Down here the light doesn’t reach, but there’s a different kind
of light, a hum of luminescent bodies in startling configurations:
the twinkling jelly, coral lit up like its own galaxy
against the dark. We make our way according to their signals,
following each beacon into the secret depths of the world.
This far below the surface we can finally admit
how little we really know — and in these lives so different
from our own, we begin to truly recognize
— Matthew Kosinski
This month, in honor of Waves, we’re diving to the deepest depths of the sea to explore the surprising — and sometimes upsetting — secrets it contains.
More than 70 percent of this planet is water — and we know almost nothing about it.
Not that we haven’t been trying. People have been practicing some form of oceanography — the study of the sea — since essentially the moment we first laid eyes on the vast ocean. The earliest seafarers, the Austronesian peoples, first developed the technology to travel long distances on the high seas around 3,000 B.C. Setting out from what is now Taiwan, they charted courses, discovered islands, and settled throughout the Indian and Pacific Oceans, often assimilating with the indigenous communities they found there. Up until the colonial era, the Austronesian peoples were the most widespread group of people with a shared linguistic history on the planet.1
Much later, oceanography of the more formally scientific tradition arose with British explorer Captain James Cook, who mapped much of the world’s uncharted waters in the 18th century. Following in his footsteps in the 19th century, Sir Charles Wyville Thomson sailed to every ocean in the world, collecting marine specimens, recording currents and temperatures, and disproving a then-popular theory that life did not exist deeper than 1,800 feet below the ocean’s surface. The 50 volumes’ worth of data generated by Thomson’s expedition are still used as reference texts by oceanographers today.2
The crew of Sir Thomson’s expedition, pictured in 1874; Source: Wikipedia
Our technology has advanced by leaps and bounds in the ensuing years, but in many ways, we’re not much further along than we were in the days of the original Austronesian excursions — especially when it comes to the deep sea. In fact, more than 80 percent of the ocean floor remains unmapped.3
In the words of Robert Ballard — the ocean explorer who discovered the wreck of the Titanic — “We know less about 71 percent of the Earth’s landscape than about the far side of the Moon. That’s a lot of terra incognita.”4
Curiously enough, if we did know more about the ocean, we might know even more about the moon, too. Or at least about some of the other celestial bodies with which we share this galaxy. As we'll cover, it’s thanks to some deep sea research that scientists uncovered one possible form of life on Mars.
The wreck of the Titanic; Source: Wikipedia
As Above, So Below
The abyssal zone — those bands of ocean between roughly 6,600 feet and 20,000 feet deep — is about as deep underwater as you can get. At 115 million square miles in total area, it is also the largest environment for life on Earth.5
But the life that thrives in these dark stretches of sea is very different from what we’re used to here on the surface.
Most life on Earth depends on the sun. Plants photosynthesize sunlight into energy, and the plants are in turn eaten by animals, which are eaten by other animals, and so on. Yet sunlight can rarely reach much deeper than 656 feet below the ocean’s surface.6 So how do massive creatures like the nearly eight-foot giant tube worm flourish on the ocean floor?
“The life that thrives in these dark stretches of sea is very different from what we’re used to here on the surface.”
A hydrothermal vent in the Pacific Ocean; USGS.gov
The answer is chemosynthesis, the creation of energy from inorganic substances like hydrogen sulfide, which is deadly to most forms of life.
Scientists long assumed that nothing could live in the deepest parts of the ocean. Then, in 1977, researchers exploring the Galápagos Rift made a surprising discovery: life. And lots of it. These bustling communities of creatures clustered around hydrothermal vents, essentially geysers along the ocean floor. The water spewing out of these vents was laden with toxic minerals from the earth’s crust, which should have foreclosed all possibility of life in the vicinity.7
The giant tube worm thrives around hydrothermal vents, thanks to a symbiotic relationship with chemosynthetic bacteria; Wikipedia
Scientists struggled to come up with an explanation, but microbiologist Colleen Cavanaugh posited chemosynthesis as a possible answer. According to Cavanaugh’s theory, bacteria around the hydrothermal vents were feeding on toxic minerals. In turn, the tube worms, snails, and other deep sea animals derived their nutrients from the bacteria, creating the basis of a parallel food web. Eventually, research would confirm Cavanaugh’s theory.8
The discovery of life that can subsist on inorganic material has massive implications not only for our understanding of the planet we inhabit, but also for our understanding of the entire universe. It may even point to life on Mars. Researchers have noted that while the surface of Mars is inhospitable, radioactive elements in the planet’s crust could break water molecules down into hydrogen and oxygen, giving chemosynthetic bacteria something to feast on.9
That’s not to say there’s definitely life on Mars today — just that there could be, or at least could have been some time in the past. And the secret to uncovering this possibility was right under the sea all along.
Scientists aren’t certain whether there’s liquid water on Mars, but they’ve discovered plenty of ice; Science Alert
You Can't Manage What You Can’t Measure
Of course, there are also more immediately practical reasons to pay attention to the deep sea. For example, better maps of the ocean floor could help us track underwater landslides, which are important warning signs before some tsunamis.10
Moreover, despite its apparent isolation, the deep sea is just as affected by climate change as every other part of the planet. Unfortunately, our lack of information about the deep sea makes it hard for us to understand and respond to the exact nature of the impact.
As we covered in last year’s Ignite series, the ocean is a vital defense against climate change. Seawater absorbs a tremendous amount of ambient heat in the atmosphere. Microorganisms in the deep sea convert carbon and methane, two leading factors in climate change, into minerals, effectively removing these gases from the air and trapping them underwater. To paraphrase the Ocean and Climate Platform, a network of scientists and political bodies dedicated to understanding the impact of climate change on the ocean, it is in large part thanks to the deep sea that climate change is “still bearable” at this moment in time.11
A vampire squid flits through particles of “marine snow,” a crucial source of nutrients for deep sea life; Source: Forbes
But climate change threatens to upend the entire oceanic ecosystem, starting at the surface. A lot of deep sea life derives nutrients from “marine snow,” a “rain of organic matter” that trickles down from the surface of the sea. The snow is largely composed of plankton, dead animals, and other organic materials. As life dies out at the surface, less and less snow falls to the depths, severely restricting a vital food supply for undersea animals.12
Similarly, the warming waters of the ocean’s surface don’t mix as freely with the colder, deeper waters. The problem here is that those upper levels of water contain more oxygen, and the mixing of surface water and deep water is crucial to keeping the oxygen flowing in underwater environments.13
“Animals living on the deep sea floor are relatively isolated from environmental change,” says marine ecologist Andrew Sweetman. “Most of the animals have adapted strategies for living under constant environmental conditions where the oxygen doesn’t change over hundreds of years, the temperature doesn’t change over hundreds to thousands of years. It is very unlikely that they are going to be able to adapt [to climate change].”14
The dumbo octopus — named after the Disney film Dumbo — is one of many deep sea creatures threatened by climate change; Source: Wikipedia
As Sweetman’s comments imply, scientists know the deep sea will be hit hard by climate change, but they’re not exactly sure what to expect. The lack of research into the deep sea means that we don’t have much of a baseline to measure changes against. That makes it incredibly hard, if not altogether impossible, to pinpoint warning signs or even devise plans for protecting the abyssal environment.15
Who’s Going to Take Responsibility?
The problem of climate change in deep sea environments also exposes the inadequacy of our anthropocentric view of the planet. Sixty-four percent of the deep sea lies beyond national boundaries, meaning it is under no nation’s jurisdiction. As a result, political leaders are by and large reluctant to lead the charge when it comes to studying and protecting the open ocean.16
Of course, the Earth doesn’t really care where we’ve drawn our national borders. Climate change has already shown us that: Even though developed nations produce most of the emissions driving the phenomenon, developing nations are bearing the brunt of the environmental damage.17 The same holds true for the ocean floor: Whether we “own” it or not, what we’re doing on dry land affects it deeply, often in dangerous ways.
Some species of deep sea corals glow in the dark. By absorbing and amplifying the slim amount of light that reaches below the water’s surface, these coral species give photosynthetic algae a source of energy; Source: Gizmodo
The good news is that, in recent years, some scientists and political operatives have started taking steps to address what they call the “policy vacuum” surrounding deep sea conservation.18 For example, the Biodiversity Beyond National Jurisdictions treaty currently being negotiated in the United Nations would help establish marine protected zones, create channels for collaboration between scientists to study the deep sea more closely, and develop standards for deep sea management.19
It remains to be seen exactly how this UN treaty will play out, but one thing is for sure: If we want to preserve the stunning, otherworldly ecosystems of the deep sea, we’ll need to trade human-centric thinking for a much more holistic worldview that sees how every part of the planet is connected to every other part — arbitrary national boundaries be damned.
“How should we relate to that which we don’t yet understand? How should we value the mysteries of the world?”
In addition to matters of ownership, the vast secrets of the deep sea pose a more philosophical — but no less pertinent — set of questions for humankind: How should we relate to that which we don’t yet understand? How should we value the mysteries of the world?
It’s possible an array of hidden treasures and natural miracles are waiting to be discovered in the darkest parts of the sea. Indeed, many of the scientists pushing for more investment in deep sea research stress that the genetic diversity of yet-to-be studied oceanic life could hold keys to new advances in medicine and the sustainable management of our natural resources. If we choose to look away from the unknown, we may never find out what it has to tell us.