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 beauty of the underwater world, its magnificence and diversity is always striking nature lovers going to see the marine inhabitants. The basis of this diversity is very unusual inhabitants.

Introducing interesting facts about corals.

Corals have the most extraordinary colors, which is beautifully overflowing in oceanic departures.

In total, there are more than 6 thousand such underwater inhabitants in the world and this is one of the richest varieties of intestinal.

Corals are quiet enough

So, for their growth, they need full-fledged conditions: sufficient salinity of water, transparency, heat and a lot of food. That is why coral reefs live in the waters of the quiet and atlantic oceans.

Interestingly, in the World Ocean, the territory of coral reefs has about 27 million square meters. km.

The big barrier reef is considered one of the greatest creatures of these underwater growths. Stretching chapter near Australia.

Lime reserves Thanks to coral reefs, almost inexhaustible

Some territories of such reefs are so large that they can be full of coral islands.

Coral islands have their own life and vegetation. Here you can even find cacti and high shrubs.

The local population uses corals for the production of jewelry.

It turns out very beautiful and rainbow items for the summer season.

Also, corals are used as a building material, polishing metal surfaces and the production of drugs.

If a person is damaged about a coral barrier, then the skin will be for a very long time. In place of the wound, even the suppuration may appear, regardless of whether the poisonous coral or not.

Coralles have special cells intended for protection

They are called blinking and at the time of danger produce poison.

The Indians were believed, according to which the Red Corals had to wear only men, and whites were only women. It was believed that these colors were some symbols of one and the other gender and in the case of "incorrect socks" each of them acquired the characterities of the opposite. How true is it is unknown.

Today, few men wears products from corals. Well, women alone allow any color gamut and red including. Apparently, precisely because of this, the Emancipation flourishes.

Other interesting facts about corals can be found on the Internet.

This is exclusively marine, mainly thermal-loving organisms. There are both single and colonial forms (last more often). There is no form of jellyfish in the development cycle.

Compared with the hydride polyps, they are arranged more difficult. A separate coral polyp colony externally resembles a hydra, but is usually located in a cup of its outer skeleton. The complication of their organization consists in the presence of a pharynx, separation of an intestinal cavity on the chambers using vertical partitions, which increases the surface of secretion and learning.

There is a separation of the muscular and epithelial parts of the epithelial-muscular cell and the formation of differentiated muscle tissue.

Nervous diffuse type system, but with more than at the hydra, the concentration of nerve cells at the mouth of the mouth.

Coral polyps multiply both useless and sexually. Sex glands develop in the Entoderm of the partitions of the intestinal cavity.

Fertilized egg starts to crush. At first it is divided in two, then each of the cells formed in turn is also divided and so on. As a result, a large number of small cells located in one layer and having a look of a small hollow ball. Following this, part of the cells is immersed inside, resulting in a two-layer embryo. An entroderma is subsequently formed from its inner layer, and from the exterior - ectoderma of the future polyp. Etoderma is covered with numerous small cilias, with which the embryo receives the ability to swim; From now on, it turns into a larva called planuel. I planned not able to eat and multiply. She swims in the thickness of the water for a while, then sits on the bottom and attached to his front end. Shortly thereafter, at the rear end (now at the top) end of the planla, the oral hole breaks down and the crush is formed. So the first polyp occurs. In colonial forms, this polyp will soon merge other polyps, those in turn following, etc. Colony arises. Upon reaching a colony of a certain degree of development, the components of its polyps begin to multiply also in the sexual way, forming eggs. On this cycle closes.

Among single soft coral polyps are widely known actinia which for a variety of color is called marine flowers.

Colonial forms are numerous and diverse (shag, tree, et al.). Their skeleton consists of calcium carbonate. Lime skeletons of colonial forms form reefs and oceanic islands - the atoll. Organic skeleton Rednoble Coralused to make jewelry.

Control questions:

What features of the structure are characteristic of intestinal (on the example of the hydra)?

How does the hydra feed?

What types of reproduction has a hydra?

What common features and differences are representatives of scamphoid and coral polyps?

How do scoffoids multiply?

Representatives of the class coral polyps are invertebrates, inhabiting the depths of the seas. Basically, colonial organisms, sometimes single, polypovoid form.

general characteristics

Coral polyps belong to the type of shepherd animals, which includes the following classes: hydroids, scoffoid and coral polyps (the most numerous group). The latter are divided into subclasses: eight-beam and six best.

Coral polyps

The first (eight-grade) includes colonial individuals having eight provers (red coral, sea feather, blue coral). Polyps of the second subclass (six-high) in most cases are single, with six tentacles (acti, black corals).

Today there are about 6,000 types of coral polyps, which inhabit salt reservoirs in various climatic zones. Most are found in belts with a warm climate (fluctuations in water temperature around 18-22 degrees), may be at a considerable depth of the sea, if food - plankton is provided.

The structure of coral polyps

The shape of the body of coral polyps resembles a cylinder. The wall distinguishes three balls: eccto-, meso, endoderm.

Etoderma Forms a coating layer, often has a lime structure, which, after the organism, forms a polypnyak.

Mesoderma - This is a gelling substance, located in all cavities of the polyp. Internally, divided by chambers using partitions. The number of cameras is equal to the number of supreets.

The upper pole is represented by the oral hole, which is surrounded by bright-colored tentacles (therefore, for a long time they were considered by plants). At the bottom end, the sole is located, serves as fastening to the substrate. The mouth is communicated with the cavity of the stomach through a long tube (sip), which is presented in the form of a wide shock. At its ends there are long cakes that are constantly moving. Thus, in the cavity of the polyp continuously circulates the water required for the vital activity of coral. Oxygen and food comes here, and after metabolic processes, carbon dioxide and digestion products are outward.

Learning a fixed lifestyle, attaching to the substrate, branches as the branches of the plant. Each branch consists of small polyps that form a colony. The newly formed individuals are attached to the previous one, so they are height, the increase in growth is 1 cm. The massive growth of coral polyps form reefs.

To protect coral polyps are equipped with special filamental form organs, with stinging cells, when approaching a dangerous agent, they are thrown out of the oral hole.

The division of coral polyps can be sex and intimate (kinding). When new individuals are formed, they are free to swim in the water for a while, but they soon find a substrate, and they are attached to it and begin development.

Subclass six best corals

Six-wide corals in the field of the oral hole are tentacles, the number of which is leveling or more of six. Many have a limestone skeleton, or organic.

Tits six best corals

- Single powerless polyps, brightly painted, with the help of muscular soles slowly move along the bottom of the sea. Able to form symbiosis with racks, which help to overcome long distances, in turn, acti protect them with their stress cells. Representatives: Actinia Telia, Actinia Metridium.

- These are single or colonial polyps, with a well-developed lime skeleton (consists of calcium carbonate). Single individuals are inhabited in deep sea seas, at the bottom itself and reach 50 cm in diameter. Closer to land there are large colonies of Madeporovy Corals, they will be banned for a couple of meters and weigh a few tons. Representatives: Ceillia, Favia, Brain Coral. It is they who serve as the basis for the formation of reefs.

- Representatives of the detachment have a colonial structure. The inner skeleton is solid, allows to grow up to 6 meters in height, in the composition there is a specific protein - antipatin, which causes black color. They are used for the manufacture of jewelry, therefore there are intensive mining, which put this appearance on the edge of extinction.

Subclass of eight-beam corals

The majority of the colonial structure, consist of small polyps (up to 1 cm). On the oral hole eight proveman. The inner skeleton is represented by deposits in the mesogle of lime structures.

Eight-beam coral detachments

- Soft corals, exist due to symbiosis with photosynthetic organisms through which energy is obtained, some feed onto plankton. Take part in the formation of reefs, used as a habitat for fish.

- inhabit the depths of the seas, consist of a stem (primary zoo) and bumping individuals that diverge on the parties, forming a branch. Mixed to the bottom surface with a wide leg and lead a sedentary lifestyle.

- Inside there is a horny skeleton, some representatives are painted red (used in the jewelry industry).

Food Class Commodity Polyps

Coral nutrients are obtained in two ways.

1. The individuals living at depths are able to independently capture plankton, microscopic crustaceans, fish larva, dissolved water substances. For example, Gorgonarians have a branched structure and grow towards the flow, which facilitates the capture of nutrient particles. For normal existence, polypates also require inorganic substances: calcium, magnesium, potassium.
2. Many corals live in symbiosis with plants and are powered in the process of photosynthesis (under the action of sunlight from carbon dioxide, oxygen and glucose is formed, which are partially moving to the polyp organism).

Corals are able to change the power paths depending on the environmental change, with insufficient energy flow due to symbiosis, the consumption of plankton increases.

- Marine animals, leading colonial lifestyle, live only in warm tropical seas. The temperature of the water at which coral polyps retain viability, not less than 20 degrees. For example, a record gravity of eight-beam corals reaches 6120 meters. At the same time, the polyps live in places where many plankton, which is the main food.

Many coral polyps have a limestone skeleton (sometimes there are polyps with a horn skeleton). The skeleton of polyps can be both outdoor and inner. Lime skeleton allows them to take part in the rhyme formation.

But the class of coral polyps also includes polyps having a skeleton consisting of a protein (include black corals, hydraulic). Also, this class includes animals that have no solid skeleton, such as actius.

The lifestyle of the main mass of coral polyps is usually night. During the daytime, the polyps are compressed, and at night we will spread the tentacles. With the help of a tentacle, feed is mining.

Actinia - Ampifrion Residence (Fish Clowns)

Coral polyps: Building

Polyps have muscular cells that form muscles. Coral polyps have a well-developed nervous system. The nervous system is preferably located on the robol disk, where it forms a thick plexus.

Corals are usually called the skeleton remaining after the death of polyps. Therefore, the characteristic of coral polyps a definition appears - rhyme-forming.

Various types of coral polyps

Usually the columnar polyps are located on coral. At the top of the polyp disk, from which the plurality of the sucks are departed. Polyps fixed fixed (skeleton common for the entire colony), the connection is carried out using a membrane that covers the skeleton. The reproduction of coral polyps occurs by killing, which leads to the fact that the number of individuals involved in the formation of the skeleton is constantly increasing.

Structure of a sixth coral polyp

The structure of the eight-beam coral polyp

But the reproduction of coral polyps, occurs and sexual means. This is due to the fact that in the bulk of its polypa separations. The reproduction of sexually is usually occurring as follows - spermatozoa goes into the garbage cavity, from where they go out.

In the same way, through the mouth penetrate the oral cavity of the female individual. Formed by the fertilization of the egg, it develops for some time in the mesogle. As a result of the development of the egg, the larvae is formed, which leave the mother's individual and swim freely. The larvae settle on the bottom, which gives the beginning of the new polypam. But this process is not required for all polyps. In many, the formation of the larva does not occur.

Miscellaneous reproduction of Aktini

Subclasses of coral polyps

Modern science distinguishes two subclass of coral polyps. The subclass includes eight-beam and six-world polyps. As can be seen from the name of the subclasses, the eight-beam coral polyps are the owners of eight tentacles, while they have an inner skeleton, and eight partitions in a garbage cavity.

Six-coral coral polyps

Polyps have a non-six tentacles (an analogy with eight-beam), and a plurality of tentsers, the number of which is multiple of six. In the gastric cavity, the six-high polyps have a complex system of internal partitions (the number of partitions is also multiple of six). Mostly six-haired polyps have an outdoor lime skeleton.

Class coral polyps refers to rhyme-forming.With its livelihood of coral polyps, like coastal, so atolls and barrier reefs.

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