Jellyfish are invertebrates that, along with corals, gorgonians and also anemones belong come a group called the cnidarians (knidé = nettle, from the Greek). This pet group has stinging cells which they use both to catch their prey and also as a form of defense. This cells contain a capsule with a rolled-up filament and also a poison. Once a prey animal makes call with the jellyfish, the capsule opens and the filaments are ejected and also stick onto the prey, injecting your poison.

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Jellyfish are pelagic animals they live in the open seas native tropical to Artic waters and, although they deserve to propel themselves through rhythmic motions of their umbrella, they room basically in ~ the mercy that the currents that the sea.

Because your body is 95% water, they space perfectly camouflaged. The body of a jellyfish exhibits radial symmetry and also is split into three main parts: the umbrella, the oral arms (around the mouth) and also the stinging tentacles. They have actually an interior cavity, in which cradle is lugged out. This cavity has actually a solitary aperture which attributes both the mouth and also the anus.


Jellyfish are carnivores and can increase in size rapidly and also procreate in huge numbers when food is abundant. However, if food is scarce, they can end up being smaller. This animals, that a gelatinous consistency, have actually a an extremely unsophisticated anatomy i beg your pardon is nevertheless very effective. Lock feed greatly on zooplankton, little crustaceans, and also in part cases, little fish and also other jellyfish also form part of their diet. The is a strange sight to watch the jellyfish’s latest food inside its body before it is digested.


In order to reproduce, males and also female jellyfish relax sperm and eggs right into the water (sexual reproduction). After fertilization, they construct larvae which give rise to new jellyfish or polyps that resolve on the sea floor. From this polyps, by method of asexual reproduction, new free-living jellyfish may develop.


The tentacles, v their stinging cells, offer as defense and also as a an effective weapon for catching prey. As soon as they come into contact with your victims, the nematocysts (cells loaded through poison) present in the tentacles relax their harpoons or filaments and also release a toxicity substance the paralyses the prey. The oral arms help in the capture and ingestion that the captured animal.

Natural Predators

Among the predators the the jellyfish, the following have to be identified: s sunfish, grey triggerfish, turtle (especially the leatherback sea turtle), some seabirds (such together the fulmars), the whale shark, some crabs (such as the arrow and also hermit crabs), some whales (such as the humpbacks).

Some other cnidarians such as anemones, particular nudibranches (small molluscs without shells) additionally feed on jellyfish. Several of these may even take over your stinging cell to usage in their own defense.

Types that Jellyfish

Jellyfish space classified in the animal Kingdom in ~ the Phylum the the Cnidarians the belongs come the sub-Kingdom that Metazoans (organisms v tissues, organs and systems that organs through radial the opposite such together the jellyfish, anemones hydra and corals).

Within Cnidarians, the is feasible to distinguish four large groups, each v its own characteristics.

They are:

Portuguese male of battle (Physalia physalis).


They present the phases the polyp and jellyfish alternately. They space generally small and they deserve to be colonial or solitary. The siphonophores are contained in this class. They room floating swarms of polyp individuals and jellyfish with great and plentiful poisonous cells because that self-defense which, in specific cases, can be lethal to humans. The siphonophores form complicated colonies of people specializing in various functions; part serve together the flotation organ, others for nutrition, defense or for feeling. Amongst the best-known varieties of siphonophores, are the by-the-wind sailor (Velella spirans) or the Portuguese man of battle (Physalia physalis), i beg your pardon can develop painful burns for bathers, and even love failure.

Portuguese man of battle (Physalia physalis).

Moon jellyfish (Aurelia aurita).


This is the group of those well-known as true jellyfish. They are the an excellent marine jellyfish, typically with a really short or even non-existent polyp phase. Examples belonging come this group incorporate the moon jelly (Aurelia aurita) i m sorry is really common in the Mediterranean, the Rhizostoma pulmo which inhabits the Mediterranean and the Atlantic or the fried egg jellyfish (Cotylorhiza tuberculata). Some varieties are luminescent, such as the violet jellyfish or mauve stinger (Pelagia noctiluca), which deserve to be yes, really striking on a night-time dive. That eight stinging tentacles deserve to reach a diameter that ten meters when spread out.

Moon jellyfish (Aurelia aurita).

Sea honest suit (Chrironex fleckeri).


A class with couple of representatives that some authors group along with the esciphozoa. They inhabit the waters that tropical and sub-tropical seas. These are the so-called crate jellyfish or sea wasps. They have their umbrella in the kind of a cube, with four sides. They have a powerful sting and they may be deadly to people within just a few minutes no antidote is administered.

Sea honest suit (Chrironex fleckeri).

Tube anemone (Cerianthus membranaceus).


All the to represent of this class are polyps, i beg your pardon never take on the jellyfish stage. It consists of corals, madreporas, actinias and also sea anemones. Some people live in isolation, such together the beadlet anemone (Actinia equina), part anemones and the colour tube anemone, (Cerianthus membranaceus). Rather within this group type colonies choose corals or red gorgonians (Paramuricea sp.)

Tube anemone (Cerianthus membranaceus).

Jellyfish Blooms

Scientists execute not know the ultimate cause of jellyfish blooms. The rise in the temperature that the water due to climatic change, the palliation in the number of predators as result of over-fishing and the increase in nutrients due to contamination that the coasts may be several of the reasons.

However, it should be detailed that the superabundance of jellyfish does not occur by chance but rather the is a symptom that the truth that the features of the water have changed due come variations in the oceanographic parameters (temperature, salinity).

The causes of the existence of great masses the jellyfish space not local, as has been showed by researcher from the Mediterranean academy of progressed Studies (IMEDEA, CSIC-UIB), but rather the is a result of impacts of the currents.

The seasonal conditions have not been identified as determining the figure of these species in coastal waters as, in projects carried out in winter, the presence of jellyfish has also been established both in oceanic and also in coastal waters.

Jellyfish usually live in between 20 and 40 miles from the coast, wherein the water is an ext salty and hotter 보다 by the coast. Coastal waters, which space colder and also less saline, act together a barrier to jellyfish. However, when the water offered by rivers (rainwater) to the coast is restricted due to drought, the salinity that the coastal waters becomes equal to that of the waters additional from the coast.

Another aspect to be afflicted with in psychic is the influence of over-fishing together certain species of fishing incidentally capture the predators of jellyfish: prefer the loggerhead sea turtle.


Preventive Measures versus Jellyfish

The adhering to recommendations have actually been noted by the researcher of the Mediterranean Centre for Marine and Environmental research (CMIMA-CSIC), Josep-María Gili and also Francesc Pages.

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If there are a huge number the jellyfish in seaside waters, the beach have to be closed for at the very least 24 hours, acquisition precautions also if the jellyfish space at some distance native the coastline.If the jellyfish space close come the beach, the finest thing is to continue to be out the the water and keep one’s street from the breaking waves.If a jellyfish is seen in the water, the is much better not come take any kind of risks even if that is some distance away. Waves may break your tentacles and the cells in the floating pieces will stay active. What is more, the is vital to recommend bathers who are not acquainted with these organisms the they need to not touch them also if they show up to be dead.Jellyfish need to not be touch in the sand, even though they appear to be dead, the stinging cell remain energetic for a period of time; even walking follow me the water’s edge have the right to be dangerous together there might be continues to be of tentacles in the sand. At least a full-day’s sunlight is essential de-activate the stinging cells located in the fragments.The area influenced must no be rubbed through sand or v a towel. New water need to never be used to clean the impacted area as the adjust in salinity could cause the stinging cell adhering come the skin come burst and liberate the poison. The is better to apply cold to the area that has actually been stung with ice for around fifteen minutes. Treatment should it is in taken in no making direct skin-contact v the ice, unless it make from seawater.If the pain continues, proceed to use a bag of ice for fifteen minutes. The tentacles that are stuck to the skin deserve to be eliminated with the aid of part pincers yet never v your bare hands.If the victim’s problem gets stability worse after using ice and other symptom arise, such together respiratory difficulty or alters to the rhythm of the heart, the is vital to go to the nearest health facility for ideal treatment. Remember human being who have actually been stung as soon as are sensitized and a second sting can create even a more severe reaction.