A Newly Discovered ‘Lost City’ Harbors a Plethora of Underwater Life

Hydrothermal vents are the very proof that life is programmed to subsist in the harshest conditions. The newly discovered 'lost city' shows a plethora of species.

Isabel Cara

We don’t know much about the dark depths of the ocean, but it is thought that such stark conditions of lack of light and oxygen may limit the existence of life in the desolate underwater wastelands. However, life seems to be programmed to subsist even in the most unlikely conditions, hydrothermal vents are a clear example of this. A few of them have been discovered in the middle of the ocean, the most recent being seen in the world’s longest underwater mountain range: the Mid-Atlantic Ridge.

Hydrothermal vents have been discovered in the oceanic darkness before, but the life in them is usually not very evident to the eyes of explorers, who access them via remote-controlled underwater vessels. In many cases, extensive sample analysis has been required to determine that life is present in the form of tiny organisms, but the latest discovery in the world’s longest underwater mountain range makes all the difference. The region features a plethora of life in detail visible.

Lost city underwater hydrothermal vents 2 - a newly discovered 'lost city' harbors a plethora of underwater life
Photo: rov subastian / schmidt ocean institute

What Hydrothermal Vents Look Like

Hydrothermal vents are fissures in the seafloor through which a significant amount of water flows out at extreme temperatures because it is geothermally heated. It is common for such underwater oases to be found near volcanically active sites in the ocean.

Sunlight begins to fade at about 200 meters depth and at 500 meters it is impossible to see anything. In conditions of scarce light, photosynthesis is almost impossible, and therefore oxygenation is also a problem in these regions. This is why it was believed that there was no life in the underwater blackness, but the hydrothermal vents are an exception and seem to be teeming with life in all its forms.

“At hydrothermal vents, seawater chemically altered through high-temperature water-rock interactions is expelled through smoldering and diffuse fluid areas,” explains the Schmidt Ocean Institute. “This water is enriched with certain chemical compounds, such as hydrogen sulfide and methane, which provides reduced food for microbial growth in a process known as chemosynthesis.”

What you can see in the images is proof that life is programmed to subsist in all corners. Most of the species that live here cannot be found in any other region, which makes the hydrothermal vents fascinating.

Lost city underwater hydrothermal vents - a newly discovered 'lost city' harbors a plethora of underwater life
Photo: rov subastian / schmidt ocean institute

“These animals harbor bacteria that grow from chemicals and return carbon production back to the host. It’s a relationship analogous to that of colorful corals with algae in shallow tropical reefs. In addition to chemosynthetic bacteria and large animals, many other smaller species thrive by feeding on bacteria or other animals, thus creating the dense communities seen at the vents,” the researchers say.

The ‘lost city’ was found near the Puy des Folles volcano and has five active sites over about 18 square kilometers. But near the Mid-Atlantic Ridge region, other high-temperature ‘black smoke’ vents were also discovered in the Grappe Deux and Kane Fracture Zone vent system.

The research will continue to understand how these vents provide the right conditions for life to develop. This a special opportunity to learn more about Earth’s processes, which still have much to teach us.

Story written in Spanish by Alejandra Martínez in Ecoosfera