A Twisted Tale of Snail Shells

Coiling matters — in more than one way

Garden Snail (Cornu aspersum). Photo by Robert Stump on Unsplash

Jeremy the Garden Snail was a gastropod superstar. The snail made the news for its shell. Neither unexpectedly big nor vividly coloured, the shell looked, at first glance, like any other shell and its owner like any other snail — a bit grey, a bit slimy, and with the standard complement of tentacles. But Jeremy differed from the average Garden Snail in one profound way: its shell coiled to the left.

Jeremy was a shellebrity.

The shells of most Garden Snails (Cornu aspersum, Helicidae) are variable in size and pattern, but they do not vary in one significant feature — direction of coiling. If you pick up a Garden Snail and hold it so the spire points upwards and the aperture faces you, the aperture will be on the right. In malacological terms, the direction of coiling is dextral.

But Jeremy was sinistral. A shell that opens on the left is phenomenally rare among Garden Snails (1 in 40,000) and it was enough to slide Jeremy into the headlines.

About 370 years before Jeremy made the news, artist Wenceslaus Hollar (1607–1677) created a series of etchings for the Earl of Arundel. His subjects were invertebrates — mostly butterflies and moths. Among the insects was a lone snail. It might have been a Garden Snail, a Roman Snail…