Description of jellyfish, reproduction, types and meaning. Rare and unusual species of jellyfish Yellow jellyfish
Jellyfish is an invertebrate marine animal with a transparent gelatinous body, equipped with tentacles along the edges. She is a lower multicellular creature, belongs to the type of intestinal. Among them there are free-floating (jellyfish), sessile (polyps), attached forms (hydra).
The body of the intestinal cavities is formed by two layers of cells - the ectoderm and endoderm, between them is the mesoglea (non-cellular layer), the body also has radial symmetry. Animals of this type have the appearance of an open bag at one end. The hole serves as a mouth, which is surrounded by a corolla of tentacles. The mouth leads into a blindly closed digestive cavity (gastric cavity). Digestion of food occurs both inside this cavity and by individual cells of the endoderm - intracellularly. Undigested food remains are excreted through the mouth opening.
Jellyfish belong to the scyphoid class. The scyphoid jellyfish class is found in all seas. There are species of jellyfish that have adapted to live in large rivers that flow into the sea. The body of the scyphomedusa has the form of a rounded umbrella or bell, on the lower concave side of which the oral stalk is placed. The mouth leads to the pharynx, which opens into the stomach. From the stomach, radial channels diverge to the ends of the body, forming the gastric system.
In connection with the free lifestyle of jellyfish, the structure of their nervous system and sensory organs becomes more complicated: clusters of nerve cells appear in the form of nodules - ganglia, balance organs - statocysts, light-sensitive eyes. Scyphomedusa have stinging cells located on tentacles around the mouth. Their burns are very sensitive even to humans.
Jellyfish breeding
Jellyfish are dioecious, male and female sex cells are formed in the endoderm. The fusion of germ cells in some forms occurs in the stomach, in others in the water. Jellyfish combine in their developmental features both their own and hydroid signs.
Among the jellyfish there are giants - a fisaria or a Portuguese boat (from three or more meters in diameter, a tentacle up to 30 m), such creatures can even eat a person. Recently, they have been seen near the Sea of Japan, and the Japanese and Chinese, who are trying to cook even with them, have added them to various salads, thereby poisoning quite a few people.
The jellyfish looks flabby, but it is dense to the touch. Although it has neither an internal nor an external skeleton, it retains a certain shape. This is partly due to the fact that the gelatinous mass is permeated with strong connective tissue fibers. In addition, the jellyfish pumps water into itself - in the same way, an inflatable raft becomes rigid when it is pumped with air. This way of maintaining the shape of the body, called the hydrostatic skeleton, is also characteristic of sea anemones and worms.
Jellyfish food
Jellyfish - a predator captures food with tentacles and digests it in the body cavity with the help of enzymes from digestive cells.
Jellyfish movement:
The movement of jellyfish is made by "walking" and "tumbling".
Irritability
Irritability is produced by nerve cells scattered throughout the body.
Meaning: eaten
Some jellyfish are deadly and poisonous to humans. So, for example, when bitten by a Cornerot, significant burns can occur. When bitten by a cross, the activity of all systems of the human body is disrupted. The first meeting with a cross is not dangerous, the second is fraught with consequences due to the development of anophyloxia. The bite of a tropical jellyfish is fatal, and the bite of an ordinary jellyfish passes in 3 days and does not carry any consequences.
Interesting facts about jellyfish
Jellyfish help fight stress! In Japan, jellyfish are bred in aquariums. The smooth, unhurried movements of jellyfish calm people down, although keeping jellyfish is very troublesome and expensive.
The first robot jellyfish appeared in Japan. Unlike real jellyfish, they not only swim smoothly and beautifully, but also, if the owner wishes, they can “dance” to the music.
A certain type of jellyfish is caught off the coast of China and eaten! Their tentacles are removed, and the “carcasses” are kept in a special marinade, which makes the jellyfish turn into a translucent cake of delicate thin cartilage. In the form of such cakes, jellyfish are brought to Japan, where they are carefully selected for size, color and quality. For one of the salads, the jellyfish cake is cut into thin strips about 3-4 mm wide, mixed with steamed vegetables, herbs and poured with sauce.
Jellyfish make a fairly long way of development. The fertilized eggs develop into larvae that swim freely in the water. These larvae attach themselves to the seafloor and grow into polyps. As a result of division, small jellyfish can bud from the polyp. They grow to adult size and reproduce. This process is called "alternation of generations". Almost all jellyfish live in sea water. However, there are also several freshwater species. In Europe, it is a freshwater jellyfish kraspedakusta with a diameter of only 2 cm, living in ponds and shallow lakes. Now it has become a rarity.
Jellyfish are round like a ball, flat like a plate, elongated like a transparent airship, very small, like, for example, a sea wasp, and huge, like a giant of the Arctic waters, a fiery red lion's mane, whose domed body grows up to two and a half meters in in diameter, and bundles of writhing filamentous tentacles, reaching 30 m in length, can cover a five-story house.
Much more modest in size, the jellyfish pelagia, or night light, strikes experienced sailors with a bright light in the middle of the night in the waters of the Mediterranean Sea.
Not everyone knows that the beauty of most types of jellyfish can be very deceptive. Indeed, to a greater or lesser extent, but all jellyfish are poisonous. The only difference is that some species are practically not dangerous to humans, others sting like nettles, and a painful burning sensation can be felt for several days, and still others cause paralysis that can lead to death.
There are also jellyfish that are completely harmless to humans. This is the well-known glassy-white "eared" jellyfish - Aurelia. It lives in all tropical and temperate seas, including ours - in the Black Sea. These are summer animals. Autumn storms bring death to them, so they have adapted, so to speak, to "postpone" their offspring for the winter. In anticipation of cold weather, small, a little more than a centimeter, lumps of living tissue, carriers of the genetic code of Aurelia, settle to the bottom of the sea. They are not afraid of either storms or cold snaps, and with the advent of spring, tiny disks separate from them, which grow into adults in one summer.
By the way, if you rub the body of Aurelia into human skin, it becomes immune to "burning" jellyfish, such as, for example, the same Black Sea rosistoma, in another way - cornerot.
The most dangerous of all existing jellyfish are sea wasps. They are found in the warm waters of the Indian and Pacific oceans. It's hard to believe that this little wad of living slime is actually the real killer. And meeting with him is almost more dangerous than with a shark. The venom of the sea wasp is so strong that, if it enters the bloodstream, it can stop a person’s heart in a few minutes. In search of food, such as demersal shrimp, these deadly creatures sometimes come very close to the shore. As a result, more than fifty people have died in the coastal waters of Australia from the poison of these little killers in recent years.
The largest existing jellyfish is the giant arctic, whose umbrella reaches 2.2 m in diameter; its tentacles are 35 m long. As you can see, even jellyfish can be gigantic! This giantess, as well as many other jellyfish, paralyze their prey with stinging cells. This poison can be very painful and even dangerous for humans. So some caution will not hurt if you meet a jellyfish with long threads in the sea. On the other hand, one should not think that touching each jellyfish threatens to burn.
Speaking of jellyfish, one cannot help but recall their closest relatives - siphonophores, or, as they are also called, Portuguese warships. The elongated bodies of these animals, similar to air bubbles, sway above the water and outwardly really resemble caravels under sail. Thanks to the obliquely placed crest on its float, the siphonophore goes "in full sail", always remaining at an acute angle to the wind. And behind it, like a train, very long (up to 15 meters) and very poisonous tentacles stretch.
The main difference between the Portuguese warship and the jellyfish is that this is not one creature, but a whole community of completely different individuals, each of which has its own task - some control the movement, others catch the prey, others paralyze it, and the fourth digest and share nutrients with all members of the colony.
On the voyage, the Portuguese warship is accompanied by its own "retinue". These are small nomei fish that hide from predators under the reliable protection of long tentacles. The poison of the stinging cells of ships does not affect nimble escorts.
Jellyfish can be dangerous not only for people, but also for ships. Vessel engines are cooled by outboard water, which enters through a special hole in the bottom. And if jellyfish fall into this hole, they tightly block the water supply. The engine overheats and fails until divers clear the live plug.
The Guinness Book lists the hairy jellyfish cyanide, caught in the northwestern part of the Atlantic in 1865. Its hat was 2.28 meters across, and its tentacles extended 36.5 meters. That is, if you stretch the tentacles in different directions, the length of such a jellyfish will be 75 meters. This is the longest animal on Earth!
Since ancient times, people have known strange shapeless sea animals, to which they gave the name "jellyfish" by analogy with the mythological ancient Greek goddess Medusa Gorgon. The hair of this goddess represented a moving bunch of snakes. The ancient Greeks found similarities between the evil goddess and sea jellyfish with poisonous tentacles.
The habitat of jellyfish is all the salty seas of the oceans. Only one freshwater species of these marine inhabitants is known. Each species occupies an area limited to one body of water and can never be found in another sea or ocean. Jellyfish are cold-water and thermophilic; deep-sea and those that keep near the surface.
However, at the surface, such species swim only at night, and during the day they dive to the depths in search of food. The horizontal movement of jellyfish is passive in nature - they are simply carried by the current, sometimes over long distances. Due to their primitiveness, jellyfish do not contact each other in any way, they are solitary animals. Large concentrations of jellyfish are explained by the fact that the current brings them to places rich in food.
Due to the highly developed colorless mesoglea, the body of the flower cap jellyfish (Olindias formosa) looks almost transparent. Varieties of jellyfish
More than 200 species of jellyfish are known in nature. Despite the primitive structure, they are very diverse. Their sizes vary from 1 to 200 cm in diameter. The largest jellyfish is the lion's mane (cyanoea). Some of its specimens can be up to 1 ton in weight and with a tentacle length of 35 m.
Jellyfish are shaped like a disk, an umbrella or a dome. Most jellyfish have a transparent body, sometimes with bluish, milky, yellowish hues. But not all species are so inconspicuous, among them there are truly beautiful, bright colors: red, pink, yellow, purple, speckled and striped. Green jellyfish do not exist in nature.
Species such as Aequorea, Pelagia Nightlight, Ratkeya can glow in the dark, causing a phenomenon called bioluminescence. Deep-sea jellyfish emit red light, floating near the surface - blue. There is a special kind of jellyfish (stauromedusa) that hardly move. They are attached to the ground with a long leg.
The structure of jellyfish
The internal structure and physiology of jellyfish are uniform and primitive. They have one main distinguishing feature - the radial symmetry of the organs, the number of which is always a multiple of 4. For example, a jellyfish umbrella can have 8 blades. The body of a jellyfish has no skeleton, it is 98% water. Cast ashore, the jellyfish is not able to move and instantly dries up. Its consistency resembles jelly, which is why the British called it "jelly fish".
The tissues of the body have only two layers, which are interconnected by an adhesive substance and perform different functions. The cells of the outer layer (ectoderm) are “responsible” for movement, reproduction, and are analogues of the skin and nerve endings. The cells of the inner layer (endodermis) only digest food.
The outer part of the body of jellyfish is smooth, mostly convex, the inner (lower) shape resembles a bag. The mouth is located at the bottom of the dome. It is located in the middle and is very different in structure for different types of jellyfish. The umbrella is surrounded by trapping tentacles, which, depending on the species, can be either thick and short, or thin, filiform, long.
What do jellyfish eat
Jellyfish are predators, they consume only animal food (crustaceans, fry, small fish, caviar). They are blind and have no sense organs. Jellyfish hunt in a passive way, catching with their tentacles the edible that the current brings. Trapping tentacles kill prey. This is done in different ways.
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! Some types of jellyfish inject poison into the victim, others stick prey to the tentacles, others have sticky threads in which it gets tangled. The tentacles push the paralyzed victim towards the mouth, through which the undigested remains are then excreted. It is interesting that jellyfish living at depth attract prey with their bright glow.
How jellyfish breed
Jellyfish have vegetative (asexual) and sexual reproduction. Outwardly, males are no different from females. Spermatozoa and eggs are released into the water through the mouth, where fertilization takes place. After this, a larva (planula) develops. The larvae are not able to feed, they settle to the bottom and a polyp is formed from them. This polyp can reproduce by budding. Gradually, the upper parts of the polyp separate and float away; these are actually young jellyfish that will grow and develop.
Some species of jellyfish lack the polyp stage. Juveniles immediately form from the planula. There are also species in which polyps are already formed in the gonads, from which small jellyfish are born. From each egg in jellyfish, several individuals are formed.
The vitality of jellyfish
Although jellyfish do not live long - from several months to 2-3 years, their numbers are very quickly restored even after various cataclysms. Their reproduction rate is very high. Jellyfish quickly restore lost body parts. Even if they are cut in half, two new individuals are formed from the halves.
It is interesting that if such an operation is performed at different ages of the jellyfish, then an individual of the corresponding stage of development grows out of the tissues. If you divide the larva, then two larvae will grow, and from the adult parts - jellyfish of the appropriate age.
Medusa swimming upside down Jellyfish and people
Some types of jellyfish are dangerous to humans. They can be roughly divided into two groups. Some cause allergies, the poison of others acts on the nervous system and can cause serious disorders in the muscles and heart, and in some cases death.
In order not to put yourself in danger, you need not touch the jellyfish, both living and dead. In case of a burn, wash the injured area with water, and preferably with a solution of vinegar. If the pain does not subside and there are complications, you should immediately call a doctor.
Hello my dear friends! In order to maintain our erudition at the proper level and not let us relax over the summer, I propose a topic from the field of knowledge. The material will later be useful to our children in the lessons of the world around them.
And today we will talk about sea jellyfish. Do you agree? Moreover, for those who have a trip to the sea ahead, it may be interesting to combine theory with practice, getting to know these amazing inhabitants of the water element better.
Lesson plan:
Who is she, unknown animal?
Marine animals with streamlined shapes, outwardly similar to an umbrella, with many tentacles have been living among us for a long time. The name of these maritime miracles was given in the 18th century by Carl Linnaeus, who was well acquainted with the Homeric legends about the mythical gorgon Medusa.
He noticed a certain resemblance to the head of this evil ancient Greek maiden, whose hair was composed of many moving snakes. It is because of this similarity of tentacles with her head that the animal got its name.
And today, those who have visited the sea more than once, probably met with them in the process, trying to swim around this living creature. And all because jellyfish have special stinging cells with which they “bite” painfully, mercilessly burning us, well, their prey at the same time and predators attacking them.
Do you know that?! A jellyfish with an unusual name, Turitopsis Nutricula, is considered the only immortal creature of its kind on our planet. And on average, almost all jellyfish live no longer than six months, centenarians live up to three years. Only a few species do not die, but are reborn into a new living organism.
Speaking in the language of zoologists, these marine inhabitants are none other than intestinal animals that are part of the group of multicellular invertebrates. That is why they spread so shapelessly like jelly, falling on a hard surface or in our hands - there is nothing to hold on to the fabrics!
What, what, what are our jellyfish made of?
What is a skeletal jellyfish made of? Yes, from the water! And by 98 percent! Therefore, if you put it to bask in the sun, then almost all of it will melt - it will dry out. And muscles help her move in the water.
From the edges of the body of the jellyfish are tentacles. They can be long and thin, some have short thick “legs”. According to these same tentacles, zoologists divide them into species. But no matter how many "legs" this invertebrate has - four or one hundred and four - their number is always a multiple of four. Why? This is how nature arranged it - this feature is called radial symmetry in such representatives of animals.
It is on these very tentacles that those ill-fated stinging cells containing burning poison are located.
Do you know that?! The jellyfish with the name Sea wasp is considered the most poisonous in the world among its relatives. This basketball-sized invertebrate nipper is so powerful that it can kill 60 people in a couple of minutes!
Medusa breathes underwater with her whole body, and looks at others with 24 eyes at once, which are light-sensitive cells. True, scientists say that these invertebrates cannot distinguish objects, but they are able to distinguish light from darkness.
But thanks to these special cells, many specimens glow beautifully in the dark. Those that live higher to the surface of the water know how to wink in red, and those that prefer to hide at a depth warn of their presence more often with blue light.
Jellyfish also have mouths. It is located in the lower part and may look like a tube for some, like a mace for others, and for others it can simply be a wide hole. By the way, through which the jellyfish eats, through which it throws the remnants of food into the water.
A jellyfish has a lot of things, but there is no brain! Nature did not reward the primitive being created by it with the ability to think, think, dream, and did not give sense organs either.
How does a jellyfish live?
Jellyfish can live exclusively in salt water, so you will never meet them in fresh rivers and lakes. But the oceans and seas, and not necessarily warm at all, there are those who like colder water - this is their favorite place to live.
This creature grows throughout its unconscious life and, depending on the species, it can be small, only a few millimeters, or huge, as much as two meters. The weight of some individual specimens can be several centners! Such a straight Bolshukhansky floating jellied meat!
Do you know that?! If you measure the size of a resident of the Northwest Atlantic called Cyanea (in English Cynea) along with e tentacles, then we get a figure of almost 40! meters.
This creature without brains and skeleton is a real predator! The largest sizes catch small fish and even eat their relatives. Smaller specimens are content with crustaceans and fish fry and caviar. “How is it that a jellyfish that does not distinguish any outlines is looking for food?” - you ask. With the help of those very terrible and dangerous stinging cells on the tentacles, which catch touches and without thinking, since they have nothing to think about, they instantly inject poison into the victim. Medusa thus paralyzes prey, and then begins to regale.
Now you understand that when you touch the body of a jellyfish while swimming, in the first seconds it sees another lunch or dinner in you, burning with poison! Some use their tentacles as a net to catch their prey.
Scientists have noticed that jellyfish are by nature loners. Of course, who would be friends with such gorgons! If you see colonies of accumulated umbrella hats, then they have gathered together not at all because they want to "drink tea and talk." They just got bogged down by the currents of water. So they prefer to keep their distance from each other.
What are jellyfish?
As we have already mentioned, they are divided into species by tentacles. So, here are their families.
In total, in the nature of the world's oceans, there are more than two hundred varieties of jellyfish of all shapes and colors. There are completely transparent, and red, and purple, and even spotted and striped, but there are no green ones! Why is unclear...
In general, these natural creatures are amazingly beautiful, especially when you watch them slowly floating through the water column from the side. Doubt? Rather, go to the aquarium and admire this beauty. No side by side? Then the Internet will always help you to touch the beautiful at a distance of thousands of kilometers!
For today, probably, erudition is enough?! It's time to relax, because it's still summer!
Although a video about jellyfish, most likely, will not hurt)
Have a great August!
Medusa cannonball
The cannonball jellyfish lives along the East Coast of the United States as far as Brazil. It got its name because of its unusual shape, perfectly smooth and round, like a cannonball. In Asian countries, these jellyfish are widely used in folk medicine. It is believed that they can cure lung disease, arthritis, lower blood pressure.
Olindias formosa (Olindias formosa)
This rare species of jellyfish is found off the coast of Brazil, Argentina, and Japan. Characteristic of these jellyfish is hovering at shallow depths. When the jellyfish is in this state, its tentacles are concentrated under the cap. Due to the small number of this species does not pose a danger to humans, but we should not forget that they are able to leave very severe burns.
portuguese boat
This amazing creature differs from all jellyfish in that it consists of many medusoid individuals. It has a gas bubble, floats on the surface of the water, which allows it to absorb air. The tentacles of the Portuguese boat in an extended state can reach 50 meters.
purple striped jellyfish
This type of jellyfish can be found in Monterrey Bay. They have not yet been well studied. This jellyfish is quite large and can cause serious burns to a person. Stripes and color saturation appear in jellyfish with age. In the course of warm currents, the jellyfish can also migrate to the shores of Southern California. This was especially noticeable in 2012, when 130 people received jellyfish burns (black sea nettle and purple striped).
Mediterranean or medusa fried egg
This amazing creature really resembles a fried egg, or a poached egg. Jellyfish lives in the Mediterranean, Adriatic and Aegean seas. Its important feature is that it can move independently, without relying on the waves.
Darth Vader or drug jellyfish
This species of jellyfish was found in the Arctic. It happened quite recently. In addition to such an interesting and at the same time terrifying look, the jellyfish has 4 tentacles and 12 stomach sacs. While swimming, the tentacles are retracted forward to better reach their prey.
blue jellyfish
The blue jellyfish has very stinging tentacles. It has been found off the coast of Scotland, in the North Sea and in the Irish Sea. The average transverse diameter of this jellyfish is 15 centimeters. The color varies from dark blue to bright blue.
porpit porpit
It's not exactly a jellyfish. More commonly, this creature is known as the blue button. Porpit lives on the surface of the ocean, consists of two parts: a hard golden-brown float and hydroid colonies, which in their appearance are very similar to the tentacles of a jellyfish. Porpita can be easily confused with a jellyfish.
Diplulmaris Antarctica
This magnificent creature lives in the deep waters of Antarctica and has four bright orange tentacles as well as white tentacles. The little white dots on the jellyfish are the side pieces. They live in a jellyfish, and sometimes even feed on it.
Black sea nettle
The black sea nettle is a giant bell-shaped jellyfish, 3 feet in diameter. An adult can reach 5 meters and have 24 tentacles. This type of jellyfish was found in the waters of the Pacific Ocean. they are carnivores. In food they prefer larvae, plankton, and other jellyfish.
Titles: common jellyfish, aurelia eared, eared jellyfish, moon jellyfish.
Area: Pacific, Indian and Atlantic Oceans.
Description: The common jellyfish (Aurelia eared) 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 are numerous short hollow tentacles and eight marginal bodies (ropalia). Ropals are the sense organs of the jellyfish and determine its position in the water and the rhythm of the contractions of the umbrella. Four thickened mouth arms, each with a central furrow flanked by more diluted rolled lips. Capturing infrasounds, ropalia warn the jellyfish about the approach of a storm and allow it 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 underside of the body, it leads into the pharynx, from which the intestinal cavity begins. Undigested residues are removed through the mouth. The nervous system of the jellyfish is more developed than that of polyps. In addition to the nerve plexus, most developed in the tentacles and on the underside of the umbrella, two nerve rings run along its edge. Sex glands 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.
The 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 optimum temperature is 9-19" C.
Enemies: moon fish, Pacific jellyfish, sea turtles, birds.
Food/food: digestion intra- and extracellular. The common jellyfish captures its prey with its tentacles. It preys on planktonic crustaceans, aquatic insect larvae, fish fry, hydromedusas, ctenophores, copepods, rotifers, nematodes, young polychaetes, protozoa, diatoms.
Behavior: moves in the water according to the reactive principle, pushing water out of the body cavities. The jellyfish floats horizontally in the water column.
Social structure: single organism.
Reproduction: an ordinary jellyfish reproduces sexually. Jellyfish with purple or pink gonads are males, and with yellow gonads they 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 - planula, which attaches to underwater objects and there turns into a single polyp. The polyp subsequently proceeds to asexual reproduction. It breaks up into several disks that turn into jellyfish. So in jellyfish there is an alternation of generations: asexual (polyp) and sexual (jellyfish). The life cycle is dominated by the jellyfish form, while the polyp is a short-lived form of existence.
Season/breeding period: autumn.
Puberty: about 2 years old.
Offspring: from fertilized eggs, larvae are formed - planula, covered with cilia.
Benefit / harm to humans: common jellyfish eats fish fry. In Asian countries (China, Philippines, Thailand, Malaysia, and Indonesia) it is eaten.
Population/conservation status: the population is large.