On Tuesday 18 November, 2025, the team behind a decades-long zoo project celebrated a major milestone in the recovery of ‘extinct’ snails. The team has successfully reintroduced thousands of ‘glow-in-the-dark’ snails to French Polynesia as part of a global conservation program to save the species from extinction.
This annual reintroduction of zoo-bred Extinct in the Wild and Critically Endangered Partula snails marked the largest release of these finger-nail sized snails to date, with over 7,000 snails being returned to four islands. Before their release, each snail was marked with a small dab of white UV reflective paint, which glows blue under UV light. This marking method helps the team locate and monitor the snails, as they are most active at night.
During the releases, the team made an exciting discovery – an unmarked, juvenile Partula varia. This marks the first wild-born member of this reintroduced snail species to be spotted in over 30 years, providing evidence that the species is not only surviving on their native island of Huahine, but also successfully breeding. This is a significant milestone for the program.
This discovery comes less than a year after the reclassification of another Partula snail species, Partula tohiveana, from Extinct-in-the-Wild to Critically Endangered on the IUCN Red List of Threatened Species – a global assessment of extinction risk. Additionally, the team found the first evidence of wild-born Partula tohiveana living outside of their original release area on their native island of Moorea, indicating that the snails are thriving and expanding their range.
The team hopes that future surveys and reintroductions will lead to more discoveries of wild-born snails, including Partula varia, and allow more species and subspecies to join Partula tohiveana in being downlisted.
The snails were part of carefully managed annual reintroductions, led by ZSL conservationists, which has coordinated the release of almost 40,000 snails over the last ten years. These snails, reared at various conservation zoos around the world, traveled over 15,000km to the islands.
The UV-reflective paint serves as not only a locating tool for conservationists, but also helps them differentiate between released snails and their wild-born descendants.
According to Paul Pearce-Kelly, Senior Curator of Invertebrates at London Zoo and leader of the international Partula conservation program, this progress is the result of decades of dedicated work by conservation zoos and the French Polynesian government. He also noted the importance of protecting all species for the benefit of the interconnected web of ecosystems we all rely on.
Also known as Polynesian tree snails, these molluscs play a crucial role in maintaining the health of their forest ecosystems by eating decaying plants and fungi, preventing the spread of disease and cycling important nutrients through the food chain.
The wild populations of Partula snails were devastated in the 1980s and early 1990s by the introduction of the invasive and carnivorous rosy wolf snail (Euglandina rosea) to control the previously introduced African giant land snail (Lissachatina fulica). In the early 1990s, conservationists rescued the last remaining individuals of 15 Partula species and sub-species, leading to the launch of an international program to breed and recover their wild populations.
Visitors of London and Whipsnade Zoo can support ZSL’s global conservation work, including through the Extinct in the Wild Action Partnership, by visiting the Tiny Giants invertebrate house. More information can be found at www.londonzoo.org.
