Editing Cnidaria (section)

==Interaction with humans==
[[File:Cubozoas.JPG|thumb|The dangerous ''[[Carukia barnesi]]'', one of the known species of [[box jellyfish]] which can cause [[Irukandji syndrome]].]]

Jellyfish stings killed about 1,500 people in the 20th century,<ref>{{cite book|author1=Williamson, J.A. |author2=Fenner, P.J. |author3=Burnett, J.W. |author4=Rifkin, J. |name-list-style=amp | title=Venomous and Poisonous Marine Animals: A Medical and Biological Handbook| publisher=UNSW Press| year=1996| isbn=978-0-86840-279-6| pages=65–68| url=https://books.google.com/books?id=YsZ3GryFIzEC&q=mollusc+venom+fatal&pg=PA75| access-date=2008-10-03}}</ref> and cubozoans are particularly dangerous. On the other hand, some large jellyfish are considered a [[delicacy]] in [[East Asia|East]] and [[Southeast Asia]]. [[Coral reef]]s have long been economically important as providers of fishing grounds, protectors of shore buildings against currents and tides, and more recently as centers of tourism. However, they are vulnerable to over-fishing, mining for construction materials, [[pollution]], and damage caused by tourism.

{{annotated image| float=left| caption=The dangerous "sea wasp" ''[[Chironex fleckeri]]''
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Beaches protected from tides and storms by coral reefs are often the best places for housing in tropical countries. Reefs are an important food source for low-technology fishing, both on the reefs themselves and in the adjacent seas.<ref name="Clark">{{cite book| title=Coastal Seas: The Conservation Challenge| author=Clark, J.R.| publisher=Blackwell| year=1998| isbn=978-0-632-04955-4| pages=[https://archive.org/details/coastalseasconse0000clar/page/8 8]–9| url=https://archive.org/details/coastalseasconse0000clar| url-access=registration| quote=Coral Reef productivity.| access-date=2008-11-28}}</ref> However, despite their great [[primary production|productivity]], reefs are vulnerable to over-fishing, because much of the [[organic carbon]] they produce is exhaled as [[carbon dioxide]] by organisms at the middle levels of the [[food chain]] and never reaches the larger species that are of interest to fishermen.<ref name="Barnes" /> Tourism centered on reefs provides much of the income of some tropical islands, attracting photographers, divers and sports fishermen. However, human activities damage reefs in several ways: mining for construction materials; [[pollution]], including large influxes of fresh water from [[storm drain]]s; commercial fishing, including the use of [[dynamite]] to stun fish and the capture of young fish for [[aquarium]]s; and tourist damage caused by boat anchors and the cumulative effect of walking on the reefs.<ref name="Clark" /> Coral, mainly from the [[Pacific Ocean]] has long been used in [[jewellery]], and demand rose sharply in the 1980s.<ref>{{cite book| title=Marine Minerals in Exclusive Economic Zones| author=Cronan, D.S.| year=1991| publisher=Springer| pages=63–65| isbn=978-0-412-29270-5| url=https://books.google.com/books?id=4g4nhd8USO8C&q=coral+jewellery&pg=PA63| access-date=2008-11-28}}</ref>

Some large [[jellyfish]] species of the [[Rhizostomeae]] order are commonly consumed in [[Japan]], [[Korea]] and Southeast Asia.<ref>{{Cite journal|author1=Kitamura, M. |author2=Omori, M.| title = Synopsis of edible jellyfishes collected from Southeast Asia, with notes on jellyfish fisheries| journal = Plankton and Benthos Research| volume = 5| issue = 3| pages = 106–118| year = 2010| issn = 1880-8247| doi=10.3800/pbr.5.106| doi-access = free|bibcode=2010PBenR...5..106K }}</ref><ref>{{Cite journal|author1=Omori, M. |author2=Kitamura, M.| title = Taxonomic review of three Japanese species of edible jellyfish (Scyphozoa: Rhizostomeae)| journal = Plankton Biol. Ecol.| volume = 51| issue = 1| pages = 36–51| year = 2004}}</ref><ref name=Omori2001/> In parts of the range, fishing industry is restricted to daylight hours and calm conditions in two short seasons, from March to May and August to November.<ref name=Omori2001>{{cite journal | doi = 10.1023/A:1011879821323 | last1 = Omori | first1 = M. | last2 = Nakano | first2 = E. | date = May 2001 | title = Jellyfish fisheries in southeast Asia | journal = Hydrobiologia | volume = 451 | issue = 1–3 | pages = 19–26 | bibcode = 2001HyBio.451...19O | s2cid = 6518460 }}</ref> The commercial value of jellyfish food products depends on the skill with which they are prepared, and "Jellyfish Masters" guard their [[trade secret]]s carefully. Jellyfish is very low in [[cholesterol]] and [[sugar]]s, but cheap preparation can introduce undesirable amounts of [[Heavy metal (chemistry)|heavy metal]]s.<ref>{{Cite journal|author1=Y-H. Peggy Hsieh |author2=Fui-Ming Leong |author3=Jack Rudloe | title = Jellyfish as food| journal = Hydrobiologia| volume = 451| issue = 1–3| pages = 11–17| date = May 2001| doi = 10.1023/A:1011875720415|bibcode=2001HyBio.451...11P |s2cid=20719121 }}</ref>

The "sea wasp" ''[[Chironex fleckeri]]'' has been described as the world's most venomous jellyfish and is held responsible for 67&nbsp;deaths, although it is difficult to identify the animal as it is almost transparent. Most stingings by ''C. fleckeri'' cause only mild symptoms.<ref>{{cite book| title=Greenberg's Text-atlas of Emergency Medicine
|author1=Greenberg, M.I. |author2=Hendrickson, R.G. |author3=Silverberg, M. |author4=Campbell, C. |author5=Morocco, A. |display-authors=3|name-list-style=amp | publisher=Lippincott Williams & Wilkins| year=2004|isbn=978-0-7817-4586-4| page=875| chapter=Box Jellyfish Envenomation}}</ref> Seven other [[Cubozoa|box jellies]] can cause a set of symptoms called [[Irukandji syndrome]],<ref name="Little">{{cite journal|author1=Little, M. |author2=Pereira, P. |author3=Carrette, T. |author4=Seymour, J. |name-list-style=amp | title = Jellyfish Responsible for Irukandji Syndrome| journal = QJM| volume=99| issue = 6| pages = 425–427| date = June 2006| doi = 10.1093/qjmed/hcl057| pmid = 16687419| doi-access = free}}</ref> which takes about 30&nbsp;minutes to develop,<ref>{{cite journal| author = Barnes, J.| title = Cause and effect in Irukandji stingings| journal = Medical Journal of Australia| volume = 1| issue = 24| pages = 897–904| year = 1964| pmid = 14172390| doi=10.5694/j.1326-5377.1964.tb114424.x}}</ref> and from a few hours to two&nbsp;weeks to disappear.<ref>{{cite journal|vauthors=Grady J, Burnett J | title = Irukandji-like syndrome in South Florida divers| journal = Annals of Emergency Medicine| volume = 42| issue = 6| pages = 763–6| date = December 2003| pmid = 14634600| doi = 10.1016/S0196-0644(03)00513-4}}</ref> Hospital treatment is usually required, and there have been a few deaths.<ref name="Little" />

A number of the parasitic [[myxozoa]]ns are commercially important pathogens in [[salmonid]] aquaculture.<ref>{{Cite journal |last1=Braden |first1=Laura M. |last2=Rasmussen |first2=Karina J. |last3=Purcell |first3=Sara L. |last4=Ellis |first4=Lauren |last5=Mahony |first5=Amelia |last6=Cho |first6=Steven |last7=Whyte |first7=Shona K. |last8=Jones |first8=Simon R. M. |last9=Fast |first9=Mark D. |display-authors=3|date=December 19, 2017 |editor-last=Appleton |editor-first=Judith A. |title=Acquired Protective Immunity in Atlantic Salmon Salmo salar against the Myxozoan Kudoa thyrsites Involves Induction of MHIIβ + CD83 + Antigen-Presenting Cells |journal=Infection and Immunity |language=en |volume=86 |issue=1 |pages=e00556–17 |doi=10.1128/IAI.00556-17 |issn=0019-9567 |pmc=5736826 |pmid=28993459}}</ref> A [[Scyphozoa]] species – ''[[Pelagia noctiluca]]'' – and a [[Hydrozoa]] – ''[[Muggiaea atlantica]]'' – have caused repeated mass mortality in [[salmon farm]]s over the years around [[Ireland]].<ref name="IrishTimes">{{cite web | last=O'Sullivan | first=Kevin | title=Stinger jellyfish swarms wipe out farmed salmon in west of Ireland | website=The [[Irish Times]] | date=2017-10-06 | url=http://www.irishtimes.com/news/environment/stinger-jellyfish-swarms-wipe-out-farmed-salmon-in-west-of-ireland-1.3247245 | access-date=2022-04-23}}</ref> A loss valued at £1 million struck in November 2007, 20,000 died off [[Clare Island]] in 2013 and four fish farms collectively lost tens of thousands of salmon in September 2017.<ref name="IrishTimes" />
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