In the ocean, a depth of 200 meters is the boundary between shallow and deep seas. According to the fact that different organisms are distributed in different water depths, scientists divide the deep sea into a gradual deep sea zone (200 to 3000 meters), a deep sea zone (3000 to 6000 meters) and an ultra-deep sea zone (6000 to 11000 meters). The only places in the ocean where the water depth exceeds 6,000 meters are trenches, and many trenches are in the place where the ocean plates are subducting below the continental plates, so the trenches are relatively close to the continents. Proximity to the mainland means that more sediment and organic matter flow from the mainland to the trench.
In the ocean, for every 10 meters of water depth increases, the water pressure increases by 1 atmosphere, and at a depth of 200 meters, the water pressure is already equivalent to 20 atmospheres. How can creatures withstand such high pressures? Maybe you will say: the answer I already know, this is the same reason that humans are not flattened by the atmosphere, because the pressure inside and outside our body is 1 atmosphere pressure, which is balanced; the same is true for deep-sea animals, the pressure in their bodies is the same as the pressure on the outside water, so they do not feel the pressure.
<h1 class="pgc-h-arrow-right" > but following this line of thinking, there are still two things that will make you feel awe for deep-sea animals. </h1>
First, some deep-sea animals migrate from deep to shallow and then from shallow to deep in the seawater every day and night, the vertical distance of migration is often hundreds of meters, and the water pressure difference is dozens of atmospheres, how do they adapt to pressure changes in a short period of time?
Second, experiments have shown that pressure above 600 atmospheres of pressure will cause biological cells and some biochemical reaction enzyme molecules to deform, so that the metabolism and reproduction of organisms can not be carried out normally, but why are marine animals still inhabited at a depth of 6,000 meters or even 10,000 meters?
<h1 class= "pgc-h-arrow-right" > float day and night, up and down freely</h1>
A trained diver carries an oxygen cylinder and can dive to a depth of 40 meters. However, if the speed of diving and floating is not well controlled, divers may fall into diving disease, and even lose their normal working ability. Compared with the lanternfish in the ocean, the diver's ability is really not worth mentioning.
Lanternfish are representatives of deep-sea animals, which contain more than 200 species, distributed in the water depth environment of hundreds of meters in the world's oceans, and there are also individual species living at depths of more than 2,000 meters. Many species of lanternfish have the habit of migrating vertically day and night, staying in deep water during the day and floating to shallow places to feed in the middle of the night. For example, the glitter lantern fish, which sits idly at a depth of two or three hundred meters during the day, floats to the surface of the sea at night. The Omeiko Lantern Fish (also a type of lantern fish) will dive deeper during the day, and at night they will float to a depth of tens of meters above the sea surface.
Fish can change the buoyancy of the body by regulating the amount of gas in the swim bladder (commonly known as fish bubbles), so that it can move vertically in the seawater. Lanternfish also have this ability, but some lanternfish have degraded their swim bladders, which are devoid of gas but full of fat. The volume of fat does not change with pressure. If the inside is gas, the pressure change is too large, and the swim bladder will squeeze and crack. In the process of vertical migration of lanternfish day and night, the water pressure change can reach dozens of atmospheres, and the fat-filled fish maw can adapt to the large change in pressure.
Some shrimp in the ocean, like lanternfish, migrate vertically day and night. Sakura shrimp is a small shrimp commonly found on Japanese tables and is found in Suruga Bay on the Japanese island of Honshu. Cherry shrimp hide in the deep sea hundreds of meters deep during the day and float to the surface of the sea at night to feed. There are more species of deep-sea zooplankton that can carry out vertical migration day and night, such as arrow worms in hairy clams, and some radial horns.
These deep-sea animals often span hundreds of meters of water depth when they carry out vertical migration day and night, and the water pressure also has dozens of atmospheric pressure differences. Their diving ability is dozens of times stronger than that of divers, and they do not have to worry about diving disease. How marine animals do this remains to be further studied by scientists.
<h1 class= "pgc-h-arrow-right" > abyss, "pressure mountain"</h1>
In the ocean, a depth of 6,000 meters is a hurdle, and many creatures near this depth cannot withstand the pressure of the water and disappear.
Scientists performed pressurized experiments on yeast, bacteria and deep-sea dynamics, and found that most organisms below 600 atmospheres can survive; after more than 600 atmospheres, organisms have encountered abnormal cell metabolism and reproductive abnormalities, because the pressure is too high to cause the biological cells and their internal biochemical reaction enzyme molecules to deform, so that they can not function normally. When this effect becomes severe, the organism dies. However, it is puzzling that in the trenches with a water depth of more than 6,000 meters to more than 11,000 meters, there are still some animals living freely. Why organisms can survive under extreme pressures remains a mystery to this day. Interestingly, the animals that have adapted to the "pressure mountain" in the trench seem to have become accustomed to being "abused", and they are freed from high pressure and will lose their "dignity" and do not know what to do. For example, a deep-sea crab called Gandalfus will be like a drunk at 1 atmosphere, shaking and unable to walk normally.
In trenches more than 6,000 meters deep, the tolerance of different organisms to high pressure also varies greatly. As the water depth increases, some creatures disappear one by one. For example, among fish, a small fish of the striped fin order called Huangquan Adai and a small fish called "trench bhikshuni" can tolerate a maximum water depth of about 8000 meters;
Hook shrimp and sea cockroaches can live in the deepest parts of the ultra-deep sea zone, reaching a depth of more than 10,000 meters. As arthropods, crabs and shrimp are much less tolerant of pressure than hook shrimp and sea cockroaches, and they cannot be seen when the water depth exceeds 6000 meters. Crabs and shrimp are abundant on the continental slopes, but in deeper ocean floors and trenches, hook shrimp are among the best crustaceans.
The water depth continues to increase and the biological species gradually decreases. When the water depth exceeded 8,000 meters, even starfish and sponges disappeared. At water depths of about 9,000 meters, the average biomass per square meter of seafloor surface is only a few percent. At the bottom of the trench, the biological species are extremely monotonous, with only anemones, mites (commonly known as sea intestines), hook shrimp, double-shell shellfish, sand silkworms, sea cucumbers and other animals. The largest number is the sea cucumber, and in some places only one species of sea cucumber can be seen by benthic animals.
This sea cucumber is so tender that once it leaves the sea, its body collapses due to its self-weight and becomes a puddle of liquid. There are also hook shrimp and sand silkworms in the challenger abyss, and the inspectors throw the bait meat pieces into the seabed, and these small animals will come out of nowhere to grab food.
<h1 class= "pgc-h-arrow-right" > how much pressure animals can tolerate</h1>
Since some animals are well alive in the deep sea of more than 10,000 meters, some people must ask: What is the limit of animal tolerance to high pressure? To answer this question, we might as well look at a study by physicists on other animals.
Bearworms, a small group of animals in the Phylum Tardigrades, live mainly in freshwater sediments, moist soils, and water films of bryophytes, and can also be found in the Himalayas and deep seas. A few years ago, scientists discovered that bear worms can survive at 75,000 atmospheres, making it the most high-pressure-resistant animal on Earth.
The bear worm is less than 1 mm long and moves when the surrounding environment is moist; when dry and waterless, its body can shrink by half compared to normal and enter a stationary dormant state. A few years ago, Fumihisa Ono, a physicist at Okayama University in Japan, collected bear worms near the university, dried them out, put them in a dormant state, and then pressed them to 75,000 atmospheres with an ultra-high pressure device. To the researchers' astonishment, after 20 minutes of such cruel pressure, most of the bear worms were unharmed. The pressurization time was extended, and it took 24 hours before they all died.
What is the concept of 75,000 atmospheres? It means 745 kg of pressure per square millimeter of area. On Earth, only 180 km underground is there such a huge pressure deep in the mantle. This unimaginable pressure can make rice starch instantly degenerate, and raw rice become mature rice. For living organisms, the fear of ultra-high pressure is even more multifaceted: it will crush the cell membrane, making it impossible for the cell to perform the function of metabolism and transmitting information; it can force the water molecule into the structure of the biochemical enzyme molecule that makes various functions, and then disintegrate it... Scientists don't yet understand why bearworms can tolerate such high stress, and they speculate that this may be related to the fact that the bearworm's body can actively dehydrate into a dormant state. In this state, the bear worm can carry through a variety of extreme environments.
The bearworm's ability to adapt to ultra-high pressure gives us good inspiration. At the level of human cognition today, we are not yet able to detect and explain all the mysteries of living things, and we can only be humble in the face of the mysteries of nature. The author believes that if the deepest part of the ocean reaches 20,000 or 30,000 meters, not just 11,000 meters in reality, then the depth of 20,000 and 30,000 meters will also become the reclamation and happy home of animals.