home Health technologies Sea anemone is unicellular. Animal sea anemone: habitats, appearance, lifestyle

Sea anemone is unicellular. Animal sea anemone: habitats, appearance, lifestyle

Sea anemones are large coral polyps that, unlike most other corals, have a soft body. Sea anemones are classified as a separate order in the class of Coral polyps; in addition to corals, sea anemones are related to other coelenterates - jellyfish. They received their second name, sea anemones, for their extraordinary beauty and external resemblance to flowers.

Colony of sun anemones (Tubastrea coccinea).

The body of sea anemones consists of a cylindrical leg and a corolla of tentacles. The leg is formed by longitudinal and circular muscles, which allow the body of the sea anemone to bend, shorten and stretch. The leg may have a thickening at the lower end - a pedal disk or sole. In some sea anemones, the ectoderm (skin) of the legs secretes hardening mucus, with the help of which they stick to a solid substrate, in others it is wide and swollen, such species are anchored in loose soil with the help of the sole. The structure of the leg of sea anemones of the genus Minyas is even more surprising: their sole has a bubble - a pneumocystis, 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. Mesoglea can have a very thick consistency, similar to cartilage, so the sea anemone leg is elastic to the touch.

A single sun anemone with translucent tentacles.

At the upper end of the body, sea anemones have an oral disc surrounded by one or several rows of tentacles. All tentacles of one row are the same, but in different rows they can differ greatly in length, structure and color.

Deep sea anemone (Urticina felina).

In general, the body of sea anemones is radially symmetrical, in most cases it can be divided into 6 parts; for this reason they are even classified as a subclass of Six-rayed corals. The tentacles are armed with stinging cells that can shoot thin poisonous threads. The mouth opening of sea anemones can be round or oval. It leads into the pharynx, which opens into a blindly closed gastric cavity (something like a stomach).

Often at the ends of the tentacles you can see swellings formed by accumulations of stinging cells.

Sea anemones are quite primitive animals; they do not have complex sensory 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 external influences. Thus, nerve cells on the sole of the sea anemone are sensitive to mechanical influences, but do not respond to chemical ones, and 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 Entacmaea quadricolor.

Most sea anemones have a naked body, but trumpet 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, which strengthens their integument. The color of sea anemones is very diverse; even representatives of the same species can have different shades. These animals come in all the colors of the rainbow - red, pink, yellow, orange, green, brown, white. Often the tips of the tentacles have a contrasting color, which makes them colorful. The size of sea anemones varies within very wide limits. The smallest sea anemone (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 sea anemone (Metridium farcimen) reaches a height of 1 m!

The carpet anemone (Stoichactis haddoni) has tiny wart-like tentacles, but can reach a diameter of 1.5 m.

Sea anemones are common in all seas and oceans of our planet. Largest number species are concentrated in tropical and subtropical zone, but these animals can also be found in the polar regions. For example, sea anemone metridium senile, or sea pink, is found in all seas of the Arctic Ocean basin.

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

The habitats of sea anemones cover all depths: from the surf zone, where during low tides sea anemones can literally find themselves on land, to the very depths of the ocean. Of course, few species live at depths greater than 1000 m, but they have adapted to such an unfavorable environment. Despite the fact that sea anemones are purely marine animals, some species tolerate slight desalination. Thus, 4 species are known in the Black Sea, and one is found even in the Azov Sea.

Deep-sea tube anemone (Pachycerianthus fimbriatus).

Anemones that live in shallow water often contain microscopic algae in their tentacles, which gives them a greenish tint and partially supplies their hosts with nutrients. Such 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. Sea anemones living in the tidal zone have a clear daily rhythm associated with periodic flooding and drying of the territory.

Anthopleura xanthogrammica lives 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 the burrowing lifestyle is characteristic only of sea anemones of the genera Edwardsia, Haloclava, and Peachia.

This green sea anemone lives in the Philippines.

Sedentary sea anemones, despite their name, are capable of moving slowly. Usually sea anemones move when something does not suit them in their old place (in search of food, due to insufficient or excessive light, etc.). To do this they use several methods. Some sea anemones bend their body and attach to the ground with an oral disc, after which they tear off the leg and move it to a new place. This tumbling “from head to toe” is similar to the method of movement of sessile jellyfish. Other sea anemones move only the sole, alternately tearing off different sections of it from the ground. Finally, the Aiptasia anemones fall on their sides and crawl like worms, alternately cutting different parts of the leg.

Single tube anemone.

This method of movement is also similar to burrowing species. Burrowing anemones actually don’t dig that much, most of the time they sit in one place, and they were called burrowers for their ability to burrow deep into the ground, so that only the corolla of tentacles sticks out. To dig a hole, 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, goes deeper into the ground.

The tallest sea anemone is Metridium farcimen.

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

A lush colony of sea carnations (metridiums).

Sea anemones are solitary polyps, but under favorable conditions they can form large clusters similar to blooming gardens. Most sea anemones are indifferent to their fellows, but some have a quarrelsome “character”. When such species come into contact with a neighbor, they release stinging cells; when they come into contact with the enemy’s body, they cause necrosis of its tissues. But sea anemones are often “friends” with other species of animals. The most striking example is the symbiosis (cohabitation) of sea anemones and amphiprions, or clown fish. Clown fish take care of the sea anemone, clearing it of unnecessary debris and food debris, and sometimes pick up the remains of its prey; the sea anemone, in turn, eats up what is left of the amphiprion's prey. Also, tiny shrimps often play the role of cleaners and parasites, which find refuge from enemies in the tentacles of sea anemones.

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

The cooperation of hermit crabs with adamsia sea anemones has gone even further. Adamsias generally live independently only at a young age, and then they are picked up by hermit crabs and attached to shells, which serve as their home. Crayfish attach the sea anemone not only as if, but precisely with the oral disc forward, thanks to this the sea anemone is always provided with food particles that reach it from the sand disturbed by the cancer. In turn, the hermit crab receives reliable protection from its enemies in the form of the sea anemone. Moreover, he transfers the sea anemone from one shell to another every time he changes his house. If a crayfish does not have an anemone, it tries to find it in any way, and more often, take it away from a happier brother.

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

A colony of sun anemones hiding their tentacles.

Sea anemones can reproduce asexually and sexually. Asexual reproduction occurs through longitudinal division, when the body of the sea anemone is divided into two individuals. Only in the most primitive gonactinia does transverse division occur, when a mouth grows in the middle of the leg, and then it splits into two independent organisms. Some sea anemones may experience a kind of budding, when several young organisms separate from the sole at once. The ability for asexual reproduction determines a high ability for tissue regeneration: sea anemones easily restore severed body parts.

The same sun anemones, but with tentacles extended.

Most sea anemones are dioecious, although males do not differ in appearance from females. Only in some species can both male and female reproductive cells be formed simultaneously. Sperm and eggs are formed in the mesoglea of sea anemones, but fertilization can occur either in external environment, and in the gastric cavity. During the first week of life, sea anemone larvae (planulae) move freely in the water column and during this time they are carried by currents over long distances. In some sea anemones, planulae develop in special pockets on the body of the mother.

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

Sea anemones are large coral polyps that, unlike other corals, have a soft body. Sea anemones belong to a separate class of coral polyps, and they are also related to jellyfish. They are also called sea anemones because they have such beautiful view that look like flowers.

Features of the appearance of sea anemones

The body consists of a cylindrical leg and a bunch of tentacles. The leg consists of circular and longitudinal muscles, thanks to which the sea anemone can stretch, shorten and bend. At the bottom of the leg there is a sole or pedal disc.

Mucus is released from the sea anemone's leg, which hardens, and the sea anemone sticks to the substrate. Other sea anemones have wide legs, with their help they cling, like an anchor, to loose soil, and the sole with a bladder acts as a fin. These types of sea anemones swim upside down.

At the upper end of the body is an oral disc, which surrounds a row or rows of tentacles. In one row the tentacles are the same, but in different rows they may differ in color and size. The tentacles are equipped with stinging cells, from which thin poisonous threads fly out. The mouth opening may be oval or round in shape.

Sea anemones are fairly primitive creatures that do not have complex sensory organs. The anemone's unequal system consists of a group of sensory cells located on the sole, base of the tentacles and around the mouth opening. These nerve cells respond to various stimuli, for example, cells near the mouth are able to distinguish substances, but do not respond to mechanical influence, and cells on the sole do not respond to chemical influence, but are sensitive to mechanical influence.

Most sea anemones have a naked body, but sea trumpet anemones have a chitinous cover, their leg looks like a tube, which is why they are called “tubular”. The bodies of some sea anemones are covered with grains of sand and various building materials, which make the cover more durable.

The color is so diverse that even representatives of the same species can have different shades. Sea anemones can be all the colors of the rainbow: pink, red, green, orange, white and the like. Often the edges of the tentacles have a contrasting color. The body sizes of anemones vary over a wide range.

The body height of the smallest one, gonactinia, is 2-3 mm, the largest is the carpet anemone, with a diameter of up to 1.5 meters, and the height of the metridium sea anemone reaches 1 meter.

Distribution and habitats of sea anemones

Sea anemones live in all oceans and seas. Most of these animals are concentrated in subtropical and tropical zones, but they are also found in the polar regions. For example, in the seas of the Arctic Ocean lives the sea pink or the senile metridium.

The habitats are quite diverse: from the depths of the ocean to the surf zone. Few species of sea anemones live at ocean depths of more than 1000 meters. Although sea anemones are mostly marine animals, certain species can live in fresh water. There are 4 species of sea anemones in the Black Sea, one species lives in the Sea of Azov.

Anemone lifestyle

Anemones that live in shallow water often have microscopic algae in their tentacles, which gives them a green tint and supplies them with nutrients. These sea anemones live in illuminated places and are active mainly during the day, as they depend on the photosynthesis of algae. And certain species cannot tolerate light at all. Sea anemones that live in the tidal zone have a clear diurnal regime, which is associated with the time of drying and flooding of the territory.

All sea anemones can be divided into 3 types according to their lifestyle: swimming, sessile and burrowing. Most sea anemones are sessile, the burrowing ones include the genera Haloclava, Edwardsia and Peachia, and only the genus Minyas is swimming.

Sea anemones are attached to the bottom using the so-called “sole”.

Sedentary sea anemones, contrary to their name, are capable of moving slowly. As a rule, they begin to move if something does not suit them, for example, lighting or lack of food. Sea anemones move in several ways. Some species arch their body and attach themselves to the ground with their oral disc, then tear off their leg and move it to a new place. Sessile jellyfish move in a similar way. Other species move their sole, alternately tearing off sections of it from the ground. And the third way is that sea anemones lie on their sides and crawl like worms, while different parts of the leg contract.

In fact, burrowing sea anemones do not burrow that often. They sit most of their lives, and they are called burrowers because they can burrow into the ground, and only the corolla of the tentacle remains visible from the outside. In order to dig a hole, sea anemone acts quite in an interesting way: collects water in the oral cavity, and alternately pumps it to one end of the body, and then to the other, so it goes deeper, like a worm, into the ground.

Sessile small gonactinia is sometimes capable of swimming; during swimming, it rhythmically moves its tentacles, its movements are similar to contraction of the dome. Floating species float passively on the water with the help of pneumocystis, and move with the help of the current.

Relationships between sea anemones and other marine inhabitants

Sea anemones lead a solitary lifestyle, but if conditions are favorable, then these polyps unite in colonies, forming beautiful flowering gardens. Basically, sea anemones do not show interest in their relatives, but some of them have a quarrelsome disposition. When these anemones touch a relative, they attack it with stinging cells, which cause tissue necrosis.

But sea anemones often get along well with other species of animals. The most striking example of symbiosis is the life of sea anemones and clown fish. The fish take care of the polyps, clearing them of food debris and various debris, and the sea anemones eat the remains of the clown fish’s prey. And shrimp often find shelter from enemies and food in the tentacles of sea anemones.

Sea anemones - beneficial organisms. They live in tropical and subtropical waters.

The relationship between adamsia sea anemones and hermit crabs is even better established. Only young Adamsia live independently, and then hermit crabs find them and attach them to their shells. In this case, the sea anemone is attached with its oral disc forward, thanks to which it gets food particles from the soil churned up by cancer. And sea anemone protects crayfish from enemies. Moreover, when a crayfish changes its home, it transfers the sea anemone to a new shell. If the cancer has not found its sea anemone, it tries to take it away from its fellow.

Feeding sea anemones

Some sea anemones send everything that touches their tentacles into the oral cavity, even pebbles and other inedible objects, while others spit out what cannot be eaten.

Polyps feed on various animal foods. Some species filter water and extract organic debris from it, while others hunt larger prey - small fish. For the most part, sea anemones feed on algae.

Anemone reproduction

Reproduction in sea anemones can occur sexually and asexually. Asexual reproduction occurs due to longitudinal division, in this case two individuals are produced from one individual. This method of reproduction is found in the most primitive sea anemones, gonactinia. A mouth is formed in the middle of the leg of these sea anemones, after which the animal splits into two independent organisms. Since sea anemones are capable of asexual reproduction, they have a high ability to regenerate tissue: sea anemones quickly restore lost body parts.

Most sea anemones are dioecious. But there are no differences between male and female sea anemones. In certain species of sea anemones, both female and male reproductive cells can simultaneously form.

The process of fertilization in sea anemones can occur in the gastric cavity or in the external environment.

In the first week of life, anemone larvae move freely in the water, due to which they are carried over long distances by the current. In some species, larvae develop in special pockets that are located on the bodies of the mother.

Sea anemones are large coral polyps that, unlike most other corals, have a soft body. Sea anemones are classified as a separate order in the class of Coral polyps; in addition to corals, sea anemones are related to other coelenterate animals - jellyfish. They received their second name, sea anemones, for their extraordinary beauty and external resemblance to flowers.

Colony of sun anemones (Tubastrea coccinea)

The body of sea anemones consists of a cylindrical leg and a corolla of tentacles. The leg is formed by longitudinal and circular muscles, which allow the body of the sea anemone to bend, shorten and stretch. The leg may have a thickening at the lower end - a pedal disk or sole. In some sea anemones, the ectoderm (skin) of the legs secretes hardening mucus, with the help of which they stick to a solid substrate, in others it is wide and swollen, such species are anchored in loose soil with the help of the sole. The leg of sea anemones of the genus Minyas is even more surprising: their sole has a bubble - a pneumocystis, 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. Mesoglea can have a very thick consistency, similar to cartilage, so the sea anemone leg is elastic to the touch.

Single sun anemone with translucent tentacles

Deep sea anemone (Urticina felina)

Often at the ends of the tentacles you can see swellings formed by accumulations of stinging cells

Sea anemones are quite primitive animals; they do not have complex sensory 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. Thus, nerve cells on the sole of the sea anemone are sensitive to mechanical influences, but do not respond to chemical ones, and 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 Entacmaea quadricolor

The carpet anemone (Stoichactis haddoni) has tiny wart-like tentacles, but can reach a diameter of 1.5 m

Sea 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, sea anemone metridium senile, or sea pink, is found in all seas of the Arctic Ocean basin.

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

Deep sea tube anemone (Pachycerianthus fimbriatus)

Anemones that live in shallow water often contain microscopic algae in their tentacles, which gives them a greenish tint and partly supplies their hosts with nutrients. Such 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. Sea anemones living in the tidal zone have a clear daily rhythm associated with periodic flooding and drying of the territory.

Anthopleura xanthogrammica lives in symbiosis with green algae

This green sea anemone lives in the Philippines

Single tube anemone

The tallest sea anemone is Metridium farcimen.

Lush colony of sea carnations (metridiums)

Sea anemones are solitary polyps, but under favorable conditions they can form large clusters similar to flowering gardens. Most sea anemones are indifferent to their fellows, but some have a quarrelsome “character”. When such species come into contact with a neighbor, they release stinging cells; when they come into contact with the enemy’s body, they cause necrosis of its tissues. But sea anemones are often “friends” with other species of animals. The most striking example is the symbiosis (cohabitation) of sea anemones and amphiprions, or clown fish. Clown fish take care of the sea anemone, clearing it of unnecessary debris and food debris, and sometimes pick up the remains of its prey; the sea anemone, in turn, eats up what is left of the amphiprion's prey. Also, tiny shrimps often play the role of cleaners and parasites, which find refuge from enemies in the tentacles of sea anemones.

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

Colony of sun anemones hiding their tentacles

The same sun anemones, but with extended tentacles

Most sea anemones are dioecious, although males do not differ in appearance from females. Only in some species can both male and female reproductive cells be formed simultaneously. 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. During the first week of life, sea anemone larvae (planulae) move freely in the water column and during this time they are carried by currents over long distances. In some sea anemones, planulae develop in special pockets on the body of the mother.

Touching the tentacles of large sea anemones can cause painful burns from the stinging cells, but no deaths are known. Some types of anemones (carpet, horse or strawberry, etc.) are kept in aquariums.

Sea anemones

Sea anemones in a drawing by Ernst Haeckel (1904)

Scientific classification

International scientific name

Actiniaria Hertwig,

Taxonomy
on Wikispecies

Images
on Wikimedia Commons

ITIS
NCBI

Sea anemones, or sea anemones(lat. Actiniaria) - a detachment of marine cnidarians from the class of coral polyps ( Anthozoa). Representatives lack a mineral skeleton. As a rule, single forms. Most sea anemones are sessile organisms that live on hard ground. Few species (eg. Nematostella vectensis) switched to a burrowing lifestyle in the thickness of bottom sediments.

Body structure

The cylindrical body of sea anemones varies in diameter from a few mm to 1.5 meters.

Their length varies from 1.5 to 10 cm. It has a record height (1 m) Metridium farcimen from the Pacific Northwest Coast of the USA. They are attached to hard substrates using a “sole” (pedal disc). In burrowing forms that live on soft soils (for example, sand), no special organs of attachment are formed, but the expanded basal end of the body forms a swelling (physa), shaped like an onion or mushroom and serves for anchoring in the soil. In unusual tropical sea anemones of the genus Minyas(some species of this genus are colored aqua) in the swelling of the pedal disc there is an air-filled chitinous bladder. These sea anemones float passively “upside down” at the surface of the water. Similar adaptations to life in neuston arose in hydroid polyps Velella And Porpita, which can be considered as an example of parallelism in the evolution of representatives of different taxa.

Anemones in most cases bear six or more than eight simple tentacles tapering to a point. There is often a terminal pore at the tip of each tentacle. In a number of species, the tentacles are branched, have expanded tips (“knobs”), or, conversely, are reduced to the state of numerous low knobs that evenly cover the entire oral disc, as, for example, in sea anemones of the genus Stoichactis. Some sea anemones (for example, representatives of the genera Actinia And Anthopleura) protect themselves from competitors with the help of special tentacle-like outgrowths - acrorags. These outgrowths extend from the body somewhat below the bases of the true tentacles. Acroragas carry nematocysts and are capable of inflating. Sea anemones resort to this “weapon” when in contact with representatives of another species or with sea anemones of the same species, but a genetically different clone. The collision results in tissue damage and the retreat of one or both opponents.

The body of sea anemones is usually uniform along the entire length from the oral to the pedal disc, however, in representatives of some species top part body, lying just below the oral disc and tentacles, is a neck-like thin-walled introvert, or capitulum. The body wall below the introvert is usually thicker. The transitional area between the introvert and the rest of the body often bears a fold in the form of a collar (parapet), as in representatives of the genera Actinia, Metridium And Urticina. When, during the contraction of the polyp, the oral disc, tentacles and capitulum are drawn inward, the transitional region narrows so that the parapet covers and protects the remaining opening. The narrowing is caused by contraction of the sphincter muscle located in the epidermis or mesoglea.

Externally, the body wall may be more or less smooth and undifferentiated, or may bear specialized structures. Dense papillae cover the body Haloclava producta And Bunodosoma cavernata. Rows of adhesive papillae (warts) cover the body of other sea anemones, e.g. Anthopleura, Urticina, Bundosoma And Bunodactis. Grains of sand and fragments of mollusk shells are glued to these papillae, which protect the animal’s body. Some anemones have cinclids, through which water and acontia, if present, are thrown out during body contraction. Sea anemones (species of the genus Bunodeopsis), over the surface of which thin-walled vesicles (vesicles) containing zooxanthellae protrude separately or organized in groups.

Some anemones have one siphonoglyph, but, as a rule, there are two siphonoglyphs. Usually there are both complete and incomplete pairs of septa. Their number is never less than 12, and often much more. Actions may or may not be present. Acontia-bearing sea anemones (such as Aiptasia, Bartholomea And Metridium) are called aconciate. The longitudinal muscle cords in the septa are exceptionally well developed. They are attached to the oral and pedal discs and are primarily responsible for retraction of the oral disc and tentacles, as well as contraction of the entire body.

At the pole of the body, facing away from the substrate, there is a slit-like mouth surrounded by a corolla of tentacles.

Sea anemones lack a mineral skeleton: their supporting function is taken over by the intestinal cavity, which is isolated from environment when closing the mouth opening. The coordinated work of this hydroskeleton and the muscles of the body wall turns out to be quite effective: among the sea anemones there are representatives that are able to move through the thickness of the soil. Most anemones are capable of strongly contracting and expanding, which means that their shape and size depend on the specific circumstances in which they find themselves at a given time. Some species secrete a chitinous periderm, which is primarily used for defense. The periderm is usually confined to the pedal disc or body wall below the introvert. The most intense formation of chitin is characteristic of pelagic sea anemones of the genus Minyas, as well as for representatives of the group of deep-sea, so-called frilled sea anemones (genus Stylobates).

Sea anemones, which are usually attached to the substrate, can slowly “slide” along it due to the contraction of the pedal disk muscles. Burrowing forms make holes in the ground due to peristaltic contractions of the body, while movement is carried out with the pedal pole forward. Some sea anemones can “walk” on tentacles, and Gonactinia prolifera(a hydra-sized organism) swims by striking the water with its tentacles. Large sea anemone Stomphia usually attached to the substrate, but when a predatory starfish tries to attack it, the anemone can separate from the substrate and swim due to the flapping movements made by the lower part of its body.

Many anemones are brightly colored: they can be white, green, blue, orange, red, and also multi-colored.

USSR stamp

Ecology and nutrition

They feed on various small invertebrates, sometimes fish, first killing or paralyzing the prey with “batteries” of stinging cells (cnidocytes), and then pulling them to the mouth using tentacles. Large species feed on crabs, bivalves, which are washed away by waves. The edges of the mouth that form the “lip” can swell and also help capture prey. Sea anemones with numerous tentacles, such as Metridium, Radianthus And Stichodactyla, feed on particles suspended in water, but there is evidence that Stichodactyla helianthus catches sea urchins by enveloping them with its muscular oral disc. Forms that feed on particles suspended in water catch plankton inhabitants with the help of mucus that covers the surface of the body and tentacles. The cilia on the surface of the body always beat in the direction of the oral disc, and the cilia on the tentacles ensure the movement of food particles to their tips. The tentacles then bend and carry the food into the mouth.

The gastrodermis of many sea anemones contains zooxanthellae, zoochlorella, and sometimes both. They are especially numerous in the tentacles and oral disc. Individual color variability Anthopleura elegantissima determined by the predominance of zoochlorella or zooxanthellae. Tropical sea anemone Lebrunia danae has two "sets" of tentacles: a corolla of simple tentacles for catching prey and a corolla of "pseudo-tentacles" containing zooxanthellae. The pseudotentacles, in which photosynthesis occurs thanks to the symbionts, are spread out during the day, and the tentacles for catching prey are spread out at night.

May cause painful burns in humans.

Symbiosis

Sea anemones and hermit crabs form very common symbiotic systems that are often found in the seas. As a rule, one or several sea anemones settle on one crayfish. It is believed that sea anemones derive a variety of benefits from this cohabitation: the presence of a substrate (a shell occupied by a hermit crab) for attachment, transportation to food sources, including pieces of food dropped by the sea anemone from a feeding crayfish, protection from predators. Hermit crab encounters likely provide breeding opportunities not only for hermit crabs themselves, but also for sea anemones. Crayfish, in turn, receive passive protection from anemones (anemones camouflage their partner in the symbiotic system well) and active protection in the form of numerous nematocysts. Most importantly, sea anemones repel enemies of cancer such as octopuses and crabs of the genus Calappa. When a hermit crab “grows” out of its shell and, having molted, looks for a shell bigger size, it helps the sea anemone move to a new place of residence. To do this, the crayfish strokes the anemone, stimulating the relaxation of its pedal disk, and then moves it to the surface of a new shell. Some species of sea anemones themselves move to a new shell, performing a “somersault over their heads.”

As they grow, hermit crabs look for increasingly larger gastropod shells. At the moment of "relocation" the cancer is actually defenseless, since at this time it becomes vulnerable to predators. Sometimes he also has to fight with other hermit crabs, because there are often not enough suitable shells for everyone. Anemones from the genus Stylobates with the help of their expanded and flattened pedal disk, they form a chitinous “surrogate” shell, which the cancer occupies - in the deep-sea areas where these hermit crabs and their sea anemones live, there are few suitable shells. Since the sea anemone not only creates a “shell”, but also gradually expands it, the cancer avoids the dangers associated with changing the shell. Sea anemones Stylobates also benefit from the fact that they are not left “unattended” while changing the sink. In addition, the hermit crab can drive away enemies of the sea anemone and accidentally share food with it.

Small Indo-Pacific fish of the genus Amphiprion(clownfish) live between the tentacles of large sea anemones, entering into a symbiotic relationship with the latter. Sea anemones “recruit” young fish by releasing substances that attract them (attractants). Attractants are species-specific, that is, they attract organisms only of a certain species. The mucus covering the fish does not contain substances that initiate the firing of nematocysts, so they can exist between the tentacles of the sea anemone in a habitat that is deadly for other animals. The sea anemone provides the fish with protection and food remains, and the fish attract prey (fish of other species) to the “hostess”, protect it from some predators (butterfly fish), remove necrotic tissue, and also, by swimming between the tentacles, “ventilate” the sea anemone, preventing sludge pollution.

In addition to this, sea anemones also form symbiotic systems with some amphipods, shrimp of the genus Periclimenes, click crayfish, crabs of the genus Stenorhynchus and brittle stars.

Reproduction

Asexual reproduction

Spreading

Widely distributed. Sea anemones inhabit deep ocean areas or shallow coastal waters throughout the world. Most live in tropical and subtropical waters. There are an estimated 1,350 species of sea anemones. Sea anemones attach to rocks, mollusk shells and submerged wooden objects, or they live a burrowing lifestyle in mud or sand.

Notes

Literature

Dogel V. A. Zoology of invertebrates, 5th ed. - M., 1959.
Animal life, vol. 1. - M., 1968, p. 299-306.
Ruppert E.E., Fox R.S., Barnes R.D. Protists and lower multicellular organisms // Zoology of invertebrates. Functional and evolutionary aspects = Invertebrate Zoology: A Functional Evolutionary Approach / trans. from English T. A. Ganf, N. V. Lenzman, E. V. Sabaneeva; edited by A. A. Dobrovolsky and A. I. Granovich. - 7th edition. - M.: Academy, 2008. - T. 1. - 496 p. - 3000 copies. - ISBN 978-5-7695-3493-5
// Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional ones). - St. Petersburg. , 1890-1907.

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See what "Anemone" is in other dictionaries:

Sea anemones (Actiniaria), an order of six-rayed corals. Solitary (rarely colonial) non-skeletal polyps. Body from several mm to 1.5 m in diameter, with a corolla of tentacles, usually brightly colored. OK. 1500 species, in all seas, from the littoral to the depths... Biological encyclopedic Dictionary

- (sea anemones, sea nettles) beautiful, bright colors marine animals from class. polyps. A fleshy body, with a suction plate at the bottom, a mouth opening at the top, surrounded by long tentacles, giving the sea anemone the appearance of a flower. Dictionary… … Dictionary of foreign words of the Russian language

- (sea anemones) a detachment of marine coelenterates of the class of coral polyps. OK. 1500 species. Sizes from a few millimeters to 1.5 m. Single polyps without a skeleton; tentacles with stinging cells. Mainly in tropical and... Big Encyclopedic Dictionary

sea anemone- sea anemones, sea anemones, sessile animals from the type of coelenterata (Coe lenterata) and the subclass of coral polyps; A. are non-skeletal single polyps with a fleshy body in the form of a sac, the inlet of which is surrounded by many... ... Great Medical Encyclopedia

Sea anemone, order of marine coelenterates; single non-skeletal coral polyps. The body is from a few mm to 1.5 m, with a crown of tentacles (their touch can cause a burn in a person). Usually brightly colored (resembling fantastic flowers). Near… … Modern encyclopedia

Any person who has seen this amazing creature is primarily interested in: is sea anemone an animal or a plant? Many people are confused by the definition of this creature - “sea anemone”: nevertheless, most people know that an anemone is a flower. The amazingly beautiful ones that have managed to adapt to life in the form of rather vulnerable organisms amaze the imagination: you just want to take them with you, protect and shelter them. Not worth it! First of all, it’s not for nothing that these creatures are sometimes called “jellyfish-anemones”: they are quite capable of standing up, and not only for themselves. And secondly, you are unlikely to be able to create suitable living conditions for them. So, while at the resort, just enjoy the view of them and try not to swim too close, so as not to treat the rather painful burns after.

Appearance

It is the appearance of these creatures that gives rise to the eternal question: is sea anemone an animal or a plant? And by the way, until the end of the 19th century they were classified as plant species. However, science does not stand still: it has been established that “sea anemones” are animals that, in their structure and lifestyle, are close to jellyfish and other coelenterates, to which many biologists include ctenophores.

If we explain it in a primitive way, then any sea anemone (photos are presented) is one continuous mouth on a stalk. The flower-like “petals” are the tentacles responsible for delivering food. Most often, the “stand” has a flat sole, with which the “sea anemones” are attached to a rock or hard bottom; but there are species with a pointed limb - they are stuck into the bottom like a bouquet; And there are floating varieties. Observing the behavior of these creatures, you will no longer be puzzled: is sea anemone an animal or a plant? It immediately becomes clear that she is not just an animal - she is a predator.

Sea anemones are not polyps

It would also be a mistake to say that this most beautiful creature is coral. The sea anemone is, without a doubt, very close to the polyps that form the islands that captivate everyone. However, they do not form a skeleton, and corals are the skeletons of polyps. At the same time, it cannot be said that sea anemone is “soft-bodied”, since the substance that fills the space between its cells forms a very thick layer and is similar in density to cartilage in vertebrates.

What do they eat?

Another argument in doubt is whether sea anemone is an animal or plant - its diet. If those interested remember, plants feed on water (with substances dissolved in it) and what they can get from the soil. However, sea anemones prefer a completely different menu. It includes small invertebrates and small fish(if you're lucky). The method of obtaining food is also completely non-vegetative: the tentacles paralyze the prey and pull it towards the mouth. Some may object: this is also known, but they cannot boast of a mouth and dissolve prey with enzymes located directly on the leaf plate or in a trap flower. That is, they do not have organs intended exclusively for digestion.

Impact on the victim

Even if we assume that sea anemone is a plant, then we must look for an explanation for its hunting method. In each stinging cell - albeit very, very small - there is a kind of capsule containing poison. And on the outside there is a stinging thread with spines facing backwards. Visually, under a microscope, this entire device resembles a miniature harpoon. When an anemone attacks, the thread straightens, the needle pierces the victim’s body and releases poison. Not a single plant has such a complex structure - they are much lower on the evolutionary ladder and have a much simpler structure.

By the way, the stinging venom of sea anemones is dangerous even for such a large organism as a person. Of course, it will not lead to death, but it will cause a burning sensation with itching, and in some cases, necrosis will develop. Almost all of those who regularly interact with gentle “anemones” have allergies.

Famous symbiosis

It must be said that most sea flowers lead a sedentary lifestyle. However, updating the hunting grounds is what any sea anemone needs. Movement is usually accomplished through symbionts. The most famous of them (familiar thanks to the touching Soviet cartoon) is the hermit crab. The most interesting thing is that this shellfish itself transfers to its “shell” a creature that is deadly for mollusks. Enough for a long time they coexist peacefully: the crayfish carries the sea flower from place to place, the sea anemone repels the attacks made against it natural enemies. However, everything is not so rosy: the “leg” of the sea “flower” easily dissolves the organic matter that makes up the host’s shell, after which the cancer comes to an end.

Moving sea anemones

Even those sea anemones that are designed by nature to “sit” in place can move. In the end, the small inhabitants of the oceans, as people say, are “no dumber than a steam locomotive” and over time they realize the danger of some bottom area. Accordingly, ocean flowers are forced to migrate as their hunting grounds become scarce. What does the average sea anemone do in this case? She moves slowly but surely. The sole is separated from the bottom, extended a short distance, secured and tightens the rest of the body. However, small species (like gonactinia) can even swim, straightening their tentacles back.

Fish-anemone cooperation

It must be said that ocean anemones symbiote not only with hermit crabs. They also travel on other armored animals (however, for carriers this usually ends the same way, even in the case of small varieties). However, sea anemones can coexist quite peacefully with fish. Off the Australian coast, the largest sea anemones on earth (their “mouth” is often not limited to one and a half meters in diameter) provide shelter among their tentacles for amphiprions - very bright fish that feed the “host” with fallen food debris, and with the work of their fins they create additional aeration for it. At the same time, anemones are quite capable of distinguishing their friends from other fish and actively protect them from predatory attacks.

Reproduction of sea anemones

They give preference to the sexual method, which is another proof that sea flowers are animals, not plants. However, in unfavorable conditions they can use budding, in which you begin to remember the misconception about “anemone is a plant,” and longitudinal or transverse division. This is especially true for small varieties. The same gonactinia tends to split across. It is extremely interesting to observe: first of all, a wreath of tentacles grows around the circumference of the body, and then it divides. The upper half grows a sole, the lower half grows a “mouth” and another set of goads. It is noteworthy that the second division does not wait until the end of the first, so that the sea anemone of this species can be surrounded by several rings of tentacles, foreshadowing the imminent appearance of several individuals.

You can check whether an anemone is an animal or a plant at by example. Sea anemones do not regard humans as either an enemy or prey. So, when touched by a person, they simply curl up (if you don’t fiddle with them, of course). You could say they are hiding. As for the rest, the sea anemone (the photos demonstrate this) is very beautiful and interesting creature, which is interesting even just to watch.

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