.. provide nourishment for the small organisms on which jellyfish feed. In waters where there is eutrophication, low oxygen levels often result, favoring jellyfish as they thrive in less oxygen-rich water than fish can tolerate. The fact is that jellyfish are increasing is a symptom of something happening in the ecosystem." Researchers have been the ones that have as well contended that in some arias, such as the Gulf of Mexico or the Adriatic Sea, jellyfish have taken the role of fish, the former animals' number being far greater than the one of the latter's, and this can be as well put on the intensity with which the human intervene in the nature's life. Moreover, it has been observed that in the above-mentioned areas jellyfish have formed a sort of "gelatinous cover" of the water. In my opinion, this might be the reason for which during many years, Jelly researchers were trying to discover methods to get rid of these animals rather than studying them. Nowadays things have changed; scientists have attempted to understand things as they happen before finding ways to deal with them.

Captivity

Jellyfish can be kept in captivity; some species can be found in aquariums across the United States and in other countries such as Monterey Bay Aquarium, Long Beach Aquarium of the Pacific, Vancouver Aquarium, and Maui Ocean Center. In order to put into evidence the animals' features, the aquariums are oftenly blue and jellyfish are illuminated by side lighting. In natural conditions, many of the jellies are so transparent that they can be almost impossible to see.

Even though, there can be encountered some problems when keeping jellyfish in captivity, since it might be hard for them to adapt to close spaces or to the aquariums' walls. In addition, it might be prove difficult for them to move from one place to another, as they are most of the times helped by currents.

Sting treatment

It has been commonly assumed that jellyfish do not "attack" humans, their only intention being that of self-defense; therefore, stings occur when humans touch them by accident. Moreover, "all jellies sting, but not all jellies have poison that hurts humans. Of the 2,000 species of jellyfish, only about 70 seriously harm or occasionally kill people." The diversity of species is thus the main factor which should be taken into consideration when evaluating the severity of stings; other important contributors are power of the nematocyst, the thickness of exposed skin of the victim and the sensitivity of the victim to the venom. The majority of stings from jellyfish occur in tropical and warm temperate waters.

Even though most of the stings are not very dangerous, some of them, such as those of box jellyfish might be deadly or cause anaphylaxis. In this cases special medical care should be offered, which might "include administration of an antivenom and other supportive care such as required to treat the symptoms of anaphylactic shock. There are three goals of first aid for uncomplicated jellyfish stings: prevent injury to rescuers, inactivate the nematocysts, and remove any tentacles stuck on the patient. To prevent injury to rescuers, barrier clothing should be worn. This protection may include anything from panty hose to wet suits to full-body sting-proof suits. Inactivating the nematocysts, or stinging cells, prevents further injection of venom into the patient."

Species

As it has been argued above, jellyfish can be found everywhere where there is water, from oceans to lakes. In addition, scientists have discovered that there are more than 2000 species, and they have stated the main ones: Kingdom Animalia, Phylum Cnidaria - corals, jellyfish, sea anemones, hydrozoans -, Class Scyphozoa - Jellyfish -, many Orders, Families, Genera and Species.

Jellyfish's size varies from about 1 inch -2 1/2 centimeters- to 200 feet -61 meters- long. The largest jellyfish is the Arctic Lion's Mane, which is a predator, killing and eating other living creatures. If a human were to get stung by a Lion's Mane jelly it could be fatal, since the animal has enough poison to let it be absorbed by the human body. The venom can cause paralysis of the breathing muscles and therefore cause death from suffocation. The Arctic Lion's Mane lives around the Arctic Circle to Florida, in Gulf of Mexico and in the Pacific Ocean, from Alaska to southern California.

Lion's Mane is as well among the most dangerous species of jellyfish, next to the Portuguese man-of-war, which lives around the Gulf of Mexico, in the Caribbean Sea near the Bahamas and in the West Indies, the Sea nettle - Chesapeake Bay, Pacific Ocean from Alaska to southern California, Atlantic Ocean from Massachusetts to Florida and Gulf of Mexico - and Sea Wasp - Pacific Ocean near northern Australia and Philippines -.

It has been contended that the Lion's Mane is as well among the most dangerous jellyfish species, next to the Portuguese man-of-war, which lives in the Gulf of Mexico, in the Caribbean Sea near the Bahamas and in the West Indies, the Sea nettle - Chesapeake Bay; Pacific Ocean from Alaska to southern California,...

Box jellyfish live in Australia, the Philippines and many other tropical areas. They are considered dangerous because of the fatal effects of their venom, even though not all species from their class are venomous.
All in all, it seems that jellyfish are among the most interesting animal species. With a great living tradition and amazing means of adaptation to their environment, they would always be of a real subject of interest for the scientists. Sometimes dangerous or sometimes only neutral, jellyfish and their existence represent an important stage in one's approach to study about life on earth and its varieties.

Bibliography

Pieribone, V. And D.F. Gruber, Aglow in the Dark: The Revolutionary Science of Biofluorescence. Harvard University Press, 2006, 288p;

Jacobson, Morris, Wonders of Jellyfish. New York: Dodd Mead, 1978

Jellyfish - Sea Science Series, at http://www.dnr.sc.gov/marine/pub/seascience/jellyfi.html

Kyle McGilligan Bentin, "Jellyfish up close," at http://danenet.wicip.org/mmsd-it/jellyfish.html

Jellyfish, at http://en.wikipedia.org/wiki/Jellyfish

Gowell, Elizebeth. Sea Jellies. New York: New England Aquarium, 1993

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Fenner P, Williamson J, Burnett J, Rifkin J (1993). "First aid treatment of jellyfish stings in Australia. Response to a newly differentiated species." Med J. Aust, at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8469205

Nilsson, D.E., et al. (2005). Advanced optics in a jellyfish eye, at http://www.nature.com/nature/journal/v435/n7039/abs/nature03484.html;jsessionid=9EFA9C35E931A55B9A9D918A4E22C31B

Box Jellyfish, at http://en.wikipedia.org/wiki/Box_jellyfish

Jellyfish, curious creatures of the sea, at http://www.essortment.com/travel/beachfirstaid_svyg.htm

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Fenner PJ, Williamson JA, Burnett JW, Rifkin J, First aid treatment of jellyfish stings in Australia. Response to a newly differentiated species, at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8469205

Giant Jellyfish, at http://www.extremescience.com/GiantJellyfish.htm

British Marine Life Study Society - Jellyfish Page, at http://www.glaucus.org.uk/Moonjell.htm

Jellyfish - Sea Science Series, at http://www.dnr.sc.gov/marine/pub/seascience/jellyfi.html

Kyle McGilligan Bentin, "Jellyfish up close," at http://danenet.wicip.org/mmsd-it/jellyfish.html

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Gowell, Elizebeth. Sea Jellies. New York: New England Aquarium, 1993, pp. 18

Ibidem 1

Jacobson, Morris. Wonders of Jellyfish. New York: Dodd Mead, 1978, pp. 45

Ibidem 4

Pieribone, V. And D.F. Gruber (2006). www.hup.harvard.eduAglow in the Dark: The Revolutionary Science of Biofluorescence. Harvard University Press, 288p, 2006

Jellyfish Enchanted Learning System, at http://www.enchantedlearning.com/subjects/invertebrates/jellyfish/Jellyfishcoloring.shtml

Fenner P, Williamson J, Burnett J, Rifkin J (1993). "First aid treatment of jellyfish stings in Australia. Response to a newly differentiated species." Med J. Aust, at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8469205

Nilsson, D.E., et al. (2005). Advanced optics in a jellyfish eye, at http://www.nature.com/nature/journal/v435/n7039/abs/nature03484.html;jsessionid=9EFA9C35E931A55B9A9D918A4E22C31B

Box Jellyfish, at http://en.wikipedia.org/wiki/Box_jellyfish

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Ibidem 4

Jellyfish, curious creatures of the sea, at http://www.essortment.com/travel/beachfirstaid_svyg.htm

Swimmers beware: jellyfish are everywhere, at http://www.nationalgeographic.com/ngkids/9608/jellyfish/

Ibidem 1

Fenner PJ, Williamson JA, Burnett JW, Rifkin J, First aid treatment of jellyfish stings in Australia. Response to a newly differentiated species, at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8469205

Ibidem 10

Giant Jellyfish, at http://www.extremescience.com/GiantJellyfish.htm

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Ibidem 13