Jellyfish are very amazing creatures that evoke an extraordinary attitude towards them. Jellyfish can be found in every sea, in every ocean, on the surface of the water or at a depth of many kilometers.
Jellyfish are the oldest animals on the planet, their history goes back at least 600 million years. There is an incredible number of different species in nature, but even now the emergence of new ones, previously unknown to scientists, is being recorded.
Jellyfish (Polypomedusae) are one of the phases of the life cycle of cnidarians Medusozoa, which are usually divided into three types: hydroid, scyphoid and box jellyfish. Jellyfish reproduce sexually. There are males who produce sperm and females who produce eggs. As a result of their fusion, the so-called planula is formed - a jellyfish larva. The planula settles to the bottom, where over time it turns into a polyp (asexual generation of jellyfish). Having reached full maturity, the polyp begins to bud off a young generation of jellyfish, often completely different from the adults. In scyphoid jellyfish, the newly separated specimen is called ether. The body of jellyfish is a jelly-like dome, which, through contractions, allows them to move in the water column. Tentacles equipped with stinging cells (cnidocytes) with a burning poison are designed for hunting and capturing prey.
The term "jellyfish" was first used by Carl Linnaeus in 1752, as an allusion to the animal's resemblance to the head of the Gorgon Medusa. Becoming popular around 1796, the name began to be used to identify other medusoid species of animals, such as ctenophores.
Some interesting facts about jellyfish:
The world's largest jellyfish can reach up to 2.5 meters in diameter and have tentacles more than 40 meters long. Jellyfish are capable of reproducing both sexually and by budding and fission. The Australian wasp jellyfish is the most dangerous poisonous animal in the world's oceans. The venom of a sea wasp is enough to kill 60 people. Even after the death of a jellyfish, its tentacles can sting for more than two weeks. Jellyfish do not stop growing throughout their lives. Large concentrations of jellyfish are called “swarms” or “blooms.” Some species of jellyfish are eaten in East Asia, considered a “delicacy.” Jellyfish do not have a brain, respiratory system, circulatory, nervous or excretory systems.
The rainy season significantly reduces the number of jellyfish living in salt water bodies. Some female jellyfish can produce up to 45,000 larvae (planulae) per day.
Pink jellyfish from the Scyphozoan family was discovered quite recently, a little over 10 years ago, in the waters of the Gulf of Mexico and the Caribbean. Some individuals of this species reach up to 70 cm in diameter. Pink jellyfish can cause serious and painful burns, especially if a swimmer inadvertently ends up among a large concentration of these creatures.
Antarctic Diplulmaris- one of the species of jellyfish of the Ulmaridae family. This jellyfish was recently discovered in Antarctica, in the waters of the continental shelf. The Antarctic Diplulmaris is only 4 cm in diameter.
Flower cap jellyfish(lat. Olindias Formosa) is one of the types of hydroid jellyfish from the order Limnomedusae. Basically, these cute creatures live off the southern coast of Japan. A characteristic feature is motionless hovering near the bottom in shallow water. The diameter of the “flower cap” usually does not exceed 7.5 cm. The tentacles of the jellyfish are located not only along the edge of the dome, but also over its entire surface, which is not at all typical for other species. A flower cap burn is not fatal, but is quite painful and can lead to severe allergic reactions.
Purple striped jellyfish(lat. Chrysaora Colorata) from the class Scyphozoa is found only near the coast of California. This rather large jellyfish reaches 70 cm in diameter, the length of the tentacles is about 5 meters. A characteristic feature is the striped pattern on the dome. In adults it has a bright purple color, in juveniles it is pink. Purple-striped jellyfish usually live alone or in small groups, unlike most other species of jellyfish, which often form huge colonies. The Chrysaora Colorata burn is quite painful, but not fatal to humans.
Giant Nomura jellyfish(Latin: Nemopilema nomurai) is a species of scyphoid jellyfish from the order Cornerotae. This species predominantly inhabits the East China and Yellow Seas. The size of individuals of this species is truly impressive! They can reach up to 2 meters in diameter and weigh about 200 kg. The name of the species was given in honor of Mr. Kan'ichi Nomura, director general of fisheries in Fukui Prefecture. In early 1921, Mr. Nomura first collected and studied a previously unknown species of jellyfish. Currently, the number of Nomura jellyfish in the world is growing. Scientists believe climate change, overexploitation of water resources and environmental pollution are possible reasons for the population increase. In 2009, a 10-ton fishing trawler capsized in Tokyo Bay with three crew members trying to remove nets overflowing with dozens of Nomura jellyfish.
Tiburonia granrojo- a little-studied species of jellyfish from the Ulmáridos family, discovered by MBARI (Monterey Bay Aquarium Research Institute) only in 2003. It lives at depths between 600 and 1500 meters in Hawaii, the Gulf of California and Japan. Thanks to its rich dark red color, this species of jellyfish has earned the nickname Big Red. The great red jellyfish is one of the largest species of jellyfish, its diameter ranges from 60 to 90 cm. Currently, only 23 individuals of this red giant have been found and studied.
Pacific sea nettle(lat. Chrysaora fuscescens) - has a bright characteristic golden-brown color, due to which it is often kept in captivity (aquariums and oceanariums). The name of the jellyfish genus Chrysaora goes back to Greek mythology. Chrysaor is the son of Poseidon and Medusa the Gorgon; his name translated means “he who has golden weapons.” In the wild, sea nettles are found in the Pacific Ocean from Canada to Mexico. The diameter of the jellyfish's dome can reach more than 1 meter, but more often no more than 50 cm, the length of the tentacles is 3-4 meters. The tentacles of the jellyfish are very thin, so the burn looks like a bright red welt, similar to a blow from a whip. Although victims experience severe pain and burning, going to a medical facility is usually not required. You can neutralize the effects of jellyfish toxins and relieve pain with vinegar or citric acid.
Portuguese man of war(lat. Physalia physalis) is a bright and very toxic representative of colonial hydroids from the order of siphonophores. It is most common in tropical and subtropical regions of the Pacific and Indian Oceans and the North Atlantic Ocean. Recently, there has been a significant increase in the number of this species. Since 1989, physalia has appeared in the Mediterranean Sea, for the first time off the coast of Africa, then Corsica, and in 2010 it was discovered off the coast of Malta. In the period 2009-2010, cases of physalia appearing off the coasts of Ireland and Florida were recorded. Entire flotillas of Portuguese man-of-war can now be found off the coast of Guyana, Colombia, Jamaica, Venezuela, Australia and New Zealand. In fact, the Portuguese man-of-war is not a single jellyfish, since it is a whole colony of polypoid and medusoid individuals united under one “roof”. The tentacles of this unusual organism, when extended, can reach up to 50 meters in length. A Man of Portugal burn is comparable in toxicity to a poisonous snake bite. For burns, it is necessary to treat the affected area with 3-5% vinegar in order to prevent the release of poison from the stinging cells remaining in the wound. Only in rare cases do physalia burns lead to death. The Man of Portugal is especially dangerous for children, the elderly and allergy sufferers. Be extremely careful with this type of jellyfish.
Cephea cephea or the so-called “soft” jellyfish is widespread throughout the Indo-Pacific region, including the Red Sea. This large jellyfish can reach up to 50 cm in diameter.
Aurelia eared(lat. Aurelia aurita) is a scyphoid jellyfish from the order of discomedusae. Widely distributed in the coastal waters of tropical and temperate seas. In particular, the Mediterranean and Black Seas. The diameter of the aurelia dome can reach up to 40 cm. The color is pinkish-violet, the body is almost transparent. Until recently, this type of jellyfish was not considered dangerous to humans. However, there have been several recent cases of severe burns in the Gulf of Mexico. It is believed that in the waters of the Black Sea, aurelia does not pose a serious danger to humans.
Australian jellyfish or sea wasp (lat. Chironex fleckeri) from the class of box jellyfish - the most dangerous deadly animal in the world's oceans. The main habitats are the coasts of northern Australia and Indonesia. The sea wasp is one of the largest species of box jellyfish; the diameter of its dome can reach up to 20-30 cm. Its pale blue color and almost complete transparency make it especially dangerous for swimmers, since it is not easy to notice in the water. The tentacles of a jellyfish are densely covered with stinging cells containing extremely strong poison. Burns caused by box jellyfish cause severe excruciating pain and in some cases can lead to rapid death. Sea wasp venom simultaneously affects the heart, nervous system and skin. Moreover, the neurotoxic venom of a jellyfish acts much faster than the venom of any snake or spider. Cases have been recorded where death occurred within 4 minutes of contact. First aid for a sea wasp burn consists of immediately treating the affected area with vinegar, removing the tentacles that have stuck to the skin (remove only with protected hands or tweezers!) and immediately contacting a medical facility, as the administration of an antitoxic serum may be required. The Australian jellyfish is the most dangerous jellyfish in the world!
Ctenophores(Latin Ctenophora) are jellyfish-like organisms that live in sea waters almost all over the world. A distinctive feature of all ctenophores is a kind of “comb,” groups of fin-cilia used by this species for swimming. The sizes of Ctenophora range from a few millimeters to 1.5 meters. Among ctenophores, there are many deep-sea species capable of bioluminescence.
Aequorea Victoria or "crystal" jellyfish - a bioluminescent jellyfish from the order of hydromedusae. Widely distributed along the North American western Pacific coast, from the Bering Sea to Southern California.
Australian spotted jellyfish(lat. Phyllorhiza punctata) belongs to the family of pelagic jellyfish. Its main habitat is the southern Pacific Ocean. The usual size of the dome of the spotted Australian jellyfish is up to 40 cm, but in the waters of the Persian and Mexican Gulfs it reaches 70 cm. The Australian jellyfish is not dangerous to humans. However, to neutralize the poison, it is worth resorting to a proven method - treating the skin with acetic or citric acid in order to prevent possible allergic reactions. Recently, a massive proliferation of Australian jellyfish has been recorded, which can pose a serious threat to commercial fish populations. Feeding on eggs and fry, they pass up to 15,000 liters of water per day through their tentacles and swallow huge amounts of plankton and other marine life.
Mediterranean jellyfish Cassiopeia can reach up to 30 cm in diameter. Spends most of its time in shallow water, basking in the sun's rays.
Hairy cyanea or Lion's mane jellyfish (lat. Cyanea capillata, Cyanea arctica) is a large jellyfish from the order of disc jellyfish. The species is distributed in all northern seas of the Pacific and Atlantic oceans, living near the coast in surface layers of water. The bell of the Arctic cyanea (a subspecies of the hairy cyanea) can reach up to 2 meters in diameter, and the length of the tentacles is up to 33 meters. Lion's mane is generally considered a moderately stinging jellyfish. The burns it inflicts are quite painful, and the toxins contained in the poison can cause a severe allergic reaction. However, the poison of this jellyfish is not fatal to humans.
Jellyfish Chrysaora Achlyos- one of the largest species of scyphoid jellyfish. The bell size is approximately 1 m in diameter, the tentacles can reach up to 6 m in length. It has the ability of a chameleon - changing color from bright red to black.
A new species of transparent jellyfish discovered in Antarctica. Its diameter is about 2.5 cm
Aurelia aurita is a scyphoid jellyfish of the Ulmaridae family from the order Discomedus (lat. Semaestomae).
This is the largest jellyfish found in the waters of the Black and Mediterranean Seas. Her transparent umbrella reaches a diameter of 40 cm. When meeting her, it is recommended to be very careful, since even a light touch of her tentacle can cause a severe burn.
Spreading
Aurelia eared lives in the tropical and temperate waters of the seas and oceans of the planet, with the exception of the polar regions. The largest colonies of jellyfish are located in equatorial regions close to the coast.
Aurelia eareds easily tolerate pollution in their habitat and quickly adapt to environmental conditions, so they often settle in port waters or near the collectors of power plants that discharge warm waters.
Morphology
The body of Aurelia eared is 98% water. Along the edge of the umbrella there are receptor cells that perform the functions of balance organs and light-sensitive eyes. With their help, the jellyfish can identify prey and navigate in space.
The tentacles growing along the edge of the umbrella are designed to grab and move the victim to the oral cavities. Water, which constantly circulates in the intestinal cavity, plays a major role in the jellyfish’s circulatory system. Aurelia eared absorbs oxygen dissolved in water, carrying out gas exchange processes throughout its body.
Aurelia poison is not dangerous for all creatures. For example, young pilot fish often hide between its tentacles. They are not afraid of poisonous stinging glands. Very often they can eat plenty of leftover food from their owner.
Reproduction
During their development, scyphoid jellyfish undergo alternating generations. Polyps reproduce by budding, and jellyfish reproduce sexually.
Adult males release reproductive products into the water.
Then they penetrate into the brood chambers of females, where their fertilization and development subsequently occur. After this process is completed, the eggs remain in the females’ mouths until they turn into larvae. Then the larvae (planulae) detach from the mother’s body and sink to the bottom. There they develop into a single polyp called a scyphilistoma.
The polyp leads a sedentary lifestyle. With the help of tentacles, it hunts for plankton. In winter, all adult jellyfish die, leaving only polyps. With the arrival of spring, it begins to bud and produces up to 30 individuals of young jellyfish. This process is called strobilization. One polyp gives life to both male and female individuals.
The larvae of tiny jellyfish begin to swim freely. Outwardly, they are very similar to adults, but only very small. The diameter of their umbrellas reaches 2 mm.
After a month, they increase to 1 cm and acquire a well-formed umbrella, from which tentacles begin to grow. After 3 months, they develop gonads and are ready to reproduce.
Behavior
Jellyfish drift in large colonies in coastal waters. They move in a reactive manner. They draw water into the umbrella and then, contracting, push it out.
At night, Aurelia eared descends to a depth of 10 meters, and during the day it rises closer to the surface. The main food consists of small fish, planktonic organisms and small jellyfish of other species.
Aurelia's weapons are stinging cells that can infect the victim with poison. The oral lobes pick up immobilized prey and place it in the mouth, from where food enters the intestinal cavity. The oral lobes of Aurelia are outgrowths from the oral opening. Their internal surfaces are strewn with stinging glands containing deadly poison.
The intestines begin to secrete digestive enzymes and then begin to absorb the digested food. Undigested food remains are brought to the surface through the mouth.
Description
The diameter of Aurelia eared can reach 40 cm, and weight up to 10 kg. The body of the jellyfish looks like an umbrella with 8 cutouts along the edge. The flat umbrella is filled with a thick layer of gelatinous substance. Many tentacles grow along its edge.
The oral cavity is surrounded by 4 wide oral lobes. Receptor cells located along the edges serve as sensory organs.
The lifespan of Aurelia eared is about one year.
Aurelia jellyfish is a species of marine life that is very interesting and mysterious. Therefore, they are often kept in aquariums. This article contains information about who the aurelia jellyfish is: description, features of the content, reproduction of this species.
general description
In aurelia, the umbrella is flat and can reach 40 cm in diameter. Since it is based on a non-cellular substance (consists of 98% water), it is completely transparent. This quality also means that the weight of these animals is close to the weight of water, which makes swimming much easier.
It should be noted that the aurelia jellyfish has a very interesting structure. So, along the edge of her umbrella there are tentacles - small, but mobile. They are very densely packed with a huge number of stinging cells.
This jellyfish has a quadrangular mouth with 4 movable blades at the edges. Their contraction (they are covered) also makes it possible to pull the prey to the mouth and securely capture it.
The issues of keeping jellyfish are somewhat specific. Initially it's about aquariums. For jellyfish, special containers are needed to ensure a smooth circular flow. This allows animals to move calmly without fear of any collisions. This is important because the aurelia, or eared jellyfish, has a very delicate and soft body that is easily damaged.
It is necessary to ensure the correct flow speed, which should allow animals to “soar” without problems in the water column. Only in this case there should be no danger of harm to their bodies.
The specificity also lies in the fact that for jellyfish in aquariums the use of aeration is absolutely excluded. This is explained by the fact that air bubbles can end up under the dome of the animal, get stuck there and then pierce it, which is very dangerous and can lead to the death of the jellyfish.
They don’t need any special lighting; basically, simple lighting is enough.
Also note that there is no need to filter the water. As a rule, it is enough just to regularly change the water so that its quality always remains at the proper level. If there is no desire to constantly update the water, you can also install a life support system. It is important to take proper care to protect the animals. Because they can be pulled into intake devices.
In addition, it must be taken into account that the aurelia jellyfish must live in a fairly spacious aquarium, since it needs the ability to freely extend its tentacles to their full length.
Feeding
How are jellyfish fed? They are perfectly suited for a mixture that consists of brine shrimp, phytoplankton, highly crushed crustaceans and seafood. Although there are currently various ready-made foods on sale that Aurelia (eared jellyfish) can also eat. But there is one peculiarity. If the animals don’t like the food at all, they can start eating the rest of the jellyfish.
Reproduction
Jellyfish aurelia is dioecious. Thus, the testes of males have a milky white color, they are clearly visible: they are small half rings in the body of the animal. Females have violet or red ovaries, which are also visible in the light. Therefore, by the color you can understand what gender the jellyfish is. Aurelians reproduce only once during their life, and then die. Their main distinguishing feature is considered to be the manifestation of care for their own offspring (which is not characteristic of other species).
It is worth noting that fertilization of eggs, as well as their further development, occurs in special pockets. Eggs enter them through gutters from the mouth. After fertilization, the egg divides into 2 parts, each of which is subsequently also divided in half, and so on. Due to this, a single-layer multicellular ball is formed.
Some of the cells of this ball get inside, which can be compared to pressing a rubber ball. Because of this, a two-layer embryo appears.
It can swim thanks to the large number of cilia that are located on its outer part. The embryo then becomes a larva, which is called a planula. She just floats for a while and then falls to the bottom. It is attached at the front end to the bottom. Quite quickly, the rear end of the planula is transformed: a mouth appears in this place, and tentacles are also formed. And it becomes a polyp, from which small jellyfish are subsequently formed.
Jellyfish aurelia is often used in medicine. Laxatives and diuretics were produced from it in the Middle Ages. And today, from the poison contained in the tentacles of animals, drugs are produced to regulate blood pressure and treat various pulmonary diseases.
Farmers in the Caribbean use physalia poison as a poison for rodents.
Jellyfish allow you to effectively cope with stress. They are bred in special aquariums in Japan. The leisurely, smooth movements of animals calm people, but keeping them is very expensive and troublesome.
Luminophores isolated from jellyfish are used for biochemical analysis. Their genes were transplanted into various animals, for example, rodents, due to which biologists were able to see with their own eyes previously inaccessible processes. Because of this action, the rodents began to grow green hair.
Some jellyfish are caught off the coast of China, where their tentacles are removed, and the carcasses are kept in a marinade, due to which the animal turns into a cake of thin, delicate, translucent cartilage. In the form of such cakes, animals are taken to Japan, where they are carefully selected for quality, color and size and used in cooking. So, for one salad, the jellyfish is cut into small strips 3 mm wide, they are mixed with herbs, stewed vegetables, and then poured over with sauce.
Robot jellyfish also appeared there. They, unlike real animals, not only swim beautifully and slowly, but can also “dance” to music if the owner wishes.
Conclusion
Despite the fact that the aurelia jellyfish is very common, it cannot be called completely ordinary. In principle, these are very curious creatures, therefore, observing them and keeping them will be very exciting.
Those who have ever vacationed at sea have most likely seen jellyfish in the water - transparent, jelly-like, blurry, sometimes even very beautiful, creatures of different shapes and sizes.
Pale gelatinous creatures, of course, do not evoke much sympathy in humans. Meanwhile, few marine inhabitants can compare with jellyfish in originality and diversity.
Jellyfish can be round, flat, elongated, very small or, conversely, huge.
However, the beauty of most jellyfish is deceptive - almost all jellyfish are poisonous. Some more, some less. Some species are practically harmless to humans, others sting like nettles, and a painful burning sensation can be felt for several days, and some even cause paralysis that can lead to death.
For example, the most poisonous jellyfish in the world - the Sea Wasp - lives in the warm waters of the Pacific and Indian Oceans. After touching its tentacles, a person dies within one or two minutes if medical help does not arrive. Its diameter is only 12 centimeters, but the tentacles are 7-8 meters long! The venom of this jellyfish can only be compared to the venom of a cobra. Both of these poisons paralyze the heart muscle. Sea wasps come very close to the shore in search of food.
There is also a very tiny killer jellyfish with a deadly sting. Its diameter is only 12 millimeters. The bite of its deadly sting at first resembles that of a mosquito. Within an hour, victims experience severe pain in the lower back, lumbago throughout the body, convulsions, nausea, vomiting, sweating profusely and coughing. The consequences are extremely serious: from paralysis to death, cerebral hemorrhage or cardiac arrest.
So, just in case, never touch jellyfish with your hands! Don't try to catch them! And in general, stay away from them, because you can never know in advance whether this jellyfish is dangerous or not.
There are also jellyfish that are completely harmless to humans. For example, this is the well-known glassy-white “eared” jellyfish - Aurelia. It lives in all tropical and moderately warm seas, including the Black Sea.
By the way, they say that if you rub the body of Aurelia into human skin, it will become immune to certain types of stinging jellyfish. But we do not advise you to test this dubious statement in practice!
Jellyfish can be dangerous not only for people, but also for ships. Ship engines are cooled by overboard water, which enters through a special hole in the bottom. And if jellyfish get into this hole, they tightly shut off the water supply. The engine overheats and fails until divers clear the “live plug.”
And then, for example, in the Mediterranean Sea there are funny little jellyfish that glow in the dark like light bulbs!
In general, a jellyfish is something very incomprehensible. And dangerous. Even small. What can we say about the big ones! Or rather, even gigantic ones, and believe me, there are such things.
For example, the giant of the Arctic waters is the fiery red Lion's Mane or Cyanea.
Its dome-shaped body grows up to two and a half meters in diameter!
Bunches of wriggling thread-like tentacles of this beauty, reaching 30 m in length, can cover a five-story building!
The weight of different giant jellyfish can reach up to 200 kilograms! Imagine what it would be like to encounter such a creature in the water! The tentacles of giant jellyfish are usually poisonous.
Recently, the number of giant poisonous jellyfish, for unknown reasons, has greatly increased in the East China and Japan Seas, and now they are frightening residents of nearby countries.
The authorities of Japan, China and South Korea are seriously concerned about what is happening; they consider the invasion of jellyfish to be a disaster for their countries and are even going to special meetings dedicated to this problem in order to jointly figure out how to fight back against the jellyfish.
Fishermen began to find a large number of giant jellyfish in their nets, of which previously there were very few and the likelihood of encountering them was extremely low - this is how this problem was discovered.
Among Japanese divers there are fans of huge jellyfish, who dive specifically to get up close and personal with the giants. They say that they are hard to touch, the jellyfish are large and unusually impressive, they are afraid of people and do not let them near them.
These jellyfish cause a lot of damage to fishermen - the fish either die under their weight or become unusable due to their poison, and the nets simply break.
For example, in Japan, in the north of the island of Honshu, fishermen even had to stop fishing at the height of the season. Can you imagine the damage this caused to their business? In addition, the Japanese's main food is fish, and it is very disappointing not to get it because of some giant jellyfish.
For many fishermen in South Korea, China and Japan, incomes have fallen by 50-80%.
Moreover, in some places the density of jellyfish is already a hundred times higher than normal!
A similar sudden increase in the jellyfish population was recorded in 2002 and 2003. But then the largest jellyfish was only about 1 meter in diameter and weighed a little more than 100 kilograms, i.e. At the moment, the jellyfish have become almost twice as large as before!
According to one theory, the proliferation of jellyfish is facilitated by global warming, due to which sea water warms up. According to another version, the rains that fall heavily in China in the summer caused nutrients from river water to flow into the sea.
Another version is the depletion of fish stocks, due to which plankton, the main food of jellyfish, has grown.
Meanwhile, in Japan, China and South Korea they decided to start eating poisonous jellyfish, since so many of them began to be caught in the net
Cooking jellyfish is a complex process from a technical point of view, because jellyfish are not only poisonous, but also consist of 90% water. They are first boiled, then dried, then ground into powder and sold in dried or salted form, they are made into jelly and tofu - such a special Japanese soybean curd. Well, besides, of course, instead of drying and grinding into powder, you can simply fry the jellyfish.
A real culinary sensation was the Ekura-chan cookie, made from a giant jellyfish - the main enemy of fishermen in the Sea of Japan.
In the process of experiments on jellyfish and attempts to process them for food production, researchers managed to turn the body of a jellyfish into an excellent leavening agent for dough, which is used in the preparation of these unusual cookies.
The resulting powder is odorless and has a slightly bitter taste. In addition, the authors of the delicacy praise its beneficial properties: collagen and minerals contained in the bodies of jellyfish.
The Japanese willingly buy these strange cookies
By the way, in English the jellyfish is called jellyfish, which literally translates as “jelly fish” or “jelly fish,” although, you must admit, it doesn’t really look like a fish
Materials used: http://zateevo.ru/?section=page&action=edit&alias=Gigant_meduz
Titles: common jellyfish, aurelia eared, eared jellyfish, moon jellyfish.
Area: Pacific, Indian and Atlantic oceans.
Description: The common jellyfish (Aurelia auriata) is easily identified by its four horseshoe-shaped gonads. The body is in the form of a flat umbrella, gelatinous, 97.8-98.2% consists of water. Along the edges of the umbrella there are numerous short hollow tentacles and eight marginal bodies (rhopalia). Rhopalia are the sense organs of the jellyfish and determine its position in the water and the rhythm of the umbrella contractions. Four thickened oral arms, each with a central groove flanked by more diluted curled lips. By detecting infrasounds, rhopalia warn the jellyfish about the approaching storm and allow them to move away from it. The body is two-layered (consists of two layers of cells - ectoderm and endoderm), with a well-defined gelatinous mesoglea. The mouth is located in the middle of the lower side of the body, it leads into the pharynx, from which the intestinal cavity begins. Undigested remains are removed through the mouth. The nervous system of a jellyfish is more developed than that of polyps. In addition to the nerve plexus, which is most developed in the tentacles and on the underside of the umbrella, two nerve rings run along its edge. The gonads are located near the stomach or radial canals.
Color: the umbrella is colorless, and the “arms” and gonads are lilac, purple, reddish, pink or yellowish.
Size: umbrella diameter 5-40 cm.
Habitat: near the coast - warm and tropical waters. Tolerates a wide range of temperatures (from -6 to 31"C) and salinity (from 6 ppm). The optimal temperature is 9-19"C.
Enemies: moon fish, Pacific jellyfish, sea turtles, birds.
Food/food: intra- and extracellular digestion. The common jellyfish captures prey with its tentacles. Preys on planktonic crustaceans, aquatic insect larvae, fish fry, hydromedusas, ctenophores, copepods, rotifers, nematodes, young polychaetes, protozoa, and diatoms.
Behavior: It moves in water according to a reactive principle, pushing water out of the body cavities. The jellyfish swims horizontally in the water column.
Social structure: single organism.
Reproduction: the common jellyfish reproduces sexually. Jellyfish with purple or pink gonads are males, and those with yellow gonads are females. Male reproductive products are released through the mouth into the water, after which they enter the body of the female, where fertilization occurs. The egg develops into a mobile larva - a planula, which attaches to underwater objects and there turns into a single polyp. The polyp subsequently begins asexual reproduction. It breaks into several disks, which turn into jellyfish. This is how jellyfish alternate generations: asexual (polyp) and sexual (jellyfish). The life cycle is dominated by the jellyfish form, and the polyp is a short-term form of existence.
Breeding season/period: in the fall.
Puberty: about 2 years.
Offspring: From fertilized eggs, larvae are formed - planulae, covered with cilia.
Benefit/harm for humans: The common jellyfish eats fish fry. In Asian countries (China, Philippines, Thailand, Malaysia, and Indonesia) it is used as food.
Population/Conservation Status: the population is large.
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