Australia is often recognised for its unusual wildlife, from marsupials and parrots to reptiles, plants and marine life found nowhere else. But a large part of this biodiversity is still scientifically invisible. Many species have not yet been formally named, documented or classified, which means they can be difficult to protect before they are already in decline.
This five-chart story looks at Australia’s biodiversity debt: the gap between the species we know are threatened and the much larger number that may still be unnamed. It shows that the crisis is not only about iconic animals. It is also about plants, uneven state-level pressures, rising severity, and the slow pace of species discovery.
Before looking at the threatened species list, it is important to understand the scale of what is still unknown. The State of the Environment report estimates that about 70% of Australia’s native species remain unnamed or undocumented. This means the official threatened species list only shows part of the picture, because many species may not yet be visible to science at all.
Source: Australia State of the Environment 2021 – Biodiversity
When people think about threatened biodiversity, they often picture mammals, birds or reptiles. The EPBC threatened species list shows a wider story. Among formally listed threatened species, flowering plants make up the largest groups. This matters because biodiversity loss is not only about losing well-known animals, but also about losing the plant life that supports ecosystems.
Source: DCCEEW EPBC threatened species dataset
The threatened species list is not only getting larger. It is also becoming more severe. In 2000, critically endangered species made up only a small share of the national list. By 2025, that share had grown sharply. This suggests that more species are moving into the highest-risk category, where the chance of recovery becomes harder and more urgent.
Source: TERN and Australian National University, Australia’s Environment 2025
Threatened species are not spread evenly across Australia. Some states and territories contain much higher counts of EPBC-listed species than others, especially in vulnerable and endangered categories. This does not mean biodiversity protection matters only in those states, because one species can occur across multiple places. But it does show where the listed pressure is most visible in the national data.
Source: DCCEEW EPBC threatened species dataset
The final issue is time. Even when hundreds of new species are named in a year, the estimated pool of unnamed species is so large that the task could still take centuries. This creates a biodiversity debt: Australia is trying to identify life at the same time as habitats, ecosystems and species are already under pressure.
Sources: Australia State of the Environment 2021 – Flora and fauna ; DCCEEW 2023 media release ; DCCEEW 2024 media release
Together, these charts show that Australia’s biodiversity problem is bigger than the threatened species list alone. The country is still naming and documenting life while many known species are becoming more severely threatened. The story is not only about what has already been lost, but also about what could disappear before it is even properly known.