The nature of the diet of sea anemones. Anemones - Sea Anemones. Anemone Watching

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: average height actinium is 2 - 4 cm.

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

Colour: sea anemones have a colorful shape different colors, predominantly red and green color, rarely brown. Colorless sea anemones are also found.

Movement and nutrition

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.

Sea anemones or sea anemones are of increasing interest to scientists simply lovers of the animal world. They are very similar to flowers, but belong to the group of large polyps. The difference between anemones and other corals is that their body is soft. Biologists classify these creatures as special detachment class coral polyps, the closest relatives of sea anemones are jellyfish, prominent representatives coelenterates.

Structure

The sea anemone consists of two parts - a corolla with tentacles and a cylinder-like leg. The leg is a formation of muscle tissue - the longitudinal and annular muscles that are located here allow the body of sea anemones to change position and shape. In most sea anemones, the foot is thickened from below - this is the so-called pedal disc or sole. The skin on the soles of some sea anemones secretes a special mucus that hardens and allows these organisms to attach themselves to hard surfaces. The sole of other anemone species is expanded and swollen - with its help, sea anemones are introduced into the loosened substrate. The leg of sea anemones of the genus Minyas is equipped with a bubble - a pneumocyst, which is used as a float. This type of anemone moves in the water as if upside down. The muscle tissue of the leg of anemone is enveloped in an intercellular substance - mesoglea. This substance is quite thick, which ensures the elasticity of the legs.

From above, the body of the sea anemone is equipped with a mouth disk, which is surrounded by many tentacles arranged in several rows. The tentacles have stinging cells, which at the right moment shoot thin jets of poison. The round or oval opening of the mouth in these creatures opens the pharynx, which goes directly into the gastric cavity (the simplest stomach).

The nervous system of anemones is a group of sensitive cells that are located around the circumference of the oral disc, on the surface of the sole, and also at the base of the tentacles. Each group of such cells reacts to its own type of stimulus: the cells at the base of the legs of this creature respond only to mechanical stimulation, the cells at the opening of the mouth are able to distinguish between substances, and are indifferent to other stimuli.

The body of most anemones is uncovered. Tubular specimens have an outer chitinous coating, which makes their stem look like a hard tube. The exoderm of some varieties of such organisms includes small grains of sand and similar particles that strengthen the surface of the skin. Anemones vary greatly in color, sometimes specimens of the same species have different colors. These animals are also characterized by a wide range of sizes: the height of the smallest sea anemone Gonactinia prolifera is 2-3 mm, and the largest Metridium farcimen is 1 m.

Lifestyle

Depending on their lifestyle, sea anemones can belong to one of three groups: they can be sessile, swimming or burrowing. Almost all species of these animals are sessile; only two genera, which are quite rare, belong to the floating sea anemones.

Sea anemones of the sessile group can still move slightly noticeably. If something begins to bother these creatures in the old place (excess or lack of light, lack of food), they begin to move using various ways. There are anemones that move as if turning upside down - they bend the body and attach to the soil substrate with the so-called mouth, then detach the leg and move it. Some of the sea anemones gradually move the sole, tearing off various sections of it from the ground surface.

Anemones of the burrowing group are mainly located in one place, but they burrow into the substrate so much that only a rim of tentacles is visible on the surface of the soil.

Sea anemones of the floating group literally float with the current, moving their tentacles sluggishly.

Places of residence

Sea anemones live in literally all large bodies of water. the globe. Most of these creatures are found in the tropics and subtropics, some of them are in the polar regions.

Sea anemones are found in any depth - both in shallow water and in the deepest ocean trenches. At great depths, only a few species live that have adapted to these conditions. Some species do well in fresh water. Certain varieties of sea anemones can easily become inhabitants of a home aquarium.

The resemblance of sea anemones to plants is simply amazing. The variety of their colors and shapes only confirms this. But unlike representatives of the fauna, they can still move: spread from place to place, burrow into the ground. You should also be aware of the danger - the tentacles of large sea anemones can cause burns upon contact with them.

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 guide with tentacles sea ​​water To 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 polyp colonies are formed. But sea anemones are "friends" with others 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 most strong alliance 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.

More complicated relationship stack up with 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 Northern Arctic Ocean, but most species in warm tropical and subtropical waters.

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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 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 clusters of stinging cells.

Anemones are rather primitive animals; they do not have complex sense organs. Their nervous system 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 are specialized for different types 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 construction material, which strengthens their covers. 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 tropical and subtropical zone, 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 this hostile 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 partly supply their hosts. 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 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 it. 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 more rely on the strength of currents and are passively held on the surface of the water with the help of 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. Most a prime example- 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. Ability to asexual reproduction causes a 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 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 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.

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 annular 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 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 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 sea 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.