Almost every person at least once in his life saw the most common inhabitant of the seas - a jellyfish. This very beautiful animal, which lives mainly in tropical waters, can also be dangerous to humans. Jellyfish are active-poisonous creatures, their stinging apparatus is located on the tentacles. In tropical jellyfish, the tentacles can reach an impressive length. Class scyphoid unites, as a rule, large jellyfish, which have a complex body structure compared to polyps.

The coelenterates are interesting in that they have an alternation during the development of generations, namely: if an adult organism leads a sedentary lifestyle, for example, hydroids, then its larval generation will lead a free-floating lifestyle, sometimes taking the form of tiny jellyfish, or so-called hydromedusae. But real scyphomedusas in adulthood lead a free-floating lifestyle, and the intermediate (or larval) generation, on the contrary, will be a polyp attached to the bottom. Intestinal animals, including jellyfish, belong to two-layered animals. They have developed only two layers: the outer one - the ectoderm and the inner one - the endoderm, but they do not have the middle layer - the mesoderm. Instead, in hydroids between the layers there is a thin, so-called base plate, and in jellyfish - a loose thick layer of tissue - glia, 98% consisting of water. It is she who gives the jellyfish a gelatinous swaying appearance. Thrown ashore, the jellyfish quickly loses water, turning into something that looks like a rag of indefinite shape.

Among the jellyfish that pose a real danger to humans are the following: cyanideans, deep-sea jellyfish, cornerots, aurelias, fingerprints, crosses. The most dangerous fingerprints and the so-called sea ​​wasps.

Scyphoid

The symptoms that occur when touching the scyphomedusa are the same as with the directed action of the poison on the vital important systems body - the nervous system, the heart. Indigestion begins, caused by poisoning with many animal poisons, while it is not at all necessary that they enter the gastrointestinal tract, as, for example, when poisoning with defective mushrooms.

Cyanes are large jellyfish that live in all waters from the polar latitudes to the tropics. The diameter of the bell of such a jellyfish reaches 2.5 m, and the length of the tentacles is 30 m. Imagine meeting with such a jellyfish. If you do not notice and do not bypass it, then in a short period of time a person must dive to a depth of 30 m, and this is almost impossible. This jellyfish has wide mouth lobes, which can have a very diverse color. Representatives of this species can be found in the northern regions of the Pacific and Atlantic Oceans and even in the Baltic Sea.

Not only large, but also small species of jellyfish are dangerous to humans. At great depths, divers may encounter other types of jellyfish that prefer shallow water, but sometimes they are also found in the surface layers of water. This has happened more than once in the tropical waters of the Atlantic Ocean. Very often, getting into the nets of fishermen, jellyfish caused severe poisoning in people who tried to pull such a jellyfish out of the nets.

Some types of jellyfish, with the help of special adaptations, can attach themselves to various underwater objects and even to animals. But one of the representatives of the cornerot jellyfish, the so-called rhizostoma, is found in our seas - the Black and Azov. This whitish jellyfish has a bright blue or purple border around the edge of the bell. The diameter of its bell reaches 60 cm. It does not have tentacles along the edge of the bell, and even the oral lobes located under the bell grow together with their sides, the ends of which end in root-like outgrowths, which is why the jellyfish got the name cornerot. In water, it moves with strong shocks, easily changing direction.


Some cornerots are capable of causing not only severe lesions in humans, but also functional impairments. internal organs. The dactylometer jellyfish has an umbrella with a diameter of only about 25 cm, but possesses large quantity tentacles. Four very long oral lobes almost reach the length of the marginal tentacles and are narrowed towards the ends. Body coloration of dactylometers can vary from yellow to lilac with a brown tint. Such jellyfish are widespread in tropical and subtropical waters of the Indian, Pacific and Atlantic oceans. These animals are dangerous to humans. Faced with such a jellyfish, it feels a strong itching of the skin, turning into a burning sensation. There is a local inflammatory reaction of the skin. Symptoms of general poisoning are not very pronounced, but a person who has received an unexpected burn may not cope with stress and drown. Such cases are known.

box jellyfish

Jellyfish that pose a danger to humans include the so-called box jellyfish. They got this name for the special shape of the bell, resembling a slightly rounded cube. The tentacles of these jellyfish, unlike the scyphoid jellyfish, are outgrowths located at the four corners of the cube and are divided into smaller branches at the bottom. The outgrowths of the tentacles remotely resemble hands with smaller endings - fingers. When hitting the tentacles of box jellyfish, necrotic foci can also occur. A necrotic focus occurs due to the death of skin cells. This phenomenon looks like a festering ulcer, where blood leukocytes rush.

Among box jellyfish for humans, the most dangerous are the sea wasp and chiropsalmus. These are small jellyfish, their bell reaches about 20 cm in diameter. In addition, the transparency of the body in the water makes them hardly noticeable to swimmers. They live in the tropical waters of the Pacific and Indian oceans. Especially often they can be found off the coast of Northern Australia and the Philippines.

sea ​​wasp - poisonous species from the class box jellyfish

The sea wasp can be found off the coast of Australia and the Philippines. The diameter of its bell is very small, about 7.5 cm. The sea wasp belongs to the box jellyfish. The burn of this jellyfish is fatal even for an adult who dies within a few minutes.

Jellyfish can rightly be called one of the most mysterious inhabitants of the deep sea, causing interest and a certain fear. Who are they, where did they come from, what varieties are there in the world, what is their life cycle, are they so dangerous, as popular rumor says - I want to know about all this for sure.

Jellyfish appeared more than 650 million years ago, they can be called one of the oldest organisms on Earth.

About 95% of the body of a jellyfish is water, which is also their habitat. Most jellyfish live in salt water, although there are species that prefer fresh water. Jellyfish - phase life cycle representatives of the genus Medusozoa, "sea jelly" alternates with an immobile asexual phase of immobile polyps, from which they are formed by budding after maturation.

The name was introduced in the 18th century by Carl Linnaeus, he saw in these strange organisms a certain resemblance to the mythical Gorgon Medusa, due to the presence of tentacles that flutter like hair. With their help, the jellyfish catches small organisms that serve as food for it. The tentacles may look like long or short, spiky threads, but they are all equipped with stinging cells that stun prey and facilitate hunting.

Life cycle of scyphoid: 1-11 - asexual generation (polyp); 11-14 - sexual generation (jellyfish).

Glowing jellyfish

The one who saw how it glows dark night sea ​​water, it is unlikely that he will be able to forget this spectacle: myriads of lights illuminate sea ​​depth shimmer like diamonds. The reason for this amazing phenomenon is the smallest planktonic organisms, including jellyfish. One of the most beautiful is considered a phosphorus jellyfish. It is not found very often, living in the near-bottom zone off the coast of Japan, Brazil, and Argentina.

The diameter of the umbrella of a luminous jellyfish can reach 15 centimeters. Living in the dark depths, jellyfish are forced to adapt to the conditions, provide food for themselves, so as not to disappear altogether as a species. An interesting fact is that the bodies of jellyfish do not have muscle fibers and cannot resist water flows.

Since the slow-moving jellyfish, floating by the will of the current, cannot keep up with moving crustaceans, small fish or other planktonic inhabitants, you have to go to the trick and force them to swim themselves, right to the predatory open mouth opening. And the best bait in the darkness of the bottom space is light.

The body of a luminous jellyfish contains a pigment - luciferin, which is oxidized under the influence of a special enzyme - luciferase. Bright light attracts victims like moths - the flame of a candle.

Some types of luminous jellyfish, such as Ratkeya, Equorea, Pelagia, live near the surface of the water, and, gathering in large numbers, they literally words make the sea burn. The amazing ability to emit light has interested scientists. Phosphors have been successfully isolated from the jellyfish genome and introduced into the genomes of other animals. The results were quite unusual: for example, mice whose genotype was changed in this way began to grow green hairs.

Poison jellyfish - Sea Wasp

Today, more than three thousand jellyfish are known, and many of them are far from harmless to humans. Stinging cells, “charged” with poison, have all types of jellyfish. They help to paralyze the victim and deal with it without any problems. Without exaggeration, for divers, swimmers, fishermen is a jellyfish, which is called the Sea Wasp. The main habitat of such jellyfish is warm tropical waters, especially a lot of them near the coast of Australia and Oceania.

Transparent bodies of pale blue color are invisible in warm water quiet sandy coves. The small size, namely, up to forty centimeters in diameter, also does not attract special attention. Meanwhile, the poison of one individual is enough to send about fifty people to heaven. Unlike their phosphorescent counterparts, sea wasps can change direction, easily finding careless bathers. The poison that enters the body of the victim causes paralysis of smooth muscles, including the respiratory tract. Being in shallow water, a person has a small chance to escape, but even if health care was provided in a timely manner and the person did not die from suffocation, in places of "bites" deep ulcers form, causing severe pain and not healing for many days.

Dangerous little ones - Irukandji jellyfish

Similar action to human body, with the only difference that the degree of damage is not so deep, the tiny Irukandji jellyfish, described by the Australian Jack Barnes in 1964, have. He, as a true scientist, advocating for science, experienced the effect of poison not only on himself, but also on own son. Symptoms of poisoning - severe headache and muscle pain, convulsions, nausea, drowsiness, loss of consciousness - are not fatal in themselves, but the main risk is a sharp increase in blood pressure in a person who personally met Irukandji. If the victim has problems with cardiovascular system, then the probability of death is quite high. The size of this baby is about 4 centimeters in diameter, but thin spindle-shaped tentacles reach 30-35 centimeters in length.

Bright beauty - jellyfish Physalia

Another inhabitant of tropical waters that is very dangerous for humans is Physalia - the Sea Boat. Her umbrella is painted in bright colors: blue, purple, magenta and floats on the surface of the water, so it is noticeable from afar. Entire colonies of attractive sea "flowers" attract gullible tourists, beckoning them to pick them up as soon as possible. This is where the main danger lurks: long, up to several meters, tentacles are hidden under water, equipped with huge amount stinging cells. The poison acts very quickly, causing severe burns, paralysis and disruption of the cardiovascular, respiratory and central nervous systems. If the meeting took place at great depths or simply far from the coast, then its outcome can be the saddest.

Giant Jellyfish Nomura - Lion's Mane

The real giant is the Nomura Bell, which is also called the Lion's Mane for some external resemblance to the king of beasts. The diameter of the dome can reach two meters, and the weight of such a "baby" reaches two hundred kilos. It lives in the Far East, in the coastal waters of Japan, off the coast of Korea and China.

A huge hairy ball, falling into the fishing nets, damages them, causing damage to the fishermen and shooting themselves when they try to free themselves. Although their poison is not fatal to humans, meetings with the Lion's Mane rarely take place in a friendly atmosphere.

One of the largest jellyfish is considered Cyanea. Living in cold waters, it reaches its largest size. The most gigantic specimen was discovered and described by scientists at the end of the 19th century in North America: its dome was 230 centimeters in diameter, and the length of the tentacles was 36.5 meters. There are a lot of tentacles, they are collected in eight groups, each of which has from 60 to 150 pieces. It is characteristic that the dome of the jellyfish is also divided into eight segments, representing a kind of octagonal star. Fortunately, it does not live in the Azov and Black Seas, so you can not be afraid of them when going to the sea to relax.

Depending on the size, the color also changes: large specimens are painted in bright purple or purple, smaller - in orange, pink or beige. Cyanei live in surface waters, rarely descending into the depths. The poison is not dangerous to humans, causing only an unpleasant burning sensation and blisters on the skin.

The use of jellyfish in cooking

The number of jellyfish living in the seas and oceans globe truly huge, and none of the species is threatened with extinction. Their use is limited by the possibilities of extraction, but people have long used the beneficial properties of jellyfish for medicinal purposes and enjoy them. palatability in cooking. In Japan, Korea, China, Indonesia, Malaysia and other countries, jellyfish have long been eaten, calling them "crystal meat". Its benefits are due to the high content of protein, albumin, vitamins and amino acids, trace elements. And with proper preparation, it has a very refined taste.

Jellyfish "meat" is added to salads and desserts, to sushi and rolls, soups and main dishes. In a world where population growth steadily threatens the onset of famine, especially in underdeveloped countries, jellyfish protein can be a good help in solving this issue.

Jellyfish in medicine

The use of jellyfish for the manufacture of medicines is typical, to a greater extent, in those countries where their use in food has long ceased to be a subject of surprise. For the most part, these are countries located in the seaside, where jellyfish are directly harvested.

In medicine, preparations containing processed bodies of jellyfish are used to treat infertility, obesity, baldness and gray hair. The poison extracted from stinging cells helps to cope with diseases of the upper respiratory tract and normalize blood pressure.

Modern scientists are struggling to find medicinal product, capable of defeating cancerous tumors, not excluding the possibility that jellyfish will also help in this difficult struggle.

To the question of how long jellyfish live, scientists do not give a definite answer. Many agree that the life cycle of these animals is short and the life span of most species is two to six months.

Recently, zoologists have discovered that among the representatives of this species there are specimens that never die and are always reborn. That is why the jellyfish Turitopsis Nutrikula is considered to be the only immortal creature on the planet.

Who are jellyfish

Zoologists, speaking of jellyfish, usually mean all mobile forms of intestinal cnidarians (a group of multicellular invertebrate representatives of the animal world) that catch and kill their victims with the help of tentacles.

These amazing animals live only in salt water, and therefore they can be found in all the oceans and seas of our planet (except inland), sometimes in closed lagoons or lakes with salt water on coral islands. Among the representatives of this class there are both heat-loving animals and those who prefer cold waters, species that live only near the surface of the water, and those that live only at the bottom of the ocean.

Jellyfish are solitary animals, because they do not communicate with each other in any way, even if the currents bring them together, thus forming a colony.

We got our modern name these creatures in the middle of the 18th century thanks to Karl Liney, who hinted at the mythical head of the Gorgon Medusa, with which he noticed similarities in these representatives of the animal world. Such a name is not without reason, since these animals are similar to it.

This amazing animal is 98% water, and therefore has a transparent body with a slight tint, which in appearance resembles a jelly-like bell, an umbrella or a disk that moves by contracting the muscles of the bell wall.

Along the edges of the body are tentacles, the appearance of which directly depends on what species it belongs to: in some they are short and thick, in others they are long and thin. Their number can vary from four to several hundred (but always a multiple of four, since representatives of this class of animals are characterized by radial symmetry).

These tentacles are composed of string cells that contain poison and are therefore directly intended for hunting. Interestingly, even after death, jellyfish are able to sting for another half a month. Some species can be deadly even to humans. For example, an animal known as the "Sea Wasp" is considered the most dangerous poisonous animal in the world's oceans: scientists say that its poison is enough to poison sixty people in a few minutes.

The outer part of the body is smooth and convex, while the underside resembles a bag. In the center of the lower part there is a mouth: in some jellyfish it looks like a tube, in others it is short and wide, in others it resembles short maces. This hole also serves to remove food debris.

These animals grow throughout their lives, and their size largely depends on the species: among them there are very small ones, no more than a few millimeters, and there are also huge ones, whose body size exceeds two meters, and together with tentacles - all thirty ( for example, the largest jellyfish in the world's oceans, Cyanea, which lives in the Northwest Atlantic, has a body size of more than 2 m, and with tentacles - almost forty).


Despite the fact that these marine animals do not have brains and sensory organs, they have light-sensitive cells that act as eyes, thanks to which these organisms are able to distinguish darkness from light (they are, however, not able to see objects). Interestingly, some specimens glow in the dark, while in species living at great depths, the light is red, and those that live closer to the surface are blue.

Since these animals are primitive organisms, they consist of only two layers, connected thanks to a special adhesive substance - mesoglia:

  • external (ectoderm) - a kind of analogue of the skin and muscles. The rudiments of the nervous system and germ cells are also located here;
  • internal (endoderm) - performs only one function: digests food.

Ways of transportation

Since all representatives of this class (even the largest individuals, whose weight exceeds several centners) are almost unable to resist sea currents, scientists consider jellyfish as representatives of plankton.

Most species still do not completely succumb to water flows, and although slowly, they move using the current and thin muscle fibers of their body: contracting, they fold the body of a jellyfish like an umbrella - and the water that is in the lower part of the animal is sharply pushed out.


As a result, a strong jet is formed, pushing the animal forward. Therefore these sea ​​creatures always move in the direction opposite to the mouth. Where exactly they need to move, they are helped to determine the organs of balance located on the tentacles.

Regeneration

Another interesting feature of these creatures is their ability to restore lost body parts - absolutely all the cells of these animals are interchangeable: even if this animal is divided into parts, it will restore them, thus forming two new individuals! If this is done with an adult jellyfish, an adult copy will appear, from a jellyfish larva - a larva.

reproduction

Looking at these amazing translucent creatures, many people ask themselves the question of how jellyfish reproduce. Reproduction of jellyfish is an interesting and unusual process.

Answering the question of how jellyfish reproduce, it is worth noting that in this case, it is possible both sexually (they are of different sexes) and vegetative propagation. The first involves several stages:

  1. In these animals, the germ cells mature in the gonads;
  2. After the eggs and spermatozoa mature, they come out through the mouth opening and are fertilized, resulting in the appearance of a jellyfish larva - planula;
  3. After some time, the planula settles to the bottom and is fixed on something, after which a polyp appears on the basis of the planula, which reproduces by budding: on it, layering on each other, daughter organisms form;
  4. After some time, they peel off and swim away, representing a born jellyfish.
    Reproduction of some species is somewhat different from this scheme. For example, the pelagic jellyfish does not have a polyp stage at all - the cubs appear directly from the larva. But bougainvillea jellyfish, one might say, are born, since polyps are formed directly in the gonads, without separating from adults, without any intermediate stages.


Nutrition

These amazing animals are the most numerous predators of our planet. They feed mainly on plankton: fry, small crustaceans, fish caviar. Larger specimens often catch small fish and smaller relatives.

So, jellyfish see almost nothing and do not have any sense organs, they hunt with the help of stringing tentacles, which, having caught the touch of edible food on them, instantly inject poison into it, which paralyzes the victim, after which the jellyfish eats it. There are two more options for catching food (much depends on the type of jellyfish): the first - prey sticks to the tentacles, the second - gets entangled in them.

Classification

There are the following types of jellyfish, which differ from each other in structure.

hydrojellyfish

Hydroid jellyfish are transparent, small in size (from 1 mm to 3 cm), four tentacles and a long tube-shaped mouth are attached to the body. Among the prominent representatives of hydrojellyfish is the jellyfish Turritopsis nutricula: the only creature discovered by people, about which scientists have declared that it is immortal.

Having reached maturity, it sinks to the bottom of the sea, transforming into a polyp, on which new formations are formed, from which new jellyfish subsequently arise.

This process is repeated more than once, which means that it is constantly reborn, and can die only if some predator eats it. Here are some interesting facts about jellyfish that scientists recently told the world.

Scyphomedusa

Scyphoid jellyfish have a more complex structure compared to hydrojellyfish: they are larger than representatives of other species - the largest jellyfish in the world, the jellyfish Cyanea, belongs to this class. This giant jellyfish, about 37 meters long, is one of the longest animals on Earth. Therefore, she eats a lot: during her life, the largest jellyfish eats about 15 thousand fish.

Scyphomedusa have a more developed nervous and muscular system, a mouth surrounded by a huge number of stinging and tactile cells, and the stomach is divided into chambers.


Like all jellyfish, these animals are predators, but deep-sea ones also feed on dead organisms. The touch of a scyphoid jellyfish to a person is quite painful (the feeling if a wasp had bitten), and at the point of contact, a trace resembling a burn often remains. Her bite can also cause an allergic reaction or even a painful shock. Seeing this animal, it is advisable not to take risks and, passing by, do not touch it.

One of the brightest specimens of this species, in addition to the Cyanei jellyfish, is also the Aurelia jellyfish (the most typical representative) and the Golden jellyfish, an animal that can only be seen on the Rocky Islands archipelago in Palau.

The golden jellyfish is notable for the fact that, unlike its relatives, living only in the seas, it lives in the Jellyfish Lake, which is connected to the ocean by underground tunnels and is filled with lightly salted water. Representatives of this species differ from marine individuals also in that they completely lack age spots, there are no stinging tentacles, as well as tentacles that surround the mouth.

The golden jellyfish, although it belongs to the scyphomedusae, over the years has turned into a completely different species that does not pose a danger to humans, since it has significantly lost its stinging ability. An interesting fact is that the Golden Jellyfish began to grow green algae on its body, from which it receives part of its nutrition. The golden jellyfish, like its marine relatives, feeds on plankton and has not lost the ability to migrate - in the morning it swims away to East Coast, in the evening - sails to the west.

box jellyfish

Box jellyfish have a more advanced nervous system compared to other members of the cnidarine class. They are the fastest of all jellyfish (capable of reaching speeds of up to 6 m/min.) and can easily change their direction of movement. They are also the most dangerous representatives jellyfish for humans: the bites of some representatives of box jellyfish are fatal.

The most poisonous jellyfish in the world belongs to just this species, lives near the Australian coast and is called the Box Jellyfish or Sea Wasp: its poison can kill a person in just a few minutes. This wasp is almost transparent, of a pale blue hue, which is why it is hard to see on the water, which means it is easier to stumble upon it.


The sea wasp is the largest jellyfish in its class - its body is the size of a basketball. When the sea wasp is just swimming, its tentacles are reduced to 15 cm in length and are almost invisible. But when the animal hunts, they stretch up to three meters. Sea Wasps feed mainly on shrimp and small fish, and they themselves are caught and eaten by sea turtles - the only animals on our planet that are insensitive to the poison of one of the most dangerous creatures on Earth.

Jellyfish are animals that everyone associates with something shapeless and infinitely primitive, but their lifestyle and physiology are not as simple as it seems at first glance. The word "jellyfish" usually means animals from the Scyphoid class and representatives of the Trachilid order from the Hydroid class of the intestinal type. At the same time, in the scientific community, this word has a broader interpretation - zoologists use this term to designate any mobile forms of intestinal animals. Thus, jellyfish are closely related to mobile types of intestinal (siphonophores, sea boats) and sessile ones - corals, sea anemones, hydras. In total, there are over 200 species of jellyfish in the world.

Scyphoid jellyfish rhizostoma, or cornerot (Rhizostoma pulmo).

Because of their primitiveness, jellyfish are characterized by the uniformity of physiology and internal structure, but at the same time they differ amazing variety colors and appearance unexpected for such simple animals. One of the main hallmarks jellyfish is radial symmetry. This type of symmetry is characteristic of some marine animals, but in general it is not so common in the animal world. Due to radial symmetry, the number of paired organs in the body of jellyfish is always a multiple of 4.

The umbrella of this jellyfish is divided into blades, the number of which is always a multiple of 4.

Jellyfish are so primitive that there are no differentiated organs in their body, and the tissues of the body consist of only two layers: the outer (ectoderm) and the inner (endoderm), connected by a sticky substance - mesoglea. However, the cells of these layers are specialized to perform different functions. For example, ectoderm cells perform an integumentary function (analogous to the skin), motor (analogous to muscles), here are special sensitive cells, which are the rudiments of the nervous system and special germ cells that form reproductive organs in adult jellyfish. But the cells of the endoderm are only engaged in the digestion of food, for this they secrete enzymes that digest the prey.

Due to the highly developed colorless mesoglea, the body of the flower cap jellyfish (Olindias formosa) looks almost transparent.

The body of jellyfish is shaped like an umbrella, disk or dome. The upper part of the body (it can be called external) is smooth and more or less convex, and the lower (it can be called internal) shape resembles a bag. The inner cavity of this sac is both an engine and a stomach. In the middle of the lower part of the dome, the jellyfish have a mouth. Its structure is very different from different types: in some jellyfish, the mouth has the shape of an elongated proboscis or tube, sometimes very long, in others, short and wide oral lobes are located on the sides of the mouth, in others, instead of lobes, there are short club-shaped oral tentacles.

This chic crown is formed by the mouth tentacles of the cotylorhiza tuberculata jellyfish.

Trapping tentacles are located along the edges of the umbrella, in some species they can be relatively short and dense, in others - thin, long, filiform. The number of tentacles can vary from four to several hundred.

The tentacles of the eared jellyfish (Aurelia aurita) are relatively short and very thin.

In some species of jellyfish, these tentacles are modified and turned into organs of balance. Such organs have the form of a tube-stalk, at the end of which there is a bag or vial with a calcareous stone - statolith. When the jellyfish changes direction, the statolith shifts and affects the sensitive hairs, from which the signal is transmitted to the nervous system. The nervous system of jellyfish is extremely primitive, these animals have neither a brain nor sensory organs, but there are groups of light-sensitive cells - eyes, so jellyfish distinguish between light and dark, but they, of course, cannot see objects.

And this jellyfish has thick and long trapping tentacles combined with long and fringed mouthparts.

However, there is one group of jellyfish that completely refutes the usual ideas about these animals - these are stauromedusas. The fact is that stauromedusas do not move at all - this is a rare example of sedentary animals. Sitting jellyfish are radically different in their structure from free-swimming species, at first glance the relationship between these groups of jellyfish seems incredible.

Sedentary jellyfish Cassiopeia (Cassiopea andromeda).

The body of stauromedusa resembles a bowl on a long leg. With this leg, the jellyfish is attached to the ground or algae. The mouth is located in the middle of the bowl, and the edges of the bowl are extended into eight so-called arms. At the end of each "arm" is a bunch of short tentacles, similar to a dandelion.

Sedentary alfalfa jellyfish (Lucernaria bathyphila).

Despite the fact that stauromedusas lead a sedentary lifestyle, if necessary, they can move around. To do this, the jellyfish bends its leg in such a way that its cup leans towards the ground, and then stands on its “hands”, as if performing a headstand, after which the leg comes off and moves a few centimeters, standing on the leg, the jellyfish straightens up. Such movements are carried out very slowly, during the day the jellyfish takes several steps.

This alfalfa shows off the muscular stalk that anchors it to the bottom.

The sizes of jellyfish range from 1 cm to 2 m in diameter, and the length of the tentacles can reach 35 m! The weight of such giants can reach up to a ton!

This is the largest jellyfish in the world - cyanide, or lion's mane(Cyanea capillata), it is her long tentacles that can reach 35 m in length!

Since the tissues of jellyfish are poorly differentiated, their cells do not have color. In most jellyfish, the body is transparent or with a pale milky, bluish, yellowish tinge. This feature is reflected in the English name of jellyfish - "jelly fish". Indeed, devoid of a skeleton, soft, saturated with moisture (the water content in the body of jellyfish is 98%!), The pale body of jellyfish resembles jelly.

In water, their body retains elasticity due to saturation with moisture, but a jellyfish thrown onto land instantly falls and dries up; on land, jellyfish are not able to make even the slightest movement.

However, not all jellyfish are so nondescript. Among them there are really beautiful views, painted in bright colors - red, pink, purple, yellow. Only green jellyfish do not exist. In some species, the coloration has the appearance of a pattern in the form of small specks or stripes.

Amazing play of colors of scyphoid jellyfish.

But that's not all. Some types of jellyfish (pelagia nightlight, aequorea, ratkey and others) are able to glow in the dark. Interestingly, in deep-sea jellyfish, the emitted light is red, while those that swim close to the surface of the water are blue. This phenomenon is called bioluminescence and is the basis of a fascinating natural phenomenon - the night glow of the sea. The glow arises as a result of the decay of a special substance - luciferin, whose name is consonant with the name of the devil, obviously this phenomenon caused awe among the discoverers of bioluminescence. In fairness, it should be said that the glow of water is provided not only by jellyfish, but also by other marine organisms - small crustaceans (plankton), algae and even ... worms.

The deep-sea scyphoid atoll jellyfish (Atolla vanhoeffeni) is bright red in color and looks like an unearthly creature.

The range of jellyfish covers the entire World Ocean, they are found in all seas except inland ones. Jellyfish live only in salt water, occasionally they can be found in closed lagoons and brackish lakes of coral islands that once separated from the sea. The only one freshwater species- a tiny jellyfish kraspedakusta, which was discovered by accident in the pool ... of the London Botanical Society. Jellyfish got into the pool along with aquatic plants brought from the Amazon. Among the jellyfish you will not find pandemic species, that is, those that are found everywhere, usually each species of jellyfish occupies an area limited by any one sea, ocean or bay. Among jellyfish there are heat-loving and cold-water ones; species that prefer to stay near the surface and deep-sea. Deep-sea jellyfish almost never rise to the surface; they swim all their lives in the depths in pitch darkness. Those jellyfish that live near the surface of the sea make vertical migrations - during the day they plunge to great depths, and at night they rise to the surface. Such migrations are associated with the search for food. Also, jellyfish can migrate in a horizontal direction, although they are passive in nature, jellyfish are simply carried by the current over long distances. Jellyfish, being primitive animals, do not contact each other in any way, they can be classified as solitary animals. At the same time, in places rich in food, at the intersection of currents, jellyfish can form large clusters. Sometimes the number of jellyfish increases so much that they literally fill the water space.

Numerous jellyfish make vertical migration in the slightly saline Lake Medusa on about. Palau.

Jellyfish move rather slowly, largely using the auxiliary power of the currents. The movements are provided by thin muscle fibers in the umbrella: contracting, they seem to fold the dome of the jellyfish, while the water contained in the internal cavity (stomach) is pushed outward with force. Thus, a jet stream arises, which pushes the body of the jellyfish forward. Accordingly, jellyfish always move in the direction opposite to the mouth, but they can swim in different directions- horizontally, up and down (as if upside down). The direction of movement and their position in space are determined by the jellyfish with the help of balance organs. Interestingly, if the vials with statoliths are cut off from a jellyfish, its umbrella is less likely to contract. However, in the role of an invalid, a jellyfish is not destined to live long - these animals have excellent tissue regeneration. Due to the primitive structure, all cells in the body of jellyfish are interchangeable, so they quickly heal any wounds. Even if the jellyfish is cut into pieces or the “head” is separated from the lower body, it will restore the missing parts and form two new individuals! Characteristically, the recovery of the head end is faster than the end part. Even more surprising is that if such an operation is carried out at different stages of the development of a jellyfish, then each time individuals of the appropriate age will be formed - adults will form from an adult jellyfish, only larvae will form from the larval stage, which will continue their development as independent organisms. Thus, the tissues of one of the most primitive animals have the so-called cellular memory and "know" their age.

Medusa swimming upside down.

All jellyfish are predators because they feed exclusively on animal food. However, the prey of most jellyfish are tiny organisms - small crustaceans, fish fry, free-floating fish eggs and just small edible pieces of someone else's prey. Most large species jellyfish can prey on small fish and… smaller jellyfish. However, jellyfish hunting looks peculiar. Since jellyfish are practically blind and have no other senses, they are unable to detect and pursue prey. They find their food in a passive way, they simply catch with their tentacles the edible trifle that the current brings. Jellyfish catch the touch with the help of trapping tentacles and kill the victim with them. How do primitive helpless "jelly" do this? The jellyfish have powerful weapon- stinging or nettle cells in the tentacles. These cells can be of different types: penetrants - the cells look like pointed threads that dig into the body of the victim and inject a paralyzing substance into it; glutinants - threads with a sticky secret that "glue" the victim to the tentacles; Volvents are long sticky threads in which the victim simply gets entangled. The tentacles push the paralyzed victim to the mouth, undigested food residues are also excreted through the mouth. The poisonous secret of jellyfish is so powerful that it affects not only small prey, but also animals much larger than the jellyfish themselves. Deep-sea jellyfish lure prey with a bright glow.

The victim can not get out of this tangle of mouth and trapping tentacles of a jellyfish.

The reproduction of jellyfish is no less interesting than other life processes. In jellyfish, sexual and asexual (vegetative) reproduction is possible. sexual reproduction includes several stages. Sex cells mature in the gonads of jellyfish, regardless of the season, but in species from temperate waters, reproduction is still confined to the warm period of the year. Jellyfish are separate sexes, males and females outwardly do not differ from each other. The eggs and sperm are released into the water… through the mouth, during external environment fertilization occurs, after which the larva begins to develop. Such a larva is called planula, it is not able to feed and reproduce. A short time planula floats in the water, and then settles to the bottom and attaches to the substrate. At the bottom of the planula, a polyp is formed that can reproduce asexually- budding. It is characteristic that daughter organisms form in the upper part of the polyp, as if layering on top of each other. Ultimately, such a polyp resembles a stack of plates stacked on top of each other, the uppermost individuals gradually separate from the polyp and swim away. Free-swimming individuals of hydroid jellyfish are actually young jellyfish that gradually grow and mature; in scyphoid jellyfish, such an individual is called an ether, since it differs sharply from an adult jellyfish. After some time, the ether turns into an adult. But in the jellyfish pelagia and several species of trachilids, the polyp stage is completely absent; in them, mobile individuals are formed directly from the planula. Bougainvillea and Campanularia jellyfish have gone even further, in which polyps are formed directly in the sex glands of adults, it turns out that the jellyfish gives rise to tiny jellyfish without any intermediate stages. Thus, in the life of jellyfish, there is a complex alternation of generations and methods of reproduction, and several individuals are formed from each egg at once. The reproduction rate of jellyfish is very high and they quickly restore their numbers even after natural disasters. The life expectancy of jellyfish is short - most species live for several months, the largest species of jellyfish can live 2-3 years.

The dome of this jellyfish is decorated with stripes.

A tiny fish hides under the dome of a jellyfish.

The green turtle eats the jellyfish.

Jellyfish have been known to people since ancient times, however, due to their negligible economic value, they long time did not attract attention. The word jellyfish itself comes from the name ancient greek goddess Gorgon Medusa, whose hair, according to legend, was a bunch of snakes. Apparently, the moving tentacles of jellyfish and their poisonousness reminded the Greeks of this evil goddess. However, little attention was paid to jellyfish. The exception was the countries of the Far East, whose inhabitants loved exotic food. For example, the Chinese eat eared jellyfish and edible ropil. One side the nutritional value jellyfish is negligible, since their body mainly consists of water, on the other hand, the abundance and availability of jellyfish suggested that at least some benefit be derived from them. To do this, the Chinese first cut poisonous tentacles from jellyfish, and then salt them with alum and dry them. Dried jellyfish resemble strong jelly in consistency, they are cut into strips and used in salads, as well as boiled, fried with pepper, cinnamon and nutmeg. Despite such tricks, jellyfish are practically tasteless, so their use in cooking is limited. national cuisines China and Japan.

Eared jellyfish is one of the edible species.

In nature, jellyfish bring some benefit, cleaning sea waters from small organic debris. Sometimes jellyfish breed so strongly that they clog water sumps in desalination plants with their mass, pollute the beaches. However, jellyfish should not be blamed for this sabotage, since the culprits of such outbreaks are the people themselves. The point is that emissions organic matter and the biological debris that fills the oceans is the food of jellyfish and provokes their reproduction. This process is also facilitated by the lack of fresh water, since with an increase in the salinity of the sea, jellyfish reproduce better. Since jellyfish breed well, there are no endangered species among them.

Seasonal invasion of jellyfish in the Black Sea is a common occurrence.

AT vivo jellyfish do not pose any particular benefit or harm to humans. However, the venom of some species can be dangerous. Poisonous jellyfish can be conditionally divided into two groups: in some species, the poison has an irritating effect and can cause allergies, in others, the poison acts on the nervous system and can lead to serious disruption of the heart, muscles, and even death. For example, the "sea wasp" jellyfish that lives in the waters of Australia has caused the death of several dozen people. Touching this jellyfish causes severe burns, after a few minutes convulsions begin and many people die before they can swim to shore. However, the sea wasp has an even more terrible competitor - the Irukandji jellyfish, which lives in pacific ocean. The danger of this jellyfish is that it is very small (12 cm in diameter) and stings almost painlessly, so swimmers often ignore its bite. At the same time, the poison of this crumb acts very quickly. Despite this, the danger of jellyfish in general is greatly exaggerated. In order to protect yourself from unpleasant consequences, it is enough to know a few rules:

  • do not touch unknown species of jellyfish - this applies not only to living jellyfish swimming in the sea, but also to dead ones thrown ashore, because stinging cells can act for some time after the death of a jellyfish;
  • in case of burns, get out of the water immediately;
  • rinse the bite site with plenty of water until the burning sensation stops;
  • in case the discomfort does not go away, wash the bite site with a solution of vinegar and immediately call an ambulance (usually adrenaline injections are given in such cases).

Burns on a swimmer's hand left by a jellyfish.

Usually, a jellyfish sting victim recovers in 4-5 days, but one thing should be taken into account: jellyfish venom can act as an allergen, so if you meet the same type of jellyfish again, the second burn will be much more dangerous than the first. In this case, the reaction of the body to the poison develops faster and more powerfully, and the threat to life increases many times over. Nevertheless, the mortality from encounters with jellyfish is negligible and inferior to accidents with other animal species.

Jellyfish at the Monterey Public Aquarium.

Despite some hostility of jellyfish to humans in recent times it has become fashionable to keep them in the aquarium. The smooth continuous movements of these fantastic creatures bring peace and soothe the nerves. However, the maintenance of jellyfish in an aquarium is associated with some difficulties: jellyfish are very sensitive to water pollution, do not tolerate desalination, and require a more or less pronounced flow of water. Most often they are kept in large public aquariums, where it is relatively easy to ensure the purity of the water and create a current. However, at home, jellyfish can also be kept. For home keeping, the moon jellyfish and the cassiopeia jellyfish are used, which will reach 20 and 30 cm in diameter, respectively. For keeping both types, only a special seawater aquarium, necessarily with a powerful water purification system, including mechanical filtration. In the aquarium, you need to create a current, but at the same time, make sure that the jellyfish is not sucked into the filter by the current. Jellyfish require special lighting, so metal halide lamps will have to be installed in the aquarium. Please note that the water temperature for the moon jellyfish should not exceed 12-18 ° C, Cassiopeia may well live at room temperature. You need to feed jellyfish with live food - brine shrimp, it is easy to purchase in specialized stores, from amateur aquarists. Both species are not dangerous, but can still cause painful burns, so be careful when caring for jellyfish. Do not forget that jellyfish will not tolerate proximity to fish; only immobile animals or bottom organisms can be settled in their aquarium.

Jellyfish are amazing and very extraordinary creatures. We read and watch

Jellyfish are amazing and very extraordinary creatures, causing a whole range of emotions from delight and admiration to disgust and fear. Jellyfish can be found in every sea, in every ocean, on the surface of the water or many kilometers deep.
Jellyfish are the oldest animals on the planet, their history goes back at least 650 million years. In nature, there are an incredible number of diverse species, but even at the present time, the emergence of new ones, previously unfamiliar to mankind, is being recorded.

Jellyfish washed up on the sand of Belmedie Beach, Scotland

In fact, jellyfish or medusa generation are one of the phases of the life cycle of the cnidarian Medusozoa, which are usually divided into three types: hydroid, scyphoid and box jellyfish. Jellyfish reproduce sexually. There are males that produce sperm and females that produce eggs. As a result of their merger, the so-called planula is formed - the larva of the jellyfish. Planula settles to the bottom, where over time it turns into a polyp (asexual generation of jellyfish). Reaching full maturity, the polyp begins to bud off the young generation of jellyfish, often not at all like adults. In scyphoid jellyfish, the newly separated specimen is called the 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 burning poison, are designed for hunting and capturing prey.

Jellyfish at Shark Bay Manaday Reef Aquarium in Las Vegas, Nevada

The term "jellyfish" was first used by Carl Linnaeus in 1752 as an allusion to the animals' resemblance to the head of the Gorgon Medusa. Popularized around 1796, the name has also been applied to other medusoid species, such as ctenophores.

Jellyfish on display at Long Beach in California



Did you know? ten interesting facts about jellyfish:


The largest jellyfish in the world can reach 2.5 meters in diameter and have tentacles over 40 meters long.

Jellyfish are able to reproduce both sexually and by budding and fission.

Jellyfish "Australian wasp" 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 are able to sting for more than two weeks.

Jellyfish do not stop growing throughout their lives.

Large clusters of jellyfish are called "swarm" or "bloom".

Some types of jellyfish are eaten in East Asia considering them a "delicacy".

Jellyfish don't have a brain respiratory system, circulatory, nervous and excretory systems.

The rainy season significantly reduces the number of jellyfish that live in salt water.

Some female jellyfish can produce up to 45,000 larvae (planula) per day.


The most incredible and bizarre forms

Aequorea Victoria or jellyfish "crystal"

purple sting

Elegant dance of jellyfish

Aurelia - "butterflies"

Medusa - crown

Eared aurelia (lat. Aurelia aurita) - a species of scyphoid from the order discomedusa (Semaeostomeae)

glowing ctenophore

pink jellyfish

A pink jellyfish from the Scyphozoan family was discovered more recently, just over 10 years ago, in the waters of the Gulf of Mexico and the Caribbean. Some individuals of this species reach 70 cm in diameter. Pink jellyfish can inflict severe and painful burns, especially if the bather inadvertently finds himself among a large concentration of these creatures.

Antarctic Diplulmaris

The Antarctic Diplulmaris is a species of jellyfish in the Ulmaridae family. This jellyfish was discovered recently in Antarctica, in the waters continental shelf. The Antarctic Diplulmaris is only 4 cm in diameter.

Jellyfish colony

Aurelia eared (lat. Aurelia aurita) or moon jellyfish

Pacific sea nettle (Chrysaora fuscescens)

Flower Hat Jellyfish (Olindias formosa)


Jellyfish "flower hat" (lat. Olindias Formosa) - 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 the 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 it is quite painful and can lead to severe allergic reactions.

Scyphoid jellyfish rhizostoma (Rhizostoma pulmo) or cornerot

Incredible bioluminescent jellyfish

Jellyfish - an inhabitant of the coast of the Federated States of Micronesia

Purple-striped jellyfish (Chrysaora colorata)

Purple-striped jellyfish (lat. Chrysaora Colorata) from the class Scyphozoa is found only off 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 young ones it is pink. Usually purple-striped jellyfish are kept singly or in small groups, unlike most jellyfish of other species, which often form huge colonies. Chrysaora colorata burn is quite painful, but not fatal to humans.

Pelagia Noctiluca, known in Europe under the name "purple sting"

Giant Nomura jellyfish (Nemopilema nomurai)

Giant Nomura jellyfish (lat. Nemopilema nomurai) is a species of scyphoid jellyfish from the Cornerot order. This species predominantly inhabits the East China and Yellow Seas. The size of this species is really impressive! They can reach 2 meters in diameter and weigh about 200 kg.
The name of the species was given in honor of Mr. Kan'ichi Nomura, CEO fisheries in Fukui Prefecture. In early 1921, Mr. Nomura first collected and studied a hitherto unknown species of jellyfish.

Currently, the number of Nomura jellyfish in the world is growing. Possible reasons population growth, scientists consider climate change, overexploitation of water resources and pollution environment.
In 2009, a 10-ton fishing trawler capsized in Tokyo Bay with three crew members trying to pull nets overflowing with dozens of Nomura jellyfish.

Large red jellyfish (Tiburonia granrojo)