The great pressure of the deep sea
The ocean occupies about 71% of the total surface area of the Earth, the deepest region of the ocean for the sea level below 11,521 meters of the Mariana Trench, due to the great pressure of the deep sea, the temperature is low, the oxygen content, the natural environment is exceptionally poor, human detection of the ocean, the current view of the overall On or very low level, some scientists say that human cognition of the ocean, but not familiar with the many stars in the solar system. Take the pressure in the deep sea alone, according to the liquid pressure formula P ρgh to speculate, 1000 meters below sea level, the object is subjected to seawater pressure is nearly 100 times the sea level, equivalent to each square meter to withstand the weight of hundreds of tons of objects. So for deep-sea exploration, how to overcome the huge pressure of seawater is a serious problem that must be faced.
In order to detect the characteristics of the natural environment of the deep sea, in addition to the use of special materials and processes placed by the unmanned detector, the submarine is also a man-made object with more applications. However, in terms of current science and technology, the average dive depth of submarines is only a few hundred meters, and some of the military field of nuclear submarine dive depth to be a little larger, but only up to about 1200 meters, and then deeper, the submarine can not stand, the enormous pressure will make the submarine shell collapse, not only on the submarine structure to produce harm, but also the submarine inside the staff of the life of the health of a serious threat.
Pressure balance
In contrast, whales in the ocean generally dive to a greater depth, especially for the sperm whales that often prey on king squid in the deep sea, and can dive to a depth of more than 2,000 meters. That said, some people can't help but wonder why the whale's flesh is more powerful than a steel-built submarine when it comes to resisting the immense pressure of seawater.
The reason for this result is simply a matter of pressure balance. A container, or a closed system based on this expansion, as long as its boundary constituent substances are strong enough, theoretically this container can withstand the pressure difference between the internal and external generated, so that this closed system can maintain a relatively stable state. A steel ball, a piece of glass, an iron bar, or a glass bottle filled with water, if sunk to the bottom of the ocean, the inward seawater pressure on the surface of these objects, and the outward supportive stresses on the surface of these objects will generally remain in a state of equilibrium, and the surface of the objects will have little or no deformation that can be observed by the naked eye.
Why submarines can't dive deep
But the submarine can't, in its normal operation, its internal must be retained sufficient workspace and living space, in the same depth, the submarine outside and inside the shell of the pressure given the value of the seawater and the density of the air is directly proportional to the density of the seawater and the air, and seawater is much more dense than the air, so the more the submarine dives, the more the submarine dives, the more the submarine dives. So the deeper the submarine dives, the seawater given to the shell of the pressure and the internal air on the shell of the pressure difference will be more and more large, the submarine shell is more and more inclined to internal collapse. Currently, the material used to build large nuclear submarine structure is titanium alloy, and will be used double shell structure, which greatly improves the dive depth without sacrificing the performance of the internal work premise. However, 1200-1300 meters from the current point of view, has reached the limit of this titanium alloy, after all, at this time the submarine shell pressure, equivalent to more than 100 tons per square meter.
Take the human body as an example, in fact, to cope with the huge pressure of the deep sea is obviously very poor mobility, because we can not rely on the independent adjustment to enhance the pressure environment in the body, so as to achieve the balance of the internal and external pressures, so only in the body's limit to withstand the threshold range of the submarine, the current record of the deepest dive in the absence of equipment support for the deepest dive record for the 113 meters, there is a safeguard for the conditions of the equipment deepest record for 332 meters, and also the deepest dive record for the deepest record for the deepest record of 332 meters. The deepest dive without equipment is 113 meters, and the deepest dive with equipment is 332 meters, and it is also done under strict, scientific and systematic training. The animals that live on land, in fresh water and in shallow waters, are also capable of deep-sea diving.
The physical advantages of whales
However, whales are different, in the long-term evolutionary process, in order to adapt to the natural marine environment, especially to enhance the ability of deep-sea foraging and predation, in order to achieve the ability to maintain the balance of internal and external pressure of the body of this goal of the survival of the duress, the structure of the body has undergone a significant change, mainly manifested in the following aspects:
The whales have the advantage of a deep-sea diving. Aspects:
First, the lungs have a super strong contraction ability. With the increase of diving depth, the whale lungs will be different degrees of contraction, especially when diving to 100-200 meters, most of the alveolar space has been completely compressed, no longer gas exchange, there is no large area of space structure, which effectively avoids the generation of a huge pressure difference within the body.
Second, the muscles and bones are super tough. The whale's skeleton is very easy to bend, especially for the ribs, vertebrae and sternum, its joints are more flexible and loose, on the one hand, to effectively regulate the behavior of the body to provide convenient conditions, on the other hand, it will also be contracted with the increase in external pressure, and effectively wrapped and protect the heart, lungs and other important internal organs. At the same time, the whale muscle tissue toughness and elasticity evolved very strong, so that in terms of resistance to the outside world of great pressure, will give the body to provide enough buffer space, while the whale's skin is also exceptionally tough, the organization is also full of internal body fluids, so that it can be very well maintained inside and outside of the body of the balance of pressure, do not have to produce a great harm to the internal.
Third, the density of the brain oil substance in the whale's brain will change accordingly. When the temperature of the sea water outside becomes low, the density of the brain oil material in the whale brain will become larger, especially when it is lower than 20 degrees Celsius, it will become similar to the form of solid lipids, which greatly improves the resistance to the external pressure and sensing ability.
Fourth, the way the blood stores oxygen is also favorable to the deep sea environment. Because in the deep sea environment, the whale's lungs have been unlimited compression, basically does not have the ability to change air, in order to maintain the body's normal physiological activities require oxygen, the original lungs through the inhalation of oxygen, the vast majority of hemoglobin in the blood, muscle myocardin effectively combined for the deep-sea dive when needed.
Whale diving has its limits
However, we have to see is that although the whales in the body structure has evolved to be very adaptable to the deep sea environment, but the depth of their dive, the duration of the dive time have obvious limitations in the depth of the dive, even the strongest ability of the Kohl's beaked whales, can not break through 3000 meters, and in the thousands of meters, the depth of the dive time has obvious limitations, even the strongest ability of the Kohl's beaked whales, can not break through 3000 meters. In the depth of the dive, even the most capable of the Kirkland's beaked whale, can not break through the 3000 meters, and in the thousands of meters of the depth of the sea continued to dive in the time of more than 1 hour, more than these two limits, the whale's flesh and blood can not withstand.
A: Whales dive in the process, the lungs gradually shrink, so that the pressure inside the body increases, used to balance the pressure inside and outside the body.
Water pressure
Water pressure and water depth p = ρgh, the depth of every increase of 10.3 meters, the pressure will increase by one atmosphere, in the depth of 1,000 meters, the water pressure as high as 97 atmospheres, equivalent to 970 tons per square meter to withstand the weight.
The whale's body after a long time of evolution, has evolved to adapt to the ability to dive in the deep sea, but there is also a limit, the general whale is only more than 500 meters of shallow water activities, and sperm whales can dive up to 2,000 meters, and then deeper, if the whale's body can not withstand.
And the military nuclear submarine, the general maximum dive depth of about 300 meters, even if it is a special nuclear submarine, the maximum dive depth of 700 meters, can not be compared with the depth of the whale.
When the whale dives into deep water, the whale's lungs are greatly reduced, and the pressure in the body increases, which is used to resist the pressure of the water outside the body, making the pressure balance between the body and the external pressure, which is the reason why the whale is not flattened; however, there is a limit to the increase in the pressure in the body of the whale, and the whale's body can not withstand it after exceeding the limit.
As nuclear submarines need to carry people, the human body is in the atmospheric pressure, you need to keep at about 1 atmospheric pressure, there is not much room to adjust the internal pressure, so with the increase in the depth of the submarine, the submarine inside and outside the difference in pressure is getting bigger and bigger.
Nuclear submarines do not have the ability to resist deep water pressure by increasing internal pressure as whales do, and can only rely on metal structures to resist, so the dive depth of nuclear submarines is very limited.
But for scientific research, deep-sea submersibles have a simple structure and a multi-layer, step-by-step pressurization design that allows them to dive to depths of up to 10,000 meters.
Other examplesOrganisms often use similar principles to adapt to high-pressure environments, such as those at 10,000 meters in the Marinaia Trench, which are filled with high-pressure body fluids to balance the external and internal pressures.
Even we humans do this, an atmospheric pressure of 101.325kPa, equivalent to 10 tons of weight per square meter of skin, but the pressure in our human body is also about one atmosphere, so the body's external pressure is basically balanced, and the human body will not be flattened by atmospheric pressure.
seawater pressure, is a certain height of the seawater column to the bottom of the 1 square centimeter area of the force. Depth of every 10 meters, the pressure will increase by one atmosphere, the bottom of the sea 1000 meters, the pressure is about 100 atmospheres. An atmosphere is 0.1Mpa, that is, 1 kg pressure per square centimeter. 100 atmospheric pressure is 10MPa. 10Mpa pressure is extremely horrible, every square meter to withstand the weight of 1000 tons.
Whales, as the dominant sea, its diving ability is very strong. However, to correct one point, even whales can not dive into the depth of 10,000 meters. Fin whales can stay underwater 300-500 meters for an hour. Toothed whales Road Sperm Whales can dive up to 2,000 meters and remain in the water for up to 2 hours. Sperm whales were found strangled by cables at a depth of 2,200 meters of water in the waters off the right of the Portuguese capital, Lisbon, the deepest recorded mammal dive to date.
A depth of 2,200 meters is equivalent to more than 2,000 tons of pressure acting on the body of the whale. How does a body of flesh and blood carry the horrific pressure?We have to marvel at the magic of creation, although the whale is a mammal, but also has all the characteristics of the appearance of fish. In order to adapt to the environment, the whale's muscle tissue has become particularly flexible, the fiber tissue is extremely dense, the bones are easy to bend, especially the fish skin can make the fish body physiological tissues are full of water, to maintain the balance of the pressure inside and outside.
Not only that, whales have special physiological structures to resist the pressure in the water. Take the sperm whale, its brain has a brain oil material, brain oil in less than 29 degrees temperature slowly solidified, which makes the density increase, the center of gravity forward, you can dive deeper, in deep water, the whale's ribs and sternum, vertebrae connection is very loose, diving with the increase in external pressure and contraction, the lungs are also contracted, the depth of the water is about to the 100 meters below the alveoli will be completely contracted, no longer carry out gas Exchange, the whale's blood will be rich in oxygen, while the lungs can be greatly reduced, such a state, the whale body internal pressure is enough to resist the external water pressure, and the lungs will not be harmed.
The submarine's hull is made up of pressure-resistant plates, a mesh support system, and a main stress structure, a rigid structure that cannot be softly adjusted like a whale's while submerging, but can only be supported by stress.When the submarine dives, the submarine's pressure-resistant structure has to withstand strong deep-water pressure. The parts of the submarine's pressure-resistant structure are pressure-resistant hull, pressure-resistant command room, pressure-resistant liquid compartment and transverse bulkhead. The pressure-resistant hull of a submarine generally consists of high-strength steel shell plates, ribs and transverse bulkheads. Shell plate is the main component to ensure the strength of the submarine, and the ribs are in the form of a ring, arranged transversely inside or outside the shell. The pressure-resistant structural strength of modern submarines can ensure that the submarine can dive to a depth of 300-900 meters. Once the high-strength steel plate on the outside of the submarine is unable to support the pressure of seawater, the pressure difference between the air-filled interior of the submarine and the external seawater will deflate the entire submarine, just like a balloon being burst.