Box Jellyfish: Learn everything about this dangerous species.

The box jellyfish are probably the most dangerous invertebrates that exist today. Their bite can paralyze and in the worst cases can cause death, know many more facts about them below.

What are the Box Jellyfish?

This is a kind of jellyfish that usually inhabits the waters of Australia and the Philippines, although they can also be found in tropical waters. This species is also known by the name of Sea’s Wasp.  This denomination is more popular, and it is granted thanks to its dangerous sting.

Box jellyfish belong to the Cnidaria phylum and the Cubomedusae order. This species is similar to jellyfish belonging to the Scyphozoa class, although its taxonomic classification is not completely defined.


At least 36 species of jellyfish were known from 2007. They have been grouped into two orders and seven families. Since then, some new species have been described, and it is considered that the box jellyfish belong to the category of not described species.

The Box Jellyfish’ Evolution

It’s   extremely difficult to understand the jelly fish´s evolution process as a whole, including the box jellyfish. More than 700 million years ago they were already on Earth, which shows that they are able to adapt to the changes around them. These creatures have many differences that distinguish them from other species.

While there are theories, we really lack  any information about how this particular species was formed. Most experts believe that box jellyfish, have had to deal with several large predators, so their toxins are stronger than those of other species.

It’s   not understood why they have eyes, since very few species possess them. It is believed that the development of eyes and their advanced nervous system are part of the evolution process of this jellyfish species.

Anatomical Characteristics

Jellyfish are the migratory form of the phylum Cnidaria. In the case of the box jellyfish, their bell-shaped body is shaped cube, and possess tentacles that extend from each corner. The box jellyfish are complex animals with a mechanism for propulsion and a nervous system somewhat sophisticated for a jellyfish.

They have up to 24 eyes, (some of them with corneas and retinas), which allows them to not only detect light, but also see and circumnavigate objects to avoid jellyfish . anatomy

While some jellyfish live from symbiotic algae, the box jellyfish feed on small fish, which paralyze immediately on contact with their tentacles.

Then the tentacles are retracted, leading to the prey to the campaign for digestion.

Some species hunt every day, and at night you can see some species resting on the bottom of the ocean.

The Anatomy of this jellyfish offers a benefit that other species don’t have: they are able to move by themselves, without employing large amounts of energy to do so.

They can use water  currents  or wind to move in the direction that they need to go, although they can also move by themselves and not have to follow these guidelines if they choose it.

This means that these jellyfish are not floating on the way of their predators without any resource, which means they have better chance of survival, since they can reach their food supplies.

How  Do Box Jellyfish Reproduce?

It’s   not surprising that they have received little attention from biologists, at least in their reproductive biology. However, in recent years, scientists have learned about the life cycle of this species, and its study has confirmed that box jellyfish reproduce both sexually and asexually.

The asexual reproduction is a way in which offspring are born from a single father. That is, it does not involve sex.

In the asexual mode, the descent, perhaps understandably, is identical to the mother (clone). Let’s take a closer look at the jellyfish’  reproductive biology .

It’s   believed that box jellyfish reproduce during the spring season, when the cubozoans travel to freshwater habitats to find a mate in which they lay their eggs and sperm, after which they die. The box jellyfish gather in large numbers during spring of each year and shortly after spawning they are completely dead.

They are oviparous creatures that reproduce only once a year. The breeding season begins mainly in late summer and ends in early autumn. The male and female jellyfish reach maturity at 2 months of age and their life expectancy rarely exceeds 9 months.


Due to the ability of this species to reproduce both sexually and asexually, its life cycle is a bit complex. The cubozooans  also suffer from gamethyc  meiosis and they go through different life’s stages

    • not pigmented Larvae
    • Pigmented Larvae
    • Vegetative polyp
    • Three stages of metamorphosis from polyp to jellyfish.
    • Juvenile jellyfish
    • Adult female
    • Adult male
    • Planula (larvae)

The cubozoans’ ciliated larvae are formed by the combination of sperm and ovules. The larvae of a box jellyfish is known as planula, which is easily recognized due to their pigment spots and quick respond to light. It is probable that the pear-shaped planulas  swim for a few days (perhaps a week). When the planula settle, it becomes a polyp.

Polyp (Bentonic Stage)

A polyp in cubozoans is a stage that replaces the medusoid stage. The planula becomes a polyp and the latter begins to crawl like a worm. The polyp grows up to 1-2 mm in length. More polyps sprout from the first polyp through asexual reproduction.

However, unlike scyphozoan polyps, cubozoan polyps do not go through stunting, which in scyphozoans (true jellyfish) occurs when the polyp is divided into body segments. On the contrary, in the box jellyfish the whole polyp becomes a juvenile jellyfish.

The cnidarians’ polyps are cylindrical in shape but look like a ball with tentacles.

They use these two tentacles to grab any object or other animals. To avoid any danger, most polyps tend to hide in a crack or in a rock below.

They do so because they are very vulnerable during this phase of their life cycle. When it comes to diet, polyps feed on plankton. The polyps of the cubozoans  don’t   resemble at all the polyps of the true jellyfish, (scyphozoan).

Medusa (pelagic stage)

Polyps will soon enter the final stages of a life cycle. During this phase the polyps begin to become a small jellyfish. This happens in the spring before the monsoon rain begins. As the polyp becomes a jellyfish (completely), it probably leaves fresh water for the sea.

Here, at sea, the box jellyfish will continue to grow into adulthood until it reaches full size. The box jellyfish typically reaches a length of approximately 16 to 24 cm.

Prey and Predators

The box Jellyfish actively hunt their prey, which are usually small, in drifting places like ordinary jellyfish do.

They are capable of reaching speeds of up to 1.5 to 2 meters per second or approximately 4 knots.

The cubozoans’ poison is different from the one of the scyphozoans, and they use it to catch prey (small fish and invertebrates, including prawns and fish bait) and to defend themselves from predators.

Predators include butter fish, batfish, rabbit fish, some sea crab  and several species of turtles including the hawksbill sea turtle and the flat sea turtle.

From 1884 to 1996, there have been more than 60 deaths reported by jellyfish stings in Australia. There are jellyfish species in almost all tropical and subtropical seas, but the life-threatening species seem to be restricted to Indo-Pacif.

Let’s meet  them better

Types of Box Jellyfish

From 1884 to 1996, there have been more than 60 deaths reported by jellyfish stings in Australia. There are jellyfish species in almost all tropical and subtropical seas, but the life-threatening species seem to be restricted to Indo-Pacif.

Sea wasp

Found in the coastal waters of Australia and Southeast Asia, the marine wasp is the common name of the most dangerous cnidarians: Chironex flecke-rii.

The marine wasps have a bell about 8 inches (20 centimeters) in diameter and tentacles ranging from a few centimeters to 10 feet (3 meters).

Contact with these animals triggers the most powerful and lethal poisoning process known to science.

Poisoning by the marine wasp causes immediate unbearable pain followed by heart failure. Death can occur in just three minutes.

Recent studies have identified a component in its poison  that punches a hole in red blood cells, causing a massive release of potassium, possibly responsible for lethal cardiovascular depression. The same study may also have identified a way to inhibit this effect, which in the coming years could be clinically promising.

Let’s meet them

Four Handed  Box Jellyfish

The habitat of these jellyfish (Chiropsalmus quadrumanus) extends from South Carolina to the Caribbean, including the Gulf of Mexico and even to the south of Brazil.

The four-handed jellyfish can cause extremely painful stings and is the American cousin (but a little smaller) of the Australian marine wasp. There is a documented case of a four-year-old boy who was bitten in the Gulf of Mexico and died in 40 minutes.

Box Jellyfish from Bonaire

This species  (Tamoya ohboya) is a relatively unknown and highly poisonous species found in the Dutch Caribbean. Since 1989 there have been approximately 50 sightings confirmed mainly in Bonaire and the rest on the coasts of Mexico, Saint Lucia, Honduras, Saint Vincent and the Grenadines. Only 3 cases of poisoning have been reported, which led to severe pain and damage to the skin.  Only 1 case required hospitalization.

Irukandji Syndrome

The box jellyfish found near Australia, Carukia barnesi and Malo kingi are responsible for the extremely painful symptom complex known as Irukandji syndrome. These small cubozoans measure only a few millimeters with tentacles up to 3 feet (1 meter).

Fortunately, deaths due to these species are rare, but their bites are extremely painful and can cause systemic symptoms, including cardiovascular instability, which warrants immediate medical attention.

The survivors have reported a feeling of imminent death, stating that they were sure that they could not survive over such intense and widespread pain.  However, it’s   important to emphasize that a single bite is usually not enough to lead to death.

Although the bites of lesser known cubozoan species are not necessarily lethal, they can still be very painful. An immediate medical evaluation is highly recommended.

Let´s watch


    • Investigate properly the areas in which you want to dive.
    • Avoid known jellyfish habitats if you are not sure that the dive site or swimming area is safe. If they sting, cardio-vascular stability can deteriorate rapidly with very little time for any effective intervention in the field.
    • Minimize unprotected areas: Always wear full suits, hoods, boots and gloves. Something as simple as nylon socks worn on the skin will prevent jellyfish stings.
    • Bring enough domestic vinegar to all dive sites.

First aids

If stung by any jellyfish, follow these procedures in this order:

    • Activate local emergency medical services.
    • Wash the area with sea water (or saline). Use a syringe with a continuous stream of water to help remove the remains of tentacles. Do not rub.
      • NOTE: Do not use fresh water; this could cause a massive discharge of nematocysts.
    • Monitor the victim´s respiratory tract, breathing and circulation
    • Avoid rubbing the area. The box jellyfish’s tentacles can be cylindrical or flattened, but they are covered with cnydocites, so by rubbing the area or allowing the tentacles to roll over the skin it will exponentially increase the area of ​​the affected surface and the poisoning process .
    • Apply domestic vinegar to the area. Pour generously or spray the area with vinegar for no less than 30 seconds to neutralize any invisible remnants.
    • You can pour the vinegar over the area or use a spray bottle, which optimizes the application. Let the vinegar rest for a few minutes before doing something else.
      • NOTE: This will not do anything for the pain or poison already injected, but it is meant to stabilize the non-inflamed nematocysts that remain on the diver’s skin before attempting to eliminate them.
    • Apply heat. Immerse the affected area in hot water (upper limit of 113 ° F / 45 ° C) for 30 to 90 minutes.
    • If you are helping a stinging victim, test the water first with you to evaluate the tolerable heat levels. Don´t trust the evaluation of the victim, since intense pain can affect your ability to assess tolerable heat levels. If you can´t measure the water´s temperature , a good practice is to use the hottest water you can drink without burning.
    • Keep in mind that different body’s areas have different heat tolerances, therefore, test the water in the same area where the diver was injured. Repeat if necessary. If hot water is not available, apply a cold compress or ice in a dry plastic bag.
      • NOTE: the application of heat has two purposes:
    • 1) it can mask the perception of pain;
    • 2) can help in thermolysis. Since we know that poison is a protein that has been inoculated superfluously, the application of heat can help to denature the toxin.

Always look for an emergency medical evaluation.

It always worths learning



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