- Scientists have found Partula snails born in the wild on the French Polynesian island of Moorea, showing that a 40-year effort to save these tiny creatures is working.
- Partula snails were wiped out from the wild in the late 1980s by an introduced predator, the rosy wolf snail, leading to an international zoo-based breeding program to save the species.
- Researchers used a special UV-reflective “snail varnish” to mark reintroduced snails, allowing them to identify unmarked individuals as wild-born during recent surveys.
- The success of this project demonstrates the potential for conservation efforts to bring species back from the brink of extinction and may lead to changing the status of at least one species, Partula tohiveana, from “extinct in the wild” to “critically endangered.”
On the tropical island of Moorea in French Polynesia, a species of snail about the size of a Skittle candy is cause for celebration. On September 2024, researchers found adult Partula tohiveana snails that were born in the wild.
This is the first time in decades these tiny mollusks, measuring just 1-2 centimeters (less than an inch) in length, have reproduced naturally in their native habitat. This finding marks a significant victory in a 40-year conservation effort to save these small but ecologically important creatures.
“Discovering wild-born adult snails was a great moment. Very few animal species have been re-established back in the wild so this is a fantastic achievement … the fruit of a vast amount of work,” Justin Gerlach from the University of Cambridge, one of the scientists involved in the program to breed the snails in captivity before releasing them back into the wild, said in a statement.
Partula snails were once abundant across French Polynesia in the South Pacific. However, an introduced predator devastated their populations in the late 1980s. The rosy wolf snail (Euglandina rosea), brought in to control the invasive African giant land snail (Lissachatina fulica), ended up preying on the native snail species as well, driving them to extinction in the wild.
Zoos stepped in and took the last surviving snails they could find to start breeding them in captivity. Snails were bred in zoos in the U.K., U.S. and Germany.
“Since the project began in 1986, more than 21,000 individuals of 11 previously Extinct-in-the-Wild species of Partula snails have been reintroduced on four islands in French Polynesia,” Kerry Marcus from the Bristol Zoological Society in the U.K., who was also involved in the program, said in the statement.
In April 2023, scientists brought 5,522 of the snails to the French Polynesian islands of Moorea and Tahiti. This, according to the Zoological Society of London, was the largest-ever release of extinct-in-the-wild species.
Before releasing the snails back into their native habitat, researchers took careful steps to mark them. Each tiny snail was individually counted and marked with a special “snail varnish” that glows under UV torchlight. This allows conservationists to easily spot and monitor these nocturnal creatures during nighttime observations when they’re most active.
When the team discovered unmarked P. tohiveana snails on Moorea during their surveys this year, they knew these individuals must have been born in the wild.
“Returning these rare snails back to the wild enables us to start restoring the ecological balance in these islands,” Sam Aberdeen, who works with invertebrates at London Zoo told Mongabay. “Partula snails … eat decaying plant tissue and fungi, so play an important role in maintaining forest health,”
The snails are also important to the people who live on the islands. “Partula have a strong cultural significance for the people of the French Polynesian islands, who traditionally used Partula shells for making necklaces for ceremonial occasions,” Aberdeen said. “Due to the variation in Partula species and subspecies between the islands, the different shells came to represent the cultural identity of each island.”
Finding wild-born P. tohiveana snails on the island means scientists can now work on changing this particular species’ status from “extinct in the wild” to “critically endangered.” While still in danger, this is a step in the right direction.
Although Earth is experiencing an extinction crisis, the success with the Partula snails shows that species can be brought back from the edge of extinction. The red wolf (Canis rufus), California condor (Gymnogyps californianus), and Guam kingfisher (Todiramphus cinnamominus) are a few of the other species that have been saved from extinction by captive-breeding programs.
“It’s a powerful example of how conservation zoos can combat biodiversity loss,” said Paul Pearce-Kelly, the senior curator of invertebrates and fish at London Zoo and the lead for the project to save these snails. “At a time when nature faces unprecedented challenges, these small snails are a symbol of hope for global wildlife.”
Banner image: Partula varia, marked with dot of UV paint. Photo courtesy of Paul Pearce-Kelly.
Liz Kimbrough is a staff writer for Mongabay and holds a Ph.D. in ecology and evolutionary biology from Tulane University, where she studied the microbiomes of trees. View more of her reporting here.
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