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Woods Hole scientists exploring what's inside the ocean's 'twilight zone'

The mystery of the ocean's "twilight zone" is being uncovered by scientists
The mystery of the ocean's "twilight zone" is being uncovered by scientists 04:02

FALMOUTH -- The story of the ocean is one of depths and mysteries as vast as space, where more is unknown than understood. 

This story specifically, though, is about a place where light and shadow meet, and the layer in which creatures are straight out of your imagination. The next stop on our journey is the ocean twilight zone.

The ocean twilight zone is a layer of the deep sea between 650 and 3,500 feet. It's nicknamed the "twilight zone" because light from above doesn't exist. 

"It's deep down, it's dark... it's cold," said Heidi Sosik, the lead scientist for Woods Hole Oceanographic Institution's Ocean Twilight Zone Project. 

The only light that you'd see is from bioluminescent creatures in this foreign world. 

"The ocean twilight zone is full of diversity. We have amazing life forms that we've never seen. Creatures from specialized bacteria to fish that have adaptations to live in a place where it's hard to get food," said Sosik. "We also now know that many top predators like whales and sharks actually spend a lot of time deep down in the twilight zone. They're able to dive down and feed on this amazing biomass."

In the past, scientists were only concerned with the top and bottom of the ocean. Recently, they have started unlocking the significance of this gateway to deeper water. 

"The more we learn, the more we know it plays a big role in global processes like the water cycle, the nutrient cycle, and the carbon cycle," said Sosik. 

The role the oceans play in our climate can't be understated. Two out of every three breaths humans take come from the ocean. Oceans also contain a huge amount of carbon -- almost 50 times more than in the atmosphere. Getting carbon to the bottom of the ocean keeps it sequestered for thousands of years. 

Ken Buessler, a scientist with Woods Hole, says sending carbon to the abyss starts with a bunch of hungry animals feasting on phytoplankton.

"They come up to eat plant matter and carry that carbon down with them.  It's the largest migration on the planet. Trillions of small, tiny animals and the fish that eat them move up and down every day," Buessler said.

The carbon doesn't actually get to the bottom until these animals poop. The result looks like a blizzard. 

"All that material becomes marine snow. This distributed rainfall of organic debris, carbon-based material that settles in the deep ocean," Buessler said. 

And this makes up a tons of carbon -- up to 3.6 BILLION metric tons. That's as much as all the United States vehicle emissions getting to the bottom. 

That number could be even higher. A recent study estimated there could be 10 times the amount of animals in organisms in the ocean twilight zone than previously thought. 

"The ocean is so fascinating but it's such a mystery to us. It really is one of the last frontiers. In a lot of ways. we know less about our own ocean than we do about the moon or Mars," Sosik said.

So more animals, more feasting, more marine snow leads to more evidence that understanding the ocean twilight zone will give us a clearer picture of our climate future on land. 

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