What's at the Bottom of the Marianas Trench? | Unveiled

What’s at the Bottom of the Mariana Trench?

Humans have succeeded in mapping much of the Earth . . . but not all of it. Some areas remain largely a mystery due to the difficulties in reaching them. Of these, the ocean floor is perhaps the least understood, with the strangest ecosystem. What secrets do the deepest depths hold?

This is Unveiled and today we’re answering the extraordinary question: What’s at the Bottom of the Mariana Trench?

The Mariana Trench, also known as the Marianas Trench, is the deepest place on Earth. Formed by the subduction of the Pacific Plate under the Mariana Plate, it reaches depths of over 36,000 feet. The trench forms a crescent in the ocean floor that’s 43 miles wide and runs for 1,580 miles along the edge of the Mariana Islands in the western Pacific Ocean. With so much area to it, it’s no wonder that it’s mostly unexplored.

There are a number of areas on Earth that remain largely unexplored. The Amazon Rainforest is home to a massive amount of biodiversity, and scientists are still discovering new species. Other remote locations, such as Antarctica, and the Star Mountains in Papua New Guinea, could also be hiding secrets that we have yet to discover. Expeditions to these locations are dangerous and therefore rare. Despite this, the ocean is by far the most unexplored part of the planet. Oceans cover about 70% of Earth’s surface, and of this, we’ve explored less than 5%. Even taking into account sonar maps of the seafloor, over 80% of the ocean is still unobserved. Many mysteries and potential scientific discoveries likely lie in wait in our oceans, especially at its deepest points. But because of the inhospitable conditions that far down, it’s a challenge to explore them.

The bottom of the Mariana Trench is no exception. It’s under so much water that sunlight is unable to reach the bottom, so it’s blanketed in complete darkness. Because of this, the temperature is as close to freezing as it can get without turning into ice, ranging from 34 to 39 F. At these immense depths, the pressure exerted upon objects by the ocean above is about 1,000 times the pressure on the surface, at almost 16,000 pounds per square inch. Submarines that want to explore the Mariana Trench need equipment capable of withstanding these temperatures and extreme pressure. It’s no wonder that only a handful of people have ever seen the bottom first hand.

Scientists initially weren’t sure what life could survive at such depths. But during expeditions, researchers have encountered various organisms at different levels of the trench, including Arrowtooth eels, snailfish, and spoonworms. There were also shrimp-like amphipods and translucent sea cucumbers. Life deep down was fairly simple - mainly microbes of various sorts, including single-celled amoebas. Hundreds of different microorganisms were found in the mud, as well as microbial mats that gorge on methane and hydrogen. It’s the Mariana snailfish that’s truly mastered the environment, however. It’s able to go farther and deeper than other competitors and feast on the prey in the trench. At a glance, the snailfish hardly seems able to withstand such pressures, but it’s found a way to do so regardless, proving that life can adapt to extreme circumstances in order to survive and even thrive.

However, we’ve only explored a small part of the trench. There are likely untold discoveries still awaiting scientists. Rare and exotic life has been found in the deep sea elsewhere, such as gulper eels and giant squids. The trench could harbour all sorts of strange life. Deep-sea Gigantism is a notable feature of many deep-sea creatures, such as the giant tube worm, which is much larger than its counterparts in other ecosystems. Scientists think that they became bigger to eat the resources expelled by deep-sea vents, but are at a loss to explain other instances of Deep-sea gigantism. Deep sea creatures are also likely to display bioluminescence and chemosynthesis.

Unfortunately, not everything that explorers discovered in the trench was good news. For one, they found a clear sign of humanity even at the very bottom of the ocean - plastic. Researchers had studied animals that live in extreme depths before and found evidence of microplastic in their guts, but a recent 2019 expedition to the ocean floor came across a plastic bag and various candy wrappers floating in the darkness. This came as a surprise, as no one imagined that natural environments so far removed from us could be polluted. But in addition to plastic, researchers have also found evidence of chemical contamination. Concentrations of PCBs, a toxin banned due to environmental harm, was found within the sediment at the bottom of the trench. In addition, the bodies of aquatic animals in the trench revealed levels of carbon-14, remnants from nuclear bomb testing. This tells us that humanity’s waste and byproducts are much farther reaching than originally thought, infiltrating even the remotest parts of the planet. Pollution isn’t just something that goes away simply because it’s out of sight.

Humanity has an inherent need to explore and discover. Explorers have taken on a variety of dangerous terrains just to plant a flag, some dying in their endeavors. We’ve journeyed to the moon and even plan to travel to distant planets, but we still have a large amount to discover here on Earth. Studying creatures in extreme conditions like the bottom of the ocean provides scientists with valuable insights into how life forms and is able to adapt. This is the knowledge that we need if we plan on looking for signs of other life in the cosmos, as it allows to understand where extreme life is likely to be found. It will also provide insight on the possible types of life. There could be all kinds of unseen and unknown species that defy what we think is possible, as did extremophiles upon their discovery. And that’s what’s at the Bottom of the Mariana Trench.