Rare snail that gives birth through neck returns from brink of extinction

Rare snails thought to be extinct settle into new home on Norfolk Island Thu 30 Jul 2026 at 6:37am In short: About 1,000 snails thought to be extinct for decades are settling into their new home in Norfolk Island. The Campbell's keeled glass snails were brought back from the brink of oblivion at Sydney's Taronga Zoo. What's next? Norfolk Island's latest migrant community will now be monitored in regular surveys to see if they are surviving. It is an ultra-rare species of snail that was thought to be extinct for decades and gives birth to tiny live babies through its neck. Now 1,000 Campbell's keeled glass snails are settling into their new home in the crevices of a secluded valley on Norfolk Island, after being bred back from the brink of oblivion. The distinctively shaped snail had not been seen for more than 30 years and was officially listed as extinct before it was rediscovered by Norfolk Islander Mark Scott in 2020. A photo of his find landed in the inbox of Australian Museum research scientist Isabel Hyman, who flew out to the island to confirm the discovery of the snail whose scientific name is Advena campbellii. "It was so thrilling actually because I'd spent a lot of time looking for these species before as a student and just thought it was completely gone, so it was very exciting to discover it," Dr Hyman said. But a search of the area found fewer than 50 of the snails in their natural habitat, so an Australian-first breeding and reintroduction program was set up by the Taronga Conservation Society, in conjunction with the Australian Museum, Park Australia, Western Sydney University and the Norfolk Island Regional Council. The program began in 2021 with just 16 snails that were painstakingly collected on the island and transported to a special behind the scenes quarantine facility at Taronga Zoo in Sydney. One died during the journey and the rest proved to be rather picky customers for the Taronga team, led by senior keeper Tarryn Williams Clow. "This species hasn't been kept in zoo care or in captivity before so there was definitely a lot to learn and unfortunately you can't just compare snails to snails, they are all so niche in their requirements," she said. "It wasn't all smooth sailing and at one stage we actually got down to nine individual snails. "When there are so few left in the wild any little changes we made could be really nerve-racking." Dr Hyman said working out what the snails liked to eat was one of the initial challenges and there was a lot of trial and error involved. "Things like grinding their food up more finely and preparing it more thinly, on a soft surface, not a hard surface. Reducing the lights and reducing the humidity," she said. While they happily munched on biofilm in their native habitat on Norfolk Island, quarantine requirements meant keepers had to improvise with a paste of nettle leaf, koi food, calcium carbonate, vitamins and oatmeal. Snails give birth through neck After a rocky start, the snails eventually started breeding in their new home at Taronga, and watching them do it was an eye-popping experience for their keepers. "They pop a little version of themselves out of a hole in their neck, so it's a genital pore in their neck and that's where they give birth from," Ms Williams Clow said. "Sometimes when they're having really big breeding events, they'll have a brand new snail come out of the neck every four to six days." While some varieties of marine snails give birth to live young, most land snails lay eggs, making the Campbell's keeled glass snail even more unique. During the program, another 30 wild snails were flown over from Norfolk Island, but eventually the experiment proved so successful that the zoo facility had bred more than 1,000 snails. All the snails have now been progressively released on the island in the past few weeks and the breeding program wrapped up. 'They do like to be a bit more sheltered' Norfolk Island National Park ranger Sam Burridge said the snails were so keen on baby-making some even gave birth mid-air during the journey. "Once the plane had arrived and we were unpacking them we found that some of the snails had actually given birth on the way over, so we were finding little tiny neonates that you could tell had just popped out," he said. He was part of a team that hiked deep into the valley with the tanks of snails to find the perfect hiding spots to return them to their natural habitat. "I feel like you have to just sort of think like a snail and be the snail for a bit and then you can sort of find a good spot and tuck them away," he said. "They do like to be a bit more sheltered … They like to live in the palm base that folds over itself and they really like to get in there where it is really damp and dark." There was work carried out to clear the site of predators like feral rats and chickens and systems were put in place to offer the snails the best chance of survival. "We've got an irrigation system that we've actually … built down there and the idea of that is to just maintain the sort of moisture levels that the snails like especially over the dry periods," Mr Burridge said. Dr Hyman said snails were an important part of the ecosystem and the threats that wiped out previous populations of Campbells keeled glass snails were common to snails worldwide. "There are more recorded extinctions of land snails than any other group there is," she said. Snails 'giving birth in the wild' Norfolk Island's latest migrant community will now be monitored in regular surveys to see if they are surviving, but Mr Burridge said so far the signs from a smaller release a year ago were promising. "I did a survey just before we released this new batch and we were still finding snails that were being released a year prior. It was really quite exciting and it means they do like the site … and we believe they are giving birth in the wild," he said. Norfolk Island is a hotspot for snails, with 61 native species, including five that are critically endangered. The team responsible for bringing back the Campbell's keeled glass snail is already on the hunt for the next species that could do with a helping hand.