Jellyfish are mysterious loners. Report on the topic “Jellyfish

Goals:

Expand and deepen children's understanding of jellyfish.
Show children natural connections in nature.
Dictionary: scuba.
Develop the fine muscles of children's hands.
Cultivate an interest in nature, a desire to learn something new about it.

Equipment:

Photos of jellyfish, a painting of an underwater seascape, paper, scissors, glue, brushes, napkins.

Aurelia jellyfish

Cornermouth jellyfish

Progress of the lesson:

Today we will take a trip to the underwater sea kingdom.
But can a person stay under water for a long time? Why? (Children's answers). Of course, we all need air to breathe. Do you know what device a French explorer came up with in order to stay under water for a long time? (Children's answers). This device is called scuba gear. We have come across words starting with “aqua” more than once. Remember them. (Children's answers). Aquarium, water park, watercolor. The meaning of these words is somehow connected with water. “Aqua” is water, only in a different language, in Latin.

Put on your scuba gear and let's dive into our sea. What's it called? (Children's answers). (Imitation of putting on scuba gear and diving).
Who can we meet in the waters of our Black Sea? (Children's answers). There are dolphins, mussels, rapana, katran, and anchovy.
And here is the mysterious jellyfish. Take a look at the picture.

In summer and autumn there are many jellyfish off the coast of Crimea. They clog fishing nets, disturb those swimming in the sea, and sometimes waves wash them ashore. They were called differently: sea lard, sea moon, sea heart. Why do you think? (Children's answers).

Many different small jellyfish live in our sea, and there are also large ones. They are armed. They have stinging cells under their umbrella. Take a look at the photo. Here they are, looking like tentacles. If an enemy approaches the jellyfish, it can burn him with its stinging cells. This burn resembles a nettle burn. Hence the names of jellyfish such as stinging nettle and sea nettle. For jellyfish enemies this burn is dangerous, but for humans it is not so dangerous, but painful. So when you meet a large jellyfish, look at it, admire it, but do not approach or touch it.

Jellyfish move by contracting their umbrellas. Connect the fingertips of both hands and round your palms so that you get a hemisphere - that’s the jellyfish umbrella. Now try to show how it contracts. Here the jellyfish swims slowly, but here it swims faster. (Finger gymnastics is performed). And now the jellyfish is swimming fast. There will be a storm at sea soon. How many of you know what a sea storm is called? (Children's answers). Shortly before a storm, jellyfish swim away from the shore. Scientists have noticed this and use it to warn of an impending storm.
Previously, it was believed that a jellyfish had no eyes and therefore could not see anything. But one Russian scientist carefully observed jellyfish and noticed that they were moving out of the darkness towards the light. So, jellyfish see the light! But no one believed this scientist. But he didn’t give up and found jellyfish eyes on their tentacles. It’s not for nothing that they say: “patience and work will grind everything down.”

And now the game. Stand in a circle and take the ball. You already know a lot about nature. For example, that everything in nature is interconnected, someone takes care of someone, someone eats someone. The person to whom I throw the ball must continue my sentence.

1. The hare is food for... (wolf, fox).
2. Honey is ... (the bear’s) favorite treat.
3. They eat insects - ... (birds).
4. The cormorant sea raven eats - ... (fish).
5. Deer eat - ... (grass).
6. Plankton is food -... (whales).
7. They feast on fish - ... (sharks, seagulls, etc.)

Imagine that no one eats jellyfish. These are these amazing creatures that no one will encroach on them. Except for the person. In China and Japan they eat jellyfish. And the jellyfish themselves eat plankton. But young mackerel fish are hiding under the umbrellas of jellyfish. Until they grew up and gained strength. Would you like to predatory fish feast on the babies, but they are afraid of jellyfish stinging cells. When horse mackerels grow up, they leave their shelter under the umbrella of the jellyfish and pay her with black ingratitude: they bite off the edges of the umbrella. That's how good is paid for with evil.

Paper construction “Medusa”

Now I want to invite you to make a jellyfish out of paper. With the help of scissors, glue and, of course, your skillful hands, we will make a jellyfish like this. (Paper construction. Examination of crafts.)

Questions:

1. How does a jellyfish protect itself from enemies?
2. What does a jellyfish eat?
3. Who eats the jellyfish itself?
4. What is the name of the device for a person’s long stay under water?
5. Who takes refuge under the jellyfish's umbrella?
6. How does a jellyfish move?
7. What do you know about the eyes of a jellyfish?
8. When do jellyfish swim away from the shore?
9. What names were given to the jellyfish?

You can invite children to write stories about the adventures of a jellyfish, draw illustrations, and put them in a book.

The Legend of the Jellyfish: "Heart of the Sea"

One day two brothers were swimming in the sea. The eldest, when he had taken a swim, quietly swam to the shore, and the younger one swam further and further from the shore. And fell in love sea wave brave brother: she took him, hugged him tightly and pulled him to the bottom, into the underwater kingdom of the sea.
The boy resists, screams, calls his brother for help. And the eldest is afraid to swim. He thinks: “It’s deep there, I’ll drown with him!”
- Oh, my dear brother! Oh, beloved brother, save me! – last time The boy emerged, shedding tears.
“Let God save you,” the elder said cowardly, but he himself did not dare to look at how his brother was drowning, and quickly rowed to the shore and climbed onto a stone.
The wave got angry and chased the coward, caught up, carried him into the sea and drowned him.
The sea queen sheltered her younger brother at the bottom. And she turned his tears into sparkling pearls, and his curls into corals. And the older brother of the fish and crayfish was stolen to the ground. Only no one wanted to touch the heart: this cowardly heart was so vile.
Since then, that heart has appeared in the sea. It swims timidly, furtively, slippery, cold, stinging, like nettles, it moves sluggishly, trembles, there is not even a shadow from it - transparent. But the sea disdains the heart: it throws it onto the shore, and there it dies without a trace.

The outstanding Swedish scientist and naturalist Carl Linnaeus named this amazing animal a jellyfish in 1752. This was caused by the similarity of its tentacles to the moving snakes - the hair of the legendary heroine Greek mythology, whose gaze turned a person to stone.

What is a jellyfish

Jellyfish are free-swimming, jelly-like marine animals. They are considered to be the oldest on Earth with a history dating back 650 million years. The number of their species is enormous, but scientists regularly note the emergence of new ones, previously unknown to people. They are distributed from the surface layers to the great depths of the World Ocean.

Some jellyfish live in fresh water. They are small, no more than 2.5 cm in diameter, colorless and cannot sting. Their body is formed from an umbrella-shaped cap and antennae-like tentacles. The cap, whose muscles contract, provides jet propulsion in water, antennae are usually designed to capture prey. They are equipped with special cells with burning poison.

Name, reproduction, development, nutrition and other features

Jellyfish is an extraordinary creature that never ceases to amaze people with its features. Here are some of them.

After the fusion of the sperm of male jellyfish and the eggs of female jellyfish, a larva called a planula appears. It is located at the bottom, gradually turning into an asexual polyp. When fully mature, the next generation of jellyfish breaks away from it. There are jellyfish that can reproduce by fission.
Female jellyfish are known to produce over 40 thousand larvae per day.
Jellyfish eat small organisms called plankton that drift freely with the current. They can be algae, bacteria, mollusks, fish eggs, and invertebrate larvae.
Jellyfish do not have a circulatory, nervous, excretory or respiratory system, or a brain. They grow throughout the entire period of their existence.
Only two percent of a jellyfish's body is not water. Their life on the shore, where they die, is impossible.
In some East Asian countries, certain types of jellyfish are considered a delicacy.
They feed on fish and animals living on the surface of the water or in its depths.
Jellyfish have the ability to accumulate in huge masses. Such phenomena are called flower beds or swarms.
Heavy, prolonged rains negatively affect the number of jellyfish in the seas and oceans.
For hunting and protection, jellyfish have tentacles covered with poison-containing cells that can stick into the body of the victim, immobilize or entangle it.

Big, small, poisonous and glowing

It is known that the world's largest jellyfish reach a diameter of 2.5 meters, having tentacles more than 40 meters long.

The largest jellyfish include giant jellyfish, which are common in the Yellow and East China Seas. Reaching a diameter of 2 meters, such a creature can weigh up to 200 kg. Their numbers are constantly growing, which creates problems for fishing. In 2009, nets overflowing with these jellyfish caused a small fishing vessel to capsize.

The jellyfish, called the lion's mane, also has the same size. It is common in surface layers of water near the shores of the northern Atlantic and Pacific oceans. The length of its tentacles can be up to 33 meters.

One of the fairly large jellyfish, called Australian spotted, poses a danger to fisheries. She passes over 13 tons of water through herself per day, while swallowing caviar commercial fish and other marine life.

The most dangerous poisonous ocean animal is the jellyfish that lives off the coast of Australia and Indonesia, called sea wasp. Its dome, almost invisible in sea water, reaches 30 cm in diameter. The cells covering the tentacles contain strong poison. It almost instantly affects the cardiovascular and nervous systems, as well as the skin. There are examples where a person died a few minutes after touching this animal.

IN recent years in the waters of oceans and seas in tropical and subtropical zones a jellyfish called the “Portuguese man-of-war” or physalis. In fact, this is not a single jellyfish, but a community of them gathered in one place. Its tentacles can stretch for fifty meters. The toxicity of their burn is comparable to a bite poisonous snake, which is especially dangerous for people with allergic problems, children and the elderly. However, deaths resulting from such contact are not common.

The smallest jellyfish include the Antarctic jellyfish with a diameter of 4 cm. It was recently discovered by researchers in the waters off the ice continent. Not larger size reaches a cross jellyfish living in sea grass off the coast Pacific Ocean and western Atlantic.

It got its name because of the cross-like pattern formed by colored internal organs, running along four channels digestive system. The cross is clearly visible through the transparent umbrella of the animal, along the edges of which there are tentacles capable of causing severe pain with their poisonous cells.

Some types of jellyfish are able to glow and change color. Thus, many of the “comb jellies” that live almost all over the world have bioluminescent properties. These creatures are called so because of their resemblance to a comb. In fact, these are peculiar tentacles with which they move. They can reach one and a half meters in size. Some of their ctenophores live at great depths.

Other bioluminescent jellyfish or "crystal" jellyfish are often found off the Pacific west coast of the United States, in the Bering Sea.

has the amazing ability to transform its color from bright red to black. This is a fairly large animal with a bell one meter in diameter and tentacles six meters long.

About jellyfish for children

This article provides information about jellyfish for children

One of amazing facts O jellyfish is that they are 95% water. Would you believe that the most big jellyfish grows up to 183 cm in diameter including tentacles, and its body length is about 30.5 m?

Considering them bright appearance It's hard to believe that some of these almost transparent jellyfish can bite people and cause death. Fortunately, not all jellyfish are poisonous and/or dangerous to humans. The poison is injected to paralyze the prey before it is eaten. There are over 2,000 species of jellyfish, learning the facts about jellyfish captivates many avid marine biologists. More information You will find more about jellyfish for children below.

Fun facts about jellyfish for kids

Jellyfish belong to the type Cnidaria, the characteristic feature of which is gelatin-like inanimate body located between the epithelial layers. According to evolutionary studies, these curious marine animals appeared on Earth before the massive reptiles (dinosaurs). Since then they have survived under various water conditions, in cold and warm waters, in shallow water and in deep sea water. Next, learn some amazing facts about jellyfish for kids.

Jellyfish. Color and size Depending on the type of jellyfish, their color can be white, pink, yellow, orange, red, blue, green and multi-colored. Would you believe that the width of the largest jellyfish, the box jellyfish, is about 183 cm? Their variable size and radially symmetrical body are also their distinguishing characteristics. Some types jellyfish in diameter can be about 2.5 cm, the size of others can reach 4 m. The length of the tentacles, depending on the species, can also differ; in some species of jellyfish, the length of the tentacles can reach 30.5 m.

Jellyfish. Nutrition At the bottom of the dome-shaped or bell-shaped body is the mouth of the jellyfish, surrounded by tentacles. So what do jellyfish eat? They are true carnivores, feeding on small marine organisms, zooplankton, ctenophores, crustaceans and sometimes others jellyfish. After absorbing useful nutrients, waste is released through the mouth. Predators of jellyfish are sunfish, sea turtles, Plataxidae and large marine animals.

Jellyfish. Movement The movement of jellyfish is largely dependent on ocean currents, tides and air currents. Although they are less capable of horizontal locomotion, jellyfish can control vertical movement through muscle contractions. Some of them are sensitive to light and swim below during the daytime. Jellyfish constantly need water to survive. Lack of water leads to desiccation and death of these gelatinous marine animals.

Poisonous jellyfish You may have seen a jellyfish with a body structure similar to a cubic umbrella. These jellyfish are box jellyfish. An important fact What children should be aware of is that they are naturally venomous and they produce painful stings. U box jellyfish there are several tentacles, each of which has approximately 500,000 nematocytes. These special cells contain poison for the bites of predators and people who come across the jellyfish.

One of the types box jellyfish, known as « sea wasp»(scientific name Chironex fleckeri) is considered the most poisonous species, due to the largest number deaths from him. In the Philippines, the number of deaths from this deadly jellyfish is 20-40 per year. To others poisonous species The jellyfish are the Irukandji jellyfish Malo kingi and Carukia barnesi.

Treatment of jellyfish stings Fortunately, box jellyfish do not intentionally attack people. However, anyone who accidentally gets too close to its tentacles may be bitten by this jellyfish. There are some alarming facts about jellyfish for children. To save a person's life, immediate treatment for a jellyfish sting is required. An effective remedy first aid is to pour some water on the bite site small quantity vinegar. If the wound is left untreated, the poison can soon impair heart function. The jellyfish's venom is neurotoxic and can kill a child within three minutes.

Jellyfish as food Jellyfish eaten in many parts of the world. On international market Non-poisonous species of jellyfish are available for culinary purposes. After catching jellyfish, a procedure follows for their preparation, during which their mucous lining and gonads are removed. The remaining edible parts are treated with salt and alum mixture. The final product sold in the market is salty and crunchy in taste.

Information about eared aurelia also quite interesting for children. long-eared aurelia also bites, but its bite is more painless and short-term. This is a type of small jellyfish that natural environment habitats barely survive 6 months. The causes of death after reproduction are: lack of food, high temperature and illness. However, in a controlled aquarium environment where there are no predators or competition for food, they can live for years.

Isn't this information about jellyfish interesting for children? Most important information The thing about jellyfish is that they have a transparent body and poisonous tentacles that are difficult for swimmers and divers to see. If they happen to swim near the jellyfish, it only takes a few seconds for the jellyfish to inject its venom from its tentacles. To avoid such occurrences, people should take precautions before diving in areas where there are many jellyfish.

Jellyfish - very amazing creatures, causing 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 life cycle 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.
Medusa " 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 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 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 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. Feature- 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. It's pretty 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. Typically, purple-striped jellyfish 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, general director 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. Possible reasons population growth, scientists believe climate change, overexploitation water resources and pollution environment. 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 family Ulmáridos, 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 wildlife 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 necessary. 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. Most often found in tropical and subtropical regions of the Pacific and Indian Oceans and in the North Atlantic Ocean. IN lately 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 coastal waters tropical and temperate zones. 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. At the same time, 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(lat. Ctenophora) - jellyfish-like organisms that live in sea waters almost all over the world. Distinctive feature of all ctenophores - a kind of “combs”, groups of fins-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 south basin 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, you should resort to a proven method - treat the skin with vinegar or citric acid in order to prevent possible allergic reactions. Recently recorded mass reproduction Australian jellyfish, 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 widespread in all northern seas Quiet and Atlantic Oceans, lives near the coast in surface layers of water. Bell of Arctic cyanea (subspecies hairy cyanea) can reach up to 2 meters in diameter, and the length of the tentacles is up to 33 meters. Lion's mane generally considered a moderately stinging jellyfish. The burns it inflicts are quite painful, and the toxins contained in the poison can cause 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

Among marine inhabitants, jellyfish are one of the most mysterious creatures. Meeting them can pose a mortal danger to humans, but even this does not stop researchers from trying to observe the life of these creatures and learn about how they live, reproduce, and feed. We offer a selection interesting information, which is known to the science of jellyfish.

One of the oldest and simplest organisms

Jellyfish are among the oldest organisms, with a history of existence of about 650 million years. They got their name in the 18th century. thanks to Carl Linnaeus, who saw their resemblance to the mythical Medusa Gorgon with snake-hair moving on her head. In American public aquariums, the term “jellyfish” is often used to refer to these creatures, although these creatures have nothing to do with fish.

These simple organisms lack cardiovascular, respiratory and central nervous systems. The functions of the latter are performed by nerve networks located in the epidermis, which make it possible to detect the touch of another or an organism. Respiratory functions are performed by thin skin, which absorbs oxygen over its entire surface directly from the water.

Since they are primitive creatures, they do not communicate with each other in any way, even when sea currents knock them into large groups. Such clusters are called a swarm.

Body structure

Their body is 95-98% water, so existence outside aquatic environment impossible. It can be dome-shaped, umbrella-shaped, or disc-shaped and consists of a jelly-like substance called mesoglea. In the center of the lower part is the mouth, which is used both to absorb food and to remove its remains from the body. There are tentacles along its edges. Their type and quantity varies depending on the species: they can be thick and short or thin and long.

Interesting! The number of tentacles ranges from 4 to several hundred, but their number is always a multiple of 4, since these creatures are characterized by radial symmetry.

The tentacles are equipped with stinging cells containing poison. They make hunting easier and also perform a protective function, thanks to which these protozoa do not have many natural enemies.

Relationship with corals

No matter how surprising it may sound, but jelly-like sea creatures and corals are close relatives. Both species belong to the marine animals of the coelenterate class. An even more interesting fact is that corals and jellyfish have common parent– polyps. For coelenterate animals, two forms of existence are possible:

polypoid - inherent in polyps and corals;
medusoid - inherent in jellyfish, which are organisms derived from polyps.

On the left is Physalia (Physalia aretusa) - a colony of polyps, on the right is a jellyfish

The life cycle of medusoids begins with planulae - eggs fertilized by males. They drift freely in the water until they catch on a solid object: a reef, bottom, rock. Having attached itself to it, the planula forms a polyp. After several months or even years, the future body of the jellyfish is separated from it by the budding method of ether, which will eventually turn into an adult organism.

Animals with "light"

These sea creatures do not have a central nervous system and sensory organs, but thanks to photosensitive cells they are able to distinguish light from darkness and navigate through the water column. Some of them have an interesting ability to glow in the dark, which allows them to lure prey in dark sea depths. The body of luminous varieties contains a substance called luciferin, which is oxidized by luciferase and emits bright light. The color of the glow can be yellow, green, blue or cyan.

Unusual poison delivery system

Most poisonous animals release their venom when they bite the “prey.” But this does not apply at all to jellyfish and other coelenterate organisms. Over millions of years of evolution, nature has awarded them with special organs - nematocysts - capsules with a poisonous liquid. The contact of the tentacles with the intended prey activates the nematocysts, and they release thousands of microdoses of poison into the victim’s body. This process lasts about 3 milliseconds and is considered one of the fastest actions among living organisms.

The effect of the poison kills small animals, and can have a paralyzing effect on large ones, which allows them to escape in case of danger. Some representatives of the species are “armed” the strongest poisons, which are among the most toxic natural substances in terms of danger to humans.

An interesting fact is that the tentacles of poisonous individuals pose a danger not only during the life of jellyfish, but also for a long time after their death.

Method of transportation

Despite the simplicity of their body structure, jellyfish are able to move in water independently, although they do so very slowly. Muscle fibers are used for these purposes. Working like a pump, they draw water into their dome and then contract and throw it out. As a result, a powerful recoil is formed, pushing the animal in the direction opposite to the release of water. In this case, jelly-like bodies can move up, down or diagonally, but are not able to move in the horizontal plane. They use their ability quite rarely and prefer to remain idle most of the time, drifting along with the ocean current.

Benefit for humanity

In the selection of the most interesting facts about jellyfish, it is worth mentioning their use for the benefit of people. Back in the Middle Ages, some varieties were used to make laxatives and diuretics. Today, the venom from the tentacles is used as a raw material in drugs to regulate blood pressure and treat lung diseases. Farmers who farm on the Caribbean islands use physalia poison as a poison for rodents.

The Japanese are confident that these simple sea creatures can help in the fight against stress. They are bred in special aquariums, which is quite a troublesome and expensive task. But in Japan they consider this to be completely justified, since the smooth and measured movements of jellyfish domes have a calming effect on people.

In Japan, as well as China, Korea and Indonesia, they are called “crystal meat” and eaten. Only the “umbrellas” themselves are considered edible, while the tentacles are usually thrown away.

Unique representatives

Currently, science knows about 3,000 species of these simple creatures. Not all of them belong to well-studied organisms, since many live at depths of up to 10,000 km. Among this diversity, the most interesting individuals deserve special attention, facts about which force us to take a fresh look at jellyfish.

The biggest

The hairy cyanea is the most gigantic creature, perhaps not only among jellyfish, but among all creatures. In 1865, an individual with a dome of about 2.28 m and a tentacle length of 36.5 m was discovered on the shores of Massachusetts Bay, while until that time the main record holder among animals was considered blue whale with a body length of up to 34 m. Cyaneas live in cold waters. Like many of their relatives, they are poisonous, but do not represent mortal danger for a person. The poison only causes a painful burning sensation and blisters on the skin.

The smallest

Irukandji are miniature creatures with a 12-20 mm dome and long transparent tentacles up to 1 m long. Despite their mini size, they are deadly to humans. Their venom is 10 times more toxic to the body compared to cobra venom. At the same time, it has a delayed effect, so doctors often fail to connect its effect with an irukandji bite. The list of symptoms includes excruciating pain in the back and joints, profuse sweating, nausea and vomiting, and tachycardia.

The most dangerous

The sea wasp is one of the most dangerous organisms for humans living on our planet. Even a light touch from a sea wasp's tentacles can be fatal, and in total the poison in its body is enough to kill at least 50 people. Interesting fact: the size of the wasp's tentacles is 10-20 cm in length and 5 mm in thickness, but during an attack they can stretch up to 3 m, turning into thin needles. Dangerous jellyfish live in the warm waters of Australia and Oceania. Main danger for swimmers and divers is that the sea wasp is almost transparent, so it is difficult to notice in the water column.