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💴 | Enjoy Numazu, a sacred place for deep-sea fish, through hometown tax payment!Hometown tax refund in Numazu City, Shizuoka Prefecture, attention is "deep sea"


Enjoy Numazu, a sacred place for deep-sea fish, through hometown tax payment!Hometown tax refund in Numazu City, Shizuoka Prefecture, attention is "deep sea"

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More than 100 kinds of deep-sea creatures from all over the world that are difficult to capture and transport are exhibited.

Numazu City, Shizuoka Prefecture, delivers "deep sea" related products such as deep sea fish as a reward for hometown tax payment.Water depth 2,5 ... → Continue reading


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Exhibit more than 100 types

deep sea

deep seaThere is no clear definition of (shinkai)[1]Generally refers to the sea area with a water depth of 200 m or more.[2][3][4][5].

The deep seaphotosynthesisrequired forSun lightBecause it does not arrive[3], What is the surface layer?Environment,EcosystemIs very different.To adapt to harsh environmental conditions such as high water pressure, low water temperature, darkness, and low oxygen conditionsBiology Is unique進化Some of them have unique morphology and ecology that cannot be imagined from the surface organisms.In addition, due to the difference in properties, the surface layer and the deep sea seawater do not mix, and there is an almost independent seawater circulation system.

The average depth of the Earth's oceans is 3,729 meters, which occupies about 80% of sea level. 21世紀の現在でも大Even today in the XNUMXst centuryWater pressureDeep sea exploration is not easy because of the obstacles, and manned and unmanned people who can dive deepsubmarineMost of the deep sea is an unexplored territory, as few countries have[6].

Deep sea structure

The deep sea refers to the part of the sea that is deeper than 200 meters.This is not necessarily a strict definition, and there are other uses, but in most cases it is treated this way.普通はこれより浅い海の部分を表層(epipelagic)というUsually, the part of the sea shallower than this is called the surface layer (epipelagic).[7].

This is a judgment based on living things in particular, and the main reason is that plants (plankton) can photosynthesize at this depth by sunlight.At this depth, visible light is almost blocked, creating a dark world.However, in strict measurement, there is light that passes deeper, and the depth reaches 1,000 meters.そのため200 - 1,000メートルを弱光層、それ以深を無光層と呼ぶ例もあるTherefore, there are cases where XNUMX-XNUMX meters is called a weak light layer and deeper than that is called an aphotic zone.[8].

The deep sea is divided by depth as follows, and this division isPelagic zoneIs called.Numerical values ​​may vary depending on the classifier.In some cases, the deep sea layer is not included.

  • 200-1,000 meters
  • Bathyal zone 1,000-3,000 meters
    • 1,000-1,500 meters
    • 1,500-3,000 meters
  • Abyssal zone 3,000-6,000 meters
  • Deeper than 000 meters

Abyssal zone

At a depth of 4,000-6,000 meters, there is a vast deep sea floor that occupies almost half of the surface area of ​​the earth.Abyssal zoneIt is said.これより深い超深海帯はThe deeper abyssal zoneTrenchOnly the deep part of the sea is applicable, and the ratio to the whole sea is less than 2%.

The deepest point in the world is the westThe Pacific Oceanに 位置 す るMariana Trench OfChallenger DeepIt is 10,920 ± 10 meters below sea level.


Water temperature

The water temperature drops sharply in the upper abyssal zone and more slowly in the lower abyssal zone.深海帯では水温はほとんど変化せず、水深3,000メートル以深では水温は1.5℃程度で一定になるIn the abyssal zone, the water temperature hardly changes, and at a depth of XNUMX meters or deeper, the water temperature becomes constant at about XNUMX ° C.[9].

Water temperature changes rapidly at depths of 200-1,000 meters in low latitudesWater thermocline(Thermocline) exists and is born only in hot weather in mid-latitude waters.It does not exist in high latitude waters.

Up to a depth of 300 metersMixed layerThere is an area where seawater can move up and down, which is around 30 ° C just below the equator in low latitudes, 10-20 ° C in mid-latitudes, and constant at around 2-3 ° C from the surface to the deep sea in high latitudes. It has become.低・中緯度の両海域では1,000メートルより深い深海は2 - 3℃前後となって一定となるIn both low and mid-latitude waters, the temperature deeper than XNUMX meters is constant at around XNUMX-XNUMX ° C.[6].

Water pressure

The deeper the water, the biggerWater pressureIn order to keep the internal pressure of manned submersibles at the same level as the ground, it is necessary to have enough strength to withstand the ambient pressure that increases by 10 atm every 1 meters.深海生物はすでに体内の圧力が周囲の水圧と同じになっており、深海中では押しつぶされることはないが、逆に短時間で海上に引き上げられると体内に溶け込んでいたガスが膨張してしまうDeep-sea creatures already have the same pressure in the body as the surrounding water pressure and are not crushed in the deep sea, but on the contrary, if they are pulled up to the sea in a short time, the gas dissolved in the body will expand.[6].


Various substances including salt are dissolved in seawater, and the density is higher than pure water 1.024 --1.028 g / cm.3It has become a degree.海水密度はSeawater densitySalinityIt is also affected by temperature.密度も水温同様に緯度と深度で異なっており、低緯度海域では水深300 - 1,000メートル付近で密度が急激に変化するLike the water temperature, the density differs depending on the latitude and depth, and in low latitude waters, the density changes rapidly at a water depth of around XNUMX-XNUMX meters.(English edition(Pycnocline) exists and is born only in summer in mid-latitude waters.It does not exist in high latitude waters.

Up to a depth of 300 metersMixed layerThere is an area where seawater can move up and down, called 1.024 g / cm in low latitudes.3In the vicinity, high latitude sea area is 1.028 g / cm from the surface layer to the deep sea3It is strong and constant, and the mid-latitude waters are between the two.Deep sea deeper than 2,000 meters in any area is 1.028 g / cm3Become a strong constant[6].


The salinity varies depending on the latitude, and there is a slight difference of 3.3-3.7% near the surface layer, but as the depth increases, it approaches a constant value of around 3.5% regardless of the latitude.北と南のNorth and south回 帰 線The salinity is highest in the vicinity, thinning at high latitudes, especially in the Arctic to below 3.3%.It is around 3.5% near the equator.水深300 - 1,000メートル付近で塩分濃度が急激に変化するSalinity changes sharply near a depth of XNUMX-XNUMX meters(English editionThere is[6].

Sunlight and deep sea

The sunlight required for photosynthesis does not reach the deep sea and thereforePhytoplanktonCannot exist in the deep sea.しかし水深1,000メートル程度まではわずかながら日光が届いており、深海の生物はそれを感知できる大きなHowever, there is a small amount of sunlight reaching a depth of about XNUMX meters, and deep-sea creatures can detect it.eyeMany have.

Red light is absorbed by water molecules more than blue light, so everything below 10 meters looks blue. At 70 meters, there is only 0.1% of the light above the ground, which is quite dark to the human eye. At 200 meters, humans can no longer feel the color, and the world becomes gray. 400メートルを限界にヒトの視覚では知覚できない世界になるA world that cannot be perceived by human vision with a limit of XNUMX meters[6].

Mixing and separating seawater

Seawater mixes freely up to a depth of 200 meters,ThermoclineThe seawater above and below does not mix with each other.

Deep water

In the deep seaDeep waterSeawater with physical and chemical characteristics different from the surface layer is distributed.Unlike the surface layer, it is not affected by the wind, but there are two places on the earth (North Atlantic OfGreenlandOffshoreAntarctic Ocean) Is the deep sea water (North Atlantic deep sea water and Antarctic low water)Hot salt circulationIs slowly moving through the oceans around the world.

In addition, it is known that seawater called the North Pacific Middle Water is distributed in the North Pacific at a depth of several hundred meters.

Deep flow

Even in the deep sea of ​​several thousand meters, there is a flow of seawater at a speed of several centimeters per second,Deep flowIs called.Deep sea water has nothing to do with "deep sea water" sold as drinking water in Japan.深層流は地球規模のDeep currents are globalHot salt circulationConsists of.核実験のときに生じたOccurred during a nuclear testTritiumUsing a radioisotope called (tritium), we measured the time it took for seawater that had once sunk into the deep sea to spring up to the surface again, and found that it took about 2,000 years on average.[6].


The deep sea is a harsh environment for the dark world and living things with high water pressure, low water temperature, and no light.photosynthesisThe sunlight that can be used in the water reaches only a depth of several tens of meters.

In the deep seaDeep sea fishIn addition to being inhabited by many organisms that have completely different morphologies and ecology from the surface layer,Sea lily,coelacanthEtc. PreviouslyfossilIt also inhabits organisms with a primitive form known only as.However, deep-sea creatures are surprisingly familiar in modern times.Sakura shrimp,Haliporoides siboga,Pink Shrimp(Amaebi),Hawk crab,Snow crab,Cod,Red snapper,Akoudai,HakeDue to the development of fishing gear and freezing / transportation technology, there are numerous deep-sea creatures that have come to be distributed as food.

The deep sea is also a rather harsh environment for microorganisms, and the number decreases as the depth increases.光合成を糧とするシアノバクテリア類は早々にいなくなり、表層ではほとんど検出されないCyanobacteria that feed on photosynthesis disappear quickly and are rarely detected on the surface.ArchaeaThe proportion of species increases (below 1,000 meters)BacteriaThe number of detected species and archaea is almost equal[10]).Many of these require special conditions for culturing, and most of them are unculturable species.たとえばFor exampleHirondellea gigasLive inMariana TrenchFound from Moritella yayanosii Requires as high a pressure as 500-1,100 atm for growth.

Oxygen microlayer

At a depth of 600-1,000 metersDissolved oxygen amountIs extremely smallOxygen Minimum Zone (OMZ)There is.これは上層から降下してくるThis descends from the upper layerorganic matterTheBacteriaUses dissolved oxygen in water when it decomposes, so at this depthoxygenIs exhausted.The appearance of living things is sparse in the oxygen microlayer, but after this, the amount of dissolved oxygen increases slightly and the density of living things also rises slightly.

Material production

In the deep seaBiological communityDue to the lack of producers in Japan, it relies heavily on material production in shallow waters.There are two methods, direct use and indirect use.

Direct use is when deep-sea creatures surface in shallow water and forage.Naked eagleMany deep-sea fish that live in the mesopelagic zone move to shallower waters at night for foraging.

Indirect use means the remains and excrement of shallow sea creatures.DetritusIt sinks in such a state and is used as food for deep-sea creatures.深海では水中に雪のように漂うFloating like snow in the deep seaMarine snowCan be seen, and this is also an example.また、まれにAlso, rarelyA whaleIt is also known that the carcasses of the animals sank to the bottom of the sea and feed on many animals (Whale fall community).

Connection with shallow sea

As mentioned above, there is basically a lack of producers in the deep sea, creating an ecosystem consisting of only consumers and decomposers.The energy that supports it depends on production in shallow water.

On the other hand, photosynthesis takes place in shallow water, but at the same time, inorganic nitrogen, etc.fertilizerThe consumption of minutes is also intense.They are made by the activities of consumers and decomposers, but their amount is also a limiting factor that determines the amount of photosynthesis.In other words, it is chronically in short supply.On the other hand, since there are no producers in the deep sea, fertilizers are being produced even though the density is low for both consumers and decomposers.In most places, there is no large flow between these seawaters, but in some places such seawater creates a flow that blows up into shallow waters.そのことをThatUpwellingHowever, the place where such a flow occurs becomes a place where fertilizer-rich seawater is supplied, and can support a much richer biota than other places.

Chemically synthesized ecosystem

In the deep seaFood chainDescends from the surface of the seaorganic matterWas thought to depend only on1970 eraThrough deep-sea exploration underway in each country, we became independent without relying on shallow-sea products.EcosystemIt became clear that there was.This ecosystem is called.

Ridge,Submarine volcanoAroundHydrothermal ventThen, hot water of 300 ℃ or more is spouting.その周囲には熱水中に含まれるSurrounded by hot waterHydrogen sulfideAnd hydrogen as an energy source to surviveChemotrophic bacteria,ArchaeaIs breeding.これらを体内にPut these in your bodySymbiosisMakeTube worm(Lamellibrachia) AndCalyptogena, Feed bacteria, and feed those organismsSea anemone,Gandalfus yunohana, Etc. are being discovered one after another in hydrothermal vents around the world.

The population density of organisms is usually lower in the deep sea away from the coast, but the area around the hydrothermal vents is densely populated with organisms.

Deep sea exploration

With the momentum to seek new marine resources and mineral resources in the deep sea, each country began to explore the deep sea from around 1970.これまでに新種の生物やNew species of creatures so farmethane hydrate,Manganese nodule,Cobalt crust,Hydrothermal depositEtc. have been found one after another, but it can be said that the deep sea is still an unknown world.

Deep sea exploration ship

The main deep-sea exploration vessels owned by each country are as follows.

Shinkai 6500
JapanThe manned deep-sea exploration vessel owned byShinkai 2000"When"Shinkai 6500". 「しんかい2000」は"Shinkai XNUMX" 2003 Retired to, and now only "Shinkai 6500" is in operation.
As the name suggests, the Shinkai 6500 can dive to a depth of 6,500 meters. Three people can board, two of whom are pilots, and only one scholar, called an observer, who conducts deep-sea surveys can board.It dives at a speed of about 3 meters per second and reaches a depth of 2 meters in about 1 hours.One dive time is about 0.7 hours.
As an unmanned deep-sea exploration vehicle owned by Japan that does not have a direct crew member and conducts deep-sea exploration while connected to the mother ship with a cable, "Kaikou"UROV7K" "Deep Toe" "Hyper dolphin, Etc., and the deepest dive is "Kaikou".
Originally, "Kaikou" consisted of a master unit called "Launcher" and a slave unit called "Vehicle".By diving to a depth of 2 meters with these two connected, and further separating the vehicle, it was possible to dive to a depth of 7,000 meters, which is deeper than any other spacecraft in the world.However, in 11,000, a cable broke and an accident occurred in which the vehicle was lost.For this reason, another unmanned spacecraft "UROV7KIs remodeled and used as a substitute for the vehicle.Since the dive depth of "UROV7K" is 7,000 meters, it is currently in operation as "Kaikou 7000". Even at 7,000 meters, the dive depth is deeper than any existing spacecraft in the world. The "Kaikou" launcher itself can still dive up to 11,000 meters, but the launcher does not have an exploration function.
A self-contained radio probe owned by Japan[11]..It does not require operation by cable connection and can continue to sail for a long time.Also self-supporting "Urashima"Successfully sailed 317 km continuously. "Yumeka"Mainly conducts undersea resource surveys and"Jinbei""Otohime”Mainly investigates the global environment.
The United States of AmericaOwned byAlvinIs a manned deep-sea exploration vehicle capable of diving to a depth of 4,500 meters.There is only one pilot and two observers, for a total of three people.
Although it is an old research vessel completed in 1964, it has excellent durability and is still in active use, and many discoveries have been made so far.The total dive time of deep-sea exploration vessels around the world is less than Alvin's dive time.
mealSpeaking ofRussiaThe space station that he once owned is famous, but here is the manned deep-sea exploration vehicle of the same name. 6,000メートルまで潜航でき、深海に沈むCan dive up to XNUMX meters and sink into the deep seaTitanicIt is also known for taking pictures of.
Bathyscaphe Trieste
Designed in Switzerland1953 Launched toBathyscaphe TriesteIs known as a manned submersible that dives to a depth of about 10,900 meters.However, because it was a submersible that focused on "diving safely and deeply," it was inferior in terms of sustainability and versatility to the submersibles that were developed later.
Deepsea Challenger
Deepsea Challenger (DCV 1) is known as the deepest seabed in the worldMariana Trench OfChallenger DeepIt is a manned deep-sea exploration boat designed to reach. March 2012, 3, Canadian film directorJames CameronReached the deepest point by maneuvering.


[How to use footnotes]
  1. ^ Nihon University Encyclopedia (Nipponica)
  2. ^ Yuji Hatada, Yuichi Nogi and others "Deep-sea bioresource applied research-Search for new useful enzymes from deep-sea microorganisms-"Journal of the Society of Extremophiles" Vol. 8, No. 2, Society of Extremophiles, 2009, pp. 85-91, two:10.3118 / jjse.8.85,2019/4/27Browse.
  3. ^ a b International Marine Environment Information Center. “What is the deep sea". 2016/7/18Browse.
  4. ^ World Encyclopedia Second Edition
  5. ^ [1]
  6. ^ a b c d e f g Minako Takizawa, "The Wonders of the Deep Sea," Nihon Jitsugyo Publishing Co., Ltd., March 2008, 3, first edition ISBN 9784534043542
  7. ^ So far Tatsuzawa (2008), p.20
  8. ^ Deep Sea and Earth Dictionary Editorial Committee (2014), p.3
  9. ^ "Deep Sea Biological Encyclopedia" p. 221
  10. ^ Karner MB, DeLong EF, Karl DM (2001). “Archaeal dominance in the mesopelagic zone of the Pacific Ocean”. Nature 409 (6819): 507–10. PMID 11206545. 
  11. ^ Unmanned and swiss, 2012 meters under the sea ... New spacecraft of Japan Agency for Marine-Earth Science and Technology Asahi Shimbun April 4, 6[Broken link]


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