In many costume dramas, they almost like to send coral, that kind of particularly large ornament, but I never thought that such a beautiful coral is not a stone or a plant, but it is a strange marine animal.
As one of the oldest marine creatures on Earth, corals have lasted for hundreds of millions of years and can be said to have witnessed the history of the earth. Coral is gorgeous and mysterious, in ancient times, Wang Mian in the "Red Plum Qi Ten", through the poem "Taoist people do not dream of Luofu, sit and watch the coral sea sun red", the seabed colorful and diverse corals were described. In life, we may often hear corals, coral reefs, and even some people may have heard the word polyps, so what is the relationship between these three words?
Coral is a kind of marine organism, although it looks like a plant in appearance, but it actually belongs to the category of animals, which is formed by the aggregation of marine organisms and polyps (that is, coral is an aggregate of polyps, mainly three types of hard corals, soft corals, gorgonians, and other types of red corals, blue corals, sheng corals, horn corals, polyp corals, etc.). They have a lot of tentacles on their heads, and there are many small tentacles around their mouths, which are used to catch tiny creatures in the ocean, and they are classified as jellyfish.
Polyps are a member of the class Polyps (there are many subclasses under the class Polyps, which include the subclass Tetracoral, the Bedplate Coral, the Hexacoral, and the Octocta. Among them, the subclass Tetracorals and the Bedplate Coral subclass have become extinct, while the Hexacorals and Octoctocrals have survived to this day, with about 6,500 species worldwide, widely distributed in tropical, temperate and cold oceans. A kind of coelenterate, they are relatively small, usually only a few millimeters long, single in shape, cylindrical, radially symmetrical, living in groups for generations, in the process of growth, can absorb calcium and carbon dioxide in seawater, and then secrete limestone, which is later compacted and petrified to form islands and reefs, and then become coral reefs.
So, in fact, polyps are attached to corals to live. Polyps multiply rapidly in the tropics, grow fast, old ones die, new ones grow, bones grow and sand grow, and over time, corals become a variety of coral reefs and coral islands. The Spratly and Paracel Islands in the South China Sea, the Maldives in the Indian Ocean, the Fiji Island in the South Pacific, and the world-famous Great Barrier Reef were all built by tiny polyps. There are five main types of coral reefs: fringing reefs, atolls, barrier reefs, platform reefs, and point reefs.
According to the bone texture and polyp size, corals are generally divided into several types, such as large polyp stony corals, small polyp stony corals, soft corals, and sea anemones. Since most corals can sprout and reproduce, and these buds do not leave the mother's body, they eventually become a connected and co-living group, which is the main origin of corals as dendritic forms.
Not all corals can become coral reefs, according to whether they can form hard reefs, polyps are divided into two categories: "reef-building" and "non-reef-building", reef coral polyps, can absorb calcium and carbonate ions from seawater, synthesize calcium carbonate, this is the "bone" that supports its shape, but its "bone" grows outside the body, it dies after the physical body is dissolved, "bone" turns into a reef, and also becomes the foundation of new coral polyps, the cycle repeats, after tens of thousands of years of accumulation can grow into a coral reef on the bottom of the sea. Non-reef-building corals also have calcium carbonate skeletons, but they are so small that the bones of the polyps will separate and dissipate when they die, leaving nothing behind.
We know that coral is a great ornament, and we sometimes see ornaments made of coral in stores, and of course, these ornaments are just the skeletons of dead polyps, not live polyps. The remains and secretions of the vast majority of corals form loose reef bones that cannot be used as gem material. Red corals, which can be regarded as gemstones, live in groups at deep seabeds, but do not form coral reefs, and the skeleton of this coral is dense and hard. From a biological point of view, there are many types of corals, and from a gemological point of view, corals can be divided into reef-building corals and gem-quality corals. Reef-building corals grow in shallow seas, have ornamental value, loose and fragile materials, grow quickly, have a wide variety of species, and can be used as ornamental stones. Gem-quality corals, which grow in the deep sea, have harder materials, fewer species, and less distribution, and can be divided into two categories: calcareous corals and corals.
The beautiful color of coral comes from the symbiotic algae in the body, zooxanthellae. Polyps themselves are transparent, but healthy polyps have a type of coralline algae in their endothelial cells, and it is this symbiotic algae that gives them their color. It lives in the body of polyps and lives a symbiotic life with them. In photosynthesis, zooxanthellae use sunlight and carbon dioxide in seawater to produce oxygen, part of which is supplied to polyps to ingest, promoting the growth of coral skeletons. Without zooxanthellae, the polyp's brilliant color will be gone. Therefore, most of the corals we see in the offshore waters are yellow-brown.
In addition to yellow-brown corals, there are red, pink, blue, purple, and even other brilliant colors such as fluorescent effects, which are all thanks to chromoproteins and fluorescent proteins, the so-called "chromoproteins", which are a general term for a large group of proteins, which combine with pigment molecules to show different colors. For example, hemoglobin in human blood is a type of chromoprotein. When subjected to some environmental stress, the chromoproteins and fluorescent proteins in the coral will be expressed into red, blue, purple, pink and even a variety of colors with fluorescent effects to protect the coral, and the most precious red coral is a first-class protected animal at the same level as the giant panda.
There are four main groups of benthic animals living in coral reefs
Molluscs, foraminifera, echinoderms, arthropods.
According to research, once the coral reef ecosystem is destroyed, at least
It will take 60 years to recover. The total area of the world's coral reefs is about 900,000 km2, and they have maintained their vitality for 230 million years. But now, according to the 2004 State of the World's Coral Reefs report, two-thirds of the world's coral reefs have been severely damaged and are at risk of further degradation. In recent decades, global warming, marine pollution, and human overfishing of fish are bringing an unprecedented crisis to coral reefs, with many coral reefs bleaching and dying.
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