Country diary: why did the snail tiptoe across the road?

Crook, County Durham: Rain makes for an easy journey, but dry and dusty asphalt is a different matterForty-nine early morning lockdown walks, and I'd only been rained on twice. Today balanced the account a little, with raindrops hammering on my umbrella. Not a day for lingering, with a cold wind and scudding grey clouds, but ahead, crossing the asphalt of the lane, was a fellow traveller, almost luminous in the gloom: a white-lipped snail, Cepaea hortensis.Cepaea shells come in several colour schemes, with variable numbers of thick or thin spiralling brown bands or, more rarely hereabouts, simply bright yellow with no bands at all. Since the 1940s academic careers have been built on fathoming the evolutionary significance of this genetically determined variation within the genus. Climate, habitat and susceptibility to predation all play a part in the local frequency of morphs. Continue reading...