Ecological Exploration Series
Series Lineup
By Jung Yeon-Tae,
President of the Korea Construction Infonet and Essayist
At the deepest point on Earth, the Mariana Trench plunges nearly 11,000 meters below the ocean’s surface. Not a single ray of sunlight reaches this realm.
The temperature hovers around two degrees Celsius, and the pressure is more than a thousand times what the human body can endure. By ordinary standards, life should not exist there.
Yet science has quietly overturned that assumption. Life does exist in the deep sea—not as a rare exception, but as a stable and structured ecosystem.
At its center are microorganisms.
Life Without Light
We often associate life with sunlight: photosynthesis, oxygen, and green plants. But deep-sea life follows a completely different rule.
Its foundation is chemosynthetic bacteria. From cracks in the ocean floor, hot fluids rich in hydrogen sulfide, methane, and iron ions erupt into the water.
Chemosynthetic bacteria oxidize these substances to generate energy and synthesize organic matter. Here, chemical reactions replace sunlight as the source of life.
Crabs, clams, shrimp, and giant tube worms survive by feeding on the organic matter produced by these microbes. In this ecosystem, microorganisms are not supporting actors—they are the architects. Even in total darkness, life finds another language to persist.
Cities Born from Black Smoke
In 1977, the research submersible Alvin made a groundbreaking discovery near the Galápagos Rift. What appeared to be black smoke billowing from the seafloor turned out to be hydrothermal vents surrounded by thriving communities of life.
What initially resembled an entrance to hell was, in fact, a cradle of life. Tube worms, giant clams, deep-sea shrimp, and crabs all depend on chemical energy supplied by microbes.
These organisms not live on sunlight, but on heat from Earth’s interior. This discovery reshaped humanity’s understanding of life. Life does not require light. Life emerges wherever energy flows.
A City Built on Death
Another astonishing deep-sea ecosystem is known as a whale fall. When a whale dies and sinks to the ocean floor, its massive body becomes the foundation of a community that can last for decades.
Fish and crabs feed on the soft tissue first. Microorganisms then break down fats and proteins, producing hydrogen sulfide. Chemosynthetic bacteria flourish on this chemical fuel, attracting other organisms that depend on them.
From the death of a single whale, thousands of species are sustained. In the deep sea, microbes serve as quiet alchemists, transforming death into life.
The Question the Deep Sea Asks Humanity
Deep-sea microbes pose a silent question to us: “If there were no light, could you survive?”
They require no sunlight, no air, no human intervention. With nothing but chemistry and energy, they fill the vast darkness of the ocean.
This is precisely why scientists study them so closely. Similar environments may exist on Mars, Europa, or Enceladus—worlds believed to harbor subsurface oceans or hydrothermal activity.
Deep-sea microbes are not merely part of Earth’s story; they are a reference model for the search for extraterrestrial life.
Earth Still Breathes in the Darkness
The deep sea is the last realm humanity has explored, yet it may be the closest reflection of Earth’s earliest form of life.
Even without light, under crushing pressure and extreme cold, life endures. Microorganisms prove this truth without words.
Life exists where the sun never shines. And in that darkness, Earth is still breathing—quietly, persistently.
About the Author
Jung Yeon-Tae is the President of the Korea Construction Infonet and an essayist. His writing explores the relationship between science and humanity, bridging nature, the cosmos, and philosophy.
Korean version available here.
