A globe-spanning attempt to catalogue ocean life found over 1,100 species last year. But many times that number remain undiscovered, with worrying implications for conservation.
Fixing that knowledge gap means spreading understanding about how to classify species around the world.
Classifying the world’s animals might seem to be quite literally an academic problem. But nations have agreed to protect 30% of their oceans and land by 2030 and pledged to halt biodiversity loss in international conventions. That requires knowing what biodiversity is there, so you can tell whether you are losing it.
“To be able to conserve and manage and understand the biogeography and the biodiversity of our planet … species are that foundational basic unit that we use. That’s how we’ve chosen to categorize life,” says Michelle Taylor, head of science at the Ocean Census, which seeks to discover, identify and classify marine species.
Last month the Ocean Census announced it had described 1,121 new species in 2025, including corals, crabs, sea anemones and a deep-sea fish distantly related to sharks that was barely longer than the 40cm ruler it was photographed next to. Researchers at an Ocean Census workshop in Germany this year described over over 200 species of isopods – an order of crustaceans that includes land-dwelling woodlice – in two weeks. (In scientific terms, a species is “discovered” not when it is first seen or caught, but when it is described in a paper published in a journal.)
The online World Register of Marine Species database now lists a quarter of a million accepted species, with an average of over 2,000 new entries per year for the last decade.
But estimates for the number of species in the ocean are in the range of around 2.2 million. A lot of work is still to be done.
“I think there is an enormous capacity to scale up at the moment,” says Taylor.
Why bother?
Many parts of the ocean are poorly sampled and the life there poorly characterised. This can be because they are far from land, under thick ice, or deep below the surface. It can also be because they are overseen by less wealthy countries that lack expensive research ships and other equipment needed to work out what lies below the surface.
As well as describing species found on expeditions and hauled out of dusty archives worldwide, Ocean Census is pushing to build capacity to discover species in countries that have traditionally lacked it.
“The biodiversity of this planet is focused around the equator and around the Global South and mostly developing nations,” says Taylor, noting that taxonomy has a “natural place” in these areas.
Earlier this year, a global team of experts gathered in South Africa and huddled over microscopes, peered into jars and leafed through references to catalogue samples from the ocean depths around the Comoros. This country between Madagascar and Mozambique has a population of less than a million spread over three islands totalling under 2,000 sq km. But it oversees an ocean territory of 160,000 sq km.
To explain the importance of such work, Taylor, who also teaches at the University of Essex, cites a project by one of her students on a type of shallow water coral that can be found from Hawaii to the Red Sea. This work suggests that, although superficially similar, there may be nine species across this range. “Which suddenly means that they [the individual species] cover a much smaller area, which means that they actually have … a higher risk of going extinct if they cover a smaller area and you manage them differently,” says Taylor.
“Working out different species plays into just so many different areas of science and management and conservation.”
Hence the workshops that bring experts from across the world together. Next year the census will focus on South America, with workshops in Chile, Brazil, Uruguay and Argentina, Taylor notes.
Crisis? What crisis?
In a much-cited 2002 article in Nature, leading UK-based scientist Charles Godfray warned that “much of taxonomy is perceived to be facing a new crisis – a lack of prestige and resources that is crippling the continuing cataloguing of biodiversity”.
Godfray told Dialogue Earth this month that since then, taxonomy has embraced the online world, “and a thousand flowers can bloom”. But this has come with the disadvantage that resources can be difficult to access and impermanent. Individual projects may be siloed at specific institutions or vanish entirely when funding runs out.
“The amount of literature now available on the web is definitely helping taxonomy in the Global South, though resources are [still] very scarce,” he says.
This isn’t just an ocean issue. A study of plant taxonomists published last year found 48% of 89 countries had fewer than ten people working in this area, with many countries worldwide lacking equipment as well as staff. “There are particularly striking taxonomic shortages in large parts of the world which are highly biodiverse but economically challenged,” warned the authors.
A 2022 survey of over 630 botanical and zoological taxonomists worldwide reported that 36% of them worked in Europe and 32% of them in North America. Only 1.5% were in Africa.
But Ana Rita Simões, who works on plant taxonomy at various institutions including the Missouri Botanical Garden and was one of the people behind the plant taxonomy survey, says this is not quite as simple as the Global North having capacity and the Global South needing to build it.
“We have countries, even in the Global South, like Brazil, which are doing really well, or the Philippines, which has really good capacity,” she told Dialogue Earth. “One of the things our survey highlighted is even Europe has very little taxonomic capacity and very little training opportunities.”
Simões also flags that changes in funding mean scientists’ jobs are often no longer purely taxonomy, and may include other responsibilities too. For instance, her role involves taxonomy, herbarium curation and conservation, as well as training and teaching.
Taylor notes it’s “very rare” to have a full-time taxonomist. “They work on environmental impact assessments or they work in museums or they’re evolutionary biologists. People that do taxonomy wear many different hats.”
And they have a lot of work to do.
There may still be over a million ocean species to discover.
