Amphibians, among the most threatened groups of animals on Earth, have officially crossed a major scientific milestone. Researchers have now described more than 9,000 amphibian species worldwide, marking a significant achievement for taxonomy and biodiversity science. The finding comes from a new research paper that tracks global trends in amphibian discovery, while also warning that many species may go extinct before they are ever documented.
The study, authored by Sky T Button, Franco Andreone and Amaël Borzée, describes the milestone as the result of decades of sustained research efforts across continents. According to the authors, the number of recognised amphibian species has more than doubled over the last 40 years, reflecting advances in field surveys, genetic tools and taxonomic collaboration. Annual species descriptions peaked only recently, with 180 new species recorded in 2017 and 179 in 2020.
Yet, the researchers caution that the milestone masks a deeper crisis. An estimated 6,000 to 7,000 amphibian species may still remain undescribed, and many of them are likely already under severe threat from habitat loss, climate change, disease and pollution. While the current total of 9,000 species may represent more than half of all amphibians on the planet, the race between discovery and extinction is intensifying.
Frogs dominate, while hidden species remain elusive
The paper highlights stark differences across amphibian groups. Frogs and toads, known scientifically as anurans, dominate global amphibian diversity, accounting for nearly 88 per cent of all known species. Salamanders make up about 9 per cent, while caecilians limbless, burrowing amphibians that resemble worms or snakes represent just 3 per cent of described species.
Both frogs and salamanders followed a similar pattern of discovery, with slow growth in species numbers for much of modern history, followed by a sharp rise in descriptions from the late 20th century onward. Although the rate of new descriptions has dipped slightly in the past four years, the authors note that it remains unclear whether this reflects a genuine slowdown or disruptions caused by the COVID-19 pandemic, which significantly delayed scientific research worldwide.
Caecilians remain the least understood group. Their underground lifestyle and the need for manual excavation make them particularly difficult to study. As a result, discoveries often occur in short bursts tied to focused research projects, rather than through steady long-term exploration.
South America leads global amphibian diversity
Geographically, South America stands out as the world’s richest region for amphibians, hosting about 37 per cent of species with known range data. Asia follows with 23 per cent, while North America accounts for 17 per cent, Africa 15 per cent, Oceania 9 per cent and Europe just 1 per cent.
When adjusted for land area, the contrast becomes even sharper. South America supports nearly three times more amphibian species than would be expected based on its size alone, making it the most amphibian-diverse continent by a wide margin. Europe, by comparison, emerges as the least amphibian-rich region despite receiving some of the most intensive scientific attention over the years.
The authors argue that these patterns highlight global imbalances in research effort, with some of the most biodiverse regions still lacking adequate funding and local scientific capacity.
Looking ahead, the study estimates that amphibian species will continue to be described well into the next century. Based on current trends, at least 3,000 additional species could be identified by 2100, bringing the likely total to between 15,000 and 16,000 species worldwide.
However, the authors stress that discovery alone is not enough. In a social media post responding to the milestone, Gina Della Togna, Executive Director of the Amphibian Survival Alliance, described the moment as both a celebration and a call to action. She pointed out that amphibians are the most threatened vertebrate group on the planet, yet receive less than 2.8 per cent of global conservation funding.
As species discovery continues at an unprecedented pace, many newly identified amphibians are already at risk of extinction. Conservationists warn that without urgent investment in taxonomy, threat assessment and targeted protection efforts particularly in biodiversity-rich but underfunded regions countless species could vanish before science even learns their names.
The milestone of 9,000 species, the researchers conclude, is not an endpoint, but a reminder of how much remains unknown and how little time may be left to act.