These strange underwater animals could save our lives. If we don’t destroy them first.

In 1987, the Food and Drug Administration (FDA) approved the world’s first medication to treat HIV. The drug, known as AZT, was a beacon of hope for the millions of people who were living with the virus. It helped lengthen countless lives.

In 2010, the agency approved a drug called Halaven to treat advanced breast cancer. In a clinical study, people who took the drug lived, on average, 25 percent longer than those who received other anticancer treatments, according to the drug’s maker.

In 2020, the FDA approved Remdesivir to treat Covid-19. The drug is given intravenously, making it harder to access than some other antivirals, but research indicates that it dramatically reduces the risk of death in patients hospitalized with the infection. A 2020 trial of more than 1,000 people hospitalized with Covid-19 found that remdesivir significantly reduced their risk of dying, and those who took it recovered faster.

These drugs have one thing in common: They are derived from a sponge. Yes, a sponge. Or more specifically, a sea sponge.

Sea sponges, a kind of aquatic animal found in oceans and some lakes, may look blobbish. They may live in the shadows of more picturesque corals and fish. Yet sponges are some of the most important animals on Earth. They not only provide homes for countless other critters, but they’re a living pharmacy that helps save human lives. They produce more chemical compounds than most (if not all) other animals on the planet, and many of those chemicals possess anticancer, antiviral, antimalarial, and antibacterial properties.

That’s what makes this so concerning: Troves of these creatures could soon be stamped out. As demand for clean technologies rises, so does the need for more metals such as nickel and cobalt. Companies and countries are now looking to the deep sea as a potential place to mine them, yet this region — though perceived by some as desolate — is full of sponges. Most of those sponges have yet to be studied, their chemical compounds still unknown.

This has created a complex conundrum: Deep-sea metals are essential to the fight against climate change, and climate change harms wildlife. But those sponges, and other animals of the deep sea, may be essential, too, by helping to treat human ailments. Is it worth sacrificing these animals when scientists don’t even know what they do?

What even is a sponge?

Before there were dinosaurs, there were sponges. They’ve lived on Earth for hundreds of millions of years, making them one of the oldest — if not the oldest — animals on the planet. That means sponges have had plenty of time to evolve clever adaptations to life in the world’s oceans and lakes.

Most of the roughly 15,000 known sponge species feed by pumping water through their bodies and filtering out tiny organisms. A sponge the size of a milk carton can filter a swimming pool worth of water every day, said Chris Freeman, a marine ecologist at the College of Charleston. They’re basically Britas of the sea. You can actually see these pumps in action when divers inject fluorescent dye around the base of a sponge:

Some sponges, meanwhile, are carnivorous: They eat meat. These include the unusually shaped and aptly named ping-pong tree sponge and harp sponge, shown below. These related sponges, found in the deep sea, are covered in barbed, Velcro-like hooks, which they use to ensnare tiny crustaceans that are swept into them by ocean currents. The sponges then absorb these animals into their bodies. (It’s not clear why they take such odd shapes, but it may help them capture food or reproduce.)

There are also glass sponges — sponges that build skeletons out of silica, likely as a form of protection. Most remarkable is a glass sponge known as Venus’s flower basket, which has been shown to house a mated pair of shrimp inside its intricate glass structure. The shrimp enter when they’re young and small enough to squeeze through openings in the structure, but as they grow up they become too big to escape. They spend their lives caged inside the sponge’s skeleton.

It’s beneficial imprisonment. In exchange for cleaning the sponge, the shrimp are given food (sponge excrement) and a safe place to live. And when they procreate, their babies are small enough to escape, pair up, and search for their own glass homes.

The deep-sea mining conundrum

Many of these sponges live among other weird creatures in the deep sea, hundreds of feet down, far away from humans. The region has long been left alone, its depths inaccessible to scuba divers and left unexploited by miners — until now.

As the world moves away from fossil fuels and toward cleaner technologies, it relies more and more on batteries, like those you find in electric cars. This, of course, is a good thing for a planet threatened by climate change. But even green technologies require inputs including metals like cobalt, manganese, and nickel.

That’s where the deep sea comes in. Scientists have known for decades that the sea floor is laden with mineral deposits that are embedded in rocks, some of which are just sitting on the seabed. These deposits are difficult and expensive to harvest, yet rising demand for metals has made the business case for it more compelling. Many companies and countries are already gearing up to mine, especially in the Clarion-Clipperton Zone, a large patch of ocean that lies between Hawaii and Mexico.

Courtesy of MBARI

Companies have argued that deep-sea mining — which can entail sinking large tractor-like machines to vacuum up mineral-rich rocks — would be less harmful to the environment than existing mining operations. There’s no doubt that mining minerals like cobalt on land has a long history of environmental destruction and human rights abuses. Exploiting the deep sea, those companies say, is a better alternative, even though it will damage the environment.

The problem with those arguments is that they assume the deep sea is relatively lifeless, that there’s not much to lose. It’s true that these potential mining hot spots lack iconic underwater landscapes like vibrant coral reefs or kelp forests. But what they do have is lots of marine sponges. A recent study, for example, suggests that sponges are among the most common animals in the Clarion-Clipperton Zone. Some of them live directly on top of the very mineral deposits that companies want to extract.

What’s there to lose? Potential life-saving compounds.

In any given CVS or Walgreens pharmacy, there are lots of drugs that come from plants, animals, or microorganisms. Aspirin, for example, is derived from the bark of a willow tree. “Nature has been a source of most drugs currently in use,” said Bill Baker, an expert in natural chemicals at the University of South Florida, referring to both compounds found in nature and those that were inspired by the structure or behavior of natural chemicals.

On land, plants are the standout source of medical compounds, partly because humans have been using them as natural remedies for centuries. But at sea, it’s sponges; they’re the “dominant source” of marine chemicals, Baker said.

Like plants, sponges are stuck in place, so they use chemicals to defend themselves from predators and other potential attackers. Pumping all that water also means they’re exposed to huge amounts of viruses and pathogens that may try to harm them. Chemicals, again, are their defense.

And they produce a lot of them. In the last 50 years or so, scientists have discovered more than 10,000 new chemical compounds from sponges, according to one 2019 paper. That amounts to roughly a quarter of all the compounds found in the marine realm to date, Baker said. It’s a lot.

A more recent review found that, within the last decade alone, researchers have documented more than 2,700 new sponge compounds. Importantly, roughly half of them have been shown to have properties that make them potentially useful to medicine, from fighting cancer cells and tumors to resisting malaria and bacterial infections. What’s especially fascinating is that many of these useful compounds are actually produced by bacteria or other microorganisms that live within sponges and make up their microbiome.

Only a handful of these sponge compounds or their derivatives are actually on the market today as commercial drugs including Halaven and Remdesivir. The drug development process can take a few decades, Baker said, and scientists really only started exploring the ocean for drugs in the 1980s.

This is an important point: The ocean is still largely unexplored, especially places that are hard to reach like the deep sea. “We’ve only sampled the low-hanging fruit,” he said. In the Clarion-Clipperton Zone, for example, scientists don’t even know what lives there, let alone what chemical properties those animals possess. Recent studies suggest that 90 percent of the region’s species are not yet known to science.

The limited research that does exist indicates that deep-sea sponges may possess chemicals that help combat bacterial resistance and forms of cancer. And so a big concern is that mining in a place like the Clarion-Clipperton Zone could destroy unknown sources of lifesaving medicines.

Put another way: It’s not clear what there is to lose. This is true not only in the deep sea but in all kinds of ecosystems, from rainforests to prairies to coral reefs.

“We’re destroying biodiversity as rapidly as we can,” said Eric Schmidt, a professor of medicinal chemistry at the University of Utah. “Commonly, when you investigate a new species, new molecules are found with unknown potential. So there’s a chance that we don’t know even what we’re destroying.”