Box jellyfish

Box jellyfish
Chironex sp.
Carukia barnesi
Scientific classification
Kingdom: Animalia
Phylum: Cnidaria
Class: Cubozoa
Werner, 1975
Orders

Box jellyfish (class Cubozoa) are cnidarian invertebrates distinguished by their cube-shaped medusae. Some species of box jellyfish produce extremely potent venom: Chironex fleckeri, Carukia barnesi and Malo kingi. Stings from these and a few other species in the class are extremely painful and can be fatal to humans.

Nomenclature

"Box jellyfish" and "sea wasp" are common names for the highly venomous Chironex fleckeri.[1] However, these terms are ambiguous, as "sea wasp" and "marine stinger" are sometimes used to refer to other jellyfish.

Anatomy

"Cubomedusae", from Ernst Haeckel's Kunstformen der Natur, 1904

The medusa form of a box jellyfish has a squarish, box-like bell. From each of the four lower corners of this hangs a short pedalium or stalk which bears one or more long, slender, hollow tentacles. The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates.[2] As a result, box jellyfish can move more rapidly than other jellyfish; in fact, speeds of up to six meters per minute have been recorded.[3]

In the center of the underside of the bell is a mobile appendage called the manubrium which somewhat resembles an elephant's trunk. At its tip is the mouth. The interior of the bell is known as the gastrovascular cavity. It is divided by four equidistant septa into a central stomach and four gastric pockets. The eight gonads are located in pairs on either side of the four septa. The margins of the septa bear bundles of small gastric filaments which house nematocysts and digestive glands and help to subdue prey. Each septum is extended into a septal funnel that opens onto the oral surface and facilitates the flow of fluid into and out of the animal.[2]

The box jellyfish's nervous system is more developed than that of many other jellyfish. Notably, they possess a nerve ring around the base of the bell that coordinates their pulsing movements, a feature found elsewhere only in the crown jellyfish. Whereas some other jellyfish have simple pigment-cup ocelli, box jellyfish are unique in the possession of true eyes, complete with retinas, corneas and lenses. Their eyes are set in clusters called rhopalia, located in pockets halfway up the outer, flat surfaces of the bell. Each contains two rhopalial ocelli with lenses, one directed upwards and the other downwards and inwards towards the manubrium.[2] This enables the animal to see specific points of light, as opposed to simply distinguishing between light and dark. Box jellyfish also have twenty ocelli (simple eyes) that do not form images, but detect light and dark; they therefore have a total of twenty-four eyes.[4] Near the rhopalia are statoliths which detect gravitational pull and help the animal to orient itself.[5]

Box jellyfish also display complex, probably visually guided behaviors such as obstacle avoidance and fast directional swimming.[6] Research indicates that, owing to the number of rhopalial nerve cells and their overall arrangement, visual processing and integration at least partly happen within the rhopalia of box jellyfish.[6] The complex nervous system supports a relatively advanced sensory system compared to other jellyfish, and box jellyfish have been described as having an active, fish-like behavior.[7]

Some species have tentacles that can reach up to 3 m (9.8 ft) in length. Box jellyfish can weigh up to 2 kg (4.4 lb).[8]

Distribution

Although the notoriously dangerous species of box jellyfish are largely restricted to the tropical Indo-Pacific region, various species of box jellyfish can be found widely in tropical and subtropical oceans, including the Atlantic Ocean and the east Pacific Ocean, with species as far north as California, the Mediterranean Sea (for example, Carybdea marsupialis)[9] and Japan (such as Chironex yamaguchii),[10] and as far south as South Africa (for example, Carybdea branchi)[11] and New Zealand (such as Copula sivickisi).[12]

Age and growth

It has been found that the statoliths, which are composed of calcium sulfate hemihydrate, exhibit clear sequential incremental layers, thought to be laid down on a daily basis. This has enabled researchers to estimate growth rates, ages, and age to maturity. Chironex fleckeri, for example, increases its inter-pedalia distance (IPD) by 3 mm (0.12 in) per day, reaching an IPD of 50 mm (2 in) when 45 to 50 days old. The maximum age of any individual examined was 88 days by which time it had grown to an IPD of 155 mm (6 in).[5]

Behavior

The box jellyfish actively hunts its prey (small fish), rather than drifting as do true jellyfish. They are capable of achieving speeds of up to 1.5 to 2 metres per second or about 4 knots (7.4 km/h; 4.6 mph).[8]

A fully grown box jellyfish can measure up to 20 cm (7.9 in) along each box side (or 30 cm (12 in) in diameter), and the tentacles can grow up to 3 m (9.8 ft) in length. Its weight can reach 2 kg (4.4 lb). There are about 15 tentacles on each corner. Each tentacle has about 500,000 cnidocytes, containing nematocysts, a harpoon-shaped microscopic mechanism that injects venom into the victim.[13] Many different kinds of nematocysts are found in cubozoans.[14]

The venom of cubozoans is distinct from that of scyphozoans, and is used to catch prey (small fish and invertebrates, including prawns and bait fish) and for defence from predators, which include the butterfish, batfish, rabbitfish, crabs (blue swimmer crab) and various species of turtle including the hawksbill sea turtle and flatback sea turtle. It seems that sea turtles are unaffected by the stings because they seem to relish box jellyfish.[8]

Danger to humans

Box jellyfish warning signpost at a Cape Tribulation beach in Queensland, Australia
Jellyfish/stinger net exclosure at Ellis Beach, Queensland, Australia

Although the box jellyfish has been called "the world's most venomous creature",[15] only a few species in the class have been confirmed to be involved in human deaths, and some species pose no serious threat at all. For example, the sting of Chiropsella bart only results in short-lived itching and mild pain.[16]

In Australia, fatalities are most often perpetrated by the largest species of this class of jellyfish, Chironex fleckeri. 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 2 to 5 minutes. She postulated that a zinc compound may be developed as an antidote.[17]

In Australia, C. fleckeri has caused at least 64 deaths since the first report in 1883,[18] but even in this species most encounters appear to only result in mild envenoming.[19] Most recent deaths in Australia have been in children, which is linked to their smaller body mass.[18] In parts of the Malay Archipelago, the number of lethal cases is far higher (in the Philippines alone, an estimated 20-40 die annually from Chirodropid stings), likely due to limited access to medical facilities and antivenom, and the fact that many Australian beaches are enclosed in nets and have vinegar placed in prominent positions allowing for rapid first aid.[19][20] Vinegar is also used as treatment by locals in the Philippines.[21]

A vinegar post in Queensland, Australia

The recently discovered and very similar Chironex yamaguchii may be equally dangerous, as it has been implicated in several deaths in Japan.[10] It is unclear which of these species is the one usually involved in fatalities in the Malay Archipelago.[10][21] In 1990, a 4-year-old child died after being stung by Chiropsalmus quadrumanus at Galveston Island in the Gulf of Mexico, and either this species or Chiropsoides buitendijki are considered the likely perpetrators of two deaths in West Malaysia.[21] At least two deaths in Australia have been attributed to the thumbnail-sized Irukandji jellyfish.[22][23] Those who fall victim to these may suffer severe physical and psychological symptoms, known as Irukandji syndrome.[24] Nevertheless, most victims do survive, and out of 62 people treated for Irukandji envenomation in Australia in 1996, almost half could be discharged home with few or no symptoms after 6 hours, and only two remained hospitalized approximately a day after they were stung.[24] Warning signs and first aid stations have been erected in Thailand following the death of a 5-year-old French boy in August 2014.[25][26] A woman died in July 2015 after being stung off Koh Phangan,[27] and another at Lamai Beach at Ko Samui on 6 October 2015.[28]

Box jellyfish are known as the "suckerpunch" of the sea not only because their sting is rarely detected until the venom is injected, but also because they are almost transparent.[29]

In northern Australia, the highest risk period for the box jellyfish is between October and May, but stings and specimens have been reported all months of the year. Similarly, the highest risk conditions are those with calm water and a light, onshore breeze; however, stings and specimens have been reported in all conditions.

In Hawaii, box jellyfish numbers peak approximately seven to ten days after a full moon, when they come near the shore to spawn. Sometimes the influx is so severe that lifeguards have closed infested beaches, such as Hanauma Bay, until the numbers subside.[30][31]

Treatment of stings

Once a tentacle of the box jellyfish adheres to skin, it pumps nematocysts with venom into the skin, causing the sting and agonizing pain. Flushing with vinegar is used to deactivate undischarged nematocysts to prevent the release of additional venom. A 2014 study reported that vinegar also increased the amount of venom released from already-discharged nematocysts; however, this study has been criticized on methodological grounds.[32]

Removal of additional tentacles is usually done with a towel or gloved hand, to prevent secondary stinging. Tentacles can still sting if separated from the bell, or after the creature is dead. Removal of tentacles may cause unfired nematocysts to come into contact with the skin and fire, resulting in a greater degree of envenomation.

Although commonly recommended in folklore and even some papers on sting treatment,[33] there is no scientific evidence that urine, ammonia, meat tenderizer, sodium bicarbonate, boric acid, lemon juice, fresh water, steroid cream, alcohol, cold packs, papaya, or hydrogen peroxide will disable further stinging, and these substances may even hasten the release of venom.[34] Heat packs have been proven for moderate pain relief.[35] Pressure immobilization bandages, methylated spirits, or vodka should never be used for jelly stings.[36][37][38][39] In severe Chironex fleckeri stings cardiac arrest can occur quickly.

In 2011, University of Hawaii Assistant Research Professor Angel Yanagihara announced that she had developed an effective treatment by "deconstructing" the venom contained in the box jellyfish tentacles.[40] Its effectiveness was demonstrated in the PBS NOVA documentary Venom: Nature's Killer, originally shown on North American television in February 2012.[41]

Protection during swimming or diving

Wearing pantyhose or full body lycra suits during diving (both by women and men, also under scuba-diving suit) is an effective protection against box jellyfish stings.[42] The pantyhose were formerly thought to work because of the length of the box jellyfish's stingers (nematocysts), but it is now known to be related to the way the stinger cells work. The stinging cells on a box jellyfish's tentacles are not triggered by touch, but are instead triggered by the chemicals found on skin.[8]

Taxonomy

At least 36 species of box jellyfish were known as of 2007.[43] These are grouped into two orders and seven families.[44] A few new species have since been described, and it is likely that undescribed species remain.[10][11][16]

Class Cubozoa

References

  1. ↑ Chironex fleckeri at Encyclopedia of Life
  2. 1 2 3 Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. pp. 153–154. ISBN 978-81-315-0104-7.
  3. ↑ Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 139–149. ISBN 0-03-056747-5.
  4. ↑ "Jellyfish Have Human-Like Eyes". LiveScience. 2007-04-01. Retrieved 2012-08-27.
  5. 1 2 Pitt, Kylie A.; Lucas, Cathy H. (2013). Jellyfish Blooms. Springer Science & Business Media. p. 280. ISBN 978-94-007-7015-7.
  6. 1 2 Skogh, C.; Garm, A.; Nilsson, D.E.; Ekström, P. (December 2006). "Bilaterally symmetrical rhopalial nervous system of the box jellyfish Tripedalia cystophora". Journal of Morphology 267 (12): 1391–405. doi:10.1002/jmor.10472. PMID 16874799.
  7. ↑ Nilsson, D.E.; Gislén, L.; Coates, M.M.; Skogh, C.; Garm, A. (2005). "Advanced optics in a jellyfish eye". Nature 435 (7039): 201–205. doi:10.1038/nature03484. PMID 15889091.
  8. 1 2 3 4 "Box Jellyfish, Box Jellyfish Pictures, Box Jellyfish Facts". NationalGeographic.com. Retrieved 2012-08-27.
  9. ↑ Carybdea marsupialis. The Jellies Zone. Retrieved April 28, 2010
  10. 1 2 3 4 Lewis C, Bentlage B (2009). "Clarifying the identity of the Japanese Habu-kurage, Chironex yamaguchii, sp nov (Cnidaria: Cubozoa: Chirodropida)" (PDF). Zootaxa 2030: 59–65.
  11. 1 2 Gershwin L, Gibbons M (2009). "Carybdea branchi, sp. nov., a new box jellyfish (Cnidaria: Cubozoa) from South Africa" (PDF). Zootaxa 2088: 41–50.
  12. ↑ Gershwin L (2009). "Staurozoa, Cubozoa, Scyphozoa (Cnidaria)". In Gordon D. New Zealand Inventory of Biodiversity. 1: Kingdom Animalia.
  13. ↑ Williamson JA, Fenner P J, Burnett JW, Rifkin J., ed. (1996). Venomous and poisonous marine animals: a medical and biological handbook. Surf Life Saving Australia and University of New North Wales Press Ltd. ISBN 0-86840-279-6.
  14. ↑ Gershwin, L (2006). "Nematocysts of the Cubozoa" (PDF). Zootaxa (1232): 1–57.
  15. ↑ "Girl survives sting by world's deadliest jellyfish". Daily Telegraph (London). 27 April 2010. Retrieved 11 Dec 2010.
  16. 1 2 Gershwin, L. A.; Alderslade, P (2006). "Chiropsella bart n. sp., a new box jellyfish (Cnidaria: Cubozoa: Chirodropida) from the Northern Territory, Australia" (PDF). The Beagle, Records of the Museums and Art Galleries of the Northern Territory 22: 15–21.
  17. ↑ Salleh, Anna (13 December 2012). "Box jelly venom under the microscope". Australian Broadcasting Corporation.
  18. 1 2 Centre for Disease Control (November 2012). "Chironex fleckeri" (PDF). Northern Territory Government Department of Health.
  19. 1 2 Daubert, G. P. (2008). "Cnidaria Envenomation". eMedicine.
  20. ↑ 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.
  21. 1 2 3 Fenner PJ (1997). The Global Problem of Cnidarian (Jellyfish) Stinging (PhD Thesis). London: London University. OCLC 225818293.
  22. ↑ Fenner PJ, Hadok JC (October 2002). "Fatal envenomation by jellyfish causing Irukandji syndrome". The Medical Journal of Australia 177 (7): 362–3. PMID 12358578.
  23. ↑ Gershwin, L (2007). "Malo kingi: A new species of Irukandji jellyfish (Cnidaria: Cubozoa: Carybdeida), possibly lethal to humans, from Queensland, Australia". Zootaxa 1659: 55–68.
  24. 1 2 Little M, Mulcahy RF (1998). "A year's experience of Irukandji envenomation in far north Queensland". The Medical Journal of Australia 169 (11-12): 638–41. PMID 9887916.
  25. ↑ "Box jellyfish warning in Ko Phangan Please credit and share this article with others using this link:http://www.bangkokpost.com/most-recent/428690/phangan-warns-of-poisonous-jellyfish. View our policies at http://goo.gl/9HgTd and http://goo.gl/ou6Ip. © Post Publishing PCL. All rights reserved.". Bangkok Post. 25 August 2014. External link in |title= (help)
  26. ↑ "Jellyfish warning for travellers swimming in Thailand". Tourism Authority of Thailand Newsroom. TAT. Retrieved 24 May 2015.
  27. ↑ http://www.phuketgazette.net/thailand-news/Box-jellyfish-sting-kills-woman-Koh-Phangan/61634
  28. ↑ http://www.khaosodenglish.com/detail.php?newsid=1444198839&typecate=06&section=
  29. ↑ "Facts About Box Jellyfish". iloveindia.com. Retrieved 2010-04-28.
  30. ↑ "Jellyfish: A Dangerous Ocean Organism of Hawaii". Retrieved 2010-10-06.
  31. ↑ "Hanauma Bay closed for second day due to box jellyfish". Retrieved 2010-10-06.
  32. ↑ Wilcox, Christie (9 April 2014). "Should we stop using vinegar to treat box jelly stings? Not yet—Venom experts weigh in on recent study". Science Sushi. Discover Magazine Blogs. Retrieved 26 April 2015.
  33. ↑ Zoltan T, Taylor K, Achar S (2005). "Health issues for surfers". Am Fam Physician 71 (12): 2313–7. PMID 15999868.
  34. ↑ Fenner P (2000). "Marine envenomation: An update – A presentation on the current status of marine envenomation first aid and medical treatments". Emerg Med Australasia 12 (4): 295–302. doi:10.1046/j.1442-2026.2000.00151.x.
  35. ↑ Taylor, G. (2000). "Are some jellyfish toxins heat labile?". South Pacific Underwater Medicine Society journal 30 (2). ISSN 0813-1988. OCLC 16986801. Retrieved 2013-11-15.
  36. ↑ Hartwick R, Callanan V, Williamson J (1980). "Disarming the box-jellyfish: nematocyst inhibition in Chironex fleckeri". Med J Aust 1 (1): 15–20. PMID 6102347.
  37. ↑ Seymour J, Carrette T, Cullen P, Little M, Mulcahy R, Pereira P (2002). "The use of pressure immobilization bandages in the first aid management of cubozoan envenomings". Toxicon 40 (10): 1503–5. doi:10.1016/S0041-0101(02)00152-6. PMID 12368122.
  38. ↑ Little M (June 2002). "Is there a role for the use of pressure immobilization bandages in the treatment of jellyfish envenomation in Australia?". Emerg Med (Fremantle) 14 (2): 171–4. doi:10.1046/j.1442-2026.2002.00291.x. PMID 12164167.
  39. ↑ Pereira PL, Carrette T, Cullen P, Mulcahy RF, Little M, Seymour J (2000). "Pressure immobilisation bandages in first-aid treatment of jellyfish envenomation: current recommendations reconsidered". Med. J. Aust. 173 (11–12): 650–2. PMID 11379519.
  40. ↑ UHMedNow, "Angel Yanagihara's box jellyfish venom research leads to sting treatment", March 4, 2011
  41. ↑ PBS Nova, Venom: Nature's Killer (transcript)
  42. ↑ http://lifehacker.com/5560147/use-pantyhose-to-protect-yourself-from-jellyfish-stings[][]
  43. ↑ Daly, Marymegan; et al. (2007). "The phylum Cnidaria: A review of phylogenetic patterns and diversity 300 years after Linnaeus" (PDF). Zootaxa (1668): 127–182.
  44. ↑ Bentlage B, Cartwright P, Yanagihara AA, Lewis C, Richards GS, Collins AG (February 2010). "Evolution of box jellyfish (Cnidaria: Cubozoa), a group of highly toxic invertebrates". Proceedings. Biological Sciences 277 (1680): 493–501. doi:10.1098/rspb.2009.1707. PMC 2842657. PMID 19923131.

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