Deep down into the sea, 200 to500 feet belowthe surface, lifeforms flourishwhere they shouldn’t. Down here, little light penetrates, which is somewhatof a problem for solar-powered beings like coral. Yet here, stubbornly, the reefsstill sprawl, supporting hordes of fish and invertebrates, forming an ecosystem thats almost totally foreign to science. This is the mysterious twilight zone.
For a long time, researchers have considered this place too deep for traditional scubadiving and too shallow to justify exploring with expensive submersibles.But thanks to some fancy new technology, researchers at the California Academy of Sciences are beginning to dive to the twilight zone, observing and collecting its many bizarre denizens. And on Friday, theyre bringing the mysterious reefs to you and me with an unprecedented exhibit in San Francisco. If youre not one of the handful of people in the world trained to dive 400 feet deep( where the pressure is nearly 200 pounds per square inch, by the way) for seven hours at a time, this is your glimpse at one of countries around the world least-understood ecosystems.
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Caption: The deep reef might lie in the darkness, but it still explosions with color.Kathryn Whitney/ California Acade
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Caption: It’s a surprisingly complex ecosystem teeming with life.Kathryn Whitney/ California Acade
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Caption: The fish Bodianus izuensis( left) and Sacura speciosa call the deep reef home.Kathryn Whitney/ California Acade
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Caption: Kathryn Whitney/ California Acade
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Caption: Luiz Rocha
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Caption: Corals go about life a bit differently down here. Instead of relying on sunlight, they snag plankton floating by.Luiz Rocha
What induces this all possible is a device called a rebreather. With regular scuba gear, you can last around an hour exhaling a mix of nitrogen and oxygen. But at these depths, instead of breathing nitrogen, divers must exhale helium. If we exhale nitrogen, which is what most of the air we breathe is composed of, it induces us drunk, says Luiz Rocha, the curator of fishes at the Academy. And we won’t want to be drunk at 400 feet.
The problem is, helium is a wildly expensive gas. So the divers recycle it. There’s a canister on our back that filters the carbon dioxide out, and then we keep breathing the same helium over and over again and add oxygen as we need it, says Rocha. This significantly boosts their time in the water.
Descending into the depths by way of a handy scooter.Luiz Rocha
For all of the lovely technology, though, the divers still run smack into the limitations of the human body. Running down that deep means youll get the bends( the excruciating formation of bubbles in the blood stream) if you ascend too quickly. So the divers have to come up very, very carefully, stopping at predetermined depths for predetermined quantities of day. The closer you get to the surface, the longer you wait–two hours at a depth of 35 feet.
Fish have the same problem: They’re equipped with a gas-filled organ called a swim bladder that helps keep them neutrally buoyant. If divers ascend too quickly with fish in hand, that organ will swell and push the stomach out of the beings mouth. Not ideal for a specimen destined for an aquarium.
Typically fishermen will deflate swollen fish by puncturing them with a needle. I’m an aquarium guy, so I don’t like to poke holes in fish if I can avoid it, says Bart Shepherd, director of the Academys Steinhart Aquarium. So we developed our own technology, a submersible portable decompression chamber that we actually dive with. The divers just stuff it with fish and seal it.
Academy scientists developed their own mini decompression chamber to transport the sensitive specimens to the surface.Steven Bedard
Back on the surface, technicians slowly equalize the pressure to acclimate the specimens to conditions theyll find at the aquarium. This entails the aquarium doesn’t have to futz with the pressure in the tanks, although they do “re going to have to” nail the lighting and temperature, of course.
Perhaps the most enchanting of thefinds you can see are bottom-dwelling beings called ctenophores, which really aren’t meant to be bottom-dwelling. These are gelatinous animals that typically swim around hoovering up plankton. But this assortment sits tight and unfurls long lines to snag its prey , no swimming involved. The Academys scientists have taken to calling the vivid critters sea Peeps, though Ill note that eating them would demonstrate a mistake.
Ctenophores, aka ocean Peeps, from the deep reef.Kathryn Whitney/ California Acade
The exhibit also features the deep reef’s corals–and the secret to how this ecosystem manages to churn in the darkness. Whereas corals in the shallows rely on symbiotic solar-powered algae for energy, the corals in the deep are hunters. Well, passive hunters, snagging plankton as it floats by, but hunters nonetheless. They form the basis of this lively ecosystem.
Collecting specimens like this is pivotal to understanding a habitat thats largely a mystery to science, especially one as fragile as a reef. The great question now is if deep reefs face the same crisis as shallow ones: the coral bleaching, the overfishing, the pollution. Divers already find fishing lines caught up in these deep reefs.
And thats not all. One of the most disconcerting things I’ve ever seen on a dive was a folded up, employed nappy sitting on the bottom at about 330 feet, says Shepherd.Soiled nappies aside, the good news is the twilight zone is now within sciences reach.
