They might not look like anything fancy – indeed, they often look more like a glamorous rock or a strange seaweed than an animal – but a humble sea sponge might someday save your life. This broad bag of organisms produces an unknowable variety of antibacterial, antiviral, antifungal, antimalarial, or anti-inflammation chemicals, making them fascinating candidates for drugs of the future.
Unfortunately, humanity has been acting recklessly with this natural resource and we now run the risk of destroying many would-be savior sponges before we understand their full potential.
Marine sponges are amorphous creatures, extremely varied in their form, that stay fixed to the seafloor. They lack complex nervous systems, digestive systems, or circulatory systems. However, they shouldn’t be mistaken for a plant or a pretty rock – they actually belong to one of the oldest lineages of animals on the planet.
There are well over 5,000 described sponge species found across Earth’s seas (and some of its freshwaters), but there are likely to be thousands more that scientists have not yet documented, each potentially brimming with benefits. It’s estimated that over 200 new bioactive chemicals are discovered in sea sponges every single year, some of which have already proved to be useful medicines in recent decades.
The first sponge-derived medicine was approved by the FDA in 1969 in the form of a compound isolated from a demosponge called Tectitethya crypta. Known as cytarabine, scientists used the compound to form the basis of a drug that blocks DNA replication in leukemia and lymphoma tumors, effectively killing the cancer. Still to this day, it’s one of the central treatment options for leukemia patients.
In 1981, acyclovir – an antiviral compound harnessed from a Caribbean sponge – was approved to treat herpes, chickenpox, and shingles. Later in that decade, the FDA approved the world’s first medication to treat HIV, known as AZT, which was derived from chemicals pumped out by a sponge.
Even today, scientists are utilizing these sponges to discover new drugs. In October 2023, researchers showed that a Mauritian marine sponge, Neopetrosia exigua, produces bioactive agents that can selectively kill liver cancer cells with minimal harm to healthy cells.
Another promising avenue is using sea sponges to identify new antibiotic drugs, which could help ease the looming problem of antibiotic resistance.
“The deep sea comprises the vast majority of the world’s microbiome. But the majority of our antibiotic research has focused [on the] land-based microbiome, so there’s huge potential for potential novel antibiotics from deep sea sources. Sea sponges harbor huge colonies of novel bacteria species which are competing for nutrients, and producing antibiotics to fend off the competition,” Dr Eleanor Best, a veterinary surgeon at the University of Bristol who’s researching new antibiotic opportunities, said in a statement earlier this year.
You might think it would be wise to guard this “pharmacy of the oceans” with all our energy and dedication. However, mounting industrial activity is posing an existential threat to many sponge species, both known and unknown.
In May 2023, scientists announced they had discovered over 5,000 new marine species, including many sea sponges, in a patch of sea known as the Clarion-Clipperton Zone (CCZ), located in the central and eastern Pacific between Mexico and Hawaii.
Unfortunately, this area is in the sights of deep-sea mining operations because it holds the world’s largest trove of manganese, nickel, cobalt, and other metals that are crucial for making batteries. If deep-sea mining goes ahead, it could prove devastating for the ecosystem and its much-needed sponges.
Beyond the CCZ, sea sponge diversity is also being threatened by infrastructure development, pollution, and climate change. The good news is that sea sponges are remarkably resilient to low oxygen and warming waters, meaning they might be able to tolerate climatic upsets, much more so than corals and other marine species.
Nevertheless, their surprising resilience should not undermine the fact that these living drug factories are facing a very tricky future, despite their immense promise.