C. fleckeri, commonly known as the Sea Wasp, is the most dangerous jellyfish and considered to be one of the most dangerous creatures in the world. This species is pale blue in color, posing a danger to swimmers since its transparency makes it difficult to see in the water.
"Chironex fleckeri is one of the simplest organisms. The bi-radially symmetrical body has well developed tissues and specialized cells. The outer covering of ectoderm made of milky slime substance and an inner layer of endoderm makes it displobastic. It has an organic exoskeleton and hydrostatic skeleton and it is an encephalized organism with a non-cellular mesoglea separating the two layers and spreading to a vast bulk of its body which aids its buoyancy. With only a single opening (the mouth and entrance to the cavity), the body encompasses a single sac-like body space called the Gastro-vascular ..It is called the box jellyfish because its transverse section appears to be squared-umbrella -shape with its tentacles at the corners of the box margin. The edge of the umbrella turns inwards forming a circular shaped structure called Velarium. It possesses four dark spots (primitive eyes) that are sensitive to light. These enable it to avoid colluding with foreign objects, detection of foods, and orientation for swimming. It has a simple but well-developed and sophisticated nervous and sensory systems but no specialized excretory respiratory and circulatory organs since most of its living cells are in direct contact with the water." (McEldowney)
Chironex fleckeri, also known as box jellyfish, lives in and around the waters of Australia and Southeast Asia. They inhabit parts of the Indian Ocean, Pacific Ocean, and the Great Barrier Reef. Box jellyfish have been found in the waters on the western coast of Australia in the Exmouth Gulf to Gladstone in the northern waters of Australia. Humans are frequently stung by this species in the oceanic waters of Queensland, on Australia's eastern coast. Box jellyfish may also be responsible for stings near the Philippines.
Biogeographic Regions: australian (Native ); indian ocean (Native ); pacific ocean (Native )
Found in the coastal areas of Northern Australia, Africa, the Gulf of Mexico (near Texas), South-Eastern Asia, and adjacent areas of the tropical Indo-west Pacific.
The name box jellyfish is derived from the shape of their bell, which is box-shaped when healthy. The bell is transparent and is usually between 16 and 24 cm, though some reach a diameter of 35 cm. The tentacles of box jellyfish dangle from pedalia, the corners of the bell. There can be as many as 15 tentacles hanging from each of the four pedalia for a total of up to 60 tentacles per jellyfish. Each of the tentacles has a slight blue-gray tint and can grow up 3 m in length. Each tentacle contains millions of nematocysts, which are microscopic hooks where venom is held and delivered. Box jellyfish contain sensory organs including 24 eyes, but they do not have a brain.
Range mass: 2 (high) kg.
Range length: 3 (high) m.
Other Physical Features: ectothermic ; radial symmetry ; venomous
Square in shape, they can grow to be as big as a baseball. Their 60 tentacles are each approximately 15 feet long
Box jellyfish tend to inhabit shallow, murky saline waters near Australia. They are mainly found in the ocean but are also found inland in freshwater rivers and mangrove channels when spawning. During heavy storms, they move into deeper waters where the water is calm to avoid damage. Box jellyfish also inhabit shallow rivers during the reproductive season and during their polyp stage. Once young jellyfish mature into medusa, they follow the river out to sea.
Habitat Regions: saltwater or marine
Aquatic Biomes: reef ; rivers and streams; coastal
Water temperature and chemistry ranges based on 1 sample.
Depth range (m): 25 - 40
Temperature range (°C): 28.191 - 28.191
Nitrate (umol/L): 0.356 - 0.356
Salinity (PPS): 35.488 - 35.488
Oxygen (ml/l): 4.269 - 4.269
Phosphate (umol/l): 0.294 - 0.294
Silicate (umol/l): 5.700 - 5.700
Depth range (m): 25 - 40
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Adult box jellyfish tend to feed in shallow waters, mainly on small fish and prawns. Until they are fully grown, box jellyfish feed primarily on shrimp, most commonly Acetes australis. Box jellyfish rely on their venomous tentacles to capture their prey. The millions of nematocysts on their tentacles enable box jellies to deliver lethal does of venom to their prey, immobilizing or killing them in a short amount of time. Because each nematocyst is so small and releases only a minute amount of venom, box jellyfish discharge as many of its nematocysts as possible. Once the tentacles capture the prey, box jellyfish bring it in closer to their bell and other tentacles, allowing use of nematocysts from other tentacles to more quickly immobilize and kill the prey.
Animal Foods: fish; aquatic crustaceans
Primary Diet: carnivore (Eats non-insect arthropods)
Box jellyfish prey on prawns, shrimp, and small fish, though box jellyfish do not greatly affect populations of these species. Green turtles (Chelonia mydas) prey upon box jellyfish, but jellyfish are not their primary source of food.
Box jellyfish have few known predators because of the stinging cells (nematocysts) on their tentacles. These nematocysts are extremely venomous to most species. The only known predator of box jellyfish are green turtles. Venom does not penetrate the thick skin of green turtles, which are thus unaffected by the stings of box jellyfish.
- Green turtles Chelonia mydas
Life History and Behavior
Because box jellyfish have no brain, it is difficult to define their communication and perception. Box jellyfish do have eyes, which have photoreceptors. Photoreceptors give box jellyfish the ability to detect light from dark, but it is uncertain whether this species can process shapes and figures. Box jellyfish, however, are attracted to light and tend to avoid darker shapes. Box jellyfish can also detect vibrations, which is thought to be useful for finding prey and avoiding predators. Currently, little is known regarding methods of communication between jellyfish. If box jellyfish do communicate with one another, it is most likely through chemical signals.
Perception Channels: visual ; vibrations
After the reproduction of sexually mature medusa, box jellyfish develop planulae, cells grouped together after fertilization. Planulae soon develop into polyps, which are sessile and small (1 to 2 mm) and look like a living ball with two tentacles. Polyps use their two tentacles to attach to a hard surface, such as a stone or the shell of other animals. Polyps usually attach themselves to a surface where they are not exposed, often on the underside or a crevice of the hard surface. Polyps rely on schools of plankton for food. A polyp can reproduce asexually via budding. After a polyp has metamorphosed into a small medusa, it travels from freshwater rivers to the sea. Once in the sea, a maturing box jellyfish continues to grow until it reaches its full size of 16 to 24 cm.
Development - Life Cycle: metamorphosis
Because box jellyfish die shortly after spawning, their lifespan is thought to be under a year. The longest lived box jellyfish in captivity survived nine months. Until the invention of a modified tank in the 1990s, it was near impossible to keep box jellyfish alive in captivity for more than a few days. Water is in constant motion in new tanks, allowing box jellyfish to float in the current without being caught in the corners of the tank.
Status: captivity: 9 (high) months.
Box jellyfish find mates by swimming to freshwater rivers during the spring. Here, jellyfish release their sperm and eggs directly into the water. Shortly after spawning, box jellyfish die.
Every spring, box jellyfish gather to spawn in rivers and similar bodies of water. Mature box jellyfish release sperm or eggs into the water. Once fertilization occurs, planula attach to a hard surface and develop into a small polyp, which may asexually reproduce via budding. Once the polyp has finished budding, it develops into a juvenile medusa, which grows into a sexually mature medusa.
Breeding interval: Box jellyfish breed once a year.
Breeding season: Box jellyfish breed from late summer to early fall.
Average age at sexual or reproductive maturity (female): 2 months.
Average age at sexual or reproductive maturity (male): 2 months.
Key Reproductive Features: seasonal breeding ; sexual ; asexual ; oviparous
Mature box jellyfish die soon after the release of sperm and eggs and, as such, do not invest in the upbringing of their offspring.
Parental Investment: no parental involvement
Evolution and Systematics
Jellyfish deliver deadly toxins to enemies and prey via special stinging cells, called nematocysts.
"Only coelenterates, such as jellyfish, know how to make certain special stinging cells, their nematocysts. Contact with a big coelenterate (the Portuguese man-of-war is especially vicious) is extremely unpleasant for a person and often fatal for a fish." (Vogel 1998:30)
Learn more about this functional adaptation.
Molecular Biology and Genetics
Barcode data: Chironex fleckeri
Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen.
Other sequences that do not yet meet barcode criteria may also be available.
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Download FASTA File
Statistics of barcoding coverage: Chironex fleckeri
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1
Box jellyfish are not considered at risk by the IUCN, CITES, or the US Federal List. Furthermore, there are no conservation efforts for box jellyfish.
US Federal List: no special status
CITES: no special status
Relevance to Humans and Ecosystems
Box jellyfish are believed to be the most venomous creatures in the world. Their stings are extremely deadly to human beings, and have caused over 60 deaths in the last century. The amount of venom injected into humans by box jellies influences the certainty of death. It is estimated that if a total of 6 m of tentacles comes into contact with human skin - and therefore all nematocysts on those tentacles “fire” - the amount of venom injected is sufficient to cause death in just a few minutes. Shortly after a human is stung, they typically encounter symptoms such as extreme pain, shortness of breath, and purple welts. Some victims may also become irrational and suffer cardiac arrest. All of these symptoms typically commence within five minutes of being stung and can last up to two weeks before subsiding. Although box jellyfish are fully capable of killing adult humans, most fatalities are documented in children and young adults. To reduce fatalities, box jellyfish nets have been constructed on many beaches where box jellyfish stings are known to occur. Despite these nets, there are still reports of stings every year.
Negative Impacts: injures humans (bites or stings, venomous )
The study of box jellyfish venom has led to a successful anti-venom agent, which can save human lives if administered quickly. Additionally, while this research is still in its infancy, scientists hope to better understand why jellyfish venom is so harmful to the human cardiovascular system. Once determined, this information can hopefully be used to design more effective medicine for other cardiovascular problems.
Positive Impacts: source of medicine or drug ; research and education
Chironex fleckeri, commonly known as sea wasp, is a species of box jellyfish found in coastal waters from northern Australia and New Guinea north to the Philippines and Vietnam. It has been described as "the most lethal jellyfish in the world", with at least 63 known deaths in Australia from 1884 to 1996.
Notorious for its sting, C. fleckeri has tentacles up to 3 m (9.8 ft) long covered with millions of cnidocytes which, on contact, release microscopic darts delivering an extremely powerful venom. Being stung commonly results in excruciating pain, and if the sting area is significant, an untreated victim may die in as few as three minutes. The amount of venom in one animal is said to be enough to kill 60 adult humans (although most stings are mild).
C.fleckeri was named after North Queensland toxicologist and radiologist Doctor Hugo Flecker (http://adb.anu.edu.au/biography/flecker-hugo-10199 ) "On January 20th 1955, when a 5-year-old boy died after being stung in shallow water at Cardwell, north Queensland, Flecker found three types of jellyfish. One of which was an unidentified: a box-shaped jellyfish with groups of tentacles arising from each corner. Flecker sent it to Dr Ronald Southcott in Adelaide, and on December 29th 1955 Southcott published his article introducing it as a new Genus and species of lethal box jellyfish. He named it Chironex fleckeri, the name being derived from the Greek `cheiro' meaning `hand', and the Latin `nex' meaning `murderer', and `fleckeri' in honour of its discoverer." (from http://www.marine-medic.com.au/pages/medical/chironex.asp)
C. fleckeri is the largest of the cubozoans (collectively called box jellyfish), many of which may carry similarly toxic venom. Its bell grows to about the size of a basketball. From each of the four corners of the bell trails a cluster of 15 tentacles. The pale blue bell has faint markings; viewed from certain angles, it bears a somewhat eerie resemblance to a human head or skull. Since it is virtually transparent, the creature is nearly impossible to see in its habitat, posing particular danger to swimmers.
When the jellyfish are swimming, the tentacles contract so they are about 15 cm long and about 5 mm in diameter; when they are hunting, the tentacles are thinner and extend to about 3 m long. The tentacles are covered with a high concentration of stinging cells called cnidocytes, which are activated by pressure and a chemical trigger; they react to proteinous chemicals. Box jellyfish are day hunters; at night they are seen resting on the ocean floor, apparently 'sleeping'. However, this 'sleeping' theory is still debated.
In common with other box jellyfish, C. fleckeri has four eye-clusters with 24 eyes. Some of these eyes seem capable of forming images, but whether they exhibit any object recognition or object tracking is debated; it is also unknown how they process information from their sense of touch and eye-like light-detecting structures due to their lack of a central nervous system. During a series of tests by leading marine biologists including Australian jellyfish expert Jamie Seymour, a single jellyfish was put in a tank. Then, two white poles were lowered into the tank. The creature appeared unable to see them and swam straight into them, thus knocking them over. Then, similar black poles were placed into the tank. This time, the jellyfish seemed aware of them, and swam around them in a figure-eight. Finally, to see if the specimen could see colour, a single red pole was stood in the tank. When the jellyfish apparently became aware of the object in its tank, it was seemingly repelled by it and remained at the far edge of the tank. Fascinated by this, the experts believed they had found a repellent for the creature and put forward the idea of red safety nets for beaches (these nets are usually used to keep the jellyfish away, but many still get through its mesh). The test was repeated, with similar results, on Irukandji jellyfish, another toxic species of box jelly.
Distribution and habitat
The medusa is pelagic and has been documented from coastal waters of Australia and New Guinea north to the Philippines and Vietnam. In Australia, it is known from the northern coasts from Exmouth to Agnes Water, but its full distribution outside Australia has not been properly identified. To further confuse, the closely related and also dangerously venomous Chironex yamaguchii was first described from Japan in 2009. This species has also been documented from the Philippines, meaning the non-Australian records of C. fleckeri need to be rechecked.
C. fleckeri is best known for its extremely powerful and occasionally fatal "sting". The sting produces excruciating pain accompanied by an intense burning sensation, like being branded with a red hot iron. In Australia, fatalities are most often caused by the larger specimens of C. fleckeri.
In December 2012, Angel Yanagihara of the University of Hawaii's Department of Tropical Medicine found the venom causes cells to become porous enough to allow potassium leakage, causing hyperkalemia which can lead to cardiovascular collapse and death as quickly as within two to five minutes with an LD50 of 0.04 mg/kg, making it the most venomous jellyfish in the world (to laboratory mice). She postulated a zinc compound may be developed as an antidote. Occasionally, swimmers who get stung will undergo cardiac arrest or drown before they can even get back to the shore or boat.
If a person does manage to get to safety, treatment must be administered urgently. CPR may be required; for less serious stings, treatment with ice packs and antihistamines is an effective method of pain relief. Adhering tentacles should be removed carefully from the skin using protected hands or tweezers. Removed tentacles remain capable of stinging until broken down by time, and even dried and presumably dead tentacles can be reactivated if wetted.
An antivenom to the box jellyfish's sting does exist. After the immediate treatment described above, it must be administered quickly. Hospitals and ambulance services near to where the jellyfish live possess it, and must be contacted as soon as possible. The jellyfish's venom is so powerful, however, that even if the victims get to safety and have the immediate treatment given, they may die before an ambulance can reach them.
In Australia, C. fleckeri has caused at least 64 deaths since the first report in 1883, but most encounters appear to result only in mild envenomation. Most recent deaths have been children, as their smaller body mass puts them at a higher risk of fatal envenomation.
C. fleckeri and other jellyfish, including the Irukandji (Carukia barnesi), are abundant in the waters of northern Australia during the summer months (November to April or May). They are believed to drift into the aforementioned estuaries to breed. Signs like the one pictured are erected along the coast of North Queensland to warn people of such, and few people swim during this period. Some people still do, however, putting themselves at great risk. At popular swimming spots, net enclosures are placed out in the water wherein people can swim but jellyfish cannot get in, keeping swimmers safe.
History of sting treatment
Until 2005, treatment involved using pressure immobilisation bandages, with the aim of preventing distribution of the venom through the lymph and blood circulatory systems. This treatment is no longer recommended by health authorities, due to research which showed that using bandages to achieve tissue compression provoked nematocyst discharge.
Until 2014, the application of vinegar was a recommended treatment because vinegar (4-6% acetic acid) permanently deactivates undischarged nematocysts, preventing them from opening and releasing venom. This practice is no longer recommended after it was demonstrated in vitro that while vinegar deactivates unfired nematocysts, it causes already-fired nematocysts (which still contain some venom) to release the remaining venom.
- Fenner, P. J. (2000). Chironex fleckeri – the north Australian box-jellyfish. marine-medic.com
- Fenner PJ, Williamson JA (1996). "Worldwide deaths and severe envenomation from jellyfish stings". The Medical Journal of Australia 165 (11–12): 658–61. PMID 8985452.
The chirodropid Chironex fleckeri is known to be the most lethal jellyfish in the world, and has caused at least 63 recorded deaths in tropical Australian waters off Queensland and the Northern Territory since 1884
- Biology, 7ed. Campell & Reece[page needed]
- Lewis, C. and B. Bentlage (2009). Clarifying the identity of the Japanese Habu-kurage, Chironex yamaguchii, sp nov (Cnidaria: Cubozoa: Chirodropida). Zootaxa 2030: 59–65
- Box jelly venom under the microscope - By Anna Salleh - Australian Broadcasting Corporation - Retrieved 13 December 2012.
- The Australian Box Jellyfish. Outback Australia Travel Guide.
- Northern Territory Government (2008). Department of Health and Families. Chironex fleckeri.. Centre for Disease Control.
- Daubert, G. P. (2008). Cnidaria Envenomation. eMedicine.
- Queensland beaches stinger information page
- Queensland Government (2008). Pressure Immobilisation Technique Queensland Health
- Seymour et al. The use of pressure immobilization bandages in the first aid management of cubozoan envenomings Toxicon 2002
- Hartwick, R; Callanan V,, Williamson J. (1980). "Disarming the box-jellyfish: nematocyst inhibition in Chironex fleckeri". The Medical Journal of Australia 1 (1): 15–20. Retrieved 23 April 2014.
- Welfare, P; Little, M; Pereira, P; Seymour, J (Mar 2014). "An in-vitro examination of the effect of vinegar on discharged nematocysts of Chironex fleckeri.". Diving and hyperbaric medicine : the journal of the South Pacific Underwater Medicine Society 44 (1): 30–4. PMID 24687483.
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