Anemone animal: habitats, appearance, lifestyle. Sea anemones, they are also sea anemones, their types and description What food does sea anemone prefer

sea ​​anemone- lat. Actiniaria, a representative of the type Coelenterates, belongs to the class of coral polyps. Anemones or sea anemones are solitary invertebrates.

Structure

Anemones have a large number of smooth tentacles. The number of tentacles is a multiple of six. The number of septa in the gastrovascular cavity is also a multiple of six. The emergence of tentacles occurs gradually. Anemones can have many planes of symmetry, with a large number of tentacles and partitions.

Characteristics of the animal:

Height: The average height of sea anemones is 2-4 cm.

Diameter: The average diameter of sea anemones is 3-7 cm.

Colour: Anemones have a colorful form of different colors, mostly red and green, less often brown. Colorless sea anemones are also found.

Movement and food

The movement is very slow and is carried out thanks to the muscular sole. Anemones are able to settle on the shells of hermit crabs, and live with them in symbiosis. Cancer plays the role of a vehicle. They mainly feed on mollusks, crayfish, small fish and other marine invertebrates, therefore, sea anemones are predatory animals.

Reproduction and habitation

Anemones are dioecious animals. The formation of the sex glands occurs in the partitions or tentacles. There are anemones in the northern seas, they can also be seen in the Black Sea.

Sources:

B.N. Orlov - Poisonous animals and plants of the USSR, 1990.

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 tissue of the leg 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 referred to 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 accumulations 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.

Bubble-like 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 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 sea anemones of the genus Minyas are swimming, and only sea anemones of the genera Edwardsia, Haloclava, Peachia have a burrowing lifestyle.

This green 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 tubular 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 tallest anemone is the sausage metridium (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 with hidden 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 sea 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 they are carried by currents over long distances. In some sea anemones, planulae develop in special pockets on the mother's body.

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

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 anemones

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.

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 ​​sea anemones 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. 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 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 sea 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 ectoderm of the pharynx, 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 .

Any anemone is extraordinarily beautiful. Therefore, anemones are often called sea anemones. This, which has already become the official name, they received for their resemblance to the flowers of plants. Indeed, underwater landscapes, decorated with anemones sitting on them, can be compared with an exotic flower bed.

• They do not have an axial skeleton and are therefore invertebrates.
• These beauties belong to the type of coelenterates and are the closest relatives of corals.

And although sea anemones always live alone, and corals always form colonies, both these groups of animals have many similarities in structure.

Dear guests of the ecological park, amazing video meetings with unusual animals await you today!

How is the polyp of intestinal animals arranged?

Anemone - metridium senile (Sea of ​​​​Japan)

Metridium senile - sea anemone, the photo of which you see on this page, demonstrates the structure of a single polyp. A polyp is called a single form of this animal. Therefore, one sea anemone is one polyp. And the coral is a lot of polyps that form a colony.

But the internal structure and principle of life activity are the same for them. A separate polyp resembles a two-layer sac with one hole open at one end, inside of which there is an “intestinal” cavity.

In this cavity, food is digested, and the hole acts as a mouth. And through the same hole, undigested food remains are ejected from the body of the polyp. The mouth is surrounded by a ring of tentacles.

Watch a fragment of a hand-drawn cartoon about how sea anemones eat.

Video, sea anemone:

So, you were attentive and saw that at first the sea anemone put the caught fish into its mouth, and then threw out their skeletons from there. Amazing, isn't it?

Imagine - sea anemones are very similar in structure!

If the jellyfish is turned dome down, then we will see all the features of polypactinia:

• After all, the opening of the jellyfish is also the same - it serves as a mouth and a place for throwing out waste.
• The jellyfish has tentacles with which it catches food, and the sea anemone also has them.
• If you extend the dome of the jellyfish, you get an elongated body of an anemone.

You can even try to make such a transformation of a jellyfish into an anemone on a plasticine model.

Blind a jellyfish from plasticine, and then pull its dome down in the form of a tube and move the tentacles closer. Attach the lower part of the straw to something strong - there you have an anemone!

What are the types of anemones?

In nature, there are a variety of types of anemones. In total, there are about 1,500 species of these animals that live only in the sea. Freshwater anemones, unlike jellyfish, do not exist in nature. The sizes of anemones vary in a very wide range:

• body anemone diameter from a few millimeters to 1.5 m;
• height can reach 1 m;

Most sea anemones have a tall columnar body, in the upper part of which there is a mouth surrounded by numerous long tentacles carrying stinging cells with poison. The lower part of them is attached to the underwater substrate.

But among the sea anemones there is one amazing family. See what these sea anemones look like in an aquarium.

Video, sea anemone:

With the help of this video, you got to know the sea anemone, which is called Amplexidiscus fenestrafer or Great Elephant Ear from the Discosoma family. Isn't it a very successful and telling name?

Representatives of the discos family (Discosomatidae) are the most amazing sea anemones!

The body of the discosoma is in the form of a flexible disk, which is covered with cone-shaped tentacles from the inside. At the bottom of the disk there is a sole for attaching the animal to the substrate. In the upper central part of the disk there is a rather large mouth - a mouth opening.

They are painted in almost all colors of the rainbow: green, yellow, lilac, purple and others. Disc diameter - up to 40 cm

Symbiosis in the life of anemones

Sea anemones and hermit crab are the most common example of symbiosis (mutually beneficial cooperation) among sea anemones. Cancer - a hermit for sea anemones - is a means of transportation, since sea anemones move very slowly on their own. The anemone, whose tentacles have stinging cells, provides protection to the hermit crab.