In the universe, there are countless planets. One of the significant reasons scientists believe that life could exist on many planets is that the environments where life can survive are much harsher than we imagine.
Cold and dry polar regions, hot and arid deserts are considered places where most life on Earth cannot exist. However, this perspective is merely a human assumption. On Earth, some organisms can thrive in extreme conditions that would be considered hellish for other life forms.
These extreme environments include high temperatures, high pressures, low temperatures, and high radiation. For example, some bacteria and archaea can survive in harsh environments such as hot springs, hydrothermal vents deep in the ocean, volcanic craters, and glaciers.
Some organisms can survive in extreme environments on Earth. (Illustration: ZME)
Hot water emitted from hydrothermal vents can reach temperatures of hundreds of degrees Celsius, yet some special microorganisms and marine organisms can thrive in this environment. These microorganisms rely on chemical reactions instead of photosynthesis to obtain energy. They can harness the energy from eruptions, released sulfides, and other chemicals to carry out metabolic activities.
Among all forms of life on Earth, the most resilient species discovered by humanity is the tardigrade (commonly known as water bear), a tiny invertebrate capable of surviving extreme environmental conditions such as high temperatures, high pressures, low temperatures, and high radiation. Even in the radiation environment of outer space’s vacuum, it can survive in a dormant state for extended periods.
Water bear. (Image: ZME).
From the examples presented, it’s clear that life can exist in extreme environments mainly due to certain special, simple, and lower-level microorganisms, which can thrive even without sunlight and oxygen, showcasing remarkable adaptability.
Seventy percent of the Earth’s surface is covered by oceans. Although life is primarily found in shallow waters, scientists have also discovered traces of life in the deep ocean, thousands of meters below the surface. Due to the extremely high pressure in deep-sea environments, life there is very different from life in shallow waters.
In addition to discovering life at depths of thousands of meters beneath the sea, scientists have also found life at a depth of 2,800 meters underground.
To extract mineral resources like oil and gold buried deep underground, human-developed mines have reached depths exceeding 10,000 meters. While mining gold in these special areas, they have discovered some unique forms of life.
Unique life forms discovered during gold mining. (Illustration: CNN)
In 2005, at a gold mine named “Mboneg” near Johannesburg, South Africa, a scientific research team explored a cave where a crack filled with groundwater was found at a depth of 2,800 meters. The researchers collected a substantial number of samples.
After analyzing these samples, scientists discovered that there were indeed many microorganisms in the groundwater. However, after excluding data from samples contaminated by surface microorganisms, the results surprised the scientists, revealing that only a single species existed in the 2,800-meter-deep crack underground. In other words, this microorganism may not have been in contact with other species for a long time, living in a completely isolated world.
Due to their discovery in gold mines, they are commonly referred to as “golden mineral fungi.” This microorganism is rod-shaped, averaging about 4 microns in length, capable of movement and spore formation.
Commonly referred to as “golden mineral fungi.” (Illustration: ZME).
The groundwater temperature in the crack inhabited by golden mineral fungi is consistently above 60 degrees Celsius, with a pH of about 9.3, lacking sunlight and oxygen year-round. Most life on Earth cannot survive in such an environment, yet golden mineral fungi thrive and grow normally.
So how can golden mineral fungi survive in the cracks 2,800 meters underground? The research results indicate that in the environment where golden mineral fungi reside, there are several radioactive elements, and the energy released during the decay of these radioactive elements meets the survival needs of the golden mineral fungi. They can use this energy to synthesize the organic compounds they need from water, carbon dioxide, sulfide, and nitrogen in the rocks to maintain their metabolic processes.
It must be said that the survival ability of these life forms in extreme environments is astonishing. These environments may be hellish for other life forms, but for those that have adapted, they have found unique ways to survive. Studying these extreme life forms helps humanity gain a better understanding of the origins and evolutionary processes of life, search for extraterrestrial life, and develop new biotechnology.
