The Scyphoid class includes jellyfish that inhabit the seas and oceans (they live only in salt water), which are able to move freely among the expanses of water (with the exception of the sessile jellyfish, which leads a sedentary lifestyle).

general characteristics

Scyphoid jellyfish live everywhere; they have adapted to life in cold and warm waters. There are about 200 species. They are transported over considerable distances with the current, but can also move independently. Thus, with the help of active contractions of the dome and the release of water from it, the jellyfish can develop greater speed. This method of movement was called reactive.

The jellyfish has the shape of an umbrella or a longitudinally elongated dome. There are quite large species. Some representatives of the scyphoid class reach 2 m in diameter (Cyanea arctica). Many tentacles extend from the edges of the bell, which can grow up to 15m in length. They contain stinging cells that contain toxic substances necessary for protection and hunting.

Structural features

In the middle of the inner concave part of the umbrella there is a mouth, the corners of which turn into oral lobes (necessary for capturing food). In rootostomes, they grow together and form a filtering apparatus for absorbing small plankton.

Scyphoids are endowed with a stomach with 4 pocket-like protrusions, and a system of radial tubules, through which nutrients from the intestinal cavity are distributed throughout the body. Undigested food particles are sent back to the stomach and eliminated through the mouth.

The body of jellyfish consists of two layers of epithelial cells: ectoderm and endoderm, between them is mesoglea - jelly-like tissue. It consists of 98% water, so jellyfish quickly die under the scorching sun. Jellyfish have enormous regenerative abilities; if you cut it into 2 parts, each will grow into a full-fledged individual.

Since scyphoid jellyfish have switched to an active way of life, their nervous system has become more developed. At the edges of the umbrella there are clusters of nerve cells; nearby there are also sensory organs that perceive light stimuli and help maintain balance.

Life cycle and reproduction

Scyphoids go through two phases in their life cycle: sexual (jellyfish) and asexual (polyp).

All representatives are dioecious organisms. The germ cells originate from the endoderm and mature in the pouches of the gastric cavity.

The gametes exit through the mouth and end up in the water. During the process of fusion of germ cells and further maturation, a jellyfish larva, a planula, emerges from the egg. It sinks to depth, attaches to the bottom and enters the asexual phase.

A single polyp (scyphostoma) leads a benthic life and begins to reproduce through lateral budding. After a certain time, the scyphistoma turns into a strobila, then the tentacles begin to shorten, and transverse constrictions form on the body. This is how a division called strobilation begins. Thus, the strobila gives life to young organisms - ethers. The ethers are then converted into adults.

Lifestyle

Scyphoid jellyfish do not live in schools and do not transmit signals to each other, even while on close range. Life expectancy is about 2-3 years, sometimes it happens that a jellyfish lives only a couple of months. They are also often eaten by fish and turtles.

All jellyfish are predatory animals. They consume plankton and small fish, which are immobilized by poisonous cells. Stinging cells release poison not only during hunting, but also to all organisms passing by. Therefore, jellyfish are dangerous for people in the water. If you accidentally catch the tentacles of a jellyfish, it will burn your skin with its poison.

The most common representatives of the class of scyphoid jellyfish are Aurelia, Cyanea, which inhabits the Arctic seas, and Cornerot, which is devoid of tentacles and lives in the waters of the Black Sea.

Meaning in nature and human life

Scyphoid jellyfish are part of the food chain of the world's oceans.

In Chinese and Japanese cuisine, dishes with rhopilema or aurelia are often found. Jellyfish meat is considered a delicacy.

Cornerot is the largest jellyfish in the Black Sea with a dome diameter of about 40 cm. Thus, it serves as a shelter for fish fry and protects them from predators and unfavorable environmental conditions. Sometimes, when the fry grow up, they begin to bite off small pieces of the jellyfish, or may eat it altogether.

Scyphoid jellyfish filter water, clearing it of contaminants.

For humans, the dangerous poison of jellyfish, which causes skin burns, sometimes provokes a painful shock and a person, being at depth, can no longer surface on his own. It is not safe to touch a jellyfish even when it is dead. When touched, an allergic reaction develops, disruption of the nervous and cardiovascular systems, and convulsive attacks occur.

Jellyfish (Polypomedusae) is a representative of marine fauna. The class of jellyfish, which includes freshwater hydras, consists of many sea inhabitants, some of them very large and conspicuous.

The jellyfish has a gelatinous and sometimes almost cartilaginous body in the shape of a rain or lady's umbrella with a stem extending downwards or a bell with a tongue hanging down.

In a jellyfish umbrella, you can distinguish a convex outer or upper side and a concave inner or lower side. From the center of the lower surface of the jellyfish's umbrella, either a very short or rather long stalk extends downwards, representing an oral tube; on the lower edge of this tube there are projections of various sizes located around the mouth opening, which are called oral lobes or oral tentacles.

The edge of the umbrella, equipped on its lower surface with a layer of muscles that serves to reduce the cavity of the bell and at the same time for the movement of the jellyfish, appears either dissected into separate blades, or has the form of a border running in the form of a ring perpendicular to the oral tube. Along the edge of the bell there are usually tentacles or lassoes, the number of which varies greatly; visual, auditory, and sometimes olfactory organs are also located right there.

The stomach of the jellyfish, communicating through the pharyngeal tube with the mouth, passes into a whole series of radiant canals or elongated pockets leading to the edge of the bell. Eggs and seminal cells develop in the stomach or on the walls of the canals extending from it.

The life cycle of a jellyfish includes the formation of a polyp, then a jellyfish, then a polyp again, and so on. As for the polyp, it differs from the jellyfish in the absence of a bell. Each polyp appears as a sac-like body, closed at one end; the closed lower end of such an individual is attached to some foreign object or to a polyp, which sometimes floats freely or is attached to something.

The opposite end of the polyp is usually elongated in the form of a cone and in the center has an opening called the mouth, surrounded by tentacles. If we imagine that such a polyp, having separated from the object to which it was attached, will somewhat flatten in the dorso-ventral direction, then we will get a disk with tentacles along the edges and a mouth cone in the middle; from here it is not far to a real jellyfish: all that remains is for this disk to become convex and take the shape of a bell or an umbrella.

Thus, the oral canal of the polyp turns into the pharyngeal tube of the jellyfish, and the edge of its oral disc, bordered by tentacles, into the edge of the bell of the jellyfish with its tentacles.

As for the sac-like stomach of the polyp, it turns into water vascular system jellyfish in the following way: its close walls grow together along the periphery over some distance, resulting in radially located channels. However, polyps differ from jellyfish not only in their structure, but also in other features, the most important of which is their different participation in the reproduction process.

How does a jellyfish reproduce?

Jellyfish are organisms that develop reproductive products; polyps, which are one of the stages of development of jellyfish, the stage of the so-called nurse (since they give rise to the jellyfish themselves), reproduce asexually.

The polyps themselves develop from fertilized jellyfish eggs and are in turn produced asexually by jellyfish. There are, however, jellyfish from whose eggs only jellyfish develop; Polyps are also known that produce eggs and seed cells instead of jellyfish. Between these two extreme cases there are all sorts of transitions. At asexual reproduction the vast majority of polyps form entire colonies, composed of individual individuals that remain connected to each other; the formation of such colonies is common for the order of hydroid polyps and hydroid jellyfish (Hydroidea). All of the main characteristics of hydroid polyps indicated are also characteristic of freshwater polyps, i.e. hydras.

The sexual generation of hydroid polyps are usually hydroid jellyfish, which are characterized by the presence of a membranous rim, the so-called sail, along the edge of the bell.

Hydroid jellyfish and polyps

Freshwater polyps are among the types of hydroid polyps that do not have alternation of generations, i.e., do not develop jellyfish. These same hydroid polyps include the so-called Sarsia, named after a Swedish naturalist; The reproduction of species of this genus is associated with alternation of generations.

The tubular sarsia itself (S. tubulosa) has the appearance of slender and weakly branched bushes, 10-15 mm high; Its polyps, club-shaped, are covered with 12-16 tentacles scattered without any order. She lives in the Baltic Sea and settles on the underwater parts of wooden buildings, on sea grass, red algae and similar objects.

The club-shaped polyps of Sarsia bud, after a number of changes occurring in them, jellyfish, which are the sexual generation; These jellyfish, reaching 6-8 mm in width, are bell-shaped, equipped with a long oral tube and four long tentacles located along the edge of the bell at an equal distance from one another; At the base of each tentacle a simple eye is placed.

Adjacent to the order of hydroid polyps and hydroid jellyfish just described is the order of floating siphonophores, or tubular polyps (Siphonophora), free-floating colonies, some members of which are in the form of polyps, others in the form of jellyfish; in such colonies there are, in addition, feeding polyps armed with a long thread - a lasso, jellyfish-like individuals that produce egg cells and sperm, and, finally, some members of the colony turn into apparatus or bells that serve for the movement of the colony.

The flat siphonophores include the so-called swallowtail (Velella); this animal, swimming on the sea surface, has a disk-shaped body, pierced inside with air channels, with a crest standing vertically on its upper surface, which plays the role of a sail: on the lower side of the disk in the center there is one large feeding polyp, surrounded by many smaller ones; The tactile members of the colony are located along the edges of the disk.

The most famous species of this genus is the common sailfish (Velella spirans), which can often be found very far from the shores, from which it is driven by the wind; in this animal, at the base of small polyps, small jellyfish-like creatures bud, which already develop sexual products and thus serve for the reproduction of the sailfish.

Another form, the bladder (Physalia), most of the body of which falls on a huge air sac lying horizontally on water surface; on the lower surface of the bladder there are large and small feeding polyps, armed with long lassoes; the palps are also located here.

The common bladderwort (Ph. caravella), with violet, white-speckled polyps and a purplish-red air sac, playing the same role as the swallowtail scallop, is distributed in the Mediterranean Sea and the Atlantic Ocean; the dimensions of this form reach 30 cm in length (not counting the lassoes, which can extend very significantly).

Classification

Akalephs

Representatives of the next order, Acalephae, differ from hydropolyps, hydromedusae and siphonophores, which are similar in structure to the polypoid and medusoid individuals of the entire colony, in the structure of both polyps and jellyfish: jellyfish of this order mostly reach quite significant sizes and have an umbrella, dissected at the edges into separate lobes.

As for polyps, their characteristic feature is the presence of four regularly located longitudinal swellings located on the inner wall of their gastric cavity; in the intervals between the indicated swellings there are 4 bags.

Reproduction of Akalephs

In some cases, the egg of a jellyfish develops directly into a jellyfish, but for the most part it turns into a small goblet-shaped polyp with tentacles around the oral disc; on such an embryo, sitting motionless on algae, etc., horizontal ring-shaped constrictions begin to appear, located one below the other; in this form, the entire embryo resembles a stack of plates; soon individual discs - future jellyfish - bud off one after another and, floating freely, turn into sexually mature forms.

The long-eared jellyfish Aurelia aurita, which is very common in the Baltic and generally in the European seas, belongs to the suborder of broad-tentacled acalefs (Semostomae), characterized by the presence of 4 long, boat-shaped simple tentacles located around a cruciform mouth; it is distinguished by a flat, like a watch glass, and sometimes hemispherical umbrella and narrow, lanceolate, strongly laminated at the edges, but not lobed tentacles.

This form, often found in huge masses, is well known to all explorers of our seas; The size of the eared jellyfish varies between 1 and 40 cm in diameter, but specimens measuring 5-10 cm are most often found.

Another well-known jellyfish from the Acalephids is the hairy jellyfish (Cyanea capillata), native to northern European seas. Like other species of this genus, the described jellyfish is distinguished by the edge of the bell, dissected into 8 main lobes, and the presence on its lower surface of many long tentacles - lassoes.

The described jellyfish appears in the fall, like the eared jellyfish, in masses; its main color is yellow-brown, sometimes reddish-yellow; in diameter reaches 30-60 cm, but there are specimens more than 1 m in diameter and with tentacles more than 2 m in length.

The northern hairy jellyfish (C. arctica) reaches even larger sizes, that is, over 2 m in diameter; the length of the tentacles of this species sometimes exceeds 4 m. This jellyfish is thus the largest of all jellyfish known to us.

Rootmouth jellyfish

As for the root-mouthed jellyfish (Rhizostomeae), they differ from the previous ones in the presence of 8 long, arranged in pairs, root-shaped mouth tentacles; In most cases, these tentacles grow together in pairs, and the mouth is completely closed and its role is played by many small sucking holes located along the tentacles.

Between the indicated stomata, these jellyfish often have more or less numerous oral palps, with button-shaped thickenings at the ends.

Cotylorhiza

An example of such a jellyfish is the Mediterranean cotylorhiza tuberculata; it is a generally yellowish jellyfish, 10-20 cm wide in diameter with long sucking tubes or with suckers on long legs; the edges of the disk of this jellyfish are mottled with white spots, the oral disk is fleshy red or yellowish-brown in color; milky-white tentacles, which, however, can sometimes be amber-yellow in color, brown, purple or violet blue, festoons surrounding the sucking holes - these are the features that describe the described jellyfish in more detail.

Disc jellyfish

Both mentioned groups of jellyfish, broad-tentacled and root-mouthed, constitute the suborder of disc-shaped jellyfish (Discomedusae), the characteristic features of which are: a flat, mostly disc-shaped bell or umbrella, usually with 8 marginal sense organs; the edge of the bell is cut into no less than 16 blades; the stomach is surrounded by 8, 16, 32, or even a large number of gastric sacs; On the lower wall of the stomach there are gonads, which are very clearly visible in our eared jellyfish and are popularly called eyes.

Cuboid jellyfish

The next group of cuboid jellyfish (Cubomedusae) is defined by the following characteristics: a tall, cubic umbrella, the edge of which, reminiscent of the swimming edge of hydroid jellyfish, is in the form of a horizontally tense membrane or hanging downwards; on this edge there are 4 sensitive flasks, with an eye and an organ of hearing on each.

A representative of this group can be the Mediterranean common box jellyfish (Charybdea marsupialis), which is 2-3 cm wide and 3-4 cm high; this species, as well as other species of the same genus, is interesting for its unusually highly differentiated eyes, the structure of which resembles the structure of the eyes of vertebrates.

Sea wasp jellyfish

The sea wasp jellyfish is the most poisonous jellyfish in the world; it lives off the coast of Thailand and Australia. Its body is glassy and cube-shaped, that is, this jellyfish belongs to the cuboid jellyfish. Its stinging cells leave fatal burns. As a result, death can occur within 3 minutes.

However, there are survivors - people with strong hearts. There is an antidote against sea wasp jellyfish burns, but you must have it with you, since the victim has no more than 3 minutes from the moment of the burn to save a life. Therefore, you should swim only in places specially fenced off from jellyfish; if you decide to swim in the open ocean, then have an antidote with you.

Goblet jellyfish

Finally, the last group of goblet jellyfish (Stauromedusae) is characterized by the presence at the top of the goblet-shaped umbrella of a stalk, with the help of which the jellyfish is attached to algae, etc.; The tentacles, collected mostly in bunches, sit along the edge of the bell of these jellyfish.

Lantern

The described suborder includes, among other things, the lanternfly (Lucernaria), which belongs mainly to the northern seas; this form can move from place to place with the help of its tentacles, which is also helped by the jellyfish leg, which has the ability to arbitrarily attach or separate from underwater objects.

In the northern European, as well as in the Black and Baltic seas, the largest (up to 7 cm) and long-known species of the described genus is found - the common lanternfly (L. quadricornis): this gray, green, brown-yellow or, finally, , the black-brown jellyfish willingly settles on red algae. It is also known on the shores of Greenland and found in America, off its northeastern shores.
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The jellyfish is perhaps one of the most unusual and mysterious creatures you can encounter in the ocean. With their gelatinous bodies and dangling tentacles, they look more like horror movie creatures than real living creatures. But if you look past the weirdness above and the fact that jellyfish can sting you, you can see that Jellyfish are quite interesting creatures. They have lived everywhere for more than 650 million years. There are several thousand various types jellyfish

In this article we will learn all about these mysterious animals and their life cycle.

Jellyfish primarily live in the ocean, but they are not inherently fish... they are plankton. These plants and animals either float in water or simply have a limited swimming ability with which they control their horizontal movement. Some types of plankton are microscopic single-celled organisms, while others can reach several feet in length. Medusa sizes can range from less than an inch to 7 feet long, with tentacles up to 100 feet long.

Jellyfish are also members of the biological phylum Cnidaria, (from the Greek word for "nettle") and the class Scyphozoa (from the Greek word for "cup", referring to the body shape of the jellyfish). In all coelenterates, the mouth is located in the center of their body, surrounded by tentacles. Corals, sea anemones and the Portuguese man-of-war siphonophora are also of the same type as the Cnidarian jellyfish.

Jellyfish are approximately 98% water. If Medusa is thrown ashore on the beach, she will soon disappear - evaporate like water. Most jellyfish are bell-shaped. Their bodies have radial symmetry, which means that parts of the body expand from center point like spokes in a wheel. If you cut Medusa in half at any time, you will always get equal halves. Jellyfish have very simple bodies - they have no bones, brain or heart. To see light, detect smells and navigate, they use sensory nerves that are rudimentary at the base of their tentacles.

Medusa's body generally consists of six main parts:

Epidermis, which protects internal organs

Gastrodermis, which forms the inner layer

Mesoglea, middle or jelly, is what is located between the epidermis and gastrodermis

Gastrovascular cavity, which performs the functions of the esophagus, stomach, and intestines simultaneously

An opening that functions as both a mouth and anus - tentacles located at the edges of the body

An adult Jellyfish is a Medusa ( plural: Medusa), named after Medusa Gargona, a mythological creature with snakes for hair who could turn people to stone at first sight. The process of fertilization in jellyfish is approximately the following: the male releases his sperm through a hole into the water, the sperm swims into the female holes and fertilizes the eggs.

Several dozen Jellyfish can hatch from one egg. They then drift freely in the ocean, searching for a surface to attach to, such as underwater rocks. When they attach to a surface, they turn into polyps - with a hollow cylindrical mouth and tentacles at the top. The polyps later develop into buds of young Jellyfish, which are called Ephyrae. After a few weeks, the Jellyfish swim away to grow into larger Jellyfish, and the whole cycle repeats again. Average term Medusa's lifespan is about three to six months.

general characteristics

Jellyfish is an invertebrate marine animal with a transparent gelatinous body, along the edges, equipped with tentacles. She is a lower multicellular creature, belongs to the type of coelenterates. Among them there are free-swimming (jellyfish), sessile (polyps), and attached forms (hydra).

The body of coelenterates is formed by two layers of cells - ectoderm and endoderm, between them there is mesoglea (non-cellular layer), and the body also has radial symmetry. Animals of this type have the appearance of an open sac at one end. The hole serves as a mouth, which is surrounded by a corolla of tentacles. The mouth leads into the 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.

Jellyfish belong to the scyphoid class. The class of scyphoid jellyfish is found in all seas. There are species of jellyfish that have adapted to live in large rivers flowing into the sea. The body of scyphojellyfish has the shape of a rounded umbrella or bell, on the lower concave side of which an oral stalk is placed. The mouth leads into the pharynx, which opens into the stomach. Radial canals diverge from the stomach to the ends of the body, forming the gastric system.

Due to the free lifestyle of jellyfish, the structure of their nervous system and sensory organs becomes more complex: clusters of nerve cells appear in the form of nodules - ganglia, balance organs - statocysts, and light-sensitive eyes. Scyphojellyfish have stinging cells located on the tentacles around the mouth. Their burns are very sensitive even for humans.

jellyfish animal reproduction hydra

Reproduction of jellyfish

Jellyfish are dioecious; male and female reproductive cells are formed in the endoderm. The fusion of germ cells in some forms occurs in the stomach, in others in water. Jellyfish combine their own and hydroid characteristics in their developmental features.

Among the jellyfish there are giants - Physaria or Portuguese man-of-war (from three meters or more in diameter, tentacles up to 30 m), such creatures can even eat a person. IN Lately they were spotted near the Sea of ​​Japan, and the Japanese and Chinese, who even try to cook from them, added them to various salads, thereby poisoning quite a few people.

The jellyfish looks flabby, but it feels dense to the touch. Although it has neither an internal nor an external skeleton, it retains a certain shape. This is ensured in part by 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 acquires rigidity when it is inflated with air. This method of maintaining body shape, called a hydrostatic skeleton, is also characteristic of sea anemones and worms.

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 the Gorgon. The hair of this goddess was a moving tuft 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 World Ocean. Only one freshwater species of these marine inhabitants is known. Each species occupies a habitat limited to one body of water and will never be found in another sea or ocean. Jellyfish are either cold-water or heat-loving; deep-sea and those that stay near the surface.

However, such species swim near the surface only at night, and during the day they dive into 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

Types of jellyfish

More than 200 species of jellyfish are known in nature. Despite the primitiveness of the structure, they are very diverse. Their sizes range from 1 to 200 cm in diameter. The largest jellyfish is the lion's mane (cyanea). Some of its specimens can weigh up to 1 ton and have tentacles up to 35 m long.

Jellyfish are shaped like a disk, an umbrella, or a dome. Most jellyfish have a transparent body, sometimes with bluish, milky, or yellowish tints. But not all species are so inconspicuous; among them there are truly beautiful, bright colors: red, pink, yellow, purple, speckled and striped. There are no green jellyfish in nature.

Species such as Equorea, Pelagia nocturna, and Rathkea can glow in the dark, causing a phenomenon called bioluminescence. Deep-sea jellyfish emit red light, while those floating near the surface emit blue light. There is a special type of jellyfish (staurojellyfish) 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 hallmark– radial symmetry of 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 does not have a skeleton; it consists of 98% water. When thrown ashore, the jellyfish is unable to move and dries up instantly. Its consistency is similar to jelly, which is why the British called it “jelly fish.”

Body tissues have only two layers, which are connected to each other by an adhesive substance and perform different functions. The cells of the outer layer (ectoderm) are “responsible” for movement, reproduction, and are analogues of skin and nerve endings. The cells of the inner layer (endoderm) 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 from different types jellyfish The umbrella is surrounded by hunting tentacles, which, depending on the species, can be either thick and short or thin, thread-like, and long.

What do jellyfish eat?

Jellyfish are predators; they consume only animal food (crustaceans, fry, small fish, caviar). They are blind and have no senses. Jellyfish hunt passively, catching with their tentacles the edibles that the current brings. The hunting tentacles kill the prey. This is done different ways.

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

Some types of jellyfish inject poison into the prey, others glue the prey to the tentacles, and others have sticky threads in which it becomes entangled. The tentacles push the paralyzed victim towards the mouth, through which undigested remains are then expelled. Interestingly, jellyfish living in the depths attract prey with their bright glow.

How do jellyfish reproduce?

Jellyfish have vegetative (asexual) and sexual reproduction. Externally, males are no different from females. Sperm and eggs are released through the mouth into the water, where fertilization occurs. After this, the 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 do not have a polyp stage. Young individuals are immediately formed from the planula. There are also species in which polyps are formed in the gonads, from which small jellyfish are born. Each egg cell in jellyfish produces several individuals.

Vitality of jellyfish

Although jellyfish do not live long - from several months to 2-3 years, their numbers are restored very quickly even after various disasters. 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.

Interestingly, if such an operation is performed in at different ages jellyfish, then an individual of the corresponding developmental stage grows from the tissues. If you divide the larva, then two larvae will grow, and from the adult parts - jellyfish of the appropriate age.

Jellyfish swimming upside down

Jellyfish and people

Some types of jellyfish pose a danger to humans. They can be roughly divided into two groups. Some cause allergies, the poison of others affects nervous system and can cause serious muscle and heart problems and, in some cases, death.

To avoid putting yourself in danger, you should avoid touching jellyfish, both living and dead. In case of a burn, you should wash the injured area with water, or better yet, a vinegar solution. If the pain does not subside and there are complications, you should immediately call a doctor.