The inner deep or layer is the lowest layer in the ocean, which lies beneath the thermocline and above the ocean floor, at a depth of 1000 fathoms (1800 m) or more. Little or no light penetrates this part of the ocean, and most of the organisms that live there depend on the subsistence of falling organic matter produced in the photon zone. For this reason, scientists once assumed that life would be very rare in the deep ocean, but almost every investigation has revealed that, on the contrary, life abounds in the deep ocean.
From the time of Pliny to the end of the nineteenth century... man believed there was no life in the depths. It took a historic expedition on the Challenger ship between 1872 and 1876 to prove Pliny wrong; deep sea dredges and trawlers bringing living creatures from all within reachable depths. But even in the 20th century scientists continue to imagine that life at a very large depth is not substantial, or somehow unimportant. Perpetual darkness, almost unimaginable pressure, and extreme colds beneath a thousand meters, they thought, so frightening to have all life except out. The opposite is actually true... (under 200 meters) lies the largest habitat on earth.
In 1960, Bathyscaphe
It has been suggested that more is known about the Moon than the deepest part of the ocean. Little is known about the level of life on the deep seafloor until the discovery of shrimp colonies and other organisms that developed around the hydrothermal vents in the late 1970s. Prior to the discovery of submarine ventilation, it has been accepted that almost all life on earth obtains its energy (one or another way) from the sun. The new discovery reveals a group of creatures that acquire nutrients and direct energy from heat sources and chemical reactions associated with changes in mineral deposits. These organisms thrive in completely lightless and anaerobic environments in highly saline water that can reach 300 ° F (150 ° C), withdraw their food from hydrogen sulfide, which is highly toxic to almost all terrestrial life. The revolutionary discovery that life can exist under extreme conditions alters opinions about the possibility of life elsewhere in the universe. Scientists now speculate that Europa, one of Jupiter's moons, may be able to support life beneath its ice surface, where there is evidence of a global ocean of liquid water.
Video Deep sea
Karakteristik lingkungan
Light
Natural light does not penetrate the deep ocean, with the exception of the mesopelagic top. Because photosynthesis is not possible, plants can not live in this zone. Since plants are the primary producers of almost all of the Earth's ecosystems, life in these oceans must depend on energy sources from elsewhere. Except for the area close to the hydrothermal vents, this energy comes from organic material floating down from the photon zone. The submerged organic material consists of algae particles, detritus, and other forms of biological waste, collectively referred to as sea snow.
Pressure
Since the pressure in the ocean increases by about 1 atmosphere for every 10 meters depth, the amount of pressure experienced by many marine organisms is extremely extreme. Until recent years, the scientific community has no detailed information about the impact of pressure on most deep-sea organisms because the specimens encountered arrive at a dead or dying surface and can not be observed at the pressure at which they live. With the emergence of a trap that combines a special pressure-retaining chamber, larger metazoa animals have been extracted from the deep sea in good condition.
Salinity
Salinity is very constant throughout the deep ocean, about 35 parts per thousand. There are some minor differences in salinity, but none are ecologically significant, except in the Mediterranean Sea and the Red Sea.
Temperature
The two largest and fastest temperature changes regions in the ocean are the transition zone between surface water and deep water, thermocline, and transitions between the deep ocean floor and the hot water flow in the hydrothermal vents. Thermoclines vary in thickness from a few hundred meters to nearly a thousand meters. Under the thermocline, the mass of sea water is cold and much more homogeneous. Thermocline is the strongest in the tropics, where the temperature of the epipelagic zone is usually above 20 ° C. From the epipelagic base, the temperature drops more than a few hundred meters to 5 or 6 ° C at 1,000 meters. This keeps dropping down, but this figure is much slower. Below 3,000 to 4,000 m, the water is isothermal between 0 and 3 Â ° C. The cold water comes from the heavy sinking of surface water in the polar regions.
At some depth, the temperature is practically unchanged over a long period of time. There is no seasonal temperature change, nor is there an annual change. There is no other habitat on earth that has this constant temperature.
Hydrothermal ventilation is a direct contrast with constant temperature. In this system, the water temperature as it appears from a "black smoker" chimney may be as high as 400 ° C (it is stored from the boil by high hydrostatic pressure) while within a few meters may retreat downwards. up to 2 - 4 Â ° C.
Maps Deep sea
Biology
The area under the epipelagic is divided into a further zone, beginning with mesopelagic extending from 200 to 1000 meters below the surface of the ocean, where so little light penetrating primary production becomes impossible. Below this zone the deep sea begins, consisting of a bathypelagic dispensary, abyssopelagic and hadopelagic . Food consists of falling organic matter known as 'sea snow' and carcasses originating from the above productive zones, and rare both in terms of spatial and temporal distributions.
Rather than relying on gas for their buoyancy, many deepwater species have a jelly-like flesh consisting mostly of glycosaminoglycans, which gives them a very low density. It is also common among deepwater squid to combine agar tissue with flotation chamber filled with coelomic fluid which comprises a waste product of ammonium chloride metabolism, which is lighter than the surrounding water.
Sea fish have special adaptations to overcome this condition - they are small in size, usually below 25 cm (10 inches); they have a slow metabolism and an unspecialized diet, preferring to sit and wait for food instead of spending energy looking for it. They have elongated bodies with weak, watery muscles and skeletal structures. They often have long, hinged jaws with repetitive teeth. Due to the sparse distribution and lack of light, finding a partner is difficult to breed, and many organisms are hermaphrodite.
Because light is so rare, fish often have tubular eyes that are larger than normal, with only stem cells. Their field of vision upwards allows them to search for possible silhouette of prey. But the game also has adaptations to overcome predation. This adaptation is primarily concerned with the reduction of silhouette, a form of camouflage. The two main methods used to achieve this are the reduction of their shadow areas with lateral compression of the body, and counter-reflection through bioluminescence. This is achieved by the production of light from the ventral photoporor, which tends to produce such light intensity to create the bottom of the fish with an appearance similar to the background light. For more sensitive eyesight in low light, some fish have a retroreflector behind the retina. The flashfish has these plus photophores, a combination they use to detect eyeshine in other fish (see tapetum lucidum ).
Deep-sea organisms are almost completely dependent on the sinking of living and dead organic substances that fall to about 100 meters per day. In addition, only about 1-3% of the surface production reaches most seabed in the form of sea snow. Larger foods fall, such as whaling, are also occurring and research has shown that this may happen more often than what is believed to be today. There are many carnivorous eaters that are primarily or wholly in large fall foods and the distance between whaling bodies is estimated to be only 8 kilometers. In addition, there are a number of filter feeders that consume organic particles using tentacles, such as Freyella elegans (see Freyellidae family).
Marine bacteriophages play an important role in cycling nutrition in deep-sea sediments. They are very abundant (between 5x10 12 and 1x10 13 phages per square meter) in sediment around the world.
Chemosynthesis
There are a number of species that do not rely on dissolved organic matter for their food and these are found in hydrothermal vents. One such example is the symbiotic relationship between the tube worms Riftia and the chemosynthetic bacteria. This is a chemosynthesis that supports complex communities that can be found around hydrothermal vents. This complex community is one of the few ecosystems on the planet that do not rely on sunlight for their energy supply.
Exploration
The deep sea is one of the less explored areas on Earth. The pressure even in mesopelagic becomes too large for traditional exploratory methods, demanding an alternative approach to deep ocean research. Terawai camera stations, small manned submarines and ROVs (remotely operated vehicles) are the three methods used to explore the depths of the ocean. Due to the difficulties and costs of exploring this zone, current knowledge is limited. The pressure increases at about one atmosphere for every 10 meters which means that some areas in the deep ocean can reach pressures above 1,000 atmospheres. This not only makes depth very difficult to reach without mechanical assistance, but also presents significant difficulties when trying to learn about any organism that might live in this area because their cell chemistry will be adapted to such a vast pressure.
See also
- Deep sea fish
- Deep sea water
- Underwater landslide
- Blue Planet
Note
External links
- Deep Sea Foraminifera - Deep Sea Foraminifera from 4400m depth, Antarctica - image gallery and description of hundreds of specimens
- Deep Ocean Exploration at the Smithsonian Sea Portal
- Deep Sea Creatures Facts and images from the deepest part of the ocean
- How Far Is Ocean Facts and infographics in the depths of the ocean
Source of the article : Wikipedia
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