For the first time in nearly four decades, scientists have discovered tiny tree snails breeding in the wild in French Polynesia. The species is called Partula tohiveana, and they were previously thought to be extinct in the wild.
But global conservation efforts have helped the snails make a comeback within the islands in the South Pacific. Over the last decade, scientists have been transporting thousands of captive-bred snails to French Polynesia every year and letting them roam free.
The researchers kept track of the reintroduced snails by marking their shells with a speck of UV-reflective paint. It makes them more visible at night, which is when they're most active.
In September, the scientists made their yearly trip, releasing more than 6,000 snails on Mo'orea, Tahiti, and Huahine, just three of the 118 islands that make up French Polynesia.
On Mo'orea, they encountered some unmarked Partula tohiveana in the wild. These snails did not have the paint on their shells, meaning that they've been breeding on their own.
"This is the kind of news you work your whole career for," said Kayla Garcia, a zoological manager of invertebrates at the St. Louis Zoo, one of the institutions working to save the species.
"This is an amazing discovery, an amazing accomplishment, and you just can't help but feel all of the good feelings coursing through you."
Now, conservationists will start the process of getting the snails' status moved from "extinct in the wild" to "critically endangered."
Partula snails are very small, measuring less than an inch in length, but they are essential for the ecosystem on French Polynesia's islands.
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They consume decaying plant matter and fungi to keep the forests healthy. They are also an important part of Polynesian culture since the shells of each species symbolize each island's cultural identity.
The downfall of Partula snails began in 1967 when French authorities allowed African giant land snails to be brought to the islands as a food source for human residents. These snails were not native to the area, and soon enough, they escaped into the wild.
African giant land snails can grow up to eight inches long. They feed on more than 500 plant species and crops. They also eat stucco on homes and can carry a parasite that causes meningitis in humans. They reproduce very quickly -- one snail can lay up to 2,500 eggs a year.
Their invasive presence devastated the islands' ecosystem. Authorities released another snail to try to stop them.
The rosy wolf snail, also known as the cannibal snail, was supposed to hunt and eat the African giant land snail to drive their population down.
Instead, the carnivorous snails targeted smaller and slower native snail species, causing at least 51 of the 77 known Partula species to go extinct.
In the early 1990s, biologists from the Edinburgh Zoo and the London Zoo collected all the remaining Partula snails they could find and kickstarted a breeding program to keep the species afloat.
Now, more than 30,000 individuals have been reintroduced into the wild and have successfully reestablished themselves. They offer hope that a species can thrive once more, even after enduring such hardships.