Anemones do not have a skeleton and why. Anemone animal: habitats, appearance, lifestyle. Impact on the victim

If the colonies of hydroids and gorgonians look like bizarre bushes and trees, then large coral polyps sea ​​anemones(Actiniaria) resemble fantastic flowers. In many languages, they are called sea anemones (see color table 9).

The anemone order includes solitary, only occasionally colonial animals leading a mobile lifestyle. Only a few deep-sea species are immovably attached to the substrate. Anemones have a cylindrical body shape with a flattened upper (oral disc) and lower end (sole). But in some anemones, mainly those that lead a burrowing lifestyle, the sole may not form.

The number of gastric septa in most sea anemones is at least six pairs, or a multiple of six. The formation of new pairs of partitions occurs almost always in the intermediate gastric chambers. However, there are deviations from such an arrangement of partitions, in which the number of partitions is equal to eight or a multiple of eight or ten. Typically, such deviations are especially characteristic of the most primitive sea anemones. It is known that in the process of individual development, all sea anemones go through a stage of four-ray symmetry, which, possibly, indicates the relationship of sea anemones with eight-ray coral polyps. The greatest similarity with modern eight-ray corals in actinium from the genus Edwardsia. These anemones lead a burrowing lifestyle, living in silty sandy soils of shallow coastal waters. Their body, on the surface of which eight longitudinal ridges are distinguishable, has an elongated worm-like shape. The recesses between them correspond to the eight gastric septa. In addition to eight complete septa, old Edwardsia specimens develop four more, but already incomplete septa, in the upper part of the body. Rolls of longitudinal muscle cords lie in these sea anemones, as well as in octocoral corals, on the ventral sides of the septa. Eight complete and eight incomplete septae are also formed in another archaic sea anemone, Gonactinia. The most well-known European species gonactinia G. prolifera has the appearance of a small, 2-3 mm long and 1-2 mm wide, transparent column with a pale pink or red color. The oral disk of an anemone is surrounded by sixteen delicate tentacles arranged in two rows. Her pharynx is so short that, with her mouth open, eight main radial septa are easily discernible in her gastric cavity. Gonactinia attach their soles to the substrate, most often to mollusk shells, and sometimes even to the trunks of hydroid polyps.

The number of partitions, a multiple of ten, is observed in representatives of the family Myniadidae, very peculiar anemones that have switched to a free-floating lifestyle. They are supported in the water by a special air chamber, similar to the pneumatophore siphonophore, called the pneumocyst. It is formed as a result of a strong invagination of the sole. The edges of the sole at the same time approach and close over the center of the disk recess. Anemones therefore float at the surface of the water with their mouth down. Like many other swimming coelenterates, the Myniadidae are blue. In the rest of the anemones, the number of partitions, as already mentioned, is equal to six pairs or a multiple of six.

The free edges of the gastric septa have mesenteric filaments rich in glandular and stinging cells. Some sea anemones also form special filaments - acontions, on which stinging capsules are especially numerous. To protect against attack, these threads are thrown out by anemones through the mouth or through special holes in the walls of the body or tentacles. The oral disk of anemones is surrounded by tentacles. Depending on the number of tentacles, they are arranged in one or two or even more concentric rows. In each circle, the tentacles are the same size and shape, but the tentacles lying in different circles are often quite different from each other. As a rule, the tentacles correspond to the spaces between the gastric septa. Usually the tentacles have a simple conical shape, but sometimes significant deviations from it are observed. In some species, swellings form at the ends of the tentacles due to the fact that numerous batteries of stinging capsules develop there. Some tropical shallow water anemones develop branching or feathery tentacles. At their ends, one or two pairs are formed, which serve as an additional means for the rapid emptying of the body cavity.

The mouth opening of higher sea anemones is oval or slit-like. The pharynx is strongly laterally compressed and has two siphonoglyphs. Only the described primitive species have only one underdeveloped siphonoglyph or it is absent altogether. The beating of the cilia of the siphonoglyph creates two currents of water: one directed inside the gastric cavity and bringing oxygen (in some anemones - and food particles), and the other moving in the opposite direction and taking out carbon dioxide and excretion products.

The muscular system of sea anemones reaches a high level of development for coelenterates. The ectodermal system consists of longitudinal fibers lying in the tentacles and radial fibers around the mouth opening. The endodermal system consists of the annular musculature of the tentacles, oral disc, pharynx, body walls, and foot disc. On the gastric septa lie longitudinal muscle rollers.

The nervous system of sea anemones consists of an ectodermal network of nerve cells present in all parts of the body and an underdeveloped endodermal network covering only the gastric septa. Especially many nerve cells are concentrated at the bases of the tentacles and on the oral disc. However, this does not lead to the formation of a perioral nerve ring, since the nerve cells are very loosely located here. Another cluster of nerve cells is located near the sole. It is interesting to note that different parts of the body are particularly sensitive to certain stimuli. The sole, for example, is sensitive to mechanical irritations and does not perceive chemical ones. The oral disc, on the contrary, is very sensitive to chemical irritations and almost does not react to mechanical ones. Perhaps only the walls of the body and the tentacles react to mechanical, chemical and electrical stimuli, but the tentacles are much more sensitive to them than the walls of the body.

The common reaction of an anemone to irritation is to contract the body. At the same time, the oral disk and tentacles retract, and the body walls close over them, compressed by a special muscular ring. Anemones that lead a burrowing lifestyle, as Edwardsia described above, are quickly buried in the ground. With prolonged exposure to an irritant, sea anemones tend to crawl as far as possible from it.

Anemones do not form a skeleton, although the ectoderm of some species secretes a chitinoid cuticle covering the lateral surface of the body and the sole. Perhaps only in deep-sea sea anemones from the family Galatheanthemidae, leading an immobile, attached way of life, a strong cuticular sheath, which encloses the long worm-like body of anemones, takes on the character of a protective skeleton, similar to the ectodermal skeleton of most hydroid polyps. Dark brown protective cases galatpeanthemide rise to a height of 2-3 to 150 mm. Above their mouth, about 1 cm in diameter, protrudes the upper part of the anemone's body with a corolla of numerous thin tentacles. Galateanthemids are one of the deepest coelenterates. They were first discovered several years ago, when a period of systematic exploration of the maximum depths of the ocean began. These sea anemones most often live on the bottom and slopes of deep oceanic depressions - the Kuril-Kamchatka, Philippine, Japanese and others - at a depth of 6-10 thousand meters. Their lifestyle has not yet been completely studied.

The body of anemones is sometimes very strong, although they are devoid of a skeleton. The fact is that the mesoglea of ​​actinium usually reaches a significant development and often acquires the density of cartilage due to the appearance in it of a dense fibrous connective substance.

sea ​​anemones reproduce both asexually and sexually. However, asexual reproduction plays a much smaller role in them. Cases of budding in Actiniaria are generally very rare. More often there is a division of one individual into 2 and even into 3-6 unequal parts. Transverse division noted only in primitive actinium Gonactinia. In G. prolifera, for example, it proceeds as follows: at a certain height, a corolla of tentacles first grows from the walls of the body, then the upper part laces off and separates from the lower one. At the top, the sole is restored, and at the bottom, the oral disk and pharynx, as well as the second circle of tentacles, are formed. Second division gonactinium sometimes starts before the first has finished.

More often in anemones, longitudinal division occurs. In this case, the oral fissure is first divided into two, and then the entire oral disc is subjected to the same division, and then the body of the sea anemone is already dissected. Longitudinal division turns out to be a very lengthy process. Several months may pass from the moment it begins to the complete separation of the newly formed sea anemones. Occasionally, longitudinal division of anemones is noted, proceeding in the opposite direction - from the sole to the oral disk. In these cases, the division goes very quickly and ends in 2-3 hours (Fig. 178).

In addition to the described methods of asexual reproduction, sea anemones have developed another very peculiar method - the so-called laceration, in which several small individuals are formed at once. During laceration, a small section of the sole of an anemone is separated from the sole, containing the remains of gastric septa. This site then gives rise to new anemones (Fig. 178). Although division by laceration has been known since 1744, the complex process leading to the formation of young sea anemones has not yet been studied.

The ability of anemones to regenerate is very high, although it cannot be compared with that of freshwater hydras.

The main method of reproduction of sea anemones is the sexual process. The sex cells of sea anemones are of endodermal origin and mature in the mesogleal layer of the gastric septa. Anemones, as a rule, have separate sexes, although there are cases of hermaphroditism. In these cases, the male germ cells are formed before the female ones (the so-called protandric hermaphroditism). Fertilization can be both external and internal. In the latter case, young sea anemones reach the gastric cavity of the parent organism at the planula stage or the stage of formation of tentacles and gastric septa.

Reproduction of anemones living in the cold waters of the northern and southern latitudes usually begins in spring and ends by summer. On the contrary, in tropical waters anemones begin to breed at the height of summer. Floating planula larvae stay in plankton for 7-8 days and during this time they are carried by currents over considerable distances.

Sea anemones inhabit almost all the seas of the globe, but, like other coral polyps, they are especially numerous and diverse in warm waters. Toward the cold polar regions, the number of anemone species is rapidly declining. According to their way of life, anemones can be divided into bottom and pelagic. Myniadidae are an exclusively pelagic group. Bottom anemones have a very wide range of vertical distribution, occurring from the surf to the maximum depths of the ocean. But the vast majority of anemone species have adapted to living at shallow depths of coastal shallow water. These are typical components of the rocky fauna, forming dense settlements, moreover, often represented by a single species.

The distribution of shallow sea anemones largely depends on sea water temperature and salinity. In cold subpolar regions, the distribution of sea anemones is more or less circumpolar. Some cold-water anemones are found both in the Arctic and in the Antarctic, i.e., they form the so-called bipolar areas. In the tropical zone there are circumtropical species, but they are much less common than circumpolar ones. This is explained by the fact that tropical shallow areas are usually separated from each other by vast expanses of the ocean with its great depths. Large sea anemones Stoichactis have a typical circumtropical distribution. Some species of anemones, however, are insensitive to changes in water temperature. Such sea anemones are usually more widespread. Actinia equina, a common species in our northern seas, is found, for example, in the Atlantic Ocean as far as the Gulf of Guinea. Extensive ranges, as a rule, are also found in abyssal anemone species. Narrow localized ranges, however, are characteristic of ultra-abyssal anemone species living at depths of more than 6000 m. Individual species of the genus Galatheanthemum, for example, seem to live in certain deep-water basins of the Pacific Ocean.

Although sea anemones are typical marine animals, many of them tolerate significant desalination. Several anemone species are found in the Kiel Bay and Ostsee, four species have entered the Black Sea. Sea anemones are no longer found in the Azov and Baltic Seas. It is curious that even in the relict Lake Mogilnoye on the island of Kildin, a shredded form of Metridium dianthus, which is quite common in the northern seas, was found living there.

Burrowing sea anemones, such as Edwardsia or Haloclava, burrow more or less vertically into silt or silty sand and, when active, only stick out the upper end of their body with a rim of a few tentacles from the mink. They prefer not to leave their burrow, but if necessary they can crawl to a new place with the help of undulating contractions of the worm-like body. Having found a suitable soil, the sea anemone stops moving and quickly fills its gastric cavity with water. She then releases some of the water and closes her mouth tightly. By this, she avoids in the process of instillation the accidental loss of water remaining in the gastric cavity. When digging, the rear end of the body bends down towards the ground, and rhythmic waves of contractions of the ring muscles begin to run through the body. At the same time, the water remaining in the cavity is constantly pumped from the anterior to the posterior section and vice versa. With the help of peristaltic contractions, the body of an anemone is pushed deeper and deeper into the ground. After about an hour of hard work, the animal disappears completely into its new burrow.

Most sea anemones have soles and are sedentary. But if necessary, they can also slowly move along the substrate. Usually, the forward movement of sea anemones is carried out with the help of a fleshy sole. Part of it then separates from the substrate, moves forward, in the direction of movement, and is fixed again there. After that, it is separated from the substrate and the other part of the sole is pulled up. In particular, this is how Actinia equina, a widespread and very common species in our northern seas, moves. In the aquarium, A. equina was observed moving from the walls of the aquarium to nearby stones. The edge of the sole, separated from the glass wall, was strongly extended and leaned towards the stones. Then the sea anemone hung with its tentacles down between the wall of the aquarium and the stone, to which the edge of the sole was already attached. After a while, it separated and pulled itself up to the stone and its other edge. On the oral disk of this sea anemone, 192 tentacles are arranged in 6 rows. These sea anemones, brightly colored in red or green, are very beautiful, especially in full bloom with a crown of delicately colored, slightly transparent tentacles. In the northern seas, the predominant color of these sea anemones is green, and in the southern seas - red. A. equina, due to its surprising simplicity, is one of the favorite objects for observations in aquarium conditions. Curiously, live anemones can even be mailed wet or wrapped in wet seaweed.

Anemones of other species move along the ground in a different way. So, for example, Aiptasia carnea completely separates its sole from the substrate and falls on its side. In such a lying position on the ground, this anemone begins to move with its hind end forward with the help of peristaltic rhythmic contractions of the body in exactly the same way as burrowing anemones move. A. carnea always chooses night time for its travels.

Small sea anemones, like Gonactinia prolifera, can even swim by rhythmically throwing their tentacles back.

Most shallow sea anemones avoid daylight and crawl from sunlit places into shaded rock crevices. If an anemone placed in an aquarium is suddenly illuminated with a bright light, it will rapidly shrink. Most shallow sea anemones are therefore dormant during the day. They spread their tentacles at night or at dusk. However, littoral species of anemones are either indifferent to light, or even strive for it, crawling to illuminated places or turning their oral disk towards the light. In a passive state, they are at night.

Littoral species, which are indifferent to light, develop a different daily rhythm of life associated with tidal changes in the water level. A. equina, for example, spreads its tentacles with the tide and contracts with the tide. The circadian rhythm of this sea anemone is so persistent that after placing it in the aquarium it persists for several more days. Well-fed anemones can remain in a reduced state for a long time. On the contrary, hunger and low water temperature make sea anemones stay active for more than a day.

The diet of sea anemones has been relatively well studied. In some anemones, the grasping movements of the tentacles play the main role in feeding, in others, the ciliary movement of ciliated cells scattered in the ectoderm. The former feed on various small living organisms, the latter on organic particles suspended in sea water. There are two main types of cilia movement. In primitive anemones, for example, in Gonactinia, whose ciliated cells evenly cover the entire body, organic particles that fall on the body are enveloped in mucus and distilled by the beating of cilia from the bottom up, towards the oral disc, and then into the mouth. The beating of the cilia goes in the same direction on the tentacles. In the event that the food bolus falls on the tentacle, then here it is distilled towards its upper end. The tentacle bends towards the mouth, and the food is picked up by the stream directed already towards the pharynx. Particles unsuitable for food are captured by the flow created by the cilia of the tentacles, and, like food particles, move to the upper end of the tentacle. However, this tentacle no longer bends towards the mouth, but in the opposite direction. From the end of the tentacle, these particles are washed away by the flow of water.

In more highly developed anemones, cilia form only on the oral disc and tentacles. In particular, we find such a ciliated apparatus in Metridium dianthus, or sea ​​cloves, one of the most beautiful anemones found in our waters (color table 9). On a long columnar body, numerous, over a thousand, thread-like tentacles are located in separate groups. Coloring M. dianthus is extremely diverse - from pure white to dark red. The movement of cilia on the tentacles and the oral disk of these sea anemones is always directed towards the top of the tentacles. All particles that land on the oral disc or tentacles therefore move in the same direction. The tentacle, after the food bolus reaches its top, curves towards the mouth. Then the lump is picked up by the cilia lining the pharynx and moves into the gastric cavity. Particles that are unsuitable for food also move to the upper ends of the tentacles, from where they are washed off with water or discarded.

Anemones, grasping food with tentacles, feed on various living organisms, as well as pieces of meat left after the meal of some other predator. Numerous experiments that have been carried out give a good idea of ​​the mechanism for grasping the victim and transporting it into the gastric cavity. Usually hungry anemones sit quite still, with tentacles widely spaced. But the slightest changes occurring in the water are enough for the tentacles to produce oscillatory "search" movements. When the sea anemone senses food, not only part or all of the tentacles extend towards it, but often the whole body of the sea anemone also leans towards the food. Having caught the prey, the tentacles of the sea anemone contract and bend towards the mouth. It is very interesting to note that the pulling of the tentacles to the mouth often proceeds reflexively, even regardless of whether the victim is seized or not. If large prey is captured, for example, a small fish, then all the tentacles of the predator are sent to it, and all of them take part in transporting the victim to the mouth. Small prey is introduced into the pharynx with the help of a water current caused by the beating of ciliated cells in the pharyngeal ectoderm, larger prey - with the help of peristaltic contractions of the pharyngeal tube. In sea anemones, which have short tentacles, the pharynx is slightly turned outward and pulled up to food, which is held above the oral disk by tentacles that are unable to bend down to the mouth opening. So eats, in particular, bighorn sea anemone- Urticina crassicornis, found from the Mediterranean to the North and Norwegian seas. Numerous (up to 160) short and thick tentacles of this sea anemone surround its low and thick body. The coloration of U. crassicornis is extremely diverse, and it is unlikely that two identically colored specimens of this sea anemone can be found at once.

U. crassicornis is also very remarkable in the sense that its mode of reproduction depends on climatic conditions: in warmer waters, this sea anemone spawns eggs, and in cold waters (for example, off the coast of Svalbard), it becomes viviparous.

Some sea anemones immediately sense the difference between food and non-food particles and never grasp them. Others, especially in a state of hunger, seize any objects - stones, empty shells, filter paper, etc. After saturation, the sea anemones, so illegible before, no longer introduce objects unsuitable for food into their throats. If filter paper is impregnated with meat extract, then at first the sea anemone willingly seizes it. But over time, anemone ceases to be too trusting. She will be able to fall for deception only after a certain period of time, feeling hungry.

With repeated repetition of such an experiment, actinium completely ceases to react to paper soaked in meat extract.

Anemone species that feed on organic particles suspended in sea water have an underdeveloped tentacle stinging apparatus. These anemones usually form long acontions, which perfectly protect them from attack. On the contrary, in predatory species of sea anemones, stinging batteries of tentacles become very numerous. A volley of ejected stinging filaments not only kills small organisms, but often causes severe burns in larger animals, and even in humans. Catchers of toilet sponges are often badly burned by sea anemones. After a burn, the skin of the hands begins to turn red, itching and burning in the damaged area are accompanied by headache and chills. After a while, the sore spots of the skin die off and deep ulcers form.

Very many species of anemones are commensals of other animals or enter into a peaceful symbiosis with them. These relationships of anemones to other animals have been discussed in detail previously.

Animal life: in 6 volumes. - M.: Enlightenment. Edited by professors N.A. Gladkov, A.V. Mikheev. 1970 .

Its second name - sea anemone - actinia received for its extraordinary beauty. This marine life really looks like a beautiful flower. Unlike other coral polyps, anemone has a soft body. According to the biological classification, sea anemones are a type of coelenterates, a class of coral polyps. They are closely related to jellyfish.

Anemone has a soft body compared to other corals.

Description of sea anemone

To determine whether an anemone is an animal or a plant, it is necessary to study the features of its structure. Actinia belongs to the animal kingdom. Her body is cylindrical. From above it is decorated with a rim of tentacles.

External features

Sea anemones come in a variety of colors. In nature, there are varieties of all colors and shades. Many species have contrasting tentacle coloration, which makes these animals even more attractive.

The sizes of these coelenterates are also striking in variety:

• the height of gonactinia does not exceed 3 mm;
• the diameter of the carpet anemone reaches 1.5 m;
• the height of the sausage metridium species can be up to 1 m.

body structure

The main part of the body - the leg - consists of muscles that are located along the ring and longitudinally. Due to the contractions of these muscles, the polyp can bend and change its length. On the bottom of the leg there is a so-called sole. Its surface is arranged differently in different species. Some, with the help of the sole, "root" in loose soil, others secrete a special substance with which they attach to hard surfaces. In the genus Minyas, the sole is equipped with a pneumocyst - a special bubble that acts as a float and allows you to swim with the sole up.

The muscle fibers of the leg are surrounded by the intercellular substance mesoglea, which has a dense cartilaginous texture and gives the body elasticity.

On the upper part of the body there is a mouth disk, around which tentacles are arranged in several rows. In one row, all tentacles are the same, but in different rows they can differ significantly in appearance and structure. Each tentacle is equipped with stinging cells that emit thin poisonous threads.

The oral disc leads into the pharynx, and from there a passage opens into the gastric cavity - a primitive likeness of the stomach. The nervous system of the sea anemone is very simple, it is represented clusters of sensory neurons around the oral disc and in the sole area:

• nerve cells around the sole react only to mechanical stress;
• accumulations around the mouth opening and tentacles distinguish the chemical composition of substances.

habitats

Actinia is a coelenterate organism, common throughout the world. Most varieties can be found in tropical latitudes, but some species live even in polar regions, where the ambient temperature is very low. Metridium, or sea carnation, lives in the Arctic Ocean.

The depth of the animal's habitat is also striking in its diversity. Sea anemones can also live in the surf zone, where they land on land at low tide, and in the very depths of the seas and oceans. Some species have adapted to survive at depths of more than 1,000 meters. In the waters of the Black Sea, 4 species of these polyps were found, and in the Sea of ​​\u200b\u200bAzov - 1 species.

Shallow water inhabitants often depend on the processes of photosynthesis, as microscopic algae settle in their tentacles. These species are common in places with good lighting and are active during daylight hours.

Other varieties, on the contrary, do not like bright light and tend to go to the depths.

Lifestyle and nutrition

Anemone feeds on organic food. These polyps can catch and perceive their prey in different ways:

• some species swallow everything, including small pebbles and debris;
• part of the anemones throws out all the inedible objects that they have come across;
• the largest and predatory ones catch and kill fish that are nearby;
• some polyps live in symbiosis with algae and feed on them.

The “hungry” sea anemone opens its tentacles-rays wide and catches everything that swims past it. After the sea anemone is satiated, she rolls her tentacles into a ball and hides them. The same reaction is noted when drying out or approaching danger.

All sea anemones are usually divided into three varieties:

• sedentary;
• floating;
• digging.

Sedentary varieties are named so rather conditionally, since they are able to move slowly. Polyps begin to move when they have little food, too little or too much light. Movement can be done in several ways:

• "tumbles" - when anemones stick their mouths to the ground and tear off the leg, rearranging it to another place;
• alternately tearing off from the soil one or the other part of the sole;
• crawling, contracting different muscles of the body.

Burrowing sea anemones sit most of the time, burrowing into the ground so that only the corolla remains outside. In order to make a hole for itself, the animal draws water into the gastric cavity and pumps it, deepening in this way into the soil.

Floating varieties are held on the water and given to the force of the current. They can rhythmically move their tentacles or use pneumocysts.

Polyps begin to move when they have little food, too little or too much light.

Reproduction methods

Sea anemones reproduce in a variety of ways. With the asexual method, the body of the polyp is divided in the longitudinal direction with the formation of two individuals. The exception is gonactinia, the most primitive species, which divides transversely. In the middle of the polyp leg, a second oral opening is formed, then two separate individuals form.

Some organisms reproduce by budding from the underside of a stalk, producing several new individuals.

These coelenterates are mostly dioecious, although it can be impossible to distinguish male and female from each other by external signs. Sexual reproduction takes place in the following way:

1. Sex cells are formed in the thickness of the intercellular substance.
2. Fertilization can occur in the gastric cavity or in water.
3. As a result, planulae (larvae) are formed, which are freely carried by the current over long distances.

Anemones can reproduce both sexually and asexually.

Interaction with other organisms

Although sea anemones are of the solitary polyp type, in some situations these organisms can aggregate and form giant colonies. Most sea anemones are indifferent to their own kind, although some species can be very aggressive and quarrelsome.

With other types of marine animals and plants, sea anemones can coexist very closely. A common example is the clownfish symbiosis. The sea anemone “eats up” the prey after the fish, and that, in turn, cleans the polyp from debris and food debris.

Often small shrimp act as symbionts: they hide from enemies among the tentacles of anemones and at the same time clear organic debris and debris.

Adamsia sea anemones can only live in symbiosis with hermit crabs, which attach polyps to their shells. In this case, the sea anemone is located in such a way that its oral disk is directed forward and food particles get into it. Cancer, in turn, receives reliable protection from predators. Changing the shell, the hermit will transfer to a new "dwelling" and sea anemone. If cancer somehow loses "its" polyp, it can even take it away from a relative. This existence benefits both species.

Flowers can be found not only in fields and meadows, but also at the bottom of the sea. White, blue, yellow - all the colors of the rainbow ... The current, like the wind, sways the petals ...

Actually this anemones or sea anemones, and with plants, except for external resemblance, they have nothing in common. Anemones are relatives of coral polyps and jellyfish. The body consists of an elastic cylindrical leg and a corolla of tentacles. The basis of the body is the leg, which is formed by circular and longitudinal muscles, which allows the body to bend, stretch and contract. Some sea anemones have a thickening at the bottom of the legs - the sole; with its help, sea anemones are glued to the soil or stones.

At the upper end of the body is a mouth disk surrounded by several rows of tentacles. In one row, all tentacles are the same in color, structure and length, but in different rows they differ. Often at the tips of the tentacles there is a cluster of stinging cells that shoot out thin poisonous threads. Poisonous tentacles serve anemones as a weapon of attack and a means of defense. Actinium poison leaves burns on the body of the victim, wounds heal for a long time, ulcers form.

Anemones can be divided into peaceful and more aggressive - predators. Calm individuals feed on everything that floats in the water. They direct sea water with tentacles to the oral cavity and filter it. Maybe something delicious! Some anemones eat everything that comes across - paper, pebbles, and shells, while others can distinguish between edible and inedible prey. Predators catch crustaceans, shrimps, small fish and other small things, paralyzing them with poisonous threads. The digestive process proceeds quickly - after 16 hours only the shell remains from the crustacean. Hungry, the anemone releases its tentacles forward in search of a new victim.

In case of danger, sea anemones hide in their cavity by retracting their tentacles. So from a large living "flower" a small bud is formed. When the danger blows, they open their living "petals" again.

When the habitat is depleted and the sea anemones do not have enough food or insufficient lighting, they can move from place to place. "Walking" can be done in several ways. Some ammonias cling to the soil with their mouth disk, tear off the leg and rearrange it to a new place. Other parts tear off the sole from the ground, and thus move slowly. Still others fall on their side and, like a caterpillar, contracting various muscles of their body, crawl. There are sea anemones that can swim. They actively wave their tentacles, like the movements of a jellyfish dome, and swim where the current takes them.

sea ​​anemones- solitary organisms, and do not tolerate neighborhood. They sting unwanted neighbors with stinging cells. Only in rare cases are colonies of polyps formed. But anemones are "friends" with other marine life, for example, with clown fish. The fish cares for and cleans the tentacles of debris and food debris. In return, in case of danger, the sea anemone hides the fish under its tentacles. Clownfish is one of the few representatives of marine fauna that has developed immunity to the poison of stinging cells.

But the strongest alliance is with hermit crabs. The simplest alliance with cancer of the species Eupagurus excavatus. He finds an empty shell, on which an anemone is already sitting, and populates it.

A more complicated relationship develops with a hermit crab Pagurus arrosor. This crayfish is not looking for an empty shell; it can plant sea anemones on its own house. Cancer with light stroking and tapping attracts sea anemones. She does not sting him at all, but on the contrary, as if "blooms", straightening her tentacles. Pagurus arrosor puts a claw on the anemone, it carefully tears off the sole from the ground and crawls onto the shell of its new neighbor. If there is still room on the shell, the cancer can plant another sea anemone there. There were cases when on the back of a hermit crab there was a whole "garden" of eight sea anemones.

But the most striking symbiosis is observed in hermit crab Eupagurus pride-axi with marine animation Adamsia palliata. Cancer puts a very small sea anemone on its back and never partes with it. When the crustacean grows up and needs to change the shell to a more spacious one, Adamsia comes to the rescue. Over time, her sole grows and expands, hanging over the shell. The base of the stem becomes wider and wider, with time it hardens and becomes elastic, forming Eupagurus pride-axi a comfortable dwelling.

There are anemones that do not wait for their roommate, but are looking for him themselves. Autholoba reticulata clings to a stone or polyp with tentacles, not a sole, and in such a suspended state waits for cancer to crawl under it. When the crustacean appears, she grabs his claw with her sole, and then completely moves to his back.

Such cooperation is beneficial to both parties. Cancer receives protection and picks up food that has fallen, anemone expands its habitat and hunting area.

Sea anemones can be found in all seas and oceans, even in the Arctic Ocean basin, but most species are found in warm tropical and subtropical waters.

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sea ​​anemones, or sea ​​anemones, refer to class of coral polyps. This is the largest group of coelenterates, numbering more than 6,000 thousand species. Most of the members of the group are colonial corals, which are described on the following pages. But the most famous are sea anemones. They are larger and most often live as single individuals rather than colonies. They live in the shallows along the coasts, usually attached to rocks, plants, shells or other surfaces. However, anemones are capable of slow movement, crawling or sliding on their soles. If they are "in a hurry" they can do somersaults. Few can swim - using the contraction of the tentacles or the bends of the whole body. But usually we see only the swaying movements of anemones, which they make in the process of obtaining food. sea ​​anemones- this is, but they do not have a medusoid stage in their life and live all their lives in the form of polyps. Outwardly, they resemble, but are larger and much more complicated, in addition, most often they do not unite in colonies, but live alone. The sole of the sea anemone is thicker, and the tentacles around the mouth opening are thicker and stronger. In addition, most sea anemones are colored in bright reds, yellows, pinks, browns and blues. This coloration is a warning to other animals that anemones are not edible and can sting with their tentacles.

Most anemones feed by catching small fish, shrimp and other animals with their tentacles. The stinging cells of the tentacles kill or paralyze prey. Sea anemones do not have eyes, but they react to touch and fire venomous stingers. Moreover, they are able to detect the substances emitted by the bodies of their victims. Thanks to this, more and more new ones are connected to the retention and killing of prey. The poison of most ordinary anemones is not strong enough to harm a person.
The mouth opening of anemones, located in the middle of the tentacles, stretches so wide that the animal is able to swallow prey much larger than itself! Food enters and is slowly digested in the gastric cavity located in the body of the animal. Undigested remains are excreted from the body of anemones through the same opening through which food enters. Anemones reproduce in the same way as hydras - by growing young individuals on the surface of their bodies. In addition, they produce eggs and sperm like most animals.
Anemones do not look aggressive. But in the process of fighting for the best place on the rocks, they slowly push each other, trying to push the opponent from the rocks into the mud and sand.

The short tentacles of the Dahlia anemone are covered with cones, to which pieces of gravel, shells and blades of grass are glued. With the onset of low tide, the sea anemone retracts its tentacles and becomes like a piece of gravel.
The orange anemone has powerful strong tentacles around the mouth opening.
Some sea anemones live longer than humans. They can reach over seventy years of age in sheltered and food-rich large marine lagoons or clear water areas.
Usually anemone tentacles are arranged in circles, the number of tentacles is a multiple of 6 or 8.
The Pseudocorynactis anemone has bright, rounded yellow-orange tips on wide-spread, pale blue tentacles.
The largest sea anemone is the discoma. It can reach 60 cm in diameter. Lives between corals on the Great Barrier Reef in Australia.
One of the most common multi-colored anemones is the horse anemone. It lives on rocks in the tidal zone. It is most often red, but can be brown, orange, or green.

coral polyps:
- About 6,000 species of marine life
- A stalked body attached by the sole to the substrate, bearing tentacles at the apex (polypoid stage only)
- Rounded body with tentacles, genitals and other organs, the number of which is a multiple of 6 or 8

• Type: Cnidaria (Coelenterata) Hatschek, 1888 = Coelenterates, cnidarians, cnidarians
• Subtype: Anthozoa Ehrenberg, 1834 = Corals, coral polyps
• Class: Hexacorallia = Six-pointed corals
  • Order: Actiniaria = Anemones, sea flowers, sea anemones

Anemones, sea anemones - order Actiniaria

Sea anemones or sea anemones (Actiniaria) are a detachment from the class of six-ray corals, subtype Corals or coral polyps (Anthozoa). There are about 1500 known species of sea anemones. Sea anemones are rather large, fleshy animals, reaching a height of one meter. They have soft tubular bodies that are completely devoid of a calcareous skeleton.

The body of anemones is cylindrical in shape, which is truncated from above. It has a slit-like mouth surrounded by rows of tentacles. The bottom of the sea anemone body ends with a "sole", with the help of which the animal sticks, thus attaching itself to underwater objects.

At first glance, the similarity of anemone tentacles with flower petals is striking, and most of all they resemble chrysanthemum, dahlia and aster flowers. Anemones can be painted in a variety of colors. Among these animals there are species with purple, brown, snow-white, green and even pale blue bodies.

Anemones are widely distributed in the oceans. They live in arctic latitudes and in equatorial waters, in coastal sands and at sea depths devoid of light, sinking to the bottom of the deepest oceanic trenches to a depth of over 10,000 meters. Sea anemones can be found on algae, sponges, corals and other marine animals. However, most anemone species prefer shallow coastal shallow waters, and water with a fairly high salinity. And they live mostly alone, in search of shelter they are able to overcome short distances.

At the ends of the tentacles in some species of anemones, trapping threads are formed due to the formation of a large number of stinging capsules here. At the same time, stinging capsules serve as sea anemones both for attack and for protection from enemies. The poison of the stinging threads, hitting the victim, instantly paralyzes it, as soon as the sea beauty touches them with tentacles. Even a person who unintentionally touches an anemone has a burn on the skin, and the hand swells for a long period. In addition, there is a general intoxication of the body, which is accompanied by headache and chills. After some time, at the site of the burns, the affected skin dies off, and deep, poorly healing ulcers form.

At the same time, the poison of the stinging anemone capsules is still not an absolutely reliable means of protection against enemies. So, some molluscs pursue sea anemones, as they are more or less insensitive or insensitive to their poison, and some types of fish, without harming themselves, easily swallow sea anemones. But many small fish are excellent food for predatory sea anemones.

The peaceful cohabitation of this sea "flower" and some fish, which is often found in nature, is also well known. Without the slightest harm to themselves, clown fish live among the tentacles of anemones. And the secret is in the protective mucus-shell that these fish are covered with, it is she who protects them from the poison of anemone tentacles. Clownfish, even in search of food, do not swim far from the sea anemone, and in case of danger they immediately hide in the thick of its tentacles. And the fish, in turn, eating their prey near the mouth of anemones and losing its remains, feed their protector, as it were, and with the active movements of their fins, they significantly improve its gas exchange. Thus, from such cohabitation, both clown fish and sea anemones receive mutual benefit, so their union is strong.

Other cases of symbiosis of sea anemones with marine organisms are also known. And the most classic example of such a relationship is the symbiosis of sea anemones and hermit crabs. And it happens like this: the hermit crab Eupagurus excavatus is looking for an empty shell of mollusks with sea anemones already attached to it, and in the case of such a find, it crawls from its shell to the found one. Or maybe the crayfish carefully remove the anemone from the stone and transplant it onto its shell ...

Sea anemones feed mainly on various small invertebrates, sometimes fish become their prey, which they first kill or paralyze with the “batteries” of their stinging cells or cnidocytes, and only after that they are pulled to the mouth with the help of tentacles. Large species of sea anemones also feed on crabs and bivalves. In them, the edges of the mouth can swell, forming a semblance of a lip, which also contributes to the capture of prey.

Anemones such as Metridium, Radianthus and Stichodactyla, which have numerous tentacles, feed mainly on food particles suspended in the water. But the anemone Stichodactyla helianthus is able to catch sedentary sea urchins, covering them with its muscular oral disc. Those anemones that feed on particles suspended in the water catch plankton inhabitants with the help of sticky mucus that covers the surface of the body and tentacles. Cilia located on the surface of the body always direct prey towards the oral disc, and cilia on the tentacles move food particles to the tips of the tentacles, after which the tentacles bend and send food to the mouth.

In sea anemones, both asexual and sexual reproduction can be observed. Asexual reproduction, which takes place by fission or fragmentation of the body, is very common for sea anemones. The agamic species Aiptasia pallida, Haliplanella luciae, and Metridium senile are characterized by a very specialized form of fragmentation, the so-called pedal laceration. At the same time, small fragments of the edge of the sole can separate from the sea anemone when it moves, or they can simply creep away from the motionless sea anemone. As a result of such spreading around the base of the body of the parent individual, a kind of "witch's ring" is formed from young small anemones, into which separate fragments of the maternal sole soon turn. Asexual reproduction by longitudinal division of the body is also noted in representatives of many species of sea anemones, but division in the transverse direction is rare, in particular in Gonactinia prolifera and Nematostella vectensis.

Sexual reproduction is provided by both dioecious and hermaphroditic anemones. On the septa, which look like longitudinal swollen strands lying between the mesenteric thread and the retractor muscle, the gonads are located. Fertilization and development of eggs can occur both in the gastric cavity and in sea water during external fertilization. The planula larva, which can be planktotrophic or lecithotrophic, after a certain period of time (varies in different species), undergoes metamorphosis, turning into a new anemone.