How many oceans on Earth: disputes over the exact number. Traditional geography taught that there are four oceans in the world - Pacific, Atlantic, Arctic and Indian.

Our planet is the most amazing of all the planets of near and far space.

On its surface there is a unique layer - the hydrosphere. This is the water shell of the Earth. It is found on other planets, but only on ours it is in three states of aggregation - solid, liquid and gaseous.

In addition to water, on the surface of the Earth there is land - solid areas of the earth's crust. These areas are fragments of the cooling earth's surface. The earth can be compared to an egg - inside it is a hot liquid mantle, and the earth's crust is only a thin shell.

The Earth's surface is heterogeneous, it has a different thickness and is broken into "fragments" - tectonic plates that move at different speeds and in different directions. Sometimes they collide and diverge. In different periods of the existence of the planet, the answer to the question, how many continents are on Earth, was different and the reason was in tectonics.

More than three hundred million years ago, there was only one mainland - Pangea. under the influence of magmatic eddies, it split into two continents - Laurasia and Gondwana (about 200 million years ago). Only 40 million years ago, the surface of the planet acquired the appearance that is familiar to us: now there are six continents on the planet:

the largest is Eurasia;
the hottest is Africa;
the most elongated from north to south - North America;
South America;
the coldest is Antarctica;
the smallest is Australia.

The continents move relative to each other and may soon reconnect. For example, North America is moving towards Eurasia at a rate of about 20 mm per year.

In addition to the continents, the Earth is rich in islands. The largest of them is Greenland. An island belonging to the North American tectonic plate.

More than half of the Earth's surface is covered by water - the oceans. On any map, you can see that the entire huge water mass is a single massif. However, science identifies several oceans.

The biota of the ocean depends on the physical parameters, therefore, the flora and fauna in different parts of the oceans will be different.

So how to answer the question how many oceans are on Earthusing knowledge about the structure of our planet? Most scientists distinguish 4 oceans:

Pacific Ocean;
Atlantic Ocean;
Indian Ocean;
Arctic Ocean.

In some sources, the fifth ocean is distinguished - the Southern. It is located in the southern hemisphere of the Earth and washes the coast of Antarctica. Opponents of its isolation believe that this ocean is the place where the rest of the oceans meet, the water masses do not have time to mix in this part, so they retain their integrity. In any case, there is no clear definition of the number of oceans yet, but it is safe to say that there are no more than five and no less than four.

In addition to the physical parameters of the sea, they differ in size: in depth, the width of the water surface, and the coastline. For example, it has been established that the largest sea in the world in terms of surface area is Sargasso (Atlantic Ocean basin) - an area of 6000 thousand km 2, and the deepest - Coral (Pacific Ocean basin), having a depth of 9174 meters.

In Russia, the largest sea is the Bering Sea (basin of the Arctic Ocean) - an area of 2315 thousand km 2.

Earth is the only inhabited planet in . What is called the World Ocean, how it is located on Earth, and how to divide into separate reservoirs, you can find out by reading this article.

The continents divide the entire hydrosphere located on the surface of the earth into reservoirs that have a separate circulation system. At the same time, scientists have found that under the water column there are not only seamounts, but also rivers and their waterfalls. The ocean is not a separate part, it is directly associated with the interior of the earth, its bark and all.

It is thanks to these accumulations of fluid in nature that such a phenomenon as circulation is possible. There is a special science, which is called oceanology, and deals with the study of the fauna and flora of the underwater depths. In its geology, the bottom of the reservoir near the continents is similar to the structure of the land.

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World hydrosphere and its research

What is called the oceans? For the first time, this term was proposed to be used by the scientist B. Varen. All bodies of water and their components are together area of the world ocean most of the hydrosphere. It contains 94.1% of the entire area of the hydrosphere, which is not interrupted, but is not continuous - it is limited by continents with islands and peninsulas.

Important! World waters have different salinity in different parts of it.

World ocean area- 361,900,000 km². History singles out the main stage in the study of the hydrosphere as the "Age of Geographical Discoveries", when continents, seas and islands were discovered. The most important for the study of the hydrosphere were the travels of the following navigators:

Ferdinand Magellan;
James Cook;
Christopher Columbus;
Vasco de Gamma.

Intensive study of the area of the World Ocean began only in the 2nd part of the 20th century already with the use of modern technologies (echolocation, submersions in bathyscaphes, studies of geophysics and geology of the seabed). There were various methods of study:

with the help of research vessels;
conducting major scientific experiments;
using deep-sea manned vehicles.

And the first scientific research in the 20th century began on December 22, 1872 on the Challenger corvette, and it was it that brought results that radically changed people's idea of the structure, flora and fauna of the underwater world.

Only in the 1920s, echo sounders began to be used, which made it possible to find out the depth in a few seconds, and to have a general idea of the nature of the bottom.

With the help of these instruments, it was possible to determine the profile of the bed, and the Gloria system could even scan the bottom in whole strips of 60 m, but given the area of \u200b\u200bthe oceans, this would take too much time.

by the most major discoveries become:

In 1950 - 1960. discovered the rocks of the earth's crust, which are hidden under the water column, and were able to determine their age, which seriously influenced the idea of the age itself. The study of the bottom also made it possible to learn about the constant movement of lithospheric plates.
Underwater drilling in the 1980s made it possible to thoroughly study the bottom at depths of up to 8300 m.
studies by seismologists have provided data on prospective oil deposits and rock structure.

Thanks to research and scientific experiments, not only all the data that is known today was collected, but life at depth was also discovered. There are special scientific organizations who are still studying today.

These include various research institutes and bases, and they are characterized by territorial distribution, for example, the waters of the Antarctic or the Arctic are studied by different organizations. Despite a long history of research, scientists claim that they currently know only 194,400 of the 2.2 million species of marine life.

Division of the hydrosphere

You can often find questions on the web: How many oceans are on earth 4 or more? It is generally accepted that there are only four of them, although for a long time scientists doubted 4 or 5. To accurately answer the above question, you should find out the history of the allocation of the largest reservoirs:

XVIII-XIX centuries scientists identified two main, and some three, water areas;
1782-1848 the geographer Adriano Balbi designated 4;
1937-1953 - designated 5 world water bodies, including the waters of the South, as a separate part from other seas, due to certain specific features of the waters close to Antarctica;
1953-2000 scientists abandoned the definition of the Southern water area and returned to past statements;
In 2000, 5 separate water areas were finally identified, one of which is the South. This position was adopted by the International Organization of Hydrographers.

Characteristics

All divisions happen based on differences in climatic conditions, hydrophysical features and in salt compositions of water. Each reservoir has its own area, specifics and features. Their names come from some geographical features.

Quiet

Quiet is sometimes called the Great because of its large size, because it is the largest ocean on earth and the deepest. It is located between Eurasia, Australia, North and South America, and Antarctica.

Thus, it washes all existing Earths, except for Africa. As mentioned above, the entire hydrosphere of the Earth is connected, therefore it is not surprising that the water area is connected with other waters with the help of straits.

The volume of the Pacific Ocean is 710.36 million km³, which is 53% of the total volume of world waters. Its average depth is 4280 m, and the maximum is -10994 m. The deepest place is the Mariana Trench, which was properly explored only in last 10 years.

But the bottom was never reached, because the equipment does not yet allow it. Recent studies have confirmed that even at such a depth, in conditions of terrible underwater pressure and complete darkness, life still exists. The shores are unevenly populated. The most developed and largest industrial areas:

Los Angeles and San Francisco;
Japanese coasts and South Korean;
Australian coast.

Atlantic

area of the atlantic ocean- 91.66 million km², which makes it the largest after the Pacific, and allows it to wash the shores of Europe, both Americas and Africa. It is named after the titan named Atlas from Greek mythology. It communicates with the waters of the Indian Ocean and others, thanks to the straits, and touches directly at the headlands. A characteristic feature of the reservoir is a warm current and exchangeable Gulfstream. It is thanks to him that coastal countries have a mild climate (Great Britain, France).

Despite the fact that the area of the Atlantic Ocean is smaller than that of the Pacific, it is not inferior in terms of the number of species of flora and fauna.

The reservoir makes up 16% of the entire hydrosphere of the Earth. The volume of its waters is 329.7 million km3, and the average depth is 3736 m, with a maximum depth of 8742 m in the Puerto Rico trench. On its shores, the most active industrial areas are European and American shores, as well as South African countries. This body of water is incredible. important for world shipping, after all, it is through its waters that the main trade routes connecting Europe and America run.

Indian

Indian is third largest on the surface of the Earth is a separate reservoir, which got its name from the state of India, which occupies most of its coastline.

She was very famous and rich in those days when the water area was actively studied. The reservoir is located between three continents: Eurasian, Australian and African.

As for other oceans, their borders with the waters of the Atlantic are drawn along the meridians, and the border with the South cannot be clearly established, since it is blurred and conditional. Numbers for characteristics:

It occupies 20% of the entire surface of the planet;
The area is 76.17 million km², and the volume is 282.65 million km³;
The maximum width is about 10 thousand km;
The average depth is 3711 m, and the maximum depth is 7209 m.

Attention! The waters of the Indian differ in high temperature, compared with other seas and water areas. Due to this, it is extremely rich in flora and fauna, and the warmth is due to its location in the Southern Hemisphere.

Seaways pass through the water area between the four main trading floors of the world.

Arctic

The Arctic Ocean is located in the north of the planet and washes only two continents: Eurasia and North America. This is the smallest ocean in terms of area (14.75 million km²) and the coldest.

Its name was formed according to its main characteristics: location in the North, and most of the waters are covered with drifting ice.

This water area is the least studied, since it was singled out as an independent reservoir only in 1650. But at the same time, trade routes between Russia, China and America run through its waters.

Southern

The South was officially recognized only in 2000, and includes part of the waters of all the waters listed above, except for the Arctic. It surrounds Antarctica and does not have an exact northern boundary, so it is not possible to indicate its location. Because of these disputes about its official recognition and lack of precise boundaries, there is still no data on its average depth and other important characteristics of a separate reservoir.

How many oceans on Earth, names, characteristics

Continents and oceans of the Earth

Output

Thanks to scientific research, today all 5 reservoirs that make up most of the entire hydrosphere of the Earth are known and examined (albeit not completely). It is worth remembering that they all communicate with each other and are an important factor in life of many animals, so their pollution will lead to an ecological disaster.

There are 4 oceans on our planet Earth

What are the names of the oceans on our planet?

1 - Pacific Ocean (the largest and deepest);

2 - Atlantic Ocean (in terms of volume and depth, it is the second after the Pacific Ocean);

3 - Indian Ocean (the third in volume and depth after the Pacific and Atlantic);

4 - Arctic Ocean (the fourth and smallest in volume and depth among all oceans)

What is the ocean? - This is a huge body of water located among the continents, which is constantly in interaction with the earth's crust and the earth's atmosphere. The area of the world's oceans, together with the seas included in it, is about 360 million square kilometers of the Earth's surface (71% of the total area of our planet).

Over the years, the world ocean was divided into 4 parts, while others divided it into 5 parts. For a long time, 4 oceans were indeed distinguished: Indian, Pacific, Atlantic and Arctic (except for the Southern Ocean). The southern one is not part of the oceans because of its very conditional boundaries. However, at the beginning of the 21st century, the International Hydrographic Organization adopted a division into 5 parts including the list of territorial waters called the "Southern Ocean", but at the moment this document still does not have official legal force, and it is believed that the southern ocean is only conditionally listed. by its name as the fifth on Earth. The Southern Ocean is also called the Southern Sea, which does not have its own clear independent boundaries, and it is believed that its waters are mixed, that is, the water currents of the Indian, Pacific and Atlantic oceans included in it.

Brief information about each ocean of the planet

Pacific Ocean- is the largest in area (179.7 million km 2) and the deepest. It occupies about 50 percent of the entire surface of the Earth, the volume of water is 724 million km 3, the maximum depth is 11022 meters (the Mariana Trench, the deepest known on the planet).
Atlantic Ocean- the second largest after the Pacific. The name was given in honor of the famous titan Atlanta. The area is 91.6 million km 2, the volume of water is 29.5 million km 3, the maximum depth is 8742 meters (an ocean trench, which is located on the border of the Caribbean Sea and the Atlantic Ocean).
Indian Ocean covers approximately 20% of the Earth's surface. Its area is just over 76 million km2, its volume is 282.5 million km3, and its greatest depth is 7209 meters (the Sunda Trench extends for several thousand kilometers along the southern part of the Sunda island arc).
Arctic Ocean considered the smallest among all. So, its area is “only” 14.75 million km 2, its volume is 18 million km 3, and the greatest depth is 5527 meters (located in the Greenland Sea).

The ocean (ancient Greek Ὠκεανός, on behalf of the ancient Greek deity of the Ocean) is the largest water body that makes up part of the World Ocean, located among the continents, having a water circulation system and other specific features. The ocean is in constant interaction with the atmosphere and the earth's crust. The surface area of the world's oceans, which includes oceans and seas, is about 71 percent of the Earth's surface (about 361 million square kilometers). The relief of the bottom of the oceans of the Earth as a whole is complex and diverse.

The science that studies the oceans is called oceanology; fauna and flora of the ocean is studied by a branch of biology called ocean biology.

ancient meaning

In ancient Rome, the word Oceanus denoted the waters that washed the known world from the west, that is, the open Atlantic Ocean. At the same time, the expressions Oceanus Germanicus ("German Ocean") or Oceanus Septentrionalis ("Northern Ocean") denoted the North Sea, and Oceanus Britannicus ("British Ocean") - the English Channel.

Modern definition of the oceans

The World Ocean is the global volume of sea water, the main part of the hydrosphere, accounting for 94.1% of its entire area, a continuous, but not continuous water shell of the Earth, surrounding continents and islands and characterized by a common salt composition. Continents and large archipelagos divide the world's oceans into parts (oceans). Large regions of the oceans are known as seas, bays, straits, etc.

Some sources divided the World Ocean into four parts, others into five. From 1937 to 1953, five oceans were distinguished: the Pacific, Atlantic, Indian, Arctic and Southern (or Southern Arctic) oceans. The term "Southern Ocean" appeared many times in the 18th century, when a systematic study of the region began. In the publications of the International Hydrographic Organization, the Southern Ocean was separated from the Atlantic, Indian and Pacific in 1937. There was a rationale for this: in its southern part, the boundaries between the three oceans are very arbitrary, at the same time, the waters adjacent to Antarctica have their own specifics, and are also united by the Antarctic circumpolar current. However, later on, the allocation of a separate Southern Ocean was abandoned. In 2000, the International Hydrographic Organization adopted a division into five oceans, but this decision has not yet been ratified. The current 1953 definition of the oceans does not include the Southern Ocean.

In the table below, in addition to the seas belonging to the oceans, the seas belonging to the Southern Ocean are also indicated.

	Area, mln km²	Volume, mln km³	Average depth, m	Maximum depth, m
Atlantic				8,742 (Puerto Rico Trench)	Baltic, Northern, Mediterranean, Black, Sargasso, Caribbean, Adriatic, Azov, Balearic, Ionian, Irish, Marble, Tyrrhenian, Aegean; Bay of Biscay, Gulf of Guinea, Gulf of Mexico, Hudson Bay People: Weddell, Skosha, Lazareva
Indian				7 725 (Zonda Trench)	Andaman, Arabian, Arafura, Red, Laccadive, Timor; Bay of Bengal, Persian Gulf Also related to the Southern Ocean: Riiser-Larsen, Davis, Cosmonauts, Commonwealth, Mawson
Arctic				5,527 (in the Greenland Sea)	Norwegian, Barents, White, Kara, Laptev, East Siberian, Chukchi, Greenland, Beaufort, Baffin, Lincoln
Quiet				11,022 (Marian Trench)	Bering, Okhotsk, Japanese, East China, Yellow, South China, Javanese, Sulawesi, Sulu, Philippine, Coral, Fiji, Tasmanovo Also related to the Southern Ocean: D'Urville, Somov, Ross, Amundsen, Bellingshausen

Brief description of the oceans

The Pacific Ocean (or the Great) is the largest ocean in terms of area and depth on Earth. It is located between the continents of Eurasia and Australia in the west, North and South America in the east, Antarctica in the south. In the north, through the Bering Strait, it communicates with the waters of the Arctic, and in the south - with the Atlantic and Indian Oceans. Occupying 49.5% of the surface of the World Ocean and containing 53% of the volume of water in the World Ocean, the Pacific Ocean extends approximately 15.8 thousand km from north to south and 19.5 thousand km from east to west. The area with the seas is 179.7 million km2, the average depth is 3984 m, the volume of water is 723.7 million km3 (without the seas, respectively: 165.2 million km2, 4282 m and 707.6 million km3). The greatest depth of the Pacific Ocean (and the entire World Ocean) is 11,022 m in the Mariana Trench. The international date line runs through the Pacific Ocean along the 180th meridian. The study and development of the Pacific Ocean began long before the appearance of a written history of mankind. Junks, catamarans and simple rafts were used to navigate the ocean. The expedition of 1947 on a raft of balsa logs "Kon-Tiki" under the leadership of the Norwegian Thor Heyerdahl proved the possibility of crossing the Pacific Ocean in a westerly direction from central South America to the islands of Polynesia. Chinese junks made trips along the ocean coast to the Indian Ocean (for example, Zheng He's seven voyages in 1405-1433). At present, the coast and islands of the Pacific Ocean are developed and populated extremely unevenly. The largest centers of industrial development are the US coast (from the Los Angeles region to the San Francisco region), the coast of Japan and South Korea. The role of the ocean in the economic life of Australia and New Zealand is significant.

The second largest ocean of the Earth after the Pacific Ocean, the name comes from the name of the titan Atlas (Atlanta) in Greek mythology or from the legendary island of Atlantis. It extends from the subarctic latitudes to Antarctica itself. The border with the Indian Ocean runs along the meridian of Cape Agulhas (20 ° E to the coast of Antarctica (Queen Maud Land). The border with the Pacific Ocean is drawn from Cape Horn along the meridian 68 ° 04' W or the shortest distance from South America to the Antarctic Peninsula through the Drake Strait, from Ost Island to Cape Sternek.The border with the Arctic Ocean passes through the eastern entrance of the Hudson Strait, then through the Davis Strait and along the coast of Greenland Island to Cape Brewster, through the Denmark Strait to Cape Reidinupyr on the island of Iceland, along its coast to Cape Gerpyr, then to the Faroe Islands, then to the Shetland Islands and along 61 ° north latitude to the coast of the Scandinavian Peninsula.The area of the seas, bays and straits of the Atlantic Ocean is 14.69 million km2 (16% of the total ocean area), the volume 29.47 million km³ (8.9%) Area 91.6 million km2, of which about a quarter is inland seas The area of coastal seas is small and does not exceed 1% from the total water area. The volume of water is 329.7 million km3, which is equal to 25% of the volume of the World Ocean. The average depth is 3736 m, the greatest is 8742 m (Puerto Rico Trench). The average annual salinity of the ocean waters is about 35 ‰. The Atlantic Ocean has a strongly indented coastline with a pronounced division into regional water areas: seas and bays.

The Indian Ocean is the third largest ocean on Earth, covering about 20% of its water surface. The Indian Ocean is mainly located south of the Tropic of Cancer between Eurasia to the north, Africa to the west, Australia to the east and Antarctica to the south.

Its area is 76.17 million km2, volume - 282.65 million km3. In the north it washes Asia, in the west - the Arabian Peninsula and Africa, in the east - Indochina, the Sunda Islands and Australia; in the south it borders on the Southern Ocean.

The border with the Atlantic Ocean runs along the 20 ° meridian of east longitude; from the Pacific - along the 147 ° meridian of eastern longitude.

The northernmost point of the Indian Ocean is located at approximately 30° north latitude in the Persian Gulf. The width of the Indian Ocean is approximately 10,000 km between the southern points of Australia and Africa.

The Arctic Ocean (Eng. Arctic Ocean, Danish Ishavet, Norwegian and Nynorsk Nordishavet) is the smallest ocean on Earth, located between Eurasia and North America.

The area is 14.75 million km2, that is, a little more than 4% of the total area of the World Ocean, the average depth is 1,225 m, the volume of water is 18.07 million km3.

The Arctic Ocean is the shallowest of all oceans, with an average depth of 1,225 m (greatest depth of 5,527 m in the Greenland Sea).

Formation of the oceans

Today, in scientific circles, there is a version that the ocean appeared 3.5 billion years ago as a result of degassing of magma and subsequent condensation of atmospheric vapors. Most of the modern ocean basins arose in the last 250 Ma as a result of the breakup of the ancient supercontinent and the divergence to the sides (the so-called spreading) of lithospheric plates. The exception is the Pacific Ocean, which is a dwindling remnant of the ancient ocean of Panthalassa.

bathymetric position

According to the bathymetric position and the nature of the relief on the ocean floor, several of the following steps are distinguished:

Shelf - depth up to 200-500 m
Continental slope - depth up to 3500 m
Ocean bed - depth up to 6000 m
Deep sea trenches - depth below 6000 m

ocean and atmosphere

The ocean and atmosphere are fluids. The properties of these environments determine the habitat of organisms. Currents in the atmosphere affect the general circulation of water in the oceans, and the properties of ocean waters depend on the composition and temperature of the air. In turn, the ocean determines the main properties of the atmosphere and is a source of energy for many processes occurring in the atmosphere. The circulation of water in the ocean is affected by winds, the rotation of the Earth, as well as land barriers.

Ocean and climate

The ocean heats up more slowly in summer and cools more slowly in winter. This allows you to smooth out temperature fluctuations on land adjacent to the ocean.

The atmosphere receives from the ocean a significant part of the heat coming to it and almost all of the water vapor. The vapor rises and condenses to form clouds that are carried by the winds and fall as rain or snow on land. Only the surface waters of the ocean participate in heat and moisture exchange. Internal ones (about 95%) do not participate in the exchange.

The chemical composition of water

In the ocean there is an inexhaustible source of chemical elements, which is contained in the composition of its water, as well as in the deposits located at the bottom. There is a constant renewal of mineral deposits, by falling or bringing to the bottom of various sediments and solutions from the earth's crust.

The average salinity of sea water is 35 ‰. The salty taste of water is given by the 3.5% of dissolved minerals contained in it - these are mainly sodium and chlorine compounds.

Due to the fact that the water in the ocean is constantly mixed by waves and currents, its composition is almost the same in all parts of the ocean.

Flora and fauna

The Pacific Ocean accounts for more than 50% of the total biomass of the World Ocean. Life in the ocean is abundant and varied, especially in the tropical and subtropical zones between the coasts of Asia and Australia, where vast areas are occupied by coral reefs and mangroves. The phytoplankton of the Pacific Ocean mainly consists of microscopic unicellular algae, numbering about 1300 species. In the tropics, fucus, large green and especially well-known red algae are especially common, which, along with coral polyps, are reef-forming organisms.

The flora of the Atlantic is distinguished by species diversity. The water column is dominated by phytoplankton, consisting of dinoflagellates and diatoms. At the height of their seasonal bloom, the sea off the coast of Florida turns bright red, and a liter of sea water contains tens of millions of single-celled plants. The bottom flora is represented by brown (fucus, kelp), green, red algae and some vascular plants. In the mouths of the rivers, sea zoster, or eelgrass, grows, and in the tropics, green (caulerpa, wallonia) and brown (sargasso) algae predominate. The southern part of the ocean is characterized by brown algae (fucus, forestia, electus). The fauna is distinguished by a large - about a hundred - number of bipolar species that live only in cold and temperate zones and are absent in the tropics. First of all, these are large sea animals (whales, seals, fur seals) and ocean birds. Sea urchins, coral polyps, sharks, parrot fish and surgeon fish live in tropical latitudes. Dolphins are often found in the waters of the Atlantic. Cheerful intellectuals of the animal world willingly accompany large and small vessels - sometimes, unfortunately, falling under the ruthless blades of propellers. The native inhabitants of the Atlantic are the African manatee and the largest mammal on the planet, the blue whale.

The flora and fauna of the Indian Ocean is extremely diverse. The tropical region stands out for its abundance of plankton. The unicellular alga Trichodesmium (a type of Cyanobacterium) is especially abundant, due to which the surface layer of water becomes very cloudy and changes its color. The plankton of the Indian Ocean is distinguished by a large number of night-luminous organisms: peridine, some species of jellyfish, ctenophores, and tunicates. Brightly colored siphonophores, including poisonous phasalia, are abundant. In temperate and arctic waters, the main representatives of plankton are copepods, euphuazids, and diatoms. The most numerous fish of the Indian Ocean are dolphins, tuna, notothenia and various sharks. From reptiles there are several species of giant sea turtles, sea snakes, from mammals - cetaceans (toothless and blue whales, sperm whales, dolphins), seals, sea elephants. Most cetaceans live in temperate and polar regions, where, due to the intensive mixing of waters, favorable conditions arise for the development of planktonic organisms. The flora of the Indian Ocean is represented by brown algae (Sargasso, Turbinarium) and green algae (Caulerna). The calcareous algae of lithotamnia and chalimed also develop magnificently, which, together with corals, participate in the construction of reef structures. Typical for the coastal zone of the Indian Ocean is a phytocenosis formed by mangroves. For temperate and Antarctic waters, the most characteristic are red and brown algae, mainly from the groups of fucus and kelp, porphyry, and helidium. In the subpolar regions of the southern hemisphere, giant macrocystis are found.

The reason for the poverty of the organic world of the Arctic Ocean is the harsh climatic conditions. The only exceptions are the North European Basin, the Barents and White Seas with their extremely rich flora and fauna. The flora of the ocean is represented mainly by kelp, fucus, anfeltia, and in the White Sea - also zostera. The bottom fauna of the seas of the eastern Arctic is extremely poor, especially in the central part of the Arctic Basin. There are more than 150 species of fish in the Arctic Ocean, among them a large number of commercial fish (herring, cod, salmon, scorpion fish, flounder and others). Seabirds in the Arctic lead a predominantly colonial lifestyle and live on the shores. Mammals are represented by seals, walruses, beluga whales, whales (mainly minke and bowhead whales), and narwhals. Lemmings are found on the islands, arctic foxes and reindeer come along the ice bridges. The polar bear, whose life is mainly associated with drifting, pack ice or coastal fast ice, should also be considered a representative of the ocean fauna. Most animals and birds all year round (and some only in winter) are white or very light in color.

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World Ocean- the main part of the hydrosphere, a continuous, but not continuous, water shell of the Earth, surrounding the continents and islands and characterized by a common salt composition. The world ocean is a heat regulator. The world ocean has the richest food, mineral and energy resources. Although the World Ocean is a single whole, for the convenience of research, its individual parts have been given different names: the Pacific, Atlantic, Indian, Arctic Oceans and the South.

Ocean and atmosphere. The oceans, the average depth of which is approx. 4 km, contains 1350 million km3 of water. The atmosphere, enveloping the entire Earth in a layer several hundred kilometers thick, with a much larger base than the World Ocean, can be considered as a "shell". Both the ocean and the atmosphere are the fluids in which life exists; their properties determine the habitat of organisms. The ocean determines the main properties of the atmosphere and is a source of energy for many processes occurring in the atmosphere. The circulation of water in the ocean is affected by winds, the rotation of the Earth, and land barriers.

Ocean and climate. It is well known that the temperature regime and other climatic characteristics of the area at any latitude can change significantly in the direction from the ocean coast to the interior of the mainland. Compared to land, the ocean heats up more slowly in summer and cools more slowly in winter, smoothing out temperature fluctuations on adjacent land.

Composition of sea water. The ocean water is salty. The salty taste is given by the 3.5% dissolved minerals contained in it - mainly sodium and chlorine compounds - the main ingredients of table salt. Magnesium is next in number, followed by sulfur; all common metals are also present. Of the non-metallic components, calcium and silicon are especially important, since they are involved in the structure of the skeletons and shells of many marine animals. Due to the fact that the water in the ocean is constantly mixed by waves and currents, its composition is almost the same in all oceans.

properties of sea water. The density of sea water (at a temperature of 20 ° C and salinity approx. 3.5%) is approximately 1.03, i.e. slightly higher than the density of fresh water (1.0). The density of water in the ocean varies with depth due to the pressure of the overlying layers, as well as depending on temperature and salinity. In the deepest parts of the ocean, the waters tend to be saltier and colder. The densest masses of water in the ocean can remain at depth and maintain a lower temperature for more than 1000 years.

Sea water is much less transparent to visible light than air, but more transparent than most other substances. The penetration of sunlight into the ocean to a depth of 700 m has been recorded. Radio waves penetrate the water column only to a shallow depth, but sound waves can propagate under water for thousands of kilometers. The speed of sound propagation in sea water fluctuates, averaging 1500 m per second.