White-lipped Snail

Let’s start the day with a quiz: which PEI animals can be found in saltwater, freshwater, and on land? If you guessed snails, give yourself a gold star! Meet one of our common land species, the White-lipped Snail. 

Photo 1: An adult White-lipped Snail on PEI.

We have more than a dozen different species of land snails on PEI (and likely more to be found), but the two most commonly seen are Brown-lipped (Cepaea nemoralis) and White-lipped (Cepaea hortensis) Snails. These closely related species share similar and highly variable appearances: both can be yellow, pinkish or brown, and both can have up to five brown bands on the shell (although they can also be unbanded, as seen here).

The key to identification is the lip – that horizontal strip around the opening of the shell – which is dark in Brown-lipped Snails and light in White-lipped. The catch is this lip is always light in juveniles, and so you need an adult snail for identification. Look for the hard and slightly flared-out lip as indicators of adult Cepaea snails (Photo); in juveniles, the lip is straight and will bend a little if you press on it. You can find White-lipped Snails in grassy areas such as fields, meadows, and coastal sites across PEI.

The White-lipped Snail is considered introduced to North America, although the story is far from straightforward. This is a well-known European species, first recorded in North America in Massachusetts in 1837. Subsequent research found this snail to be restricted to the coast, rather than distributed well inland as it is in Europe. It was thus assumed to have arrived with settlers, and not been present in the New World long enough to have expanded inland.

That seems plausible, but the presence of White-lipped Snails in North America set off fierce (but polite) debate among scientists. Some noted the snails’ abundance on uninhabited coastal islands as evidence that they could be native. The discovery of White-lipped Snail shells in pre-Columbian shell heaps seemed to support that, until the opposing team noted that the shells were not crushed or pierced as they would have been if used by Indigenous people for food or jewellery. Further evidence was presented to show that shews buried land snails in shell heaps, suggesting the White-lipped shells could have been deposited much more recently.

Arguments and counterarguments continued throughout the 1800s and well into the 1950s (biologists take these things very seriously!). In the early 1960s, the relatively new technique of carbon dating was applied to shells from Mi’kmaq camp sites in Nova Scotia. These sites included White-lipped Snail shells, and the carbon dating estimated the camps to be 600 +/- 45 years old. A new theory emerged: the species was introduced to North America by Vikings.

Mystery solved, right? Not so fast! In 2010, researchers published the results of their analysis of snail-containing sediments from a cave in Gaspe, Quebec. They concluded White-lipped Snails may have been in North America long before the Vikings, possibly as early as 7,850 years ago. They describe this as a working hypothesis, with a hope that new research could refine their estimate further.

Determining a species’ status as native or introduced is not always easy, and it’s not always one or the other: some species have both native and introduced varieties (for example, Highbush Cranberry [Viburnum opulus]). I expect DNA analysis will eventually solve the mystery, and in the meantime, White-lipped Snails are interesting parts of PEI Untamed!