NEW YORK — An underwater voyage revealed a network of creatures thriving at the bottom of deep-sea ocean trenches.

A submersible that is used to hunt for life in deep-sea trenches.
In these extreme environments, the crushing pressure, scant food and lack of sunlight can make it hard to survive. Scientists know that tiny microbes prosper there, but less is known about evidence of larger marine life.
Researchers traveling along the Kuril–Kamchatka and Aleutian trenches in the northwest Pacific Ocean used a submersible to find tubeworms and mollusks flourishing at over 31,000 feet deep. The deepest part of the ocean goes down to about 36,000 feet.

Tubeworms are seen in an ocean trench.
Scientists surveyed this area before and had hints that larger creatures might live at such depths. The new discovery confirms those suspicions and shows just how extensive the communities are, said Julie Huber, a deep sea microbiologist with Woods Hole Oceanographic Institution.
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Mollusks are seen in an ocean trench.
"Look how many there are, look how deep they are," said Huber, who was not involved with the research. "They don't all look the same and they're in a place that we haven't had good access to before."
The findings were published in the journal Nature.

Worms and mollusks are seen in an ocean trench.
In the absence of light to make their own food, many trench-dwellers big and small survive on key elements like carbon that trickle down from higher in the ocean.
Scientists think microbes in this new network may instead be capitalizing on carbon that's accumulated in the trench over time, processing it to create chemicals that seep through cracks in the ocean floor. The tubeworms and mollusks may survive by eating those tiny creatures or living with them and snacking on the products of their labor, scientists said.
With this discovery, future studies will focus on how these deep-sea creatures adapted to survive in such extreme conditions and how exactly they harness chemical reactions for food, study authors Mengran Du with the Chinese Academy of Sciences and Vladimir Mordukhovich with the Russian Academy of Sciences said in a statement.
Their existence challenges "long-standing assumptions about life's potential at extreme depths," the authors said.
5 things you might not know about sharks
1. Humans vs. sharks
When it comes to humans versus sharks, the numbers are staggering. An average of 6 humans are killed worldwide each year by sharks, while humans kill 100 million to 273 million sharks annually, selling their body parts in markets around the globe.

A surfer rides the waves along Mexico's Pacific Coast near El Rancho village, Wednesday, May 28, 2008. Sharks have attacked three surfers in the area in less than a month, two fatally. (AP Photo/Eduardo Verdugo)
2. They're old
Sharks were swimming in the ocean depths long before dinosaurs climbed onto land. Researchers say sharks date back 400 million years.

In this March 16, 2011, photo children look at the Shark Jaw of a Megalodon, a prehistoric shark, at the Museum of Nature and Science in Dallas. The jaw is 11 feet wide and almost 9 feet tall, it consists of 182 teeth collected from South Carolina rivers. (AP Photo/Rich Matthews)
3. 465 species
There are 465 known species of sharks, ranging from the tiny spined pygmy shark (about 8 inches long) to the whale shark (about 50 feet in length). Each of these sharks plays a role in keeping other fish populations in check, which is why hunting and killing of sharks can create great imbalances in ocean life.

A diver feeds fish to a male whale shark at the Hakkeijima Sea Paradise aquarium-amusement park complex in Yokohama near Tokyo, Saturday, June 11, 2011.(AP Photo/Itsuo Inouye)
4. Not a 'miracle of evolution'
Richard Dreyfuss' character in "Jaws" claimed that the shark is "a miracle of evolution," and that the only thing it does is "swim and eat and make little sharks, that's all." That's not exactly correct.
Sharks have to eat, like every other living organism, but they don't mate until they are 12 to 15 years old. The females give birth to one or two pups at a time, making it difficult for the sharks' reproduction rates to keep pace with the annual kill rates.

FILE - In this Tuesday, July 3, 2012 photo, Rima Jabado, a marine scientist and shark researcher pulls up a baby spottail shark from the water for the tagging off the Dubai coast, United Arab Emirates. (AP Photo/Kamran Jebreili, File)
5. A sixth sense
Sharks are extraordinary hunters, who use six senses. In addition to smell, hearing, touch, taste and sight, they also are gifted with electroreception — special pores around their faces detect electrical currents from other organisms and allow them to deftly hone in on their prey.

A Sand Tiger Shark swims in its aquarium at the Zoo-Aquarium in Berlin, Germany, Tuesday, Nov. 9, 2010. (AP Photo/Michael Sohn)
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