The Desertas Island land snails hadn’t been recorded for 100 years, so it was thought they had disappeared.
But experts found tiny populations of two species of the snail, each with fewer than 300 individuals. They were found on a remote island, off the south-east coast of Madeira, in the North Atlantic Ocean.
Fewer than 300 of each snail was discovered still clinging on, despite having been “fiercely predated” by invasive mice and goats introduced by Portuguese mariners in the 1400s.
The snails are now part of a conservation recovery plan supported by the International Union for the Conservation of Nature (IUCN), in which specialists at Chester Zoo and Bristol Zoological Society are leading a final attempt to save the species by expanding their numbers.
Specialists have successfully bred the tiny creatures for the first time ever in captivity, swelling their numbers to around 1,200.
The minuscule snails were believed to have been lost forever
Chester Zoo’s curator of lower vertebrates and invertebrates, Dr Gerardo Garcia, said: “These snails had not been seen for decades and were thought to have gone extinct, so urgent action was required when only a handful of these special snails were found clinging on to survival.
“Starting with just 20 of the last known individuals on the planet from each group, there was a lot of pressure to find answers quickly.
Drawing on their experience of helping to restore populations of other imperilled invertebrates, the zoo staff created special breeding centres which closely replicate the perfect conditions for the snails to reproduce.
“Now, with more than 1,200 safely in our care, we can say that we have prevented two magnificent species from becoming extinct, which is an incredible achievement.”
Boosting the snails’ populations was the first step in a recovery plan that is being supported by the International Union for the Conservation of Nature (IUCN).
Since their rediscovery, the IUCN has listed both species (Discula lyelliana and Geomitra grabhami) as critically endangered. A conservation project to rehabilitate them in their natural habitat is also underway with the backing of the Madeiran Government in Portugal.
The Desertas Islands are now protected nature reserves under Portuguese and European law and have been recognised as biodiversity hotspots for rare invertebrates, birds and reptiles.
Dinarte Teixeira, malacologist (or mollusc expert) for the Instituto das Florestas e Conservação da Natureza in Madeira, says “this project is a dramatic call for action to protect this unique land snail species.