In 1989, just 26 tiny snails remained on a Pacific island after a disastrous human experiment. Now 17,000 are back

In 1989, just 26 Partula nodosa snails remained after a human attempt to control an invasive species triggered a devastating ecological chain reaction in Tahiti. Declared extinct in the wild, the tiny tree-dwelling snails were given a last chance through a zoo-led breeding programme. Decades later, their descendants are helping rewrite that story. More than 17,000 Partula snails have now been reintroduced to their native islands, with conservationists continuing efforts to rebuild sustainable wild populations.

P est-control plan nearly wiped out the Partula snails

Partula snails are small, tree-dwelling land snails native to islands across French Polynesia. Their populations were devastated after the introduction of the predatory rosy wolf snail, which had been brought in as a biological control measure. As per the Detroit Zoo Blog, giant African land snails were introduced to Tahiti and other South Pacific islands in 1967 as a potential source of protein for local communities. However, some escaped, multiplied rapidly and began feeding on crops, creating a threat to farmers and the local economy.

About a decade later, Florida rosy wolf snails were introduced to control the African snails. The plan backfired. The predators preferred eating Partula snails, leading to the extinction of several Partulid species in the wild.

The rescue began with just 26 snails

Nearly three decades ago, Partula nodosa was declared extinct in the wild, with only 26 individuals remaining. Those snails were sent to the Detroit Zoo as part of a cooperative breeding programme designed to prevent the species from disappearing completely. The Detroit Zoological Society had begun its wider Partula conservation project in 1989 with 115 Tahitian land snails representing five species. While the organisation focused on P. nodosa, other participating zoos worked with the remaining species. Careful breeding eventually transformed those last survivors into a growing population. Thirty years later, more than 6,000 descendants were living in North American zoos.

Thousands of snails are returning home

The international recovery programme has now returned 11 Partula species once considered extinct in the wild to their native islands. More than 17,000 snails have been reintroduced through the collaborative conservation effort. In the first week of September, as per the Detroit Zoo website, 500 adult Partula snails bred and cared for at the Detroit Zoo were set to leave Royal Oak for Tahiti. The journey covers more than 5,000 miles, with the snails destined for release into their native habitat. Partula nodosa remains classified as Extinct in the Wild, but zoo-led breeding and release programmes are working to change that. Researchers have also documented wild-born offspring following earlier reintroductions.

Each tiny snail gets an identification mark

Before travelling to Tahiti, every snail receives a small orange dot of animal-safe paint on its shell. The mark glows under ultraviolet light, allowing conservationists to identify individuals from that year's release and monitor them after reintroduction. A different colour is used for each year's release. The Detroit Zoo has been involved in Partula snail recovery since 1989, working with zoos and conservation partners to breed and return the species to its native habitat.

Beyond restoring ecosystems, the programme is also helping preserve Polynesian cultural heritage. Partula snails have unique shells and are associated with different islands, making their return significant beyond conservation alone.

About Partula snail

According to the National Geographic website, the Partula snail, also known as the Polynesian tree snail or niho tree snail, belongs to a genus containing several species, many of which are threatened with extinction. Partula nodosa is tiny, measuring little more than a pencil eraser, but its unusual physical features help it survive in the moist forests of Tahiti. The snail has a bumpy brown body, most of which consists of its muscular foot, along with almost translucent, antenna-like eyes. A gland in its foot produces mucus that forms slime trails, allowing the snail to glide across and cling to different surfaces. According to National Geographic, this mucus also lubricates the animal and contains a special protein that helps absorb moisture.

Its spiralled shell is covered in beige and cream-coloured stripes. Besides giving the snail its distinctive appearance, the shell serves an important survival function by protecting it from predators and helping prevent its body from drying out.

What do Partula snails eat?

The valleys and moist forests of Tahiti in the South Pacific provide an ideal environment for Partula snails. The land snails are often found beneath stems and on the undersides of leaves, where they feed on decaying plant matter.

Partula snails consume rotted vegetation. They spend much of their time grazing on decomposed plants and microscopic plant material found on larger vegetation. Before Partula nodosa disappeared from the wild, the snail played an important ecological role. By feeding on plant debris, it helped recycle nutrients within the ecosystem and contributed to the natural processes that support plant respiration.