The final human migration may be to the deep.
The sea levels are rising, fast, and we are doing as close to nothing about it as is possibly conceivable. Thus, we humans are bracing for adaptation, but we've no idea how far we might need to adapt. This week, Lorraine Schein imagines the ultimate adaptation—and the ultimate migration. Our final journey, after the land is washed over, may be below. Enjoy. -the Ed.
Epipelagic (sunlight/photic): from the surface to 660 feet down. The illuminated zone at the surface of the sea where enough sunlight is available for photosynthesis.
The sun sank below the horizon, a bright coral reef that cast spines of wavering red light on the gray water.
"Will I ever see the sun again?" Katexa thought as she lowered herself into the Bathystar's left arm, and closed the hatch. She hoped this was the way to save her stubborn family.
She had argued with them before she left.
"Katexa," her mother had said. "We know the sea is rising again. But our clan vowed not to abandon the land, you know this. We stay human, as long as we stay above."
Her family was among the last humans to defy the ocean's relentless advance, and now even the small island they lived on was being eroded.
There was still one hope, Katexa knew, blasphemous as it was—she had read the archives and knew of the others. They could migrate to the ocean's depths, if the Bathystar still worked well enough.
The archives were clear: Though the oceans had become filled with dead zones where no fish or sea life survived, and the melting of the polar ice caps had flooded homes on land so many times, a contingent of pioneering land humans had set off to establish a colony in the sea's depths. No further record of them remained, only stories.
Their only option might be to descend.
Which is why she had to go first, to prove to her family there was another way.
Mesopelagic (twilight) from 660 ft. down to 3,300 ft. The name for this zone stems from the Greek; meson, meaning middle. Although some light penetrates this second layer, it is insufficient for photosynthesis. At about 500 m the water also becomes depleted of oxygen. Organisms survive this environment by having efficient gills or minimizing movement. Many organisms that live here are bioluminescent.
Katexa had heard those stories many times: How humans first descended after the Great Floods that came to cover most of the Earth, going down in heavy individual submarines shaped like coffins, cushioned submarines that could be lived in, built to withstand the enormous pressure of life at the bottom of the sea.
Less than 2 percent of the ocean floor had been explored before then, but necessity drove the desperate deeper. Tired of the hardships of life on dwindling land and the constant floods, some had decided to stay in the depths, becoming Abyssals—those living in the Abyssal zone, the deepest part of the sea. Through bioengineering and adaptation, they evolved into deep sea creatures.
Her grandmother had told Katexa that even one of their own ancestors had become Abyssal. But her mother and father would say nothing on the subject.
The Bathystars now sat mostly idle. These were plankotech versions of the ancient Bathysphere (from the Greek: bathus, "deep" and sphaira, "sphere"), an air-filled submersible ball lowered into the ocean on a cable.
The Bathystar was also spherical, its center built to resist enormous pressure. It had five protrusions, like the arms of a five-pointed star that rotated it through the water slowly but efficiently. There were window-like gills in these arms, and each one was a room.
Katexa was the only one who still piloted them, for short trips between islands.
Katexa had kissed her mother and hugged her sister goodbye. She had prepared for her descent for months, wearing a face mask that shut out most of the light, and never going out during the day, avoiding the sun.
The Bathystar floated, dipping below her. She climbed into the hatch of the top star-arm, and it hissed shut above her. She hoisted herself into the steering seat and found the controls.
She set the course for down, further down than she'd ever gone.
Abyssopelagic (lower midnight): Abyssal zone from 13,000 ft. down to above the ocean floor. The name is derived from Greek (ábyssos), meaning "bottomless" (from the time when the deep ocean, or abyss, was believed to be bottomless). Very few creatures live in the cold temperatures, high pressures and complete darkness of this depth.
At first the waters were almost totally dark, only lit by the top lights of the Bathystar. Then Katexa saw a school of lantern fish, bodies glowing gently, swimming up to the surface in search of food. Since they only fed at night, she didn't have to look at her diurnalband to know that meant it must be night above-world. Next a baitball of flashlight fish passed by, the lights under their eyes blinking in a glowing-green Morse code, and luminous plankton that looked like little stars. She put on a head lantern until her eyes soon got used to dark.
Her bed was in the second arm of the Bathystar; a small kitchen with a cabinet stocked with condensed nonperishables and a tank for purifying the water from outside were in the third. It was hard to tell how much time had passed. Fading at last, Katexa climbed into bed, and fell asleep.
When she awoke, she made her way back to the control room when she saw it and gasped.
The Transparensea bobbed above her in the Bathystar's clear arm, glowing, a transparent floating ghost—its abdominal skin so thin she could see its heart, liver and intestines. It was a radiant green, because it had just been eating a meal of marine ferns and sea caterpillars.
Katexa had descended deeper, deeper than anyone from her clan ever had before, and this was her reward.
The creature's head tilted toward her as she steered past it. Its skull was translucent, but she could still see the outline of a blue whorled brain, crossed by faint sparking synapses. The Transparensea looked like her sister in profile, but then it turned and she saw it had no eyes--just luminous oval hollows where they should be.
She stammered out a greeting into the microphone, but though it halted and seemed to listen, it soon floated away.
Maybe they no longer understand human speech, as we have not yet learned theirs of ripples and dark light, she thought. One day her descendants might forget land speech too. Katexa wondered if people would be happier then. She smiled, imagining her family communicating this way.
Could this be the ancestor her grandmother had told her stories of? Then maybe in time and with genetic engineering, her family could become a new generation of Abyssals, look like them. She had heard them described as ugly, but she thought the creature eerily beautiful.
Hadopelagic: Hadal zone. Waters below 20,000 ft. The deep water in ocean trenches. The name is derived from the realm of Hades, the underworld in Greek mythology. This zone is mostly unknown, and very few species are known to live here. However, many organisms live in hydrothermal vents. The abyssal plain is covered with soft sludge composed of dead organisms from above.
Creatures become more than eyeless here. They are formless, eat sludge and sleep under eons of decayed dead. They crawl and breathe in the crevices of time.
Katexa wrote in the Bathystar's log: I miss land and trees with roots. And natural light. In the dark sea that surrounds me, I long for the sun. And earth, before the waters came.
The Transparensea hovered over the Bathystar, pressed its sinuous face against the clear curvature of the bed-arm as she slept.
One day we will rise again, grow fins, then legs. The words flowed, bubbled into the space between her mind and its floating.
It has been said that more is known about the Moon than the deepest parts of the ocean.