While no freshwater crab species are yet extinct, 17% of species are threatened with extinction.

Worryingly, approximately half of all species are too poorly known to be assessed, which reflects the general lack of scientific attention paid to this group. The species in this photo, Sundathelphusa philippina (assessed as Data Deficient), is only known from four localities in the Philippines and not much is known about its ecology, range, population size and possible threats.

The freshwater crab Nanhaipotamon formosanum (photo), which only occurs in Western Taiwan, has been listed as Vulnerable, as a result of a small range coupled with threats from deforestation and pollution.

The proportion of freshwater crabs at elevated risk of extinction is equal to that of reef-building corals and is higher than that of any other groups previously assessed (expect amphibians). Freshwater crabs are shown in red, with error bars showing the impact Data Deficient species may have on threatened levels.

The preservation of natural forests and maintenance of good water quality are of high importance to ensure the conservation of freshwater crabs. Some species, such as Geothelphusa ancylophallus (photo), although currently of Least Concern, may occur in only a relatively small geographical area and outside protected areas.

Increasing human need for freshwater together with impacts by climate change and environmental degradation especially in the developing world (where most freshwater crab species are found) suggest that many species might be at risk of going extinct in the near future. The currently threatened freshwater crabs, such as Johora singaporensis (photo) which is Critically Endangered due to threats from human development and infrastructure, may therefore only represent the tip of the iceberg.

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