Facts about coral polyps. Class coral polyps (Anthozoa). Two Coral North Atlantic

Class Coral Polyps (Anthozoa)

Coral polyps are sea colonial, less commonly solitary polyps, developing without changing generations. Preferably live in warm tropical seas, where the temperature of the water is not below 20 ° C, and at depths of not more than 20 m, in conditions of abundant plankton, which they feed. About 6 thousand types of coral polyps are known. Many of them have a limestone skeleton and are rhymers.

Coral polyps, despite the overall similarity of the structure with hydroids, differ from the last following features:

The dimensions of coral polyps are larger and they have a strongly developed mesoglya,

Most species are well developed skeleton (horny or lime). The skeleton can be an outer, formed by ectoderm, or inner, forming in Mesogle;

- touring cavity divided by partitions-setoes on the camera. There is an ectodermal throat with flavored guro-siphonoglyphs, providing water current in a gastric cavity;

- Gonada Food are formed in Entoderm. The reproduction is intact and sex. Development with metamorphosis. Larvae - I planned. There are no alternations;

Available muscular cellsforming longitudinal and transverse muscles;

- nervous system forms thick plexus on the oral disk;

Rady symmetry is broken and transition to two-radical, or bilateral, symmetry.

Fig. 96. The structure of a six-coral coral polyp (by Pfurgceller): 1 - Tentacles, 2 - mouth, 3 - Hollowness, 4 - septa, 5 - plantar plate, 6 - Cheschka, 7 - Sclermepta, 8 - polypa tissue

Fig. 97. Education of an inner skeleton in eight-beam polyps (by Hadann): 1 - Tentacles, 2 - skeletal needles at the base of the tental, 3 - stomach with septs, where eggs ripen, 4 - skeletal chips, 5 - Mesoglya, a gastric canal in the trunk of the colony, Surrounded by a skeleton, 6 - trunk of the colony

There are two subclass of modern coral polyps: octocorallia and six-beam (Hexacorallia), between which significant differences in the organization are observed. Therefore, characterizing the morphology and physiology of coral polyps, it is more convenient to give a comparative essay on Octocorallia and Hexacorallia.

Comparative morphophysiological characteristics of 6- and 8 radial coral polyps. Cylindrical polyps body. Single polyps soles are attached to the substrate, and colonial to the body of the colony is a censure. On the oral pole of the polyp is a mouth, surrounded by always hollow tentacles (Fig. 96). In terms of the number of supreets it is easy to distinguish the subclasses of coral polyps: 8-ray always eight provers and they are perishes, with lateral growth, and the 6-radiation tentacles are smooth and their number to six (Fig. 96, 97).

Gastric cavity is complicated. The mouth leads to a flattened ectodermal liner in the same direction. Octocorallia has in one end of the pharyngeal gap siphonoglyph - Grooves lined with fiscal epithelium. HEXACORALLIA siphonoglyphs have two - in both corners of the pharyngeal gap. Siphonoglyphs provide water current through a gastral cavity. The sloping throat and the presence of 1- 2 siphonoglyphs disrupt the radial symmetry of polyps, and therefore, 8-radial polyps can be carried out only one, and in b-radiation only two planes of symmetry. The throat leads to a garbage cavity that is divided

Fig. 98. Cross cuts across eight-beam and six-legis polyps (A - by Hickson, B - by Hyman): 1 - Throat, 2 - Package cavity, 3 - siphonoglyph, 4 - Ventral guitance chamber, 5 - septa, 6 - Muscular septa roller, 7 - Dorzal guitance chamber, 8 - internal chambers between septites of first order, 9 - internal chambers between secondary septs, 10 - Intermediate chambers, 11 - Ektoderma, 12 - Entoderma, Mesoglya has been launched

radial partitions - septs. Septy are the side folds of the Entoderm, and each fold consists of two layers of the Entoderma, between which the mesoglya with muscular cells is. Septy with free edge griest to the throat, and below the pharynx do not climb, forming the stomach. The edges of the septo are thickened, corrugated, seated with cutting and digestive cells, forming mesenteric threads. Their free ends are called aconizing. The extraction falling into the stomach of the polyp is tightly decomposed with mesenteric threads, killed and gradually digested under the influence of digestive enzymes. The presence of septo increases the digestive surface in the polyps. The number of septo and their location is different in two subclasses (Fig. 98).

Octocorallia has eight septus with muscle rollers. Sept pairs derived from two angles of flattened pharynx are called a guide camping chamber opposite the only siphonoglyph the fact that the muscular rollers in its septs are addressed inside. This chamber is conventionally called "ventral". On septures, the oppositely located "Dorzal" roller chamber is turned out from the camera. Thus, the arrangement of muscular rollers in septs Octocorallia also distorts radial symmetry.

HEXACORALHA SEPT has a lot, not less than 12, and their number is multiple of six. The muscular rollers in the guild cameras are turned out and disrupt the two-beam symmetry determined by the form of the pharynx and two

siphonoglyphs. Septa in 6 radial polyps form gradually. Initially, there are six pairs of sept of first order, which grow up to the throat. Between septs of each pair, the main chambers are formed, and between them - intermediates, in which additional pairs of sept of second order are formed, etc. (Fig. 98).

Nutrition in coral polyps is diverse. Many feed on plankton or catch small animals with a suckleset. Large single Polyps - Actinia (Actinia) are capable of catching and large animals: fish, shrimp. Well, recently it turned out that part of the types of coral polyps live at the expense of symbiosis with single-cell algae, which they live in Mesogle.

For coral polyps leading mainly attached lifestyle, characteristic of the presence of a skeleton, which is formed differently from different subclasses.

In 8-ray polyps, the skeleton is internal and formed in the Mesogle, it may be a horny or lime. Skeletal elements (Fig. 99) are formed in scleroblast cells. Skeletal needles can merge each other or connect the corneum, forming the skeleton of the colony. For example, a noble coral (Corallium Rubrum) is a skeletal trunk of a limestone, purple color. From above, the branch of the colony is covered with ectoderm. The inner skeleton is permeated by a network of entodermal channels that bind all members of the colony (Fig. 97).

In 6-radiation polyps, the skeleton is the outer, allocated by ectoderma, less frequently inner or absent. The growth of the outer skeleton around the young polypper comes from the sole region, where the plantar plate appears first, and it is formed lime septites - sclerothepta, and then a cup is already formed - a tek that protects the entire polyp to the level of the supreet. The skeleton often turns the skin folds from above and impresses internal.

There are polyps without a skeleton, such as acti. In many 8-ray polyps, the skeleton is poorly developed and it replaces the hydraulic cooler - the turgor of the colony, which is provided with a gastric cavity with water.

Reproduction and development. Polyps can be multiplied with use: killing, division in transverse and longitudinal directions.

Gonads ripen in Entoderma septures in Entoderma. Polyps are usually separatable. Spermatozoa through the gonad wall breaks go to the garbage cavity, and then outward and penetrate through the mouth into the cavity of the female individual. Fertilized eggs are developed for some time in the Mesogle sept. The larva-planlas usually leave the maternal polyp, and then settle on the solid substrate and are converted to polyps (Fig. 100, 5). In many coral polyps, development proceeds without metamorphosis and the larva slanted is not formed.

Overview of subclasses and detachments of coral polyps. In total, five subclasses of coral polyps, of which three subclass are known only in the fossil condition (Tabulata, Rugosa, Heliolitoidea). Two subclasses are represented by modern forms (OCTOCORALLIA and non-sweet) (Fig. 101, 102).

Eight-beam coral subclass (octocorallia)

Eight-beam corals have eight provers, eight septa, skeleton inner. There is a violation of radial symmetry to bilateral due to the presence of one siphonoglyph and the arrangement of muscular rollers in septures (Fig. 98 a).

Alcyonaria detachment - The most numerous, including about 1300 species of marine polyps. Among them, most are soft corals, without a developed skeleton, with separate sprocket scattered in mesogle. They form a colony of a variety of shape: branched, pillars, spherical. An example of soft corals can serve as a sequence colonies - "Hands" (Fig. 103). Only some species of the type of Tubipora - the organization have a developed limestone skeleton forming a tube in a mesogle, soldered by transverse records. Their skeleton remotely resembles the body, with which their name is connected. Organizers form large spherical colonies and participate in rhyme formation. On the White Sea the corals of the genus Versemia fruticosa. Aliances often form thick thickets on rocky soils.

Detachment Horn Corals (Gorgonacea) Make up polyps with an internal horny skeleton. It is also a rich detachment (1200 species), which occurs mainly in tropical areas, but some of them have gratened to habitat in the polar areas. Fan-shaped colonies form polyps of the genus Gorgonia, called Venera Fan.

Fig. 101. Eight-beam corals (on doogle): A - GERSEMIA INTERIOR, B - Marine Feather Pennatula, V - Horny Coral Leptogorgia

Gorgonaries include fishing red corals (Corallium Rubrum) and similar views of it, mined in the Mediterranean, Red and other seas. Their organic skeleton is saturated with lime and has various shades of red. Great coral make valuable jewelry.

Square Marine Feathers (Pennatulacea). Sea feathers form a first-shaped colony: with a thick barrel, on which polyps are located on the sides of the right rows. The number of species is small (300). Some species are common in the Arctic Ocean, and among them there are the largest colonies with a height of up to 2.5 m (Umbrella Encrinus). Pennatula colonies are capable of luminescence. Sea feathers, in contrast to other coral polyps, do not grow to the substrate. They hurt in the ground, and sometimes swam from place to place.

Hexacorallia subclass (Hexacorallia)

Six high corals have a lot of smooth supreets, the number of which is multiple of six. The gastrovascular cavity is divided by a complex SPAT system, the number of which is also multiple of six. Six-free symmetry is broken up to two-beam due to two siphonoglyphs and a slight-shaped pharynx. Often the skeleton is outdoor, lime, rarely absent. Severe five seats of six-world corals.

Actinia detachment (Actinaria) Includes mainly large forms of single polyps, deprived of skeleton. Actinia is able to slowly move on the sole. These are active predators, sometimes eating even small fish. Often they are brightly painted, and they are called marine anemons. Some acts are in symbiosis with racks, which serve them for movement, and actinia with blockage properties protect hermates from enemies (Fig. 104).

Ceriantharia detachment (CERIANTHARIA) - single digging polyps with severe muscles and without a skeleton.

Zoantharia detachment - Single and colonial polyps with underdeveloped muscle cells.

Antipataria detachment (Antipatharia) Forming the cereal colonies with the axial horny skeleton. This includes fishing black coral, from the skeleton of which various articles are made: tubes, handles of canes, knives.

Mad Pareria Coral (Madreporaria) - The most extensive and includes more than 2500 species. This includes both single and colonial polyps. For all Madeporovy, the presence of a powerful lime skeleton. This coral group is the main rhymers. These include cerebrals (Leptoria) in the form of a hemisphere with fancy furrows, mushroom-shaped corals (Fungia) and others.

Coral reefs and their origin. Mass settlements of coral polyps with a lime skeleton form reefs. The reef includes mainly Madeporovy polyps, but six rays corals are partially involved, as well as other animals with a skeleton: sponges, msanka, mollusks, etc.

Coral reefs are peculiar ecosystems characterized by a special composition of autotrophic and heterotrophic organisms that are interconnected with eating chains and other forms of interspecific relationships. The population of coral reefs is so great and diverse that they are called sea "oases". These are the reserves of sea fauna and flora, they deserve protection from a person.

The rhyme-forming coral polyps are distributed only in the tropical areas of the World Ocean, as they need normal ocean salinity (at least 35% ppm), high and constant water temperature (at least 20 ° C). In addition, the corals are sensitive to the illumination and saturation of water with oxygen and therefore are found in shallow water and usually do not enter into a depth of more than 50 m. The dependence of the coral distribution on the illumination is determined by their symbiosis with single-cell algae - symbiodiniums, or zooxantlerters inhabiting polyps enantoderm cells. The mutual benefit of their coexistence is as follows. Algae is obtained from corals and carbon dioxide (respiratory products) for photosynthesis, as well as some nitrogen deficit and phosphorus from the water dissimulation products of the polypa. Coral polyps, in turn, are obtained from algae oxygen necessary for breathing, as well as to activate the skeletal processes. In addition, the polyps are partially powered by algae, but not as they thought about it earlier - by digesting them in a cytoplasm, and due to direct use of photosynthesis products coming directly from algae cells. Symbiosis is also based on the rates of life cycles of these species. As all the simplest, zoocantellars have a daily reproduction rhythm, and corals exist for a long time. Dying

algae digested in the cytoplasm of the polypa. Thus, this system is based on a waste-free process. At the same time, the dependence of coral polyps from Zoocantelle, without which they die.

Reefs are coastal, barrier and atolls - coral islands of the ring-shaped form. For the first time, the hypothesis about the origin of coral reefs was offered Ch. Darwin (1836). He applied the method of historical geology on the age-old oscillations of sushi to explain the formation of the coral islands. In his opinion, all types of reefs were formed as a result of the lowering of the sushi (Fig. 105). If the island surrounded by the coastal reef, gradually lowers, his shores retreat from the reef, which completes itself to the surface of the ocean and turns into a barrier reef. With full immersion of the island, the ring remains from the former barrier reef, i.e., a coral island is formed - the atoll, which is then gradually populated by plants and animals. There are many other hypotheses about the origin of various types of reefs, however, the hypothesis of C. Darwin remains the most reasoned and withstood the test of time. Currently, this hypothesis is supplemented with new scientific data. It is assumed that the change in the sushi level depends not only on its lowering, but also on the ocean level changes during periods of glaciation or melting of ice hats in poles. From dying coral reefs immersed in the ocean, sedimentary breeds occurred - coral limestone. In Paleozoic, these breeds were formed by the subclasses of corals Rugosa and Tabulata, and starting with the Mesozoic mainly by Mad Pasy polypami.

The story about interesting facts about the corals themselves and ways of their application in jewelry will begin with the numbers:

• 6000 - so many types of coral polyps are in nature;
• 25 of them are suitable for jewelry;
• 350 - the number of possible shades in which natural corals are painted (color depends on organic impurities);
• 4000 years - the age of the most ancient corals discovered by modern researchers;
• 1-3 centimeters - so much polyp grows for the year;
• 8000 meters - maximum coral habitat depth (Batipates view);
• 27,000,000 square kilometers - the total area of \u200b\u200bcoral reefs in the World Ocean;
• 60% of reefs on the verge of disappearance as a result of the economic and other activities of people;
• 2,500 kilometers - the length of the record holder - a large barrier reef, located off the coast of Australia;
• 2900 - the number of separate reefs in it.

Corals in jewelry

Now that the jewelers use corals: an interesting natural design of the material dictates the approach of masters to its use in decorations. The fact is that the sprigs are calmed down from natural reefs and are elegant that they often do not need to be seriously refined. It is enough to polish the coral and cover with a protective varnish to get products of the charming beauty. The main advantage of such accessories is unique, since nature is not repeated in the masterpieces created by it.

If the miniature fragments of corals are used, depending on the design of the jewelry, the masters retain their incorrect natural shape or give:

• spherical;
• oval;
• cabochon (spherical, drop-shaped or oval bead with one flat face);
• carved bead;
• cutting (pieces cut from a branch of a tubular configuration).

The world coral processing center is recognized by Torre del Greco. In this small town near Naples, there is a mass of firms and handicraft industries focused on the manufacture of jewelry and jewelry.

Confirmed facts of healing corals or multiplication with their help of wisdom and wealth we do not have, but that's the beauty of products from this marine gift improves the mood, gives women confidence in their own charm - undoubtedly.

There are no people in the world that would not admire a variety of coral polyps. These bottom organisms relating to the class of sea invertebrates, representatives of the stringing type (Cnidaria) can grow both single and colonies.

Vital activity Corals

Each coral twig is a cluster of small polyps, called the colony. Each such an organism forms a limestone shell around him who serves as protection. When the birth of a new polyp occurs, it is attached to the surface of the previous one and begins to form a new shell. This is how the gradual growth of coral, which, under favorable conditions, is approximately 1 cm per year. Large accumulations of such marine organisms form coral reefs.

Class coral polyps includes the following organisms:

1. Having lime skeletons. They are involved in the process of forming reefs.

2. Possessing a protein skeleton. These include black corals and Gorgonaria.

3. Lained any solid skeleton (Actius).

Specialists allocate about 6 thousand different types of coral polyps. The name of Anthozoa translated from Latin means "animal flower". Coral polyps have a very picturesque view. They differ in the variety of shades. Their movable tentacles resemble flower petals. The largest solitary polyps grow up to 1 m in height. Often their diameter is about 50-60 cm.

Habitat area

Numerous representatives of coral polyps inhabit almost all the waters of the World Ocean. But at the same time most of them are concentrated in warm tropical seas. They develop perfectly at a temperature not lower than 20 ° C. Coral polyps live at depths of up to 20 m. This is due to the fact that plankton and small animals are inhabited in this thickness of water, which these organisms feed on.

Method of nutrition

Coral polyps, as a rule, are compressed in the daytime, and with the onset of darkness pull out their tentacles, who catch the prey sailing past them. Small polyps feed on plankton, and largely capable of digesting small animals. Most often, fish and shrimp consume single large polyps. Among this class of organisms there are also representatives that exist due to symbiosis with unicellular algae (autotrophic simplest).

Structure

Coral polyps, the structure of which differs somewhat depending on their species, have muscular cells. They form transverse and longitudinal muscles of the body. Polyps have a nervous system, which is a thick plexus in the field of the oral disk of these organisms. Their skeleton can be internal formed in mesogle, or outdoor, which is formed by ectoderma. Most often, the polyp occupies a cupid recess on coral, which is noticeably stand out on its surface. As a rule, the shape of polyps is columnar. A peculiar disk is often placed on their vertex, from which the tentacles of this body are departed. Polyps are fixed motionless on a common skeleton for a colony. All of them are interconnected by a live membrane covering the entire Skeleton of Coral. In some species, all polyps are interconnected by tubes that penetrate limestone.

The coral polyp skeleton is secreted by outer epithelium. It is most distinguished by the base (sole) of this maritime "facility". Thanks to this process, live individuals develop on the surface of the coral, and he himself is growing continuously. Most eight-beam coral polyps have a weakly developed skeleton. It replaces the so-called hydraulic coafer, which exists due to the filling of the garbage cavity with water.

The polypa body wall consists of an ectoderma (outer layer) and an entoderm (inner layer). Between them there is a layer of structured mesoglya. In the ectoderma there are cutting cells, called Knoblasts. The structure of different types of coral polyps may differ slightly. For example, actii have a cylinder form. Its height is 4-5 cm, and the thickness is 2-3 cm. This cylinder consists of a barrel (columns), lower (legs) and top. Acting is crowned with a disc on which the mouth is located (peristoma), and in its center there is an oblong gap.

Around it are located in the tentacles. They form several circles. The first and the second have 6, the third - 12, the fourth - 24, the fifth - 48 sucks. After 1 and 2, each subsequent circle has them 2 times more than the previous one. Actiia can take a variety of forms (flower, tomato, fern). The throat leads to a garbage cavity separated by radial partitions, called septites. They are the side folds of the Entoderm, consisting of their two layers. Between them is a mesogle with muscular cells.

Septy form polypa stomach. From above, they grow free edge to his sip. The edges of the septo corrugated, they are thickened and seated with digestive and blotting cells. They are called mesenteric threads, and their free ends - aconizing. Polype digestion is carried out with the help of enzymes allocated to them.

Reproduction

The reproduction of coral polyps is carried out in a special way. Their number is constantly increasing due to the useless reproduction, called the kill. Some types of polyps multiply in sexual means. Many species of these organisms separately. The spermatozoa of men's individuals through breaks in the walls of the gonad penetrates the garbage cavity and go out. Then they fall into the oral cavity of the female individual. Next occurs in fertilization of eggs, and they develop some time in the Mesogle sept.

In the process of embryonic development, tiny larvae are obtained, which are freely floating in water. Over time, they settle at the bottom and become the founders of new colonies or single individuals of polyps.

Corals like rhymers

A huge number of marine polyps participates in the formation of reefs. Corals most often call the skeletal residues of the colonies of polyps, which remained after the death of a plurality of these small organisms. Their diefing is often provoked by an increase in the content of organic substances in water and bottom sediments. The catalyst of this process is microbes. The medium rich in organica is a great place for the active development of pathogenic microorganisms, as a result of the vital activity of which the acidity of water and the content of oxygen in it decreases. Such a "cocktail" has a destructive effect on single and colonial coral polyps.

Polyps subclasses

Experts distinguish 2 subclass polyps in which different detachments of these marine organisms include:

1. Eight-beam (OCTOCORALLIA), which are soft (Alcyonaria) and horgonaria corals. They also include marine feathers (Pennatularia), colonifeera (Stolonifera), blue Polyp Helioporacea. They have eight mesenteria, the inner speaker skeleton and cereal tentacles.

2. Six (Hexacorallia), among which are distinguished by Corallimorpharia, Actinia (Actiniaria), Ceriantia (Ceriantharia), Zoanthidea, Mad Parenti (SCLERActinia) and Black Corals (Antipatharia).

Application in everyday life

Some coral polyps are successfully grown in aquarium in artificial conditions. Lime skeleton of certain types of these marine organisms are used to make jewelry. In some countries in which the mining of coral polyps is not yet prohibited, their remnants are used to build houses and other structures. Also, they are used as a decor with houses and in the gardens.

The body of the coral polyp usually has a cylindrical shape and is not divided into a torso and leg. In colonial forms of coral polyps, the base is immersed in the overall body of the colony - censarc, and single forms turn into an attachment sole.
The tentacles of these organisms are always hollow, arranged in one or more closely pinned whites.

There are two large groups of coral polyps - eight-beam (OCTOCORALLIA) and six-bearing (Hexacorallia).
At the first group, there is always an eight sucklets and they are equipped with the edges of small outgrowths - pinnons, the second group has a tental number and, as a rule, six.

The tentacles of six best corals are almost always smooth, without kicking. The upper part of the polyp, between the tentacles, is called the rotter disk. In its middle there is a sliding river hole. The inner structure of coral polyps is much more complicated than in hydroid and scorifoid polyps. The mouth leads to a compressed sip with a sip, lined with ectoderm. Typically, a groove carrying cells with very long eyelashes are located along one of the edges of the pharynx - siphonoglyph. Sometimes siphonoglyphs are two, in such cases they are located on the opposite narrow edges of the pharyngeal tube. Cilia is continuously moving and drive water inside the intestinal cavity. The latter is divided by longitudinal partitions (septs) on the camera.

In the upper part of the coral polyp body (in the pharynx), the septa is complete (you grow by one edge to the body wall, others - to the throat) or incomplete (not reaching the pharynx). There are holes in septures by which all chambers communicate with each other.
At the bottom of the coral polyp (below the pharynx), the septa will grow only to the body wall. As a result, the central part of the gastric cavity is the stomach - remains unrequited. Free edges of the septo are thickened and called mesenteric threads. They play an important role in digesting food, as there are many glazed cells that distinguish digestive enzymes in them.

In corals with one siphonoglyph, two mesenteric threads located on a pair of opposing septa are not thickened and carry cells with long strong cilias. Being in constant motion, cilia drive water from a gastric cavity of a coral polyp outward. The joint work of two mesenterical filaments and siphonoglyph (or two opposite siphonoglyphs, like actinium), provides a constant change of water in a garbage cavity. As a result, there is a constantly fresh, fresh water, rich in oxygen, and, together with it, bacteria, planktonic organisms, particles of the Detriton, which feed coral polyps. With reverse water flow, carbon dioxide, exchange products and intoleric meal remains are taken out.

The number of septs and chambers in coral polyps always coincides with the number of supreets, the cavity of which is the continuation of the corresponding chambers of the garbage. Thus, the eight-beam corals always have eight septs and cameras, six-six-six.
Septa laid gradually and always in pairs.



Like all intestinal, corals are radially symmetrical. However, in the inner organization there are features of bilateral symmetry (compressed from sides of the throat and siphonoglyphs). Through the longitudinal axis of the pharynx, only one plane of symmetry can be carried out, which divides the body of the coral polyp into two mirror halves. Cameras lying against the narrow edges of the pharyngeal tube differ from the rest of the muscular rollers. These cameras and the formulations of them are called the guides, according to which the "spinal" and "abdominal" side of the coral polyp body are determined.
Muscular cells of coral polyps are isolated from ecto- and edoderma and go to mesogly, forming a layer of longitudinal and transverse muscles in the walls of the body. In addition, in the mesogle of each septa on one side there is a thin layer of transverse, and on the other - a powerful roller of longitudinal muscles.

Mesoglya is represented in most of the six-legious corals with a thin support plate. But in eight-beam corals, it reaches significant development, especially in the trunk and branches of the colony. The Mesoglye journalism is strengthened by collagen elements and filled with a huge amount of skeletal lime needles - spikula, or glorites.
Thus, the Mesoglya is a solid support of the coral colony. At the same time, it participates in the transport of food substances, as it is permeated with a thick network of entodermal channels, binding individual intestinal cavities of coral polyps in one cavity. The same channels play an important role in the rhythmic change of the active and passive state of the coral polyps colony.

Significant development in many coral polyps reaches a skeleton. Eight-beam corals are an internal, mesogleal skeleton, consisting of scurrities that develop in special cells - scleroblasts. Sometimes, the glorites merge among themselves or combine the organic rod-like substance, forming the skeleton of coral colonies. It may consist of a pure horny.

Among the six-legious corals there are inexpensive forms (acts and periantaria). More often, however, the skeleton is available, and it can be either inner (in the form of a rod from a rod-like substance) or external (lime), but always ectodermal origin.
But neither a lime nor an organic skeleton is not able to maintain the constancy of the form of the body of coral polyps. This is provided in other way. All polyps have a kind of hydraulic designer, which reaches the greatest perfection in coral polyps.

Due to the constant current of water, created by siphonoglyphs, an increased pressure occurs in a gastric cavity, without which the coral polyp would have an empty two-layer bag. The polyp is straightened under the pressure of the liquid filling the garbage cavity. In such a state, it can be very long and almost without energy costs. Meanwhile, the remaining animals such a tense state cannot be long, since the muscles are tired, the animal must change the position of the body or move in space.
But it is not necessary to think that once plagued, a coral polyp will preserve its shape infinitely for a long time. Periodically, it is disturbed by a reduction in any muscle group. The compression of the ring muscles, for example, lengthens the body of the polypa and makes it thinner, the reduction of the longitudinal muscles supreets leads to their bending, etc.
In the case of danger, all muscles are reduced immediately, the water from the garbage cavity is extruded and the polyp is compressed or drawn into the colony.

The colonies of coral polyps are usually not polymorphic, but in some eight-beam corals there is a dimorphism - two types of the structure of polyps.
For all corals, only polypoid state is characterized. Jellyfish they do not form. Sept glands are developing in Entoderme septo coral polyps.

 Articles

Coral polyps (lat. Anthozoa) - a class of marine invertebrates from the type of stringing. Colonial and single bottom organisms. Many types of coral polyps have a lime skeleton and participate in rhyme formation. Along with them, this class includes many representatives whose skeleton consists of protein (Gorgonaria, Black Corals), as well as at all deprived of a solid skeleton (Aktini). There are about 6 thousand species. The name ANTHOZOA literally means an animal - flower, on the one hand it determines the zoological nature of this group, and on the other, it indicates their appearance. They really look like flowers: multicolored, with movable tentacles resembling petals, and many of them are quite impressive. Other up to 60 cm in diameter and height up to meter. Along with aquarium fish and plants, coral polyps contain inquariums. Skeletons of some species (coral) are used in jewelry.

Fig.1. Coral polyps (lat. Anthozoa)

Corals live in the sea; They are stationary and look like plants branches. However, it is still not plants: each branch of coral is a cluster of the smallest animals, coral polyps. Such clusters are called colonies. Each polyp forms a protective lime shell around them. When a new polyp is born, it is attached to the previous one and begins to build a new shell - so the coral "grows". Coral's "growth" is about 1 cm per year in favorable conditions. Large coral clusters form so-called coral reefs. Coral polyps dwell in warm tropical seas, where water temperature is not lower than 20 ° C, and at depths of no more than 20 meters, in conditions of abundant plankton, which they feed. Usually, the drugs are compressed, and the tentacles are pulled out at night, with the help of which they catch various small animals. Large single polyps are capable of catching and relatively large animals: fish, shrimp. Part of the types of coral polyps live at the expense of symbiosis with autotrophic simplest (single-cell algae) that they live in Mesogle. There are muscular cells forming longitudinal and transverse muscles. There is a nervous system forming a thick plexus on the oral disk.

Corals are usually called only the skeleton of the colonies remaining after the death of a plurality of small polyps. Many coral polyps are rhymers. The skeleton can be an outer, formed by ectoderm, or inner, forming in Mesogle. As a rule, the polyps occupy a cupid recess on the coral, noticeable on its surface. The shape of these polyps is columnar, in most cases with a disk on top, from which the whiskers are departed. Polyps are fixedly fastened on the entire colony of the skeleton and are interconnected by the covering living membrane, and sometimes permeating limestone tubes.

The skeleton is secreted by the outer epithelium of the polyps, and mostly their base (sole), so living individuals remain on the surface of the coral structure, and everything is growing continuously. The number of polyps participating in its formation is also constantly increasing by their useless reproduction (kinding). In many eight-beam polyps, the skeleton is developed weakly and it replaces the hydraulic cooler, provided by the filler of the gastric cavity water. The crystals are multiplied with sexually, forming tiny free-peeling larvae, which ultimately settle on the bottom and give rise to new colonies. Polyps are usually separatable. Spermatozoa through the gonad wall breaks go to the garbage cavity, and then outward and penetrate through the mouth into the cavity of the female individual. Fertilized eggs are developed for some time in the Mesogle sept. In many coral polyps, development proceeds without metamorphosis and the larva is not formed.

In a series of experiments conducted on the corals of a large barrier PAF, a trigger mechanism was revealed, which launching the death of corals. Their diefing begins with an increase in the content of organic matter in water and in sediment, and the intermediary of these processes are microbes. An organic medium is a good basis for the rapid growth of microbes, the result of oxygen and pH of the medium is reduced. This combination is mortally for corals. The acceleration of sulfate-generation using dead tissues as a substrate only accelerates the death of corals.

Differ in the following features: have large sizes; rarely single, more often colonial forms; dwell in warm tropical seas, the temperature is not lower than 20 ° C 0, the depth is not large; Most species are well developed skeleton (horny or lime), the skeleton can be an outer, formed by ectoderm, or internal, formed in Mesogle; The gastric cavity is divided by partitions - septs on the camera. There is an ectodermal throat with flavored grooves - siphonoglyphs, providing water current into a garbage cavity; Gonads are formed in Entoderma; There are muscular cells forming longitudinal and transverse muscles; The nervous system forms a thick plexus on the oral disk; Rady symmetry is broken and transition to two-beam, or bilateral symmetry is observed; The mouth is surrounded by eight tentacles (eight-beam), or the number of tentacles, a multiple of six (six-coral corals). The reproduction is intact and sex. Development with metamorphosis. Larvae - I planned. There are no generation alternations.

Nutrition in coral polyps is diverse. Many feed on plankton or catch small animals with a suckleset. Large single polyps-acts are capable of catching and large animals: fish, shrimp. Part of the species live due to symbiosis with unicellular algae. Actius - predators. Fish, crayfish, crabs - welcome their prey. Actius is enough for her tentacles, and now hundreds of poisonous "arrows" are concerned about it. Lady convulsion - And now the Actinia, tightening our mouths to the mouth, turns out his throat out of his mouth. She covers her caught animal, then it disappears with the throat inside the acti. From life in aquariums Actinia "Loins" strongly: ten times lost in weight! But it was worth it to propose food again, as they greedily began to swallow her and quickly "corrected." A few days later it was difficult to believe that the actius fasted so long.

When the actinium is played with appetite, they swallow everything without parsing, even the objects inedible and dangerous for them. One act "from the hunger" swallowed the big sink. The sink rose in her "stomach" across and blocked it into two rugs, upper and lower. It didn't get into the lower food from the mouth. Thought, acting will die. But she found the way out: At the sole of Actinia, at the very place on which this "sea flower" sits on the stone, opened his toothless zev new mouth. The tentacles and Actinia came around him soon became a happy owner of two mouths and two stomachs. Colonial polyps - "lifelong prisoners" of the colony, which is compiled. They are not given to separate from it and move independently. But acti, squeezing and sprinkling the sole, crawl along the bottom. Not quickly, but crawl, they can climb on the sink, on a stone or other item lying on the bottom. Breathing with oxygen dissolved in water, pumping it through its mouth: In the action, water falls out of the angles of a sliding mouth, and back from the middle of the slot. Actini love water with quite large salinity. In the Mediterranean Sea under Naples, where 5 50 types of actinium live in water in water, the Black Sea with the salinity of water half of them is only 4 species, and in the Azov (completely low-salted sea) - only 1 view.

Internal and external structure

Actiia has mainly large forms of single polyps devoid of skeleton. Often brightly painted and they are called marine anemons. They have the form of a cylinder, an average of up to 4-5 cm and a thickness of 2-3 cm. Consist of an average part, called a barrel (column) ending at the bottom with a leg with which is attached to the underwater rocks, and the top consisting of The oral disk, or peristoma, which is in the center of mouth in the form of an oblong slit. Around the mouth and at the edges of the trunk there are tentacles located in groups. Each group includes so much tentacles, how many gaps remain between tentacles forming the inner circle, i.e. Each period is busy tentacles from the subsequent group. The first and second circles have 6 sucks, the third - 12, fourth - 24, fifth - 48, i.e. The number consistently increases twice. The number of circles varies from one to six, eight, ten or more. Activity has a wide variety of shapes - tomato, flower, fern leaves.

Fig.2. Cross sections across eight-beam and six

Gastric cavity is complicated. The mouth leads to a flattened ectodermal liner in the same direction. HEXACORALLIA siphonoglyphs have two in both corners of the pharyngeal gap. Siphonoglyphs provide water current through a gastral cavity. The sloping throat and the presence of two siphonoglyphs disrupt radial symmetry and therefore actinium has only two planes of symmetry. The throat leads to a gastral cavity, which is divided by radial partitions - septs.

Fig.3. Schemes of the structure of coral polyps

Septy are the side folds of the Entoderma, with each fold, respectively consists of two Entoderma layers, between which the mesoglya with muscular cells is. Septy with free edge griest to the throat, and below the pharynx do not climb, forming the stomach. The edges of the septo are thickened, corrugated, seated with cutting and digestive cells, forming mesenteric threads. Their free ends are called aconizing. Mining is digested under the influence of enzymes. HEXACORALLIA SEPT has a lot, not less than twelve. The muscular rollers in the guild cameras are turned out and disrupt the two-beam symmetry, determined by the form of the pharynx and two siphonoglyphs. Actius is deprived of a skeleton.

Corals as symbiontes

Corals are a peculiar community of shallow maritime organisms of the tropical zone of the World Ocean, represent symbiosis of corals and single-cell algae. In the process of photosynthesis, single-cell algae highlighting free oxygen, necessary to coral polypami for breathing, and corals are distinguished by carbon dioxide, very necessary algae for photosynthesis. Such corals supply single-cell algae with various nutrients.

Coral reefs are high-productivity communities that combine a stable photosynthetic system and a system capable of capturing, preserving and involving in the life cycle of power supply of ocean water containing plankton and suspended particles. Actiia is in symbiosis with racks, racks, mosaic, furillary angular. Activity with blockage properties protect crayfish from enemies. Cancers - Hermits serve as an acting for movement. Actiia is placed on the surface of the sink, creating protection in the form of capes that does not impede cancer movements. The river hole of the Actinia is over the mouth of the cancer, and it freely captures part of his food. However, cancers are not the only representatives of the crustaceans, with which Actinia is associated. Such phenomena are observed in other types. Of the sixty individuals of actinolotes of the net and hepatus of the Chilean, caught on the coast of Chile, only four were without acts. Each cell of the mosaic cancer is Actinia. Ptley relationship with Actinia and fish amphiprion.

Clowns, swimming between the felts of the Actinium, lead water, and it brings oxygen, helping to breathe acts. In addition, with a current of water, small food comes to it. Very interesting symbiosis by giant sea anemones or actinium, and small brightly colored fish-clowns. Actinia - predator. Fish, which come close to the attacks of the actinium is striking the poison of its cutting cells. And clowns float among them completely calmly and eat food with food, which is assembled with actinium tentacles. Apparently, the clown protects against the effect of the poison mucus covering his body. Actinia, in turn, "redeems" the remains of food, which the clown is produced, because, grabbing prey, he brings it into a safe place - that is, to Aktini. Poisonous acting tentacles provide clown reliable shelter. Under her defense, he lays out the caviar at the sole of Actinia and even rubs sometimes about her tentacles.

Polyps play a huge role in purifying sea water from suspended organic particles. Coral limestone in some countries is used in construction. Separate types of corals are highly appreciated as a material for various jewelry. That is why some corals were on the verge of destruction and currently need careful protection from poachers. Coral polyps are the main rhyme-forming organisms.