Often called "ghost sharks," Chimaeras are among the most mysterious inhabitants of the deep ocean. Distant relatives of sharks and rays, they diverged into a distinct evolutionary lineage nearly 400 million years ago - predating the dinosaurs. CSIRO ichthyologist Dr William White discovered the new species during the 2025 Ocean Census expedition to the Coral Sea Marine Park, in partnership with CSIRO and supported by Parks Australia & Bushblitz.

The Nippon Foundation-Nekton Ocean Census/CSIRO

What is still out there in the deep ocean, beyond the reach of sunlight, beyond the places we routinely map, sample or even imagine? For most of human history, the answer to this question (or questions) has been speculation stitched together from rare expeditions and fragmented data. Afterall, deep sea science is not cheap! But now, thanks to advances in technology and philantrophic and scientific expeditions that have deeper pockets than ever before, that picture is starting to sharpen in ways that are both exhilarating and unsettling. In a landmark year for ocean science, researchers working through the Ocean Census initiative have identified 1,121 previously unknown marine species. Thirteen expeditions and nine dedicated discovery workshops brought together scientists from across the globe, accelerating what has traditionally been a slow and painstaking process into something closer to a coordinated scientific sprint.

So what does it mean when we say “new species” in a place we have barely explored? In some cases, it means creatures that look like they belong in another world entirely! Deep sea ghost sharks, formally known as “chimaeras,” were among the most striking finds. These animals are distant relatives of sharks and rays, tracing their evolutionary lineage back nearly 400 million years; while they as a whole are not new in the sense that they just evolved, they are “new” in the sense that humanity is only now documenting their existence in detail. In this case, they were seen gliding through waters more than 2,624 feet (800 meters) deep in places like the Coral Sea Marine Park off Australia’s coast. An oddity in marine science due to how they look, they serve as a reminder that entire branches of the tree of life have remained largely invisible to us due to access — or lack of it!

Then there are the smaller, but no less fascinating, organisms like symbiotic bristle worms living inside mineral structures on volcanic seamounts in Japan. New species of corals, crabs, shrimps, sea urchins and anemones galore. And when you stack these discoveries together, a rather difficult to ignore question pops up time and time again: how many ecosystems are functioning right now without ever having been properly described by science?

The scale of unknown life in the ocean is still staggering, with scientists estimating that up to 90 percent of marine species have yet to be discovered. And if we do not know what species exist, how can we fully understand food webs, ecosystem resilience or the true impact of climate change on marine systems? That cuts directly into one of the most contentious environmental debates of our time: whether we should be mining the deep sea before we even understand what lives there. Entire ecosystems may be operating in ways we have never documented, shaped by species interactions we have never observed, in environments we are only just beginning to sample. That uncertainty is one of the central reasons deep sea mining has become so controversial. If you extract mineral-rich nodules or disturb hydrothermal vents before you understand the biological communities living there, you are effectively altering systems whose structure and function are still being mapped in real time. Never mind whether mining is good or bad in principle, the fact of the matter is that there is a vast, largely uncharted biosphere that could be permanently altered by extraction activities despite demand for minerals used in batteries and renewable energy technologies.

With this in mind, part of what makes this moment significant is not only the discovery itself but how quickly it is being shared! Traditionally, the formal description of a species can take more than a decade. On average, around 13.5 years pass between discovery and publication and that delay creates a strange scientific limbo where organisms are known but not officially recognized, leaving them vulnerable in policy and conservation frameworks. The Ocean Census approach tries to collapse that gap; through its open access platform, data can be made available within days or weeks, allowing scientists worldwide to access findings far earlier than before. More than 1,400 taxonomists and researchers across 85 countries contribute to this growing network. And this is where “ecology” becomes less abstract and more… well, real. Deep ocean currents regulate climate, marine biodiversity supports fisheries, and believe it or not even organisms living thousands of meters below the surface play roles in carbon cycling and nutrient movement. If a species is removed or its habitat is disrupted, the ripple effects are not always immediate or obvious. Sometimes they unfold over decades or longer, in ways that are difficult to reverse once the physical structure of the habitat is gone. So when we talk about ecosystem resilience, we are really asking a question about thresholds. “How much disturbance can a system absorb before it shifts into a different state?” is a better question to ask, and in the deep sea, we often do not have the historical data needed to even define what a healthy baseline looks like making any prediction inherently uncertain. While we are better equipped than ever to explore the deep sea, with advanced submersibles, high resolution imaging and global collaboration networks, at the same time, human pressures on marine environments are intensifying. Warming waters, acidification, deep sea mining and overfishing are reshaping ecosystems faster than we can fully document them! So we are most likely naming species at the same time they are disappearing; in fact, scientists have already warned that many organisms may go extinct before they are formally described.

Where does that leave us? Well, if we now know that thousands of species are still waiting to be discovered, does that change how we value the ocean itself? Does it shift the way we think about the deep sea when so much of life remains unnamed, unseen and unstudied? These 1,121 new species ultimately represent more than just a catalogue of biodiversity, acting as evidence of how much we still have to learn about our own planet. And they leave us with a final question that science alone cannot fully answer: how do we protect something we are still in the process of discovering?