Interesting information about jellyfish and coral polyps. Class Coral polyps. Eight- and six-rayed corals. Characteristics, nutrition and structure. Nutrition of representatives of the class Coral polyps

Coral polyps (lat. Anthozoa) are a class of marine invertebrates of the cnidarian type. Colonial and solitary benthic organisms. Many types of coral polyps have a calcareous skeleton and participate in reef formation. Along with them, this class includes many representatives whose skeleton consists of protein (gorgonians, black corals), as well as those completely devoid of a hard skeleton (anemones). There are about 6 thousand species. The name Anthozoa literally means an animal - a flower; on the one hand, it determines the zoological character of this group, and on the other, it indicates their appearance. They really look like flowers: multi-colored, with movable tentacles resembling petals, and many of them are quite impressive in size. Others are up to 60 cm in diameter and up to a meter high. Along with aquarium fish and plants, coral polyps are kept in aquariums. The skeletons of some species (coral) are used in jewelry.

Fig.1. Coral polyps (lat. Anthozoa)

Corals live in the sea; they are motionless and resemble plant branches in appearance. However, these are not plants: each coral branch is a cluster of tiny animals, coral polyps. Such clusters are called colonies. Each polyp forms a protective calcareous shell around itself. When a new polyp is born, it attaches to the previous one and begins to build a new shell - this is how the coral “grows”. Coral “growth” is about 1 cm per year in favorable conditions. Large accumulations of corals form so-called Coral reefs. Coral polyps live in warm tropical seas, where the 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 on. Usually during the day the polyps shrink, and at night they stretch out and straighten their tentacles, with the help of which they catch various small animals. Large single polyps are capable of catching relatively large animals: fish, shrimp. Some species of coral polyps live due to symbiosis with autotrophic protozoa (single-celled algae) that live in their mesoglea. There are muscle cells that form longitudinal and transverse muscles. There is a nervous system that forms a dense plexus on the oral disc.

Corals are usually called only the skeleton of the colony, which remains after the death of many small polyps. Many coral polyps are reef builders. The skeleton can be external, formed by the ectoderm, or internal, formed in the mesoglea. As a rule, polyps occupy cup-shaped depressions on the coral, visible on its surface. The shape of these polyps is columnar, in most cases with a disc at the top, from which the corollas of the tentacles extend. The polyps are motionlessly attached to a skeleton common to the entire colony and are connected to each other by a living membrane covering it, and sometimes by tubes piercing the limestone.

The skeleton is secreted by the outer epithelium of the polyps, and mainly by their base (foot), so living individuals remain on the surface of the coral structure, and the whole thing continuously grows. The number of polyps involved in its formation also constantly increases through their asexual reproduction (budding). In many eight-rayed polyps, the skeleton is poorly developed and is replaced by a hydroskeleton, which is ensured by the filling of the gastric cavity with water. Corals also reproduce sexually, forming tiny free-swimming larvae, which ultimately settle to the bottom and give rise to new colonies. Polyps are usually dioecious. Spermatozoa enter the gastric cavity through ruptures in the gonad wall, and then out and penetrate through the mouth into the cavity of the female individual. Fertilized eggs develop for some time in the mesoglea of ​​the septa. In many coral polyps, development proceeds without metamorphosis and a larva is not formed.

In a series of experiments conducted on the corals of the Great Barrier Reef, a trigger mechanism was identified that triggers the death of corals. Their death begins with an increase in the organic content in water and sediment, and microbes are the mediator of these processes. An environment rich in organic matter provides a good basis for the rapid growth of microbes, as a result of which the oxygen content and pH of the environment decrease. This combination is lethal for corals. Accelerating sulfate reduction, which uses dead tissue as a substrate, only accelerates the death of corals.

Are different the following features: are large in size; rarely solitary, more often colonial forms; live in warm tropical seas, the temperature is not lower than 20C 0, the depth is not great; Most species have a well-developed skeleton (horny or calcareous), the skeleton can be external, formed by the ectoderm, or internal, formed in the mesoglea; The gastric cavity is divided into chambers by partitions - septa. There is an ectodermal pharynx with flagellar grooves - siphonoglyphs, which ensure the flow of water into the gastric cavity; gonads are formed in the endoderm; there are muscle cells that form longitudinal and transverse muscles; the nervous system forms a dense plexus on the oral disc; radial symmetry broken and a transition to biradial or bilateral symmetry is observed; the mouth is surrounded by either eight tentacles (eight-rayed corals), or a multiple of six tentacles (six-rayed corals). Reproduction is asexual and sexual. Development with metamorphosis. The larva is a planula. There is no alternation of generations.

Coral polyps have a varied diet. Many feed on plankton or catch small animals using tentacles. Large single polyps - sea anemones are capable of catching large animals: fish, shrimp. Some species live through symbiosis with unicellular algae. Sea anemones are predators. Fish, crayfish, crabs are their desired prey. The anemones grab her with their tentacles, and now hundreds of poisonous “arrows” pierce her. A short convulsion - and now the sea anemone, having pulled its prey to its mouth with its tentacles, turns its throat out of its mouth. It covers the caught animal with it, then it, along with its throat, disappears inside the sea anemone. From living in aquariums, sea anemones “lost weight” greatly: they lost ten times their weight! But as soon as they were offered food again, they greedily began to swallow it and quickly “recovered.” After a few days it was hard to believe that the sea anemone had fasted for so long.

When sea anemones develop an appetite, they swallow everything indiscriminately, even inedible and dangerous objects. One sea anemone “out of hunger” swallowed a large shell. The sink stood across her “stomach” and divided it into two rugs, upper and lower. No food came from the mouth into the lower one. They thought the sea anemone would die. But she found a way out: at the sole of the sea anemone, at the very place where this “sea flower” sits on the stone, a new mouth opened its toothless mouth. Tentacles soon grew around it and the sea anemone became the happy owner of two mouths and two stomachs. Colonial polyps are “lifelong prisoners” of the colony they form. They are not allowed to separate from it and move independently. But sea anemones, squeezing and unclenching their soles, crawl along the bottom. Not quickly, but they crawl, they can climb onto a sink, onto a stone or other object lying at the bottom. Sea anemones breathe oxygen dissolved in water, pumping it through their mouth: water enters the sea anemone from the corners of the slit-like mouth, and back from the middle part of the slit. Sea anemones love water with fairly high salinity. In the Mediterranean Sea near Naples, where the salt content of the water is 3.7%, about 50 species of sea anemones live, in the Black Sea, with water salinity half as much, there are only 4 species, and in the Sea of ​​Azov (a very slightly salty sea) there is only 1 species.

Internal and external structure

Sea anemones have mainly large forms single polyps without a skeleton. They are often brightly colored and are called sea anemones. They have the shape of a cylinder, with an average height of 4-5 cm and a thickness of 2-3 cm. They consist of a middle part, called a trunk (column), ending at the bottom with a leg, with which it is attached to underwater rocks, and an upper part, consisting of oral disc, or peristome, which has a mouth in the center in the form of an oblong slit. Around the mouth and along the edges of the trunk there are tentacles arranged in groups. Each group includes as many tentacles as there are spaces between the tentacles forming the inner circle, i.e. each gap is occupied by tentacles from the next group. The first and second circles have 6 tentacles each, the third - 12, the fourth - 24, the fifth - 48, i.e. the number successively doubles. The number of circles varies from one to six, eight, ten or more. The sea anemone has a wide variety of forms - tomato, flower, fern leaves.

Fig.2. Transverse sections through eight-ray and six-ray polyps

The gastric cavity is complex. The mouth leads into a pharynx, flattened in one direction, with a folded ectodermal lining. In Hexacorallia there are two siphonoglyphs in both corners of the pharyngeal cleft. Siphonoglyphs ensure the flow of water through the gastric cavity. The slit-like pharynx and the presence of two siphonoglyphs violate radial symmetry and therefore sea anemones have only two planes of symmetry. The pharynx leads into the gastric cavity, which is divided by radial partitions - septa.

Fig.3. Schemes of the structure of coral polyps

Septa are lateral folds of the endoderm, each fold correspondingly consisting of two layers of endoderm, between which there is mesoglea with muscle cells. The septa adhere to the pharynx with their free edge, but do not close below the pharynx, forming the stomach. The edges of the septa are thickened, corrugated, seated with stinging and digestive cells, forming mesenteric filaments. Their free ends are called acontia. The prey is digested under the influence of enzymes. Hexacorallia has many septa, at least twelve. The muscular ridges in the guiding chambers face outward and do not break the biradial symmetry determined by the shape of the pharynx and the two siphonoglyphs. Sea anemones lack a skeleton.

Corals as symbionts

Corals are a unique community of shallow-water marine organisms in the tropical zone of the World Ocean; they represent a symbiosis of corals and unicellular algae. During the process of photosynthesis, unicellular algae release free oxygen, which is necessary for coral polyps to breathe, and in return, corals release carbon dioxide, which is very necessary for algae for photosynthesis. Such corals supply single-celled algae with various nutrients.

Coral reefs are highly productive communities that combine a stable photosynthetic system and a system capable of capturing, preserving and incorporating nutrients from ocean water containing plankton and suspended particles. Sea anemones are in symbiosis with hermit crabs, mosaic crabs, and grooved angular crabs. Sea anemones with stinging properties protect crayfish from enemies. Hermit crabs serve sea anemones for movement. Sea anemones are placed on the surface of the shell, creating protection in the form of a cape that does not impede the movements of the crayfish. The sea anemone's mouth opening is located above the crayfish's mouth, and it freely captures some of its food. However, crayfish are not the only representatives of crustaceans with which sea anemones are associated. Similar phenomena are observed in other species. Of the sixty individuals of Actinolotus reticulata and Hepatus chiliensis caught on the coast of Chile, only four were without anemones. Each mosaic crayfish cell contains sea anemones. Sea anemones have friendly relations with amphiprion fish.

Clowns, swimming between the tentacles of sea anemones, set the water in motion, and this brings oxygen, helping the sea anemone to breathe. In addition, small food also comes to it with the flow of water. The symbiosis between giants is very interesting sea ​​anemones or sea anemones, and small brightly colored clown fish. Sea anemone is a predator. Fish that find themselves close to the tentacles of sea anemones are affected by the poison of its stinging cells. And clowns swim among them completely calmly and feed on scraps of food that they collect from the tentacles of sea anemones. Apparently, the clown is protected from the effects of poison by the mucus covering its body. The sea anemone, in turn, “eats up” the remains of food that the clown gets, because, having grabbed the prey, it brings it to a safe place - that is, to the sea anemone. The poisonous tentacles of the sea anemone provide the clown with reliable shelter. Under her protection, he lays eggs at the sole of the sea anemone and sometimes even rubs against its tentacles.

Polyps play a huge role in purifying seawater from suspended organic particles. Coral limestone is used in construction in some countries. Selected species Corals are highly valued as a material for various jewelry. That is why some corals are on the verge of destruction and currently require careful protection from poachers. Coral polyps are the main reef-building organisms.

Coral polyps or marine ones are living creatures that may not move at all, and if they move, then very little. They live at the very bottom of the sea in large groups, rarely alone and do not have a backbone.

You can find more precise definition What polyps are, biologists say - these are certain forms of aquatic animals that have stopped at some stage of development. And at the next stage you get a jellyfish. Among this class one can count about 6 thousand species, among them there are even those that do not have a skeleton, which consists only of protein.

If translated literally from Latin language the name of coral polyps, then you get this funny name - animal - flower. It is this name that indicates the shape of the polyps themselves. All of them really resemble a flower, they can be of different diameters, sometimes reaching a diameter of about 60 cm, and the height may well be a meter. Coral polyps can be used as decoration in an aquarium, and jewelers also use them to make jewelry.

Coral grows about one centimeter per year if they grow in comfortable conditions. They grow at great depths, because that is where we live a large number of plankton, they feed on it. And large polyps that live alone can feed on small fish.

Polyps can reproduce in two ways: the first is a larva, which is obtained from the mating of jellyfish, it settles somewhere and begins to grow. The second is the division of polyps into parts, in other words, infertile reproduction. Jellyfish appear due to polyps.

There are types of polyps that cannot turn into jellyfish. Such polyps create coral reefs; they have only a skeleton consisting of lime.

Since it was already said earlier that some polyps do not have a skeleton, sea anemone is one of them. It lives alone and can be of impressive size - about one and a half meters. They lead an exclusively sedentary lifestyle, but can also coexist with some species of fish. Very large sea anemones can even feed on fish that have the average size. They can easily move along the bottom by squeezing and unclenching their soles, but very slowly.

In nature, there are not only polyps that do not turn into jellyfish, since they lack this stage, but there are also jellyfish that cannot become polyps.

Polyps are very important in environment, they cleanse sea ​​water from organic particles. Coral limestone can also be used for construction, but not in all countries. It is coral polyps that take part in the formation of reefs.

Description

Coral polyps live in warm tropical seas, where the 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 on. Usually during the day the polyps shrink, and at night they stretch out and straighten their tentacles, with the help of which they catch various small animals. Large single polyps - sea anemones ( Actinia) - capable of catching relatively large animals: fish, shrimp. Some species of coral polyps live through symbiosis with unicellular algae that live in their mesoglea.

There are muscle cells that form longitudinal and transverse muscles. There is a nervous system that forms a dense plexus on the oral disc.

Subclasses

Notes

see also

Links

Wikimedia Foundation. 2010.

See what “Coral polyp” is in other dictionaries:

- (Greek). In medicine: fibrous growth or tumor like a wart on the mucous membranes human body: in the nose, straight. intestine, in the cervix. Dictionary foreign words, included in the Russian language. Chudinov A.N., 1910. POLYP in medicine... Dictionary of foreign words of the Russian language

POLYP, polyp, husband. (Greek polypus, lit. centipede). 1. The name of sessile individuals of coelenterates. Coral polyp (zool.). 2. Tumor, painful growth on the mucous membranes (med.). Polyp in the nose. Dictionary Ushakova. D.N.... ... Ushakov's Explanatory Dictionary

This term has other meanings, see Polyp. Single coral polyp of Ceriantharia with two corollas of tentacles Polyps or polypoid generation (... Wikipedia

Polyp ambiguous term: Polyp stage in life cycle Cnidarians (Cnidaria). Polyps in medicine are hyperplastic outgrowths of human tissue, for example, in the ear, nose, uterus. See also Coral polyp ... Wikipedia

POLYP, huh, husband. 1. Marine non-moving animal. Coral item 2. Painful formation (growth) from the epithelium of the mucous membrane. Nasal polyps. | adj. polypous, oh, oh. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

A; m. [from Greek. polypus multi-legged] 1. A coelenterate animal, attached at one end to a stationary object and equipped with a mouth opening at the opposite end. Freshwater, coral item 2. Benign tumor of the mucous membranes... ... encyclopedic Dictionary

polyp- A; m. (from the Greek polypus many-legged) see also. polypous 1) A coelenterate animal, attached at one end to a stationary object and equipped with a mouth opening at the opposite end. Freshwater, coral poly/p. 2)… … Dictionary of many expressions

Polyps (coelenterates)- Coral polyp from the Red Sea. POLYPS (from the Greek polypus, literally many-legged), sessile (attached) individuals of some coelenterates; solitary (hydra, sea anemones) or colonial (coral polyps). Coral polyps... Illustrated Encyclopedic Dictionary

Coral polyp; see Madrepor's article... Encyclopedic Dictionary F.A. Brockhaus and I.A. Ephron

A, m. 1. A coelenterate animal, attached at one end to a stationary object and equipped with a mouth opening at the opposite end. Freshwater polyp. Coral polyp. 2. Benign tumor of the mucous membranes. Polyps... ... Small academic dictionary

The story about interesting facts about the corals themselves and how to use them in jewelry, we will start with numbers:

• 6000 - this is how many types of coral polyps are found in nature;
• 25 of them are suitable for jewelry processing;
• 350 - the number of possible shades in which natural corals are painted (the color depends on organic impurities);
• 4000 years is the age of the oldest coral discovered by modern researchers;
• 1–3 centimeters - this is how much a polyp grows in a year;
• 8000 meters - maximum depth coral habitats (Batipates species);
• 27,000,000 square kilometers - the total area of ​​coral reefs in the World Ocean;
• 60% of reefs are on the verge of extinction as a result of economic and other human activities;
• 2500 kilometers - the length of the record-breaking atoll - Bolshoy barrier reef, located off the coast of Australia;
• 2900 - the number of individual reefs included in it.

Corals in jewelry

Now about how jewelers use corals: interesting natural design The material dictates the approach of the craftsmen to its use in jewelry. The fact is that the branches broken off from natural reefs are so intricate and elegant that they often do not need serious modification. It is enough to sand the coral and coat it with a protective varnish to get products of enchanting beauty. The main advantage of such accessories is uniqueness, since nature is not repeated in the masterpieces it creates.

If miniature fragments of coral are used, depending on the design of the jewelry, the craftsmen preserve their irregular natural shape or give it:

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

Torre del Greco is recognized as the world center for coral processing. In this small town near Naples there are a lot of companies and handicraft industries focused on the production of jewelry and costume jewelry.

Confirmed facts We don’t have healing with corals or increasing wisdom and wealth with their help, but there is no doubt that the beauty of products from this sea gift improves mood and gives women confidence in their own charm.

Many coral polyps have a calcareous skeleton (sometimes there are polyps with a horny skeleton). The skeleton of polyps can be either external or internal. The calcareous skeleton allows them to take part in reef formation.

But the class of coral polyps also includes polyps that have a skeleton consisting of protein (including black corals and gorgonians). This class also includes animals that do not have a hard skeleton, such as sea anemones.

The lifestyle of the majority of coral polyps is usually nocturnal. IN daytime the polyps shrink and spread their tentacles at night. With the help of tentacles, food is obtained.

Sea anemone - home of ampifrions (clown fish)

Coral polyps: structure

Polyps have muscle cells that form muscles. Coral polyps have a well-developed nervous system. Nervous system predominantly located on the oral disc, where it forms a dense plexus.

Coral is usually the name given to the skeleton remaining after the death of polyps. Therefore, in the characteristics of coral polyps, the definition appears - reef-forming.

Different types of coral polyps

Typically, polyps are columnar in shape and located on the coral. At the top of the polyp is a disc from which many tentacles extend. The polyps are fixed motionless (the skeleton is common to the entire colony), the connection is carried out using a membrane that covers the skeleton. Reproduction of coral polyps occurs by budding, which leads to the fact that the number of individuals participating in the formation of the skeleton is constantly increasing.

The structure of a six-rayed coral polyp

Structure of an eight-rayed coral polyp

But the reproduction of coral polyps also occurs sexually. This is due to the fact that the majority of polyps are dioecious. Sexual reproduction usually occurs as follows: sperm enter the gastric cavity, from where they are released.

In the same way, they penetrate into the oral cavity of a female individual through the mouth. The egg formed as a result of fertilization develops for some time in the mesoglea. As a result of the development of the egg, larvae are formed, which leave the mother and swim freely. The larvae settle to the bottom, which gives rise to new polyps. But this process is not necessary for all polyps. For many, larvae do not form.

Asexual reproduction of sea anemone

Subclasses of coral polyps

Modern science distinguishes two subclasses of coral polyps. Subclasses include eight-rayed and six-rayed polyps. As can be seen from the names of the subclasses, eight-rayed coral polyps have eight tentacles, while they have an internal skeleton, and eight septa in the gastric cavity.

Six-rayed coral polyps

Polyps do not have six tentacles (there is no analogy with eight-rayed ones), but many tentacles, the number of which is a multiple of six. In the gastric cavity, six-rayed polyps have complex system internal partitions (the number of partitions is also a multiple of six). Mostly six-rayed polyps have an external calcareous skeleton.

The coral polyp class belongs to the reef-forming class. Coral polyps, both coastal and atoll and barrier reefs, are responsible for their vital activity.

And with others interesting representatives invertebrates, these new articles will introduce you to: