The ocean covers 70 percent of itTierrasurface of . It contains about 1.35 billion cubic kilometers (324 million cubic miles) of water, or about 97 percent of all water on Earth. The ocean supports all life on earth and makes the planet appear blue when viewed from space. Earth is the only planet in ourssolar systemwhich is known to be includedfluidagua.
Although the ocean is a continuous body of water,OzeanographThey have divided it into five main areas: Pacific, Atlantic, Indian, Arctic and Southern Oceans. The Atlantic, Indian and Pacific Oceans merge into icy waters around Antarctica.
Climate
The ocean plays a crucial role in climate andClimate. The heat of the sun makes the waterevaporate, adding moisture to the air. The oceans provide most of this evaporated water. watersteam condensationform clouds that release their moisture in the form of rain or other formsprecipitation. All life on earth depends on this process, calledthe water cycle.
Isthe atmospheregets much of its heat from the ocean. As the sun warms the water, the ocean transfers heat to the atmosphere. The atmosphere againdistributedthe heat around the world.
because the waterabsorbedand loses heat more slowly than land masses, the ocean helps offset thistemperaturesabsorb heat in summer and release it again in winter. Without the sea to helpregularglobal temperatures, the earth's climate would be terribly cold.
ocean formation
After the earth began to form about 4.6 billion years ago, it gradually separated into layers of lighter and heavier rock. The lighter rock rose and formed the earth.Kortex. The heaviest rock sank and formed the earth.Aderjmanto.
Ocean water came from rocks within the newly formed earth. As themeltedThe rocks cooled, releasing water vapor and other gases. Eventually the water vapor condensed and covered the crust with aPrimitiveOcean. Even today, hot gases from the Earth's interior produce new water at the bottom of the ocean.
seabed
Scientists began mapping the sea floor in the 1920s using what are known as instrumentsin the ecoprobe, which measure the water depthsound waves. use of echo soundersSonarTechnology. Sonar is an acronym for Sound Navigation And Ranging. The sonar showed the seabed has dramatic physical features, including towering mountains, deepguns, tänzelndcliffs, and widthlevels.
The crust of the ocean is called a thin layer of volcanic rockBasalt. The seabed is divided into different areas. The first is theContinental plate, the almost flat underwater surface of a continent. Continental shelves vary in width. They are generally wide along the lowlands and narrow along the mountainous coasts.
A shelf is coveredSedimentfrom the nearby continent. Some of the sediment is deposited by rivers and trapped by elements such as natural dams. Most of the sediment comes from the lastIce Age period, or ice age when the oceansdeclinedand exposed the continental shelf. This sediment is calledleave the sediment.
At the outer edge of the continental shelf, the land drops steeply into the so-called continental shelfContinental slope. The slope drops almost to the bottom of the ocean. It then reduces to a gentler slope known as the Continental Rise. The continental rise descends to the bottom of the deep ocean known as thelower level.
Abyssal plains are broad, flat areas found at depths of about 4,000 to 6,000 meters (13,123 to 19,680 ft). Deep sea plains cover 30 percent of the ocean floor and are the shallowest feature on Earth. They are covered by fine-grained sediments such as clay and silt.pelagicSediments, the remains of small oceanic organisms, are also washed down from the upper layers of the ocean. Scattered across the abyssal plains are abyssal mounds and underwater volcanic pinnacles called seamounts.
From the abysmal plains in every great ocean rises a vast array of mostly submerged mountains. He called themmid-ocean ridge, the chain orbits the earth and stretches more than 64,000 kilometers (40,000 miles). Much of the mid-ocean ridge is divided by a deep central rift or fissure. Mid-ocean ridges mark the boundaries between themtectonic plates. Molten rock from the Earth's interior gushes out of the fissure, forming in a process known aspropagation on the sea floor. The biggestPartof the ridge runs right through the Atlantic Ocean and is known as the Mid-Atlantic Ridge. It was not directly seen or explored until 1973.
Some areas of the sea floor have deep, narrow depressions called the ocean.ditches. They are the deepest parts of the ocean. The deepest place of all is thisAbyss Challenger, which is located in theMarianengrabenin the Pacific Ocean near the island of Guam. Its true depth is unknown, but the most accurate measurements place the Challenger Deep at 11,000 meters (36,198 ft) below sea level, or more than 2,000 meters (6,000 ft) higher than Mount Everest, the highest point on earth. HePrintin the Challenger Deep it is about eight tons per square inch.
marine life zones
From the coast to the deepest seabed, the oceanGraswith life. The hundreds of thousands ofmarinaTypes range frommicroscopic startedto the largest creature that has ever walked the earth, the blue whale.
The ocean has five main life zones, each with organismsjusttailored to your specific marine environment.ecosystem.
Isepipelagische Zone(1) is the upper layer of the ocean lit by the sun. It extends from the surface to a depth of about 200 meters. Also known as the photic or euphotic zone, the epipelagic zone can exist in both lakes and the ocean.
Sunlight allowed in the epipelagic zonephotosynthesishappen. Photosynthesis is the process by which some organisms convert sunlight andcarbon dioxidean Energie uoxygen. In the ocean, photosynthesis takes place in plants and algae. Plants like seagrass are similar to land plants: they have roots, stems, and leaves. Algae are a type of aquatic organisms that can photosynthesize sunlight. Large algae, such as seaweed, are namedSeetang.
Phytoplanktonthey also live in the epipelagic zone. Phytoplankton are microscopic organisms that include plants, algae and bacteria. They only become visible when billions are formed.Algae bloomand appear as green or blue spots in the ocean.
Phytoplankton is the foundation of the ocean.food web. Through photosynthesis, phytoplankton are responsible for nearly half of the oxygen released into the Earth's atmosphere. like animalswing(a type of shrimp), fish and microscopic organismsZooplanktonThey all eat phytoplankton. These animals, in turn, are eaten by whales, larger fish, seabirds, and humans.
The next zone below, which extends to a depth of approximately 1,000 meters (3,300 feet), is themesopelagische Zone(2). This area is also calledTwilight-Zonebecause the light is very weak there. The lack of sunlight means there are no plants in the mesopelagic zone, but large fish and whales dive there to huntJack. The fish in this area are small andhell. One of the most common is the lanternfish, which has organs on its side that produce light.
Sometimes animals from the mesopelagic zone (such as sperm whales (Physeter macrocefalia) and squid) dive into thebathypelagic Zone(3), which is about 4,000 meters (13,100 feet) deep. The bathypelagic zone is also referred to as themidnight zonebecause the light doesn't reach it.
Animals living in the bathypelagic zone are small, but often have huge mouths, sharp teeth, andexpandableStomach that allow them to eat anything that comes their way. Most of this food comes from the remains of plants and animals that came from the upper pelagic zones. Many bathypelagic animals do not have eyes because they are not needed in the dark. Because the pressure is so great and it's so hard to findnutrient, Fish in the bathypelagic zone are slow-moving and have strong gills to extract oxygen from the water.
The water at the bottom of the oceanabessopelagische Zone(4) It's very salty and cold (2 degrees Celsius or 35 degrees Fahrenheit). At depths of up to 6,000 meters (19,700 feet), the pressure is very strong: 11,000 pounds per square inch. This makes it impossible for most animals to live. The animals in this area have strangeadjustmentsdeal with its ecosystem. Many fish have jaws that appear to be out of joint. The jaws allow them to drag their open mouth across the sea floor to find food such as clams, shrimp, and microscopic organisms.
Many of the animals in this area, including squid and fish, are bioluminescent. Bioluminescent organisms generate light through chemical reactions in their bodies. One species of anglerfish, for example, has glossy growths spreading out in front of its huge, toothy maw. When smaller fish are attracted to the light, anglerfish simply open their jaws to eat their prey.
The deepest sea zone found in ditches and ravines is calledHadalpelagische Zone(5). Few organisms live here. include smallisopods, kind ofcrustaceanrelated to crabs and shrimp.
invertebrateslike sponges and sea cucumbers, they thrive in the abyssopelagic and hadalpelagic zones. Like many starfish and jellyfish, these animals feed almost exclusively on falling dead parts or debrisdecaycalled plants and animalsDetritus marino.
However, not all bottom dwellers depend on marine litter. In 1977, oceanographers discovered a community of bacteria-eating creatures on the seafloor around what are known as ventshydrothermalVents These vents evacuate superheated waterenrichedconmineralsfrom the interior of the earth. The minerals feed unique bacteria, which in turn feed critters like crabs, clams, and tubeworms.
oceancurrents
Streams are streams of water that flow through a larger body of water. Oceans, rivers and streams have currents. the oceanssalinityand the temperature and geography of the coast determine the behavior of an ocean current. from Earthrotationand wind also affect ocean currents. Streams flowing near the surface carry heat from thezone tropicaltopostsand move the cooler water back into theEcuador. This keeps the ocean from getting extremely hot or cold.
Deep, cold currents carry oxygen to organisms throughout the ocean. They also carry ample supplies of nutrients that all living things need. Nutrients come from plankton and the remains of other organisms that sink to the sea floor and decompose.
Along some coasts, winds and currents create a phenomenon calledboost. When the wind pushes the surface water away from the shore, deep streams of cold water rise to take its place. This deep-water buoyancy brings nutrients that encourage new plankton growth and provide food for fish. oceanfood chainconstantRecyclefood and energy in this way.
Some ocean currents aregiganticand extremely powerful. One of the most powerful isgulf stream, a warm surface current that originates in the tropical Caribbean Sea and flows northeast along the east coast of the United States. The Gulf Stream is up to 80 kilometers wide and more than a kilometer deep.
Like other ocean currents, the Gulf Stream plays an important role in weather. As the current travels north, it transfers moisture from its warm tropical waters into the air above. Westerly or prevailing winds bring warm, humid air to the British Isles andScandinavia, whereby they have milder winters than in their northlatitudes. The northern parts of Norway are close to the Arctic Circle but remain ice-free most of the year due to the Gulf Stream.
The weather pattern known as El Niño involves a change in the Humboldt Current (also known as the Peru Current) off the west coast of South America. InThe childUnder these conditions, a current of warm surface water travels east along the equator, preventing the normal upwelling of the cold, nutrient-rich Humboldt Current. El Niño, which can devastate the fisheries of Peru and Ecuador, occurs every two to seven years, usually in December.
The paths of ocean currents are determined in part by the Earth's rotation. This is known as theCoriolis force. It causes large systems such as winds and ocean currents that would normally move in straight lines to drift to the right in the sea surfacenorthern hemisphereand left insouthern hemisphere.
The people and the sea
For thousands of years, humans have depended on the ocean for both food and waterRutaProHandeljexploration. Even today, people still travel the ocean and depend on the resources it contains.
Nations continue to negotiate how to determine the scope of their agreementAreabeyond the shore. United Nations Law of the Seatreatedestablished Exclusive Economic Zones (EEZs) stretching over 200nautical miles(230 miles) beyond the shore of a nation. Although some countries have not signed or ratified the treaty (including the US), it is considered the standard.
Russia has proposed extending its EEZ beyond 200 nautical miles because two mid-ocean ridges, the Lomonosov and Medeleev Ridges, are extensions of Russia's continental shelf. This area includes the North Pole. Russian explorers in asubmersibleIn 2007, a vehicle hoisted a metal Russian flag in the disputed area.
Throughout the ages, humans have navigated the oceantrade routes. Ships still transport most of them todayTransport, especially bulky goods such as machines, grain, etcPetroleum.
Seaports are areas ofHandeland culture. Water and land transport meet there, but also people from different professions: merchants whoimportjexportGoods and services; Dockers loading and unloadingload; and ship crews. The ports also have a high concentration of migrants and immigrants with a variety of ethnicities, nationalities, languages and religions.
Important ports in the USA are New York/New Jersey and New Orleans. The busiest ports in the world include the port of Shanghai in China and the port of Rotterdam in the Netherlands. Seaports are also important to a nation's military. Some ports are used exclusively forMilitary-purposes, although most share space withcommercialBusiness "The sun never sets on the British Empire" is a phrase used to explain the extent of the EmpireGreat Britain, especially in the 19th century. Although based on the small European island nation of Great Britain, British military naval power expanded its empire from Africa to America, Asia and Australia.
Scientists and other experts hope that the ocean will be used as a source on a larger scalerenewable energy. Some countries have already done sotappedEnergy from ocean waves, temperature, currents or tides to drive turbines and generate electricity.
A renewable energy source are lagging generatorstidal currentsor ocean currents. They convert the movement of currents into energy. Sea current generators have not been developed on a large scale but they are working in some places in Ireland and Norway. Someconservationistcriticize the impact of large structures on the marine environment.
Another source of renewable energy isConversion of sea thermal energy(OTEC). It uses the temperature difference between warm surface water and cold deep water to power a motor. OTEC facilities exist in places with significant differences in sea depth: Japan, India, and the US state of Hawaii, for example.
An emerging source of renewable energy issalt gradient performance, also known as osmotic power. It is an energy source that harnesses the power of fresh water entering salt water. This technology is still under development but has potential inDeltaAreas where fresh river water constantly interacts with the ocean.
fishing
Fishermen catch more than 90 million tons of shellfish every year, including more than 100 species of fish andseafood. Millions of people, from commercial fishermen to business owners such as restaurant owners and boat builders, depend on fishing for their needs.support. Fishing can be classified in two ways. In subsistence fishing, fishermen use their catch to meet the nutritional needs of their families or communities. Incommercial fishing, Fishermen sell their catch for money, goods or services. Popular trade and subsistence fish include tuna, cod and shrimp.
Deep sea fishing is also a popular recreational sport.sport fishingIt can be competitive or non-competitive. In sport fishing tournaments, individuals or teams compete for prizes based on the size of a specific species caught over a specific period of time. Both competitive and non-competitive sport fishermen require licenses to fish and may or may not keep the fish they catch. Sport fishermen are increasingly practicingcatch and releaseFishing, in which a fish is caught, measured, weighed and often captured on film before it is returned to the sea. Popularwild fish(fish caught for sport) are tuna and marlin.
Ballenerois a style of fishing that consists of theharvestof whales and dolphins. Its popularity has waned since the 19th century, but it remains a way of life for many cultures, including those of Scandinavia, Japan, Canada and the Caribbean.
The ocean offers an abundance of fishing and whaling resources, but these resources are under threat. Humans have collected so much fish and marine life for food and other products that some species have disappeared.
During the 19th and early 20th centuries, whalers killed thousands of whales for whale oil (wax made from walnut oil).Speck) andivory(whale teeth). Some species, including the blue whale (Balaenoptera Musculus) and the right whale, were hunted almost to the pointdie out. Many species are still extantthreatened with extinctionhallo.
In the 1960s and 1970s, catches of important food fish such as herring in the North Sea and anchovies in the Pacific began to decline dramatically. Governments took note of thisoverfishing– Harvesting more fish than the ecosystem can handlefill up. Fishermen were forced to go further out to sea to find fish, putting them in danger. (Deep-sea fishing is one of the most dangerous professions in the world.) Now they use advanced gadgets like electronic fish finders and largegillnetsÖdrawnets to catch more. This means there are far fewer fish to breed and replenish the stock.
In 1992, the collapse or disappearance of cod on the Grand Banks of Newfoundland, Canada put 40,000 fishermen out of work. Cod fishing was banned and to this day, neither the cod nor the fishery has recovered.
To catch the dwindling fish stocks, most fishermen use trawl nets. Drag the nets across the seabed and acres of ocean. These nets accidentally catch many small, juvenile fish and mammals. Animals caught in fishing nets intended for other species are namedBeifang. The fishing industry and fisheries management authorities are discussing how to tackle the problem of bycatch and overfishing. Those involved in the fishing industry do not want to lose their jobs, while conservationists want to maintain healthy fish stocks in the sea.
A number ofconsumerdecide to buysustainable seafood. Sustainable seafood is harvested from sources (whether wild or farmed) that do not deplete the natural ecosystem.
mining and drilling
Many minerals come from the ocean.Sal MarinaIt is a mineral that has been used as a flavoring and preservative since ancient times. Sea salt contains many additional minerals, such as B. Calcium, which ordinary table salt lacks.
Hydrothermal vents often formMassive sulphide deposits (SMS) on the sea floorthat contain precious metals. These SMS deposits are found on the seafloor, sometimes deep in the ocean and sometimes closer to the surface. New techniques are being developed to extract valuable minerals such as copper, lead, nickel, gold and silver from the seabed. Mining companies employ thousands of people and provide goods and services for millions more.
Critics of deep-sea mining say it disrupts local lifeecology. Organisms—corals, shrimp, clams—that live on the ocean floor have theirshabitatdisturbed, disrupting the food chain. In addition, habitat destruction threatens the viability of species that are coming to an endniche. Maui-Delfin (Cephalorhynchus hectori maui) for example is an endangered species native to the waters of the North Island of New Zealand. Maui's dolphin numbers have already been reduced due to bycatch. Seabed mining threatens its habitat and puts it at increased risk of extinction.
Oil is one of the most valuable resources to be extracted from the sea today.Off-Shore oil rigsBombPetroleumof wells drilled on the continental shelf. About a quarter of all oil and natural gas supplies today come from offshore oil fields around the world.
Offshore drilling is expensivemechanical engineering. An oil rig can be built directly on the seabed or it can “float” on an anchor. Depending on how far up on the continental shelf an oil rig is located, workers may need to be flown in. Subsea or underwater installations are complicated groups of interconnected oil rigs and a single oil rig. Underwater production often requires remotely operated underwater vehicles (ROVs).
Some countries invest in offshore drilling to generate profits and avoid dependence on oil from other regions. The Gulf of Mexico near the US states of Texas and Louisiana is heavily perforated. Several European countries, including the UK, Denmark and the Netherlands, drill in the North Sea. However, offshore drilling is a complicated and expensive program. There are a limited number of companies that have the knowledge and resources to work with local governments to construct offshore oil platforms. Most of these companies are based in Europe and North America, although they operate worldwide.
Some governments have banned offshore oil drilling. They cite environmental and safety concerns. There have been several accidents where the rig itself exploded, costing many lives. Offshore drilling also poses a threat to the ocean ecosystem. Spills and leaks from oil rigs and tankers that transport the material seriously harm marine mammals and birds. The oil coats the feathers, affecting the birds' ability to maintain and stay at their body temperaturelivelyin the water. The fur of otters and seals also becomes coated, and the oil that soaks into themdigestive tractfrom animals can damage their organs.
Offshore oil rigs also expose metal shavings, tiny amounts of oil, anddrilling fluidin the ocean every day. Drilling fluid is the fluid used with machines to drill holes deep into the planet. This liquid may containpollutantssuch aspoisonouschemicalsheavy metals.
pollution
However, most oil spills are not from oil spills. comes fromEscapeof pollutants in streams and rivers that flow into the sea. Most of the runoff comes from individual consumers. Cars, buses, motorcycles and even lawn mowers spill oil and grease on roads, streets and highways. (Runoff makes busy roads shiny and sometimes slippery.)Gullysor creeks wash the runoff into local waterways that eventually empty into the ocean.
The largest US oil spill into the ocean occurred in Alaska in 1989 by the tankerExxon Valdez. IsExxon Valdezat least 10 million gallons of oil ran into Prince William Sound. By comparison, American and Canadian consumers spill approximately 16 million gallons of oil into the Atlantic and Pacific Oceans each year.
For centuries, humans have used the ocean as a dumping ground for wastesewageand other debris.
In the 21st century, waste includes not only oil, but also chemical runoff from factories andAgriculture. These chemicals includeNitratejPhosphate, which are often used asfertilizer. These chemicals encourage algal blooms. An algal bloom is an increase in algae and bacteria that threatens plants and other marine life. Algal blooms limit the amount of oxygen in a marine environment, leading to what is known astote Zonen, where little life exists below the sea surface. Algal blooms can span hundreds or even thousands of kilometers.
Another source of contamination isPlastic. Most of the marine litter, or garbage, is plastic that is discarded by consumers. Plastics such as water bottles, bags, six-pack rings and packaging material are hazardous to marine life. Marine animals are harmed by plastic, either by getting caught in it or by eating it.
An example of marine pollution, which consists mainly of plastics, is theGreat Pacific Garbage Patch. The Great Pacific Garbage Patch is a floating garbage dump in the North Pacific. It's about twice the size of Texas and likely contains about 100 million tons of debris. Most of this debris originates from the west coast of North America (USA and Canada) and the east coast of Asia (Japan, China, Russia, North Korea and South Korea). Due to ocean currents and weather patterns, the patch is a relatively stable formation and contains new debris that is disintegrating. Jellyfish or other organisms eat the smallest pieces of plastic and are then eaten by larger ones.predatorsin the food web. These plastic chemicals can then enter the human diet via fish or shellfish.
Another source of pollution is carbon dioxide. The ocean absorbs most of the carbon dioxide from the atmosphere. Carbon dioxide is the carbon dioxide necessary for lifegreenhouse gasesand trapsradiationin the earth's atmosphere. Carbon dioxide forms many acids, calledcarbonic acids, in the ocean. Ocean ecosystems have adapted to the presence of certain levels of carbonic acid, but increases in carbon dioxide have led to increases in ocean acids. Thisocean acidificationerodes the shells of animals such as clams, crabs and corals.
global warming
Global warming contributes to the increase in ocean temperature andSea level.
Warmer oceans are radically changing the ecosystem. Global warming is causing cold-water habitats to shrink, meaning there is less room for animals like penguins, seals or whales. Plankton, the base of the ocean's food chain, thrive in cold water. As the water warms, marine life has less plankton to eat.
meltglacierjicecapcontribute toRising sea level. Sea level rise threatens coastal ecosystems and properties. River deltas and estuaries are prone to flooding. Coasts are more prone to sufferErosion. Seawater is more likely to contaminate freshwater sources. All of these consequences – flooding, erosion, water pollution – put low-lying island nations like the Maldives in the Indian Ocean at high risk of disaster.
To find ways to protect the oceans from pollution and the effects of climate change, scientists from around the world are collaborating on studies of marine waters and marine life. They also work together to control pollution and limit global warming. Many countries are working to reach agreements on the management and use of marine resources.
Although the ocean is vast, it is more easily polluted and damaged than previously thought. It requires care and protection as well as expert handling. Only then can it continue to provide the many resources that living beings, including humans, need.