Large Gorgona coral. Coral reef

In their natural habitat, corals resemble trees or shrubs, and when they are pulled out of the water they become similar to precious stones, because it is not without reason that they make jewelry. In fact, corals are animals, or rather colonies of the smallest organisms - coral polyps. In the world there are almost 5,000 species of coral polyps, of which about 3,500 are actually called corals. Some representatives of coral polyps, for example, anemones, are not traditionally called corals, although they are closely related to "real" corals.

Gorgonians include colonial coral polyps, in the form and size of colonies it is the most diverse among all eight-coral. The gorgonian colonies are firmly attached to the solid substrate by the extended basal part of the axial skeleton. Only a few species are able to live on soft ground. These are mainly deep-sea forms, in which, instead of the attachment plate, root-like or spade-like outgrowths usually develop. The rest of the gorgonians settle and are numerous only where they find the rocky ground necessary for strengthening. On the sandy bottom there are single undersized colonies. Horn corals or gorgonians are widespread, but they are especially numerous in the waters of the tropical belt. Of the more than 1,200 species currently known, only a few have adapted to life in cold waters.

Most often, corals are brown, white, red, less often yellow, green, black, pink. The most rare in corals are the colors of the blue-violet spectrum. But corals of red akabaria come in two colors - rich red and bright yellow. Their color depends on the presence of algae, the composition of water and the depth of the polyps. Deep-sea coral is usually lighter than coastal. Although, if there is a lot of manganese in the water, the stone will capture it and become saturated purple, even in the Mariana Trench.

Almost all hotels in Egypt, you can find dishes of Egyptian cuisine. Its products are simple and familiar to us: it is necessarily rice, beans, poultry, lamb, goat meat, as well as cheese, eggs and lactic acid products. On the coastal areas know how and love to cook fish. Here are the main dishes that will suit any tourist in Egypt: "rosette" (rice dish), "fuya medomes" (stewed beans with lemon, vegetable oil and barley groats), "el molokheya" (rice soup, green vegetables , garlic, coriander and pepper), "sweater" (just chopped meat), "magbus" (roast lamb with rice as a side dish), "briani" (rice with a large piece of fish or meat), "charis" (cooked in water with a grain of lamb). Traditional Egyptian dessert - figs and dates, a variety of oriental sweets are also delicious, for the preparation of which they use honey, nuts and milk. Among drinks Egyptians most respected Karkade - tea from brewed hibiscus flowers.

The smallest colonies can be several centimeters in length, while the largest ones reach a height of 5-6 m. The form of corals can range from a very simple one, resembling a single twig or a curved hook (the whip shape) to a complex tree-like fan, or a candelabrum. Coral reefs are large underwater formations consisting of skeletons of coral polyps that are marine invertebrates. The detachment of coral polyps that create reefs is called madrepe or stony corals - they extract calcium carbonate from seawater and create a solid, durable exoskeleton that protects their soft, baggy bodies.

Corals live in oceans around the world, but survive best in warm water. In tropical oceans, they form large structures called atolls. Atolls grow around old volcanoes and form ring-shaped islands. Coral polyps eat small marine animals such as jellyfish larvae. Some need algae to survive. Corals can breed by budding. Small buds appear on the body of the polyp. They grow up and are separated from their parents. Corals can also lay eggs that grow into new colonies. Some types of coral live hundreds of years.

Corals can be seen everywhere - from the Aleutian Islands not far from the coast of Alaska, to the warm tropical waters of the Caribbean Sea. The largest coral reefs can be seen in the transparent shallow subtropical and tropical waters of the ocean, where they grow rapidly. The largest of the coral reef systems, the Great Barrier Reef of Australia, is over 2,400 kilometers long.

Most of the significant coral reefs existing at the moment began to form 5 000-10 000 years ago. These formations mainly exist in warm, shallow waters, where a sufficient amount of sunlight penetrates the algae, which provide food for coral polyps. Coral reefs occupy less than 1 percent of the ocean floor - collectively, they would occupy an area of approximately 285,000 square kilometers, which is close to the size of the state of Nevada. However, they are among the most productive and diverse ecosystems on Earth. Approximately 25 percent of all known marine species depend on coral reefs for feeding, habitat and breeding. Corals are sometimes called "tropical forests of the sea" because of their biodiversity. They provide habitat for over 4,000 species of fish, 700 species of coral, and many thousands of other plants and animals.

It is believed that the oxygen atmosphere on Earth was formed due to the activity of cyanobacteria. Initially, all the oxygen they produced went to the oxidation of surface rocks, atmospheric gases and compounds dissolved in sea water (primarily ferrous iron). About 2.45 billion years ago, the oxidation process as a whole was completed, and free oxygen began to accumulate in the atmosphere. This process is called the oxygen revolution. The rate of increase in the level of oxygen in the atmosphere during the oxygen revolution was very high, and in about 300 million years this level reached the present, after which it began to decline.

Almost all of the oxygen on Earth is biogenic, that is, it is secreted by living things (of course, we are now talking about free oxygen, and not about oxygen atoms that make up other molecules). The main source of O2 is oxygen photosynthesis; there are simply no other known reactions capable of producing it in comparable amounts. Almost certainly oxygen-free photosynthesis appeared much earlier than oxygen. Oxygen photosynthesis has one big advantage - a completely unlimited supply of the original reagent-reducing agent (water). A group of microbes that has mastered the risky but effective energy production using oxygen is called proteobacteria. According to the generally accepted theory, it was from them that the respiratory organelles of eukaryotic cells - mitochondria - originated.

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