Undersea Canyons Are Deeper Than the Grand Canyon.

The Mariana Trench isn’t the only depressions ocean floor. The deep ocean features some of Earth’s most mindblowing canyons and trenches, including some that are deeper than the Grand Canyon. The Zhemchug Canyon, located in the Bering Sea, is the largest known submarine canyon, stretching 2.6 kilometers (8,530 feet) down compared to the Grand Canyon’s 1.8-kilometer depth (8,530 feet). The Great Bahama submarine canyon is one of the deepest undersea cave systems in the world. These colossal underwater canyons are so large they can be seen from space.

Submarine canyons offer a one-of-a-kind peak into our planet’s geologic history and potential insight into how similar structure form on other planets. The formations develop along continental shelves and slopes, which are the underwater edge of a continent. Over time, water currents erode the earth and carve out the massive canyons winding thousands of feet beneath the coastline. These canyons are rich ecosystems, home to clams and worms that live in the canyon walls. Deepwater coral and sea sponges provide habitats for a diverse population of fish and invertebrates that live and swim along the sea floor.

Cold Seeps Help Fuel Deep Sea Ecosystems.

Cold seeps, or cold vents, are areas on the deep ocean floor that release gases like methane into the surrounding water. Like hydrothermal vents, cold seeps support rich ecosystems by leaking gases that microbes convert into energy. However, while hydrothermal vents release metallic minerals, the gases that pour from cold seeps are carbon-based, meaning that they originated from organic, or living, matter millions of years ago. That means that cold seep areas are an important part of the global carbon cycle and are fueled by energy from the sun, even though they exist well beyond the reach of sunlight’s reach.

Cold seep areas are unique among deep-sea habitats because they are bursting with food sources. Giant tube worms and dense clusters of mussels provide homes to energy-producing bacteria that return the favor by serving as the animals’ digestive system. Crabs and other small crustaceans in cold seep areas feast on the waste of mussels, clams, and tubeworms, while fish and octopus have their pick of prey in the bustling ecosystem. Some of these flourishing communities are ancient, dating back as much as 4,000 years.

Black Smokers Are Ocean Chimneys Hot Enough to Melt Solid Metal.

All hydrothermal vents are hot. But black smokers take heat to the next level. These vents are formed when volcanic activity produces towering chimney-like structures that spew clouds of thick black fluid. Black smoker fluid can reach temperatures as high as 750 degrees Fahrenheit or 400 degrees Celsius. The clouds are packed with sulfur minerals that can be broken down by the microbes that live in and around black smokers. The vent’s emission gets its dark color from iron sulfide. The large sulfur deposits surrounding black smokers make them a target for deep-sea miners.

But it’s not only humans who are drawn to hydrothermal vents. Black smokers support ecosystems full of sea creatures uniquely adapted to live in the environment. The scaly-foot gastropod, a sea snail that is sometimes called a sea pangolin, uses iron sulfide deposits to construct the outermost layer of its protective shell. The Pompeii worms are covered in a fuzzy layer of bacteria that allows them to withstand blistering heat of up to 176 degrees Fahrenheit or 80 degrees Celsius, temperatures that would almost any other animal.

There Are Live Volcanoes on the Bottom of the Ocean.

Hydrothermal vents like black smokers don’t just spring up out of nowhere. The vents formed along massive underwater volcano ridges that contain an estimated one million volcanos. Although only a small fraction of these submarine volcanoes are active, they’re the source of far more volcanic activity than on land. Because these volcanoes give rise to hydrothermal vents, they are a big part of why life is possible in the deep ocean.

The mid-ocean ridge is the longest continuous volcano ridge, stretching over 40,000 miles (65,000km). The ridge’s discovery in the 1950s changed our understanding of how Earth’s tectonic plates shift to produce earthquakes and volcanic activity. However, there are still vast stretches of submarine volcanoes yet to be uncovered. For example, the deepest known submarine volcano was only discovered in 2008. The base of the West Mata volcano in northeastern Tonga rests 4,000 feet below the surface. New technology like remotely operated vehicles and satellite imaging are aiding researchers in their exploration of underwater volcanoes.

Living Fossils Are Right at Home in the Deep Ocean.

The earliest life on Earth lived deep in the ocean. So, it’s fitting that some of the oldest “living fossils” would still reside there. A living fossil is an organism that has existed in its current form for millions of years, outsurviving any near-relative species. The depths of the ocean are teeming with examples of these prehistoric creatures. The alien-like chambered nautilus appears to live just as it did over 400 million years ago, descending as deep as 2,600 feet (800 meters) to ensnare fish and small crustaceans in its tentacles. Frilled sharks, a closer relative of the long-extinct megalodon than modern sharks, have wide jaws adorned with 20 – 30 rows of razor-sharp teeth.

Perhaps the most intriguing living fossil is the coelacanth. The large fish looks unremarkable at first glance, but it has fascinated scientists for decades for the insight it provides into evolution. The fish was believed to have been extinct millions of years ago until it was spotted in the 1930s. Researchers are still learning about the fish’s unique traits that have allowed the species to survive for over 360 million years. Coelacanths are massive, growing up to 6 and a half feet long and 200 pounds. They are the longest-living fish species on record, with lifespans of up to 84 years. The fish also grow extremely slowly, not reaching sexual maturity until their 40s or 50s. Coelacanths have four fins on the bottom of their body that move like land animals’ limbs and give birth to live offspring rather than eggs like other fish.

Even the Deepest Parts of the Sea Are Polluted

Unfortunately, there is no part of the planet that is safe from human pollution, not even the depths of the ocean. A 2017 study found chemicals that enter the water decades before are still present in deep-sea water. Even worse, the toxic chemicals had seeped into the tissue of some of the animals that make call the ocean home. And because these pollutants are biodegradable, they are likely to persist in the environment indefinitely, causing unknown harm to the ecosystem.

A 2018 expedition discovered trash and microplastics in the Mariana Trench, which contains the lowest point on Earth’s surface and has been protected by international law as a U.S. national monument since 2009. The extent of the pollution in the trench and other deep-sea locations is unknown, but any level of contamination could disrupt the marine life that has flourished there for eons. Without efforts to protect the deep sea, we could lose the oldest ecosystems on Earth.

Where Do We Find This Stuff? Here Are Our Sources:

Ten things you never knew about the ocean’s deepest places

Amazing Facts – Deep Sea Conservation Coalition

9 strange deep sea creatures you want to know

The deepest-dwelling fish in the sea is small, pink and delicate

16 creatures from the bottom of the ocean that will give you nightmares

The Deep Sea | Smithsonian Ocean