutes of a sting attack, the victim suffers shortness of breath combined with intense pain and probable cardiac arrest often resulting in death.

Urgent medical attention is needed after being stung by this box jellyfish. You can treat the wounded area with vinegar to reduce the pain and to inhibit firing of further nematocysts.

Use tweezers or gloves (not bare hands) to remove the visible tentacles. You should contact EMS while monitoring the victim's vitals and administer CPR if necessary.

Preventing the Sting

Despite knowing that the Chironex fleckeri might be present in your favorite dive site, you might not necessarily need to cancel your dream diving holiday to the Great Barrier Reef. Jellyfish stings need pressure and a chemical on the skin to trigger the nematocysts.

Without direct contact with the chemical, the tentacles do not fire the stinging cells. Try to cover all bare skin as much as possible with a full body wet suit or dive skin with booties and gloves.

Curiously, biologists have found that almost all jellyfish dislike the color red. Red wet suits are not popular or fashionable but you could wear a red rash guard, skin top or your favorite red t-shirt over your normal thermal protection.

Chirodectes Maculatus

[Phylum: Cnidaria] [Class: Cubozoa] [Family: Chirodropidae] [Species: C. maculatus (spotted)]

A worthy candidate for the rarest species of jellyfish is the Chirodectes maculatus - a monospecific genus of the box jellyfish.

In fact, divers who were diving off the coast of Queensland in Australia on 2nd of May 1997 were the only humans that had seen it and filmed the spotted body of this elusive creature underwater.

It has four separate and distinct groups of tentacles that trail behind its translucent body. It also contains a bright red organ inside the center of the bell, which measures about fifteen (15) centimetres in height (5.9 inches).

Scientists believe it is the gastrovascular cavity, used as the primary organ for digestion and circulation in jellyfishes.

Here's the good news:

An observational study carried out in 2005 suggests that the Chirodectes maculatus is not venomous. This is still unknown because zoologists were reluctant to dissect it.

The animal failed to sting or adhere to a human hand or forearm during the examination. As a result, there are no recorded cases of a human sting from Chirodectes.

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