Dural Snails

Dural Land Snails might be slow movers measuring only a few millimetres but discovery of the endangered species of mollusc at Highforest had the potential to stop the project in its tracks.

It wouldn’t be the first time that ecological factors had stymied development, so Mirvac immediately sought the expertise of Dr Stephanie Clark, an internationally recognised authority on molluscs.

Dr Clark’s research has led to the discovery of thousands of previously unknown snail species, 180 of which she has named. Mirvac’s need for development certainty represented an opportunity to add to the body of knowledge about the notoriously difficult to locate Pommerhelix duralensi.

“This project has been quite different to others,” says Dr Clark. “It was much more involved and you had Council and resident groups concerned about the impact on birds. But the one that really mattered, that had legal weight to stop the development, was the Dural Land Snail. It is the only endangered species that lives on the site.

“When the species was first listed as endangered we knew very little about it. I did my PhD concentrating on the Cumberland Plain Land Snail but it was much harder to find Dural Land Snails because they like the sandstone forest.”

With a 12.8 hectare area of potential snail habitat to survey, Dr Clark conducted her searches by night and day, choosing times when rain had created optimum conditions for snails to leave their leafy hideouts.

“I walked the trails during the day so I knew what to expect and then walked them by night,” explains Dr Clark. “I walk as slowly as I can until I see something. Because I’m shortsighted I can see a 1mm snail a few centimetres in front of me.

“I photograph them using a microscope camera and take notes and then keep walking another metre, trying to avoid stepping on a snail. That’s an ‘oh dear’ moment.

“I was able to get a range of where they were on-site and found their favourite places were around the multi-storey parking deck.”

The parking station had been ear-marked for demolition but once Dr Clark identified it as snail central those plans were deferred to allow a fauna management and relocation strategy to be put in place.

“I don’t like to move things as a rule but in this case the snails were able to be moved to a nearby bush patch without it acting as an inhibitor.”

Dural Land Snails are slow movers, typically covering a distance of just a metre at night. Unlike the common garden snail, the bane of many gardeners, the native species feeds on fungi and algae and has a beneficial role to play in the forest eco-system.

First identified in 1868 and listed on the endangered species list in 2015, little is known about the Dural Land Snail. Preferring sandstone forest environments, they display behaviour patterns unlike other native land snails, sheltering under leaves, rocks and forest debris rather than burrowing or climbing.

The best time to find them is when the night temperature is about 18 degrees and the ground is wet after a day or two of rain. Juveniles, who do most of the moving, come out first followed by the adults.

Dural Land Snails are hermaphrodites with both male and female systems. Male reproductive systems mature first and they are able to transfer sperm between each other by going head to head, staying attached for 40 to 50 minutes. Once the snail has sperm, either their own or another snail’s, they will usually lay about 20 to 30 eggs in a clutch, buried in a damp dark place.

Snails looking to mate display a headwart, a round structure between the tentacles, which pops up giving off pheromones. The discovery of Dural Land Snails at Highforest was a reassuring sign for Dr Clark that despite their endangered status they are surviving, though it is difficult to know their precise number or location. Where possible Dr Clark marked smaller snails, others she photographed.

To the untrained eye a snail is a snail but Dr Clark can distinguish each of the thousands of snail species she encounters. While the focus of the survey was the Dural Land Snail, Dr Clark happened upon many other fascinating species that don’t attract quite the same level of concern.

She found Killer Snails, who eat worms, slaters and even each other, as well as Red Triangle Slugs, that climb trees cleaning up algae as they go. “You never know what you will find and it’s that sense of discovery that I love.

The taxonomist in me never gets tired of discovering new species.

When I am in a new location like Highforest, it is always a happy event. It is nice to know there are things there to be discovered.”