First Eggs Documented from Rare New Zealand Snail

A remarkable event occurred when a large carnivorous snail from New Zealand was photographed with its eggs emerging from its neck for the very first time. This event took place at Powelliphanta augusta, a site managed by the Conservation Bureau, which has been studying this species for nearly two decades.

Ingrid Gruner, a biodiversity liaison working with the bureau, shared her excitement about the footage, calling it “very remarkable.” The project has involved regular weight checks on these snails, and the appearance of the small white eggs was unexpected.

Powelliphanta land snails, among the largest snails globally, can reach sizes comparable to golf balls. They are unique to New Zealand and grow slowly, living for decades—those in captivity are believed to be 25 to 35 years old. Their diet primarily consists of slugs and earthworms.

Gruner mentioned that the team managed to capture this rare moment quite by chance. These snails reach sexual maturity around the age of eight and typically lay about five eggs, resembling chicken eggs, each year. Interestingly, these eggs can take more than a year to hatch.

Lisa Flanagan, a ranger with over a decade of experience caring for these snails, noted that their behavior starkly contrasts that of the garden snails that were introduced to New Zealand. “They are entirely different,” she said. “The introduced snails lead shorter lives and reproduce in large numbers.”

The department’s senior science advisor, Caswalker, explained that these hermaphroditic snails have genital openings in their necks, which facilitate mating and egg-laying. This unique method allows for the exchange and storage of sperm until the eggs are fertilized.

While other snail species share similar mating practices, some variations, such as those observed in Campbell’s keyring glass snails from Norfolk Island, have also been noted.

Since 2006, the department has taken steps to preserve snails facing extinction due to mining activities in their habitat on the Augustus Ridge Line near Westport, South Island. The mining operations sparked significant public outcry and legal challenges but were ultimately approved by the government.

In response, around 4,000 snails were relocated to safer sites, with an additional 2,000 used to create breeding colonies as a backup plan. Unfortunately, about 800 snails died in a maintenance accident in 2011 due to temperature mismanagement.

Prior to the department’s intervention, little was known about these snails. Officials now believe that their efforts have played a crucial role in preventing the species from going extinct. As of March, the captive population included 1,884 snails ranging from hatchlings to adults, along with 2,195 eggs. They’ve established new colonies in the wild, which are closely monitored for sustainability.