Theba pisana occurs naturally along the Mediterranean coast. It has become established in all sorts of places around the world. In Australia, the species thrives in the summer dry/winter wet climate of in the south of the continent. (Well, the summer dry/winter dry as it seems to be now.) And by thrive, I mean the snails turn up in their thousands.
So abundant is Theba in some places that it damages cereal crops. Not by eating them but by contaminating the harvest.
The snails climb vertical surfaces — fence posts, tree trunks, wheat stems — and seal onto them with a layer of mucus. They don't do much harm to the fences and tree trunks. Nor to the wheat, really. But when the harvester rumbles through, the machinery minces them up. By (did I mention it before?) the thousand. Snail paté.
If there are no fences, trees or cultivated grasses, the snails climb up the next best thing. On the cliff tops at Portland, the next best thing is cushion bush (Leucophyta) — the bad-hair day xerophyte that lives on the windswept dunes.
But Theba isn't the only snail living on the edge. A native species, Austrosuccinea (on the right in the photo) takes advantage of the humid microclimate beneath the Leucophyta. Very little is known about this succineid. So there's another project to get stuck into … but not just yet because they're mostly found on controlled land, so I'll need a permit. And that takes time.
