Series Lineup
① Earth, The Planet of Microbes — History of the Invisible Masters
② Another Universe Beneath the Soil — The Living Forces That Sustain the Earth
③ The Revolution Beneath Our Feet — The Invisible Life That Keeps Plants Alive
④ The Hidden Alliance Beneath the Soil: A Silent Revolution Led by Root-Dwelling Microbes
⑤ The Invisible Engine of Earth’s Oceans — Why Marine Microbes Hold Our Future
⑥ Life Born in Darkness — What Deep-Sea Microbes Reveal About Earth’s Hidden Face
By Jung Yeon-Tae,
President of the Korea Construction Infonet and Essayist
The deep ocean is the last region of Earth that humanity has truly come to understand. It is a place without sunlight, gripped by cold and crushed by pressures a thousand times greater than those at sea level. For generations, it was assumed to be lifeless, yet science now tells a very different story.
The deep sea is not an empty void but a separate and vibrant ecosystem. At its core lie microbes that thrive beyond light, quietly sustaining life where sunlight ends and existence was once thought impossible.
The Mariana Trench plunges to a depth of nearly 11,000 meters. Sunlight cannot reach it, temperatures hover near 2 degrees Celsius, and the crushing pressure defies human imagination. By conventional standards, life should not exist there.
Exploration has revealed a hidden truth. Life persists even under these extremes, and the deep sea emerges as another Earth beneath the Earth, structured upon a vast and intricate microbial network invisible to the human eye.
Life as we know it is often defined by sunlight. Plants depend on it, animals depend on plants, and ecosystems are traced back to photosynthesis. Deep-sea organisms, however, have evolved beyond this paradigm. They survive on chemistry, not light.
At hydrothermal vents on the seafloor, hot fluids rich in hydrogen sulfide, methane, and iron ions surge upward from the Earth’s interior. Chemosynthetic bacteria oxidize these compounds, generating energy and synthesizing organic matter that becomes the foundation of the deep-sea food web.
The Invisible System That Sustains the Planet
They are microscopic organisms that sustain the ocean and help regulate the planet itself. As humanity faces climate change, marine pollution, and the challenge of carbon neutrality, it is crucial to understand this hidden but immense biological network.
Crabs, clams, shrimp, and iconic tube worms all depend on this microbial production. These bacteria represent a different kind of life—one that illuminates the ocean not with sunlight, but with the chemical energy of the Earth itself.
The scientific world was shaken in 1977 when the research submersible Alvin discovered the first hydrothermal vent field near the Galápagos Rift. Instead of a barren seafloor, cameras revealed a thriving community clustered around plumes of black, boiling fluids.
Towering tube worms, giant clams, pale crabs, and heat-adapted shrimp flourished in a place once believed uninhabitable. Every organism in this oasis lived on energy supplied by microbes. Earth’s internal heat had replaced the sun as the engine of life.
That discovery overturned a foundational belief in biology. Life, it became clear, is not dependent on light—it is dependent on energy.
One of the most dramatic phenomena in the deep-sea ecosystem is the whale fall. When a dead whale sinks to the ocean floor, its massive body becomes a city of life that can persist for decades.
Fish and crustaceans feed first, followed by microbes that break down residual fats and proteins. This decomposition produces hydrogen sulfide, which becomes a new energy source for chemosynthetic bacteria, once again generating the organic matter that fuels an entire miniature ecosystem.
A single death sustains thousands of lives. At the center of this vast cycle, microbes work in silence—the alchemists that transform death back into life.
Deep-sea microbes pose a profound question to humanity: what does life truly require? They need neither sunlight nor oxygen. They wait for no warmth and depend on no surface nutrients.
They survive entirely through Earth’s internal chemistry, inhabiting an environment as quiet and alien as outer space. Scientists study these organisms not only to understand Earth’s ecology, but also because they may offer a blueprint for life beyond our planet.
Moons such as Europa and Enceladus are believed to harbor hydrothermal-like environments beneath their icy crusts. If life exists there, it may closely resemble the microbes that thrive in Earth’s deep ocean.
The deep sea may be the last frontier of human knowledge, yet paradoxically, it may preserve the earliest blueprint of Earth’s biological history. From within the darkness, microbes seem to tell us: “I survive without sunlight. I am life born from the heart of the Earth.”
Their existence reveals the resilience and creativity of life—its capacity to take root wherever energy flows, no matter how extreme the environment. Even without the sun, life persists. And in that vast darkness, the Earth continues to breathe.
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.
