Coral polyp. Class Coral polyps

Coral reefs are a valuable ocean resource because of their beauty, diversity of form, and indispensability to their ecosystem. seas, as they also call perhaps the most widespread and vivid expression of life in the aquatic environment.

They provide refuge for many sea ​​creatures, serve as a food source for myriad organisms, shape the topography of the seafloor and form island land areas. For humans, coral reefs are important not only because they are beautiful to admire while on vacation, they also protect the coastline from large ocean waves, and important building materials - sand and limestone - are formed from their skeletons.

Coral ecosystems are called the pharmacy of the 21st century. Based on useful compounds that were discovered in this biocenosis, many medical drugs have been created or are under development: antibacterial, tonic, digestive, cardiac, cosmetic, as well as medicines for treatment viral infections, asthma, skin cancer, arthritis.

The coral polyp class includes more than 6 thousand main species. These marine invertebrates can be solitary or form colonies. They also differ in size, the presence or absence of a skeleton, its shape and composition (calcareous or protein). Reef structures are capable of forming coral polyps of the order Madreporidae.

“Rock gardens” are formed not only by these miniature animal organisms. Majority coral polyps have mutually beneficial relationship with single-celled algae zooxanthellae, which live inside invertebrate cells. It is believed that these autotrophic protozoa are also involved in the construction of the coral skeleton. Other algae, calcareous ones, also play a major role in reef formation; they perform several functions: they create a reef frame, cement various damages and supply loose material. Some other animal organisms are also important for reef building, namely representatives of certain families of mollusks, polychaetes and sponges.

The mechanism of nutrition of polyps is interesting. About 90% of the organic matter that forms the microscopic algae zooxanthellae is transferred to the host tissue. The second type of power supply is external. Coral polyps can capture and absorb pre-stunned prey - microscopic zooplankton and small fish.

Coral polyps can reproduce in two ways: sexual and asexual. The separation of male and female gametes also occurs in two ways. During the first, which is called “spawning into the air,” sperm and eggs in huge quantities are synchronously released into the water column. A protein “cloud” forms over the coral reef, which attracts many predators that feed on plankton. Gradually, the larvae of polyps, planulae, spread ocean currents. In the second method of sexual reproduction, only free-swimming males enter the water until they meet a female coral.

These creatures are multifaceted: they can bud in several ways, divide transversely, and spread in broken fragments.

Coral reefs - unique phenomenon nature, beautiful and unique, but, unfortunately, very fragile. “Rock gardens” are extremely sensitive to changes in lighting, temperature, salinity levels and water pollution.

Human activity is one of the most serious threats to the existence of coral colonies, which last years discolor and die at an accelerated rate. Only joint actions of many countries around the world can stop or at least slow down this process. IN Lately Marine protected zones are created in which, through the cooperation of authorities and scientists, fish catches are reduced, and special measures are taken to preserve reefs. There are also world organizations making efforts to resolve this issue; they are developing ways to artificially form reefs and accelerate the growth of coral polyps.

beauty underwater world, its splendor and diversity always amaze nature lovers who go to see marine life. At the heart of this diversity are some very unusual inhabitants.

Introducing Interesting Facts about corals

Corals have the most extraordinary range of colors, which shimmer beautifully in the ocean depths.

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

Corals are quite picky

So, for their growth they need adequate conditions: sufficient salinity of water, transparency, warmth and a lot of food. That is why coral reefs live in the waters of the Pacific and Atlantic oceans.

It is interesting that in the World Ocean the area of ​​coral reefs totals about 27 million square meters. km.

The Great Barrier Reef is considered one of the greatest creations of these underwater growths. It extends near Australia.

Lime reserves thanks to coral reefs are almost inexhaustible

Some areas of such reefs are so large that they can rightfully be called coral islands.

The coral islands have own life and vegetation. You can even find cacti and tall shrubs here.

The local population uses corals to make jewelry.

The results are very beautiful and rainbow-colored products for the summer season.

Corals are also used as building material, polishing of metal surfaces and production of pharmaceuticals.

If a person is damaged by the coral barrier, the skin will take a very long time to heal. Even suppuration may appear at the wound site, regardless of whether poisonous coral or not.

Corals have special cells designed to protect

They are called stinging insects and at the moment of danger they release poison.

The Hindus had a belief that only men should wear red corals, and only women should wear white corals. It was believed that these colors are a kind of symbolism of one and the other sex, and in the case of “wrong wear”, each of them acquired the character traits of the opposite. How true this is is unknown.

Today, few men wear coral products. Well, women allow themselves any color scheme and red as well. Apparently, it is precisely because of this that emancipation is flourishing in our country.

You will find other interesting facts about corals on the Internet.

There are amazing forms of corals. Some of them resemble underwater flowers. Each “twig” of such a flower consists of many individual polyps.

   Class -
   Row - Alcionaria, Gorgonaria, Madreporaria, etc.

   Basic data:
DIMENSIONS
Diameter: individual polyps up to 2 cm, colonies on average reach 3 m.

REPRODUCTION
They reproduce asexually through fission and budding. Colonies also produce sperm and eggs. Fertilized eggs hatch into larvae.

LIFESTYLE
Habits: lead a sedentary lifestyle seabed; there are individual individuals and columns.
Food: living plankton. Madrepore corals feed on waste products of algae that live in their bodies.

RELATED SPECIES
The class of coral polyps includes more than 6,500 species of madrepore corals, sea feathers, gorgonians, sea anemones and many other animals. Jellyfish are not their close relatives.

   Coral polyps are unique underwater architects. In the shallow waters of tropical seas, they form entire fabulous forests and clearings, which are an ideal place for the existence of many marine animals.

FOOD

   Coral polyps are active at night. They feed on plankton and organic particles in the water.
   Corals catch prey using paralyzing stinging cells, the stinging fibers of which are studded with small hooks. Many coral polyps live in symbiosis with unicellular algae. Algae receive from the coral carbon dioxide and nitrogen and phosphorus compounds necessary for photosynthesis. Corals use both the main and by-products of photosynthesis - organic matter and oxygen. There is a continuous exchange of phosphorus between the owner and the cohabitant.

REPRODUCTION

   A coral colony grows as a result of budding, that is, asexual reproduction, when a small shoot appears on an old individual, which turns into a new young individual. Buds appear on tissues that connect individuals in a colony, or that grow on the base of the mother polyp. During sexual reproduction in the first phase of the month after the full moon, corals release billions of eggs and sperm into the water. All polyps of the same species release their reproductive cells into the water at the same time. Fertilized eggs develop into small larvae that become part of the zooplankton.

LIFESTYLE

   Colonies of coral polyps are a large number of individual polyps, firmly attached to each other, which together form twigs, horns or other complex shapes. Individual polyps have the shape of a short cylinder with an opening at the upper end, surrounded by a corolla of tentacles. Special channels connect several layers of cells and transmit digested food to other members of the colony. Coral polyps can be divided into two groups. The first is formed by polyps that build a calcareous skeleton; they are called madrepore corals. The second group includes polyps with feathery tentacles, such as gorgonians, sea feathers and sea anemones. Coral polyps strengthen their massive skeleton with a special layer formed by the sole. Thanks to such a strong base, in case of danger, the polyp can instantly pull the body into the calcareous skeleton. Other types of corals are like large fans, they can bend and sway under the influence of sea ​​currents, because their skeleton is created by individual calcareous rods that are located in a jelly-like substance.

HABITAT

   Most often, coral polyps are found in shallow warm seas. Usually the water temperature here does not drop below -16 C. For madreporic corals the most optimal temperature is within 23 C. If the temperature changes significantly, the corals may die. Some types of coral polyps need to be reached Sun rays. Madrepore corals are found ideal conditions at a depth of up to 45 m, soft and mobile alcyonari are found up to a depth of 100 m. Madrepore corals do not settle near river mouths because they do not survive in fresh, running water. “Hunting” coral polyps willingly settle in the area of ​​​​sea currents. Thin but elastic gorgonians perfectly tolerate light waves of water (their columns are elastic and bend), while hard but fragile madrepore corals break under the influence of water or waves.
  

DID YOU KNOW THAT...

• Corals “fight” among themselves for territory. Coral polyps shoot out stinging fibers from their neighbors or grow so that they block their light.
• Noble coral is mined in large quantities in the Mediterranean Sea. Jewelry is made from it.
• Red coral is colored in various shades of red - from light pink to dark red. The most expensive coral is the rare black coral.

  

TWO NORTH ATLANTIC CORAL

   Alcyonarians: This is a coral that lives alone. It looks like an anemone, so it is easy to confuse it with it. The animal reaches 25 mm in diameter, its transparent tentacles grow in a corolla around the slit-like mouth opening.
   Gorgonians: lives in the Atlantic Ocean, in waters warmed by the Gulf Stream. Colonies of this polyp form a horny, lime-soaked skeleton.

PLACES OF ACCOMMODATION
Found in all tropical and subtropical seas, as well as in some areas temperate zone. Reefs form on the warmer eastern parts of continents.
PRESERVATION
Corals are very fragile animals, so they are often destroyed by the anchors of ships that drag along the bottom.

These are exclusively marine, mostly heat-loving organisms. There are both solitary and colonial forms (the latter more often). There is no jellyfish form in the development cycle.

Compared to hydroid polyps, they are more complex. An individual coral polyp of a colony resembles a hydra in appearance, but is usually located in the calyx of its exoskeleton. The complication of their organization is the presence of a pharynx, dividing the intestinal cavity into chambers using vertical partitions, which increases the surface area for secretion and absorption of food.

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

The nervous system is of a diffuse type, but with a greater concentration of nerve cells at the mouth opening than in Hydra.

Coral polyps reproduce both asexually and sexually. The gonads develop in the endoderm of the intestinal septa.

The fertilized egg begins to fragment. First, it divides in two, then each of the resulting cells, in turn, also divides, and so on. As a result, a large number of small cells are formed, arranged in one layer and looking like a small hollow ball. Following this, some of the cells are immersed inside, resulting in a two-layer embryo. The endoderm is subsequently formed from its inner layer, and the ectoderm of the future polyp is formed from the outer layer. The ectoderm is covered with numerous small cilia, with the help of which the embryo gains the ability to swim; from this moment it turns into a larva called planula. The planula is unable to feed or reproduce. It swims in the water column for some time, then sits on the bottom and attaches itself to it with its front end. Soon after this, a mouth opening breaks through at the posterior end (now upper) end of the planula and a corolla of tentacles is formed. This is how the first polyp appears. In colonial forms, this polyp soon buds on itself other polyps, which in turn follow, etc. a colony appears. Once the colony reaches a certain stage of development, the polyps that make it up begin to reproduce also sexually, forming eggs. This completes the cycle.

Among solitary soft coral polyps, widely known sea ​​anemones, which are called sea flowers for their varied colors.

Colonial forms are numerous and varied (spherical, tree-like, etc.). Their skeleton is made of calcium carbonate. Calcareous skeletons of colonial forms form reefs and oceanic islands - atolls. Organic red skeletonnoble coral used for making jewelry.

Control questions:

What structural features are characteristic of coelenterates (using the example of Hydra)?

How does hydra feed?

What types of reproduction does hydra have?

Which common features and are there differences between representatives of the classes Scyphoid and Coral polyps?

How do Scyphoids reproduce?

There are no people in the world who would not be fascinated by the variety of coral polyps. These bottom organisms, belonging to the class of marine invertebrates, representatives of the phylum Cnidaria, can grow either singly or in colonies.

Vital activity of corals

Each branch of coral is a cluster of small polyps called a colony. Each such organism forms a calcareous shell around itself, which serves as its protection. When a new polyp is born, it attaches to the surface of the previous one and begins to form a new membrane. This is how the coral gradually grows, which, when favorable conditions is approximately 1 cm per year. Large clusters of such marine organisms form coral reefs.

The class Coral polyps includes the following organisms:

1. Having a calcareous skeleton. They are the ones who take part in the process of reef formation.

2. Having a protein skeleton. These include black corals and gorgonians.

3. Devoid of any hard skeleton (anemones).

Experts allocate about 6 thousand various types coral polyps. The name Anthozoa is Latin for “flower animal.” Coral polyps have a very picturesque appearance. They come in a variety of shades. Their mobile tentacles resemble flower petals. The largest single polyps grow up to 1 m in height. Often their diameter is about 50-60 cm.

Habitat

Numerous representatives of coral polyps inhabit almost all the waters of the world's oceans. But most of them are concentrated in warm tropical seas. They develop well at temperatures 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 that these organisms feed on live in this water column.

Nutrition method

Coral polyps are usually daytime they shrink, and with the onset of darkness they extend their tentacles, with which they catch prey swimming past them. Small polyps feed on plankton, while large ones are able to digest small animals. Most often, fish and shrimp are consumed by single large polyps. Among this class of organisms there are also representatives that exist due to symbiosis with unicellular algae (autotrophic protozoa).

Structure

Coral polyps, whose structure differs slightly depending on their species, have muscle cells. They form the transverse and longitudinal muscles of the body. Polyps have nervous system, which is a dense plexus in the area of ​​the oral disc of these organisms. Their skeleton can be internal, formed in the mesoglea, or external, which is formed by the ectoderm. Most often, the polyp occupies a cup-shaped depression on the coral, which stands out noticeably on its surface. As a rule, the shape of polyps is columnar. At their top there is often a kind of disk, from which the tentacles of this organism extend. The polyps are fixedly attached to the skeleton common to the colony. They are all connected by a living membrane that covers the entire skeleton of the coral. In some species, all polyps are connected to each other by tubes piercing the limestone.

The skeleton of the coral polyp is secreted by the outer epithelium. What makes it stand out most is the base (sole) of this marine “structure.” Thanks to this process, living individuals develop on the surface of the coral, and the coral itself continuously grows. Most eight-rayed coral polyps have a poorly developed skeleton. It is replaced by the so-called hydroskeleton, which exists due to the filling of the gastric cavity with water.

The body wall of a polyp consists of ectoderm (outer layer) and endoderm (inner layer). Between them there is a layer of structureless mesoglea. The ectoderm contains stinging cells called cnidoblasts. Structure different types coral polyps may vary slightly. For example, sea anemones are cylindrical in shape. Its height is 4-5 cm and its thickness is 2-3 cm. This cylinder consists of a trunk (column), a lower part (leg) and an upper part. The anemone is crowned by a disk on which the mouth (peristome) is located, and in its center there is an oblong slit.

Around it there are tentacles arranged in groups. They form several circles. The first and second have 6, the third - 12, the fourth - 24, the fifth - 48 tentacles. After 1 and 2, each subsequent circle has them 2 times larger than the previous one. Sea anemones can take the most different shapes(flower, tomato, fern). The pharynx leads into the gastric cavity, divided by radial partitions called septa. They are lateral folds of the endoderm, consisting of two layers. Between them there is mesoglea with muscle cells.

The septa form the stomach of the polyp. From above, their free edge grows to his throat. The edges of the septa are corrugated, they are thickened and seated with digestive and stinging cells. They are called mesenteric filaments, and their free ends are called acontia. Digestion of food by the polyp is carried out with the help of enzymes secreted by it.

Reproduction

Reproduction of coral polyps is carried out in a special way. Their numbers are constantly increasing due to asexual reproduction called budding. Some types of polyps reproduce sexually. Many species of these organisms are dioecious. The sperm of males penetrates the gastric cavity through gaps in the walls of the gonads and comes out. Then they get into oral cavity female individual. Next, fertilization of the eggs occurs, and they develop for some time in the mesoglea of ​​the septa.

During embryonic development, tiny larvae are obtained that swim freely in the water. Over time, they settle to the bottom and become the founders of new colonies or single individuals of polyps.

Corals as reef builders

Great amount marine polyps participates in the formation of reefs. Corals most often refer to the skeletal remains of colonies of polyps that remain after the death of many of these small organisms. Their death is often provoked by an increase in the content of organic substances in water and bottom sediments. The catalyst for this process is microbes. An environment rich in organic matter is an excellent place for active development pathogenic microorganisms, as a result of whose vital activity the acidity of water and the oxygen content in it decrease. This “cocktail” has a detrimental effect on single and colonial coral polyps.

Subclasses of polyps

Experts distinguish 2 subclasses of polyps, which include different orders of these marine organisms:

1. Eight-beam(Octocorallia), which includes soft (Alcyonaria) and horny (Gorgonaria) corals. They also include sea feathers (Pennatularia), stolonifera (Stolonifera), blue polyp Helioporacea. They have eight mesenteries, an internal spicule skeleton and feathery tentacles.

2. Six-beam(Hexacorallia), among which are Corallimorpharia, sea anemones (Actiniaria), ceriantharia (Ceriantharia), zoanthidea, scleractinia and black corals (Antipatharia).

Use in everyday life

Some coral polyps are successfully grown by aquarists in artificial conditions. The calcareous skeleton of some species of these marine organisms is used to make jewelry. In some countries that have not yet banned the extraction of coral polyps, their remains are used to build houses and other structures. They are also used as decoration in homes and gardens.