Coral polyps ( lat.Anthozoa ) - a class of marine invertebrates of the type bobbin ( Cnidaria ). Colonial and solitary bottom organisms . Many species of coral polyps possess a calcareous skeleton and are involved in reef formation . Along with them, this class includes many representatives whose skeleton consists of protein ( gorgonaria , black coral ), as well as completely devoid of a solid skeleton ( sea ββanemone ) [1] . About 6 thousand species are counted [1] . Along with aquarium fish and plants, coral polyps are found in aquariums . The material of the skeleton of some species - coral - is used in jewelry .
| Coral polyps | |||||||||||
 Madrepore coral Acropora | |||||||||||
| Scientific classification | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||
| International scientific name | |||||||||||
Anthozoa Ehrenberg , 1831 | |||||||||||
| Subclasses | |||||||||||
| |||||||||||
Lifestyle
Most coral polyps inhabit warm tropical seas, where the water temperature does not drop below +20 Β° C, and at depths of no more than 20 meters, in the conditions of abundant plankton, which they feed on. Typically, polyps shrink during the day, and at night the tentacles are pulled out and straightened, 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 (unicellular algae), which live in their mesoglye .
Building
Coral polyps possess muscular cells that form longitudinal and transverse muscles. There is a nervous system that forms a thick plexus on the oral disk.
Coral is usually called only the skeleton of the colony, remaining after the death of many small polyps. Many coral polyps are reef-makers . The skeleton may be external, formed by the ectoderm , or internal, forming in the mesoglya . 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 on top, from which the corollas of the tentacles extend. The polyps are motionlessly fixed on a skeleton common to the entire colony and are interconnected by a living membrane covering it, and sometimes by tubes penetrating limestone.
The skeleton is secreted by the external epithelium of polyps, and mainly by their base (sole), so living individuals remain on the surface of the coral structure, and it all grows continuously. The number of polyps involved in its formation is also constantly increasing through their asexual reproduction ( budding ). In many eight-ray polyps, the skeleton is poorly developed and is replaced by a hydroskeleton, which is ensured by the filling of the gastric cavity with water.
Life Cycle and Reproduction
Corals breed by budding and sexually. Polyps are usually dioecious. Sperm through breaks in the walls of the gonads exit into the gastric cavity, and then out and penetrate through the mouth into the cavity of the female. Fertilized eggs develop for some time in the mesoglysis of septum. Usually, during the embryonic development, miniature free-floating larvae are formed - planula, which after some time settle to the bottom and give rise to new individuals or colonies. In many coral polyps, development proceeds without metamorphosis and the larva does not form.
Coral Death
In a series of experiments conducted on the corals of the Great Barrier Reef , a trigger mechanism was discovered that triggered the death of corals. Their death begins with an increase in the content of organic matter in water and sediment, and microbes are a mediator of these processes. A rich organic environment serves as a good basis for the rapid growth of microbes, as a result, the oxygen content and pH of the medium are reduced. This combination is deadly to coral. Acceleration of sulfate reduction, using dead tissue as a substrate, only accelerates the death of corals [2] .
Taxonomy
There are two subclasses of modern coral polyps ( eight-beam and six-beam ), within which the following orders are distinguished [1] :
- eight-beam ( Octocorallia )
- Stolonifera
- Helioporacea ;
- soft corals ( Alcyonaria )
- horn corals ( Gorgonaria )
- sea ββfeathers ( Pennatularia )
- six-beam ( Hexacorallia )
- ceriantharia ( Ceriantharia )
- madrepore corals ( Scleractinia )
- sea ββanemones ( Actiniaria )
- Zoanthidea ( Zoanthidea )
- Corallimorpharia
- black corals ( Antipatharia ).
Notes
- β 1 2 3 Zoology of invertebrates. T. 1: from protozoa to mollusks and arthropods. Ed. W. Westheide and R. Rieger. M .: T-number of scientific publications of KMK, 2008, 512 p.
- β Naimark Elena. Corals die due to organic pollution . elementy.ru ( 06/05/2012 ). Archived June 23, 2012.
Literature
- D.V. Naumov, M.V. Propp, S.N. Rybakov. The world of coral . - Gidrometeoizdat, 1985.- S. 151. - 360 p.
- Latypov Yu. A. Massive corals of Vietnam . - Vladivostok, 2006.
Links
- Coral polyps // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- Multi-tentacled coral polyps // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907. - information on six-pointed corals
- Eight-beam polyps // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.