Anemones, or sea anemones. Is an anemone an animal or a plant? Description and photo of sea anemones

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 the 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. Longitudinal muscle ridges lie on the gastric septa.

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 rocks. 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 anemone species 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, such as 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, 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 .

About the animals included in the order Actiniaria. The name of the animals comes from the name of the earth flower, anemone.

If the classification is checked, sea anemones are included in the class Anthozoa, a type of cnidarians and a subclass of six-pointed corals. This animal is known to the world because of its symbiotic relationship with fish.

From the commonwealth with fish, sea anemones benefit - improved gas exchange and nutrition (food that remains after the meal of the fish).

A symbiosis has also developed between sea anemones and crabs of the genus Lybia. Boxer crabs use the stinging anemone polyps for their own defense against predators. Crabs pick up sea anemones and hold them as a shield. Anemones, in turn, thanks to crabs get mobility, because they cannot move independently.

Here are some interesting facts about sea anemones:

Sea anemones, like all other cnidarians, have mesoglea in their body - a jelly-like substance. Anemones have a close relationship with corals, hydra, and jellyfish.

Anemones are able to decorate any aquarium. For commercial purposes, sea anemones are treated as a collection for the aquarium. Thus, the anemone trade is increasing.

These marine life have an amazing range of color diversity. Their vitreous bodies are always bright and tender.

Anemone size.

The diameter can reach 1.8 - 3 cm. The largest sea anemones have a span of 2 meters. The smallest barely reach 4 mm.

The mouth of an anemone functions like an anus. The function of capturing and catching prey. The location of the mouth is the center of the disc cavity. And several tentacles are located around the mouth.

Anemones are harmless and harmless animals. The sea anemone is not dangerous to humans. However, some species of sea anemones have a toxin capable of causing burns to humans.

Anemones feed on fish, mollusks and small marine animals. Peaceful anemones are calm individuals: they eat everything that floats in the water. However, they distinguish between edible food and non-edible food.

• In the neighborhood of sea anemones live those fish and shellfish that are insensitive to their poison.
• For large and predatory fish, anemones serve as a place of camouflage and shelter.

This animal, the sea anemone, is completely different from other cnidarians in its way of life. They have the disadvantage of free swimming, like jellyfish do. They differ from corals in that they do not live in colonies, in groups, but one at a time - they prefer to live alone.

Life cycle of an anemone. The polyp comes from Planula after the egg, fertilized by the sperm, begins to divide.

Asexual reproduction is also characteristic of sea anemones. In some species of anemones, division is the result of
asexual reproduction.

Most anemones live in one place all the time. However, they may move to another place if it is not suitable for them to live. They move if predators pester them or the location faces prolonged dryness. To get to a new place, they use movements that resemble crawling.

The sea anemone can be consumed as food. It is used as a delicacy in southwestern Spain and southern Italy.

Sea anemones are often served battered or marinated in vinegar.

The anemone animal really looks like a flower. They were called anemones, but for some it resembles an aster. Researchers of the deep sea counted one and a half thousand different types of anemones.

Cut into pieces, sea anemones demonstrate their remarkable ability to reproduce and regenerate.

In one row, all anemone tentacles are the same in color, structure and length. however, they may differ in different rows.

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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Unusual in beauty and rather mysterious in their way of life are marine animals - sea anemones. But where do sea anemones live? What is their appearance? Now let's find out...

Scientists have long argued about what type of animals these creatures belong to, because they have something in common with both corals and jellyfish, and outwardly, anemones generally look like underwater plants.

The modern classification refers specifically to coral polyps, moreover, these living organisms are one of the largest representatives of corals.

Another name for anemones is sea anemones, the animals got this name precisely because of their resemblance to flowers.

The structure of an anemone is a body consisting of a corolla of tentacles and cylindrical legs. At the base of the leg are muscles (longitudinal and circular). The end of the leg may have a so-called sole.

Anemones are bottom plants, so they need to gain a foothold on the surface of the soil, they do this with the help of various devices.

Some representatives of this type of coral secrete a special mucus, which tends to harden over time and thus firmly fixes the body of the animal on the substrate. Other sea anemones have such a large and strong leg that they are able to dig it into the ground and in this way securely attach themselves to the underwater soil.

But there are exceptions among anemones that do not live at the bottom of the sea, but freely floating in the water column. They are also called floats. In the sole of such species there is a special bubble that prevents the animal from sinking to the bottom and constantly keeps it in a floating state.

The upper part of the leg of the sea anemone has a mouth opening, represented by a disk surrounded by many tentacles, which are arranged in rows.

These same tentacles are equipped with stinging cells that can shoot the thinnest thread, equipped with a poisonous secret. If you look at the body of an anemone, you can see a pronounced radial symmetry.

As for the various sense organs inherent in most living organisms, actinia in this sense can be called one of the most primitive.

The nervous system of these animals consists of sensory cells located at the base of the tentacles, around the oral disc, and also on the sole.

The main distinguishing feature of these sea creatures, of course, is their color. No wonder they are called sea flowers, because they have the brightest colors in their colors: pink, orange, red, white, brown, green, yellow and others. In some species, a whole rainbow palette can be found on the body, since the body has one color, and the tentacles are painted in a contrasting shade.

The size of anemones is also surprising: the smallest representatives of this group of animals can have a millimeter height, and there are also giants, whose “growth” reaches one meter.

The smallest sea anemone discovered by scientists is the gonactinium anemone (Gonactinia prolifera), its growth is only 2 millimeters.

These animals are distributed in all oceans and seas, the greatest species diversity is manifested in the tropical and subtropical zones. Anemones acclimatized even in the icy waters of the Arctic Ocean.

According to the way of feeding, sea anemones are predators. Some species swallow everything in a row (both stones and paper), others, after accidentally swallowing an extra object, spit out the unnecessary.

Anemones are large coral polyps that, unlike most other corals, have a soft body. Anemones are isolated in a separate order in the class of Coral polyps, in addition to corals, anemones are related to other intestinal animals - jellyfish. They got their second name, sea anemones, for their extraordinary beauty and resemblance to flowers.

Colony of solar anemones (Tubastrea coccinea)

The body of anemones consists of a cylindrical leg and a corolla of tentacles. The leg is formed by longitudinal and ring muscles, which allow the body of anemones to bend, shorten and stretch. The leg may have a thickening at the lower end - a pedal disc or a sole. In some anemones, the ectoderm (skin) of the legs secretes a hardening mucus, with which they stick to a solid substrate, in others it is wide and swollen, such species anchor in loose soil with the help of the sole. Even more amazing is the structure of the leg of the anemones of the genus Minyas: their sole has a bubble - a pneumocyst, which plays the role of a float. These sea anemones swim upside down in the water. The leg tissue consists of individual muscle fibers immersed in a mass of intercellular substance - mesoglea. The mesoglea can have a very thick, cartilage-like consistency, so the anemone's foot is firm to the touch.

Solitary solar anemone with translucent tentacles

At the upper end of the body, anemones have a mouth disk surrounded by one or more rows of tentacles. All tentacles of one row are the same, but in different rows they can vary greatly in length, structure and color.

Deep sea anemone (Urticina felina)

In general, the body of anemones is radially symmetrical, in most cases it can be divided into 6 parts, according to this feature they are even classified as a subclass of Six-pointed corals. The tentacles are armed with stinging cells that can fire thin venomous filaments. The mouth opening of anemones can be round or oval. It leads to the pharynx, which opens into a blindly closed gastric cavity (a kind of stomach).

Often at the ends of the tentacles one can see swellings formed by clusters of stinging cells.

Anemones are rather primitive animals; they do not have complex sense organs. Their nervous system is represented by groups of sensitive cells located at vital points - around the oral disc, at the base of the tentacles and on the sole. Nerve cells specialize in different types of external influences. So, the nerve cells on the sole of the sea anemone are sensitive to mechanical influences, but do not respond to chemical ones, and the nerve cells near the oral disc, on the contrary, distinguish substances, but do not respond to mechanical stimuli.

Vesicle-shaped thickenings at the ends of the tentacles of the four-colored entacme (Entacmaea quadricolor)

The body of most anemones is naked, but tubular sea anemones have a chitinous outer covering, so their leg looks like a tall, hard tube. In addition, some species may include grains of sand and other building material in their ectoderm that strengthens their integuments. The color of anemones is very diverse, even representatives of the same species can have a different shade. These animals are characterized by all the colors of the rainbow - red, pink, yellow, orange, green, brown, white. Often the tips of the tentacles have a contrasting coloration, which makes them colorful. The sizes of anemones fluctuate over a very wide range. The smallest anemone gonactinia (Gonactinia prolifera) has a height of only 2-3 mm, and the diameter of the oral disc is 1-2 mm. The largest carpet anemone can reach a diameter of 1.5 m, and the sausage metridium anemone (Metridium farcimen) reaches a height of 1 m!

The carpet anemone (Stoichactis haddoni) has tiny wart-like tentacles but can be up to 1.5 m in diameter.

Anemones are common in all seas and oceans of our planet. The largest number of species is concentrated in the tropical and subtropical zones, but these animals can also be found in the polar regions. For example, anemone metridium senile, or sea carnation, is found in all seas of the Arctic Ocean basin.

Cold-water sea anemone metridium senile, or sea carnation (Metridium senile)

Anemone habitats cover all depths: from the surf zone, where during low tide anemones can literally be on land, and to the very depths of the ocean. Of course, few species live at a depth of more than 1000 m, but they have adapted to such an unfavorable environment. Despite the fact that anemones are purely marine animals, some species tolerate a little desalination. So, 4 species are known in the Black Sea, and one is found even in the Sea of ​​Azov.

Deep sea anemones (Pachycerianthus fimbriatus)

Anemones that live in shallow water often contain microscopic algae in their tentacles, which give them a greenish tint and somewhat supply their hosts with nutrients. Such sea anemones live only in illuminated places and are active mainly during the day, since they depend on the intensity of photosynthesis of green algae. Other species, on the contrary, do not like light. Anemones living in the tidal zone have a clear daily rhythm associated with periodic flooding and drainage of the territory.

Anthopleura anemones (Anthopleura xanthogrammica) live in symbiosis with green algae

In general, all types of sea anemones can be divided into three groups according to their lifestyle: sessile, swimming (pelagic) and burrowing. The vast majority of species belong to the first group, only anemones of the genus Minyas are swimming, and only sea anemones of the genera Edwardsia, Haloclava, Peachia have a burrowing lifestyle.

This green sea anemone lives in the Philippines

Sedentary sea anemones, despite their name, are able to move slowly. Usually anemones move when something does not suit them in the old place (in search of food, due to insufficient or excessive lighting, etc.). To do this, they use several methods. Some sea anemones bend their body and attach themselves to the ground with their mouth disk, after which they tear off the leg and rearrange it to a new place. This head-to-foot tumbling is similar to the way sedentary jellyfish move. Other anemones move only the sole, alternately tearing off its different parts from the ground. Finally, Aiptasia anemones fall on their side and crawl like worms, alternately contracting different parts of the leg.

Single pipe anemone

This mode of movement is also close to burrowing species. Burrowing anemones don't actually dig that much, most of the time they sit in one place, and they are called burrowers for their ability to burrow deep into the ground, so that only the corolla of tentacles sticks out from the outside. To dig a mink, the sea anemone resorts to a trick: it draws water into the gastric cavity and closes the mouth opening. Then, alternately pumping water from one end of the body to the other, it, like a worm, deepens into the ground.

The highest sea anemone is Metridium sausage (Metridium farcimen)

Small sessile gonactinia can sometimes swim by rhythmically moving its tentacles (such movements are similar to the contractions of the dome of a jellyfish). Floating sea anemones rely more on the strength of currents and are held passively on the surface of the water by pneumocysts.

Lush colony of sea carnations (metridiums)

Anemones are solitary polyps, but in favorable conditions they can form large clusters similar to flowering gardens. Most anemones are indifferent to their fellows, but some have a quarrelsome "character". Such species, upon contact with a neighbor, use stinging cells; upon contact with the enemy's body, they cause necrosis of his tissues. But sea anemones are often "friends" with other animal species. The most striking example is the symbiosis (cohabitation) of sea anemones and amphiprions, or clown fish. Clownfish take care of the sea anemone, cleaning it of unnecessary debris and food debris, sometimes picking up the remains of its prey; the anemone, in turn, eats up what is left of the amphiprion prey. Also, tiny shrimp often act as cleaners and freeloaders, which find shelter from enemies in the tentacles of anemones.

Shrimp in the tentacles of a giant sea anemone (Condylactis gigantea)

The cooperation of hermit crabs with anemones adamsias has gone even further. Adamsia generally live on their own only at a young age, and then they are picked up by hermit crabs and attached to the shells that serve them as a house. Crayfish attach the sea anemone not only as if, but precisely with the mouth disk forward, thanks to this, the sea anemone is always provided with food particles that fall to it from the sand stirred up by the cancer. In turn, the hermit crab receives reliable protection from its enemies in the face of anemones. Moreover, every time he transfers the sea anemone from one shell to another when he changes his house. If the crayfish does not have sea anemones, he tries to find it in any way, and more often to take it away from a happier fellow.

Anemones perceive their prey differently. Some species swallow everything that only touches their hunting tentacles (pebbles, paper, etc.), others spit out inedible objects. These polyps feed on a variety of animal food: some species play the role of filter feeders, extracting the smallest food particles and organic debris from the water, others kill larger prey - small fish that inadvertently approached the tentacles. Anemones, living in symbiosis with algae, feed mostly on their green "friends". During the hunt, the sea anemone keeps its tentacles straightened, and when it is sated, it hides them in a tight lump, hiding behind the edges of the body. Sea anemones shrink into a ball and in case of danger or when drying on the shore (during low tide), well-fed individuals can be in this state for many hours.

A colony of sun anemones hiding their tentacles

Sea anemones can reproduce asexually and sexually. Asexual reproduction is carried out through longitudinal division, when the body of an anemone is divided into two individuals. Only the most primitive gonactinia has a transverse division, when a mouth grows in the middle of the leg, and then it breaks up into two independent organisms. In some anemones, a kind of budding can be observed, when several young organisms are separated from the sole at once. The ability to asexual reproduction determines the high ability to regenerate tissues: sea anemones easily restore cut off parts of the body.

The same solar anemones, but with extended tentacles

Most anemones have separate sexes, although outwardly males do not differ from females. Only in some species can both male and female germ cells be formed at the same time. Spermatozoa and eggs are formed in the mesoglea of ​​sea anemones, but fertilization can occur both in the external environment and in the gastric cavity. Anemone larvae (planula) move freely in the water column for the first week of life and during this time are carried by currents over long distances. In some sea anemones, planulae develop in special pockets on the body of the mother anemone.

Touching the tentacles of large sea anemones can cause painful stinging cell burns, but deaths are unknown. Some types of sea anemones (carpet, horse or strawberry, etc.) are kept in aquariums.