Scientists are discovering new species faster than ever, revealing that Earth holds far more life than we once imagined. The accelerating pace of discovery suggests millions of species may still be waiting to be found.
About three centuries ago, Swedish naturalist Carl Linnaeus launched an ambitious effort to identify and name all living organisms on Earth. He later became known as the father of modern taxonomy after creating the binomial naming system and formally describing more than 10,000 plant and animal species. Scientists have carried that work forward ever since, steadily expanding the known catalog of life on our planet.
A Record Pace of Species Discovery
New findings from a University of Arizona-led study published in Science Advances show that this effort is now moving faster than ever. Researchers report that scientists are identifying more than 16,000 new species every year. There is no indication that this pace is slowing, and the study suggests that biodiversity within groups such as plants, fungi, arachnids, fishes and amphibians is far greater than previously assumed.
“Some scientists have suggested that the pace of new species descriptions has slowed down and that this indicates that we are running out of new species to discover, but our results show the opposite,” said John Wiens, a professor in the University of Arizona Department of Ecology and Evolutionary Biology, in the College of Science, and senior author of the paper. “In fact, we’re finding new species at a faster rate than ever before.”
The study shows that there may be more than 16,000 reptile species on Earth, of which only about 12,000 have been formally described, including this hump-nosed viper from India. Credit: John J. Wiens
What the Numbers Show
The research team reviewed the taxonomic histories of about 2 million species representing all major groups of living organisms. During the most recent period with complete data, from 2015 to 2020, scientists described an average of more than 16,000 new species each year. These discoveries included over 10,000 animals (dominated by arthropods and insects), about 2,500 plants, and roughly 2,000 fungi.
“Our good news is that this rate of new species discovery far outpaces the rate of species extinctions, which we calculated to about 10 per year,” said Wiens, referencing another study he led that was published in October. “These thousands of newly found species each year are not just microscopic organisms, but include insects, plants, fungi, and even hundreds of new vertebrates.”
How Many Species Are Still Unknown
According to Wiens and his co-authors, scientists are now describing more species each year than at any time in history. By examining how discovery rates have changed over time, the team also estimated how many species may exist in total. Their projections suggest there could be as many as 115,000 fish species and 41,000 amphibian species, compared with roughly 42,000 fish and 9,000 amphibians that have been formally described so far.
They also estimate that the total number of plant species could exceed half a million.
“As the famous ecologist Robert May said, if visiting aliens asked us how many species live on our planet, we would have no definitive answer,” said Wiens. “Right now, we know of about 2.5 million species, but the true number may be in the tens or hundreds of millions or even the low billions.”
The researchers expect discoveries to continue accelerating. Scientists have already identified around 1.1 million insect species, yet many experts believe the actual total is closer to 6 million. In a previous paper, Wiens suggested the number could even reach about 20 million.
New Tools Reveal Hidden Diversity
“Right now, most new species are identified by visible traits,” said Wiens. “But as molecular tools improve, we will uncover even more cryptic species – organisms distinguishable only on a genetic level. This is especially promising for revealing more unique bacteria and fungi.”
On average, more than 100 new reptile species are described each year. John Wiens photographed this helmeted lizard in Costa Rica. Credit: John J. Wiens
Why New Species Matter to People
“Discovering new species is important because these species can’t be protected until they’re scientifically described,” Wiens added. “Documentation is the first step in conservation – we can’t safeguard a species from extinction if we don’t know it exists.”
Beyond conservation, new species discoveries can benefit humanity in other ways. Many useful natural products come from living organisms, including GLP-1 receptor agonists, widely used weight loss drugs inspired by a hormone found in Gila monsters. Compounds from spider and snake venoms, as well as substances produced by plants and fungi, are also being studied for their potential to treat pain, cancer, and other diseases.
Nature can also inspire new technologies. Some species possess unique physical traits that inform human design, such as materials modeled after the “super-clinging” feet that allow geckos to climb vertical surfaces.
“We’re still just scratching the surface of what these species can do for humanity,” Wiens said.
Mapping the Future of Discovery
Next, the researchers plan to identify where new species are most often found in order to pinpoint regions with large amounts of undiscovered biodiversity. They are also examining who is making these discoveries, including whether the field has shifted from being dominated by European scientists to researchers documenting species within their own countries.
“Even though Linnaeus’ quest to identify species began 300 years ago, 15% of all known species have been discovered in just the past 20 years,” Wiens said. “So much remains unknown, and each new discovery brings us closer to understanding and protecting the incredible biodiversity of life on our planet.”
Reference: “The past and future of known biodiversity: Rates, patterns, and projections of new species over time” by Xin Li, Ding Yang, Liang Wang and John J. Wiens, 5 December 2025, Science Advances.
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