The deep sea is a world where life is scarce. If the biomass per square meter of the seabed is expressed by weight, it averages a few hundred grams in shallow seas and only a few tens of grams in deep seas. However, there are also places in the deep ocean where biomass is unusually high.
In the 1970s, when scientists surveyed the 2,600-meter-deep sea near Mexico, they found hot springs gushing from the ocean floor and a large number of organisms living around the hot waters. The sea is located near the famous Galapagos Islands. The density of organisms around the hot springs reaches tens of kilograms per square meter, comparable to the coral reef waters of shallow seas. Since then, more deep-sea hydrothermal spring biota have been discovered, and they are like stars scattered in the night sky, existing in the world's oceans.
<h2 class="RichEditor-header-two" > hydrogen sulfide, a scarce source of energy</h2>
There is no light on the deep seabed, and certainly there are no photosynthetic plants. As a result, animals on the deep seabed generally survive by eating the remains of creatures that fall from shallow seas. Due to the shortage of nutrients, the deep seabed is a barren land where organisms are extremely rare, but around the hydrothermal vents, people have invariably discovered a variety of biological communities. It turns out that hydrogen sulfide in hydrothermal fluids provides inexhaustible energy for living things.
If you've been to many hot springs, you'll probably find that some of them have a foul smell, much like an egg stinking or stinking fart. This is the smell of hydrogen sulfide. Hydrogen sulfide is found in volcanic gases and in hot springs that spring up from the depths of the Earth, and it is toxic to many organisms, but it is a source of energy for sulfur-oxidizing bacteria. There is a class of bacteria called chemical synthesis bacteria, which use the energy generated by chemical reactions to synthesize organic matter necessary for life. Sulfur-oxidizing bacteria are also part of this class of bacteria, using the energy produced when hydrogen sulfide and oxygen react to combine carbon dioxide into organic matter. Where there is abundant hydrogen sulfide gas, they can survive and reproduce where they are. When sulfur-oxidizing bacteria increase to a certain number, they can form a symbiotic relationship with some animals and live together.
<h2 class="RichEditor-header-two" > why are deep-sea hot springs rich in hydrogen sulfide? </h2>
Hot water in hot springs is formed by surface water penetrating deep underground, being heated by rising magma, and incorporating hydrogen sulfide gas. By the same token, in deep seabeds where volcanic activity is more active, hydrogen sulfide in hot springs gushes out from deep in the oceanic crust. Submarine volcanic activity is generally concentrated in places where the oceanic crust sinks deep into the Earth, and where the oceanic crust cracks and forms a new crust. The deep-sea hot springs of the ocean are concentrated in such places. Of course, springs rich in hydrogen sulfide have not only hot springs, but also cold springs. For example, where the crust plates collide with each other, seawater rich in hydrogen sulfide and methane gas deep in the earth's crust is often squeezed into the seawater to form cold springs. Around the cold springs, bacteria and animals that depend on hydrogen sulfide for their livelihood are also concentrated.
How do sulfur-oxidizing bacteria convert hydrogen sulfide into energy sources that organisms can use? To clarify this truth, we must also start from the photosynthesis of plants.
Organisms are mainly composed of carbon, hydrogen, and oxygen, which are contained in an inexhaustible supply of water and carbon dioxide, but hydrogen and carbon are strongly combined with oxygen, respectively, and therefore cannot be directly used by organisms. To cut off this chemical binding and utilize these elements, energy is needed. Plants use sunlight to cut off this binding, and then let the elements recombine to form the necessary organic matter, this process is photosynthesis.
Sulfur-oxidizing bacteria can also produce organic matter. Unlike plants, they do not use sunlight, but use the energy produced when sulfide hydroxide for organic synthesis. Hydrogen sulfide is contained in springs, hot springs, and is abundant around decaying large animal carcasses. Deep-sea hot springs are hell for human beings, and people in that environment are not only unable to breathe, but also poisoned alive by hydrogen sulfide. But in the eyes of sulfur-oxidizing bacteria and the animals that live with them, deep-sea hot springs are a place of light full of energy and hope.
The temperature of the deep-sea hot springs is very high, reaching 380 degrees Celsius, but after pouring into the seawater, it quickly drops to 50 or 60 degrees. The temperature is only a dozen degrees at a place three or four centimeters away from the hydrothermal fluid, which is equivalent to a beachfront shoal, which is nothing less than paradise for animals. Usually, shrimp, crabs, double-shelled shellfish and unique tube worms are densely packed near the hydrothermal vents of the deep sea. Unlike shoals, animals are subjected to the enormous pressure of the sea, and animals that are accustomed to high-pressure environments are mostly killed after being salvaged to the surface. Professor Zhou Huaiyang of Tongji University's School of Ocean and Earth Sciences said crabs are an exception, perhaps because they have no blood vessels and a hard shell for protection. He once caught a crab from near a 1900-meter-deep hot spring, but he didn't expect that the crab actually survived in the laboratory tank for several days!
Animals in hydrothermal biomes are inedible. Because the chemical synthesis bacteria in their bodies absorb large amounts of hydrogen sulfide, they emit a disgusting rotten egg odor and are toxic.
Scientists already know that the interior of hot springs at high temperatures is also filled with microorganisms, which are prokaryotic bacteria invisible to the naked eye and also live on hydrogen sulfide. They are ancient, have a slow metabolism and can relax in hot water at 120 degrees Celsius.
<h2 class="RichEditor-header-two" > explore deep-sea hot springs</h2>
On June 30, 2012, The Jiaolong, an ocean submersible independently developed by China, successfully conducted a test dive, with a maximum diving depth of 7062 meters. The successful development of jiaolong has provided technical support for Chinese scientists to enter the deep sea.
Let's take an imaginary journey and follow the Jiaolong to find and see the deep-sea hot springs.
The "dragon" who has just fallen into the sea is like a drunkard, tumbling under the action of the waves, and the inspectors cannot help but feel a little stomach churning in the narrow cabin. Fortunately, after diving about 20 meters, you enter the world of silence. Through the circular observation window, you can see the fish and jellyfish that are rapidly skimming through the sparkling blue waters. As the water depth increases, the light gets dimmer and dimmer. When it was almost 200 meters deep, the world was almost completely dark, but there were still some things in the darkness that fluoresced in the stars, that is, some glowing plankton.
The "dragon" continued to dive deeper, the biological density became thinner and thinner, and the fluorescence became more and more rare. After about 40 minutes, the cabin gauges showed that the water depth had reached 1500 meters, and the dark sea water was more fluorescent.
At a depth of 2,000 meters, the "dragon" landed safely and reached the place where the hot spring gushed out. Guided by searchlights, the submarine moved carefully so as not to touch the reef. The area is lined with chimney-like protrusions, and the "chimneys" vary in height and height, the highest is more than 20 meters, equivalent to six or seven stories high, but all of them spew ink-like hot water into the seawater. The seafloor of this area is full of animals, the most numerous of which are tube worms, which gather thousands of individuals and protrude bright red feather gills from the tubes, like blooming red flowers. On the surface of the tube worm colony, orange spider crabs can be seen everywhere stretching out their slender pincers to prey. Above the animal community, there are also some fish swimming slowly. Here, it is called an underwater oasis...
The discovery of hot springs in the deep sea is a long story. In 1977, the newly commissioned U.S. deep submersible "Alvin" was inspecting the waters near the Galapagos Islands when it discovered a hot vent vent on the deep seabed. This hot spring vent is where the seawater that penetrates into the cracks in the seabed comes into contact with the magma deep underground and dissolves into metal sulfides such as iron, copper, and zinc. There, chimney-like protrusions stand up, and hot springs emerge like black smoke from the top of the "chimney.". The "chimney" itself is precipitated and accumulated after the sulfides in the hot springs come into contact with the seawater.
Since then, scientists have found many similar undersea hot vents in the deep seabeds around the world, and they are distributed along the boundaries of the Earth's plates - mid-ocean ridges and volcanic leading edges.
Looking for unknown deep-sea hot springs is like finding a needle in a haystack, because compared with the vast sea, the scope of each hot spring is too small, its diameter is generally only one or two hundred meters, and the larger one is only three or four hundred meters. Zhou Huaiyang said that there are some physical and chemical methods to find unknown hot springs, first to find a wide range, and then gradually narrow the target. Of course, in the end, it still has to be seen by the naked eye to count. In recent years, Zhou Huaiyang and his colleagues have discovered two new hot springs. Zhou Huaiyang told this writer that more than 400 hot spring areas have been found around the world so far, and this number is still increasing.
In the early years, during the scientific investigation of juan de fuca yang ridge hot spring, Zhou Huaiyang successfully placed the chimney "hat" he designed and made on the hot spring spout. Nine thermometers are inserted in the "hat" to automatically record changes in the temperature of the hot spring. Continuous monitoring of hot springs inside chimneys, as well as analysis of mineral composition changes from the cross-section of the chimney, provide researchers with detailed information on the generation and demise of hot springs.
In the vast deep sea, where there are hot springs, there are thriving biomes. However, there are different types of hot spring organisms in different oceans. After five years of surveying with the Alvin, the American old lady Cindy Van Dover, a marine biologist, found that the Pacific and Atlantic hot spring biomes were distinctly different: the Pacific Ocean was dominated by crabs and tube worms, while the Atlantic Ocean was dominated by shrimp. Around the hot springs of the Atlantic Ocean, large flocks of shrimp swim to form a whirlpool, just like the flying locusts, and their scale is no less spectacular than that of the tube worms in the Pacific Ocean.