Skip to content

Citizen snail

Grove snail (Cepea nemoralis) one-banded, yellow form from Galicia, Spain
Grove snail (Cepea nemoralis) one-banded, yellow form from Galicia, Spain

An enormous amount of work has been carried out over the years to try to understand the genetics of this little snail; the brown-lipped banded snail (Cepaea nemoralis). It has been called a model organism, and has been the subject of a huge citizen science project. So lets call it citizen snail! It is highly variable, and exists in a number of different forms, with different colours (yellow, pink and brown) and different numbers of dark bands (none, one or many). Researchers have tried to understand what influences the distribution of these polymorphisms. For example, are they determined by selection pressure (such as predation by thrushes), changes in the environment like temperature, or just genetic drift. Drifting lazily from one form to the other as the lords of randomness decree!

Recently, this obliging little snail found itself the focus of a huge effort of citizen science, to see whether it had changed over the last 40-50 years as a result of climate change (1). The question was: have recent increases in temperature ‘favoured shell morphs with a higher albedo’ (1). In other words, if its getting hotter, will the snail adapt to have lighter coloured yellow shells which reflect back more of the sunlight they receive? A bit like changing to a lighter coloured umbrella!

Participants were instructed on: i) how to find (‘hunt for’) snails, ii) how to distinguish C. nemoralis from a closely related species (C. hortensis), and iii) how to separate adults from juveniles (2). In total, over half a million snails were sampled (1). They weren’t killed, they were all put back after being examined. The results of this Evolution MegaLab project were impressive, with nearly 3,000 new records on polymorphism obtained from 15 European countries (3). In the end, it turned out that ‘there was no general increase in the frequency of yellow shells’, perhaps because the snails can always slide off into the shade if they get too hot! But the work did show an increase in the frequency of banded shell forms, perhaps – it was speculated – because of ‘changing predation pressure by birds’ (1). So they might be the subject of another study to see what birds are eating them! Perhaps we should warn them to prepared for another snail hunt!

1. Silvertown, Jonathan, et al. “Citizen science reveals unexpected continental-scale evolutionary change in a model organism.” PLoS One 6.4 (2011): e18927.


3. Worthington, Jenny P., et al. “Evolution MegaLab: a case study in citizen science methods.” Methods in Ecology and Evolution 3.2 (2012): 303-309.


rcannon992 View All

I am an entomologist with a background in quarantine pests and invasive invertebrates. I studied zoology at Imperial College (University of London) and did a PhD on the population dynamics of a cereal aphid (Metopolophium dirhodum) in the UK. I spent 5 years with the British Antarctic Survey studing cold hardiness of Antarctic invertebates and 17 years with the Food and Environment Research Agency. My main interests now are natural history, photography, painting and bird watching.

One thought on “Citizen snail Leave a comment

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

The Carrs Wetland Project

Farming, Landscape, Heritage and Conservation

jidjottings, by Lowell A. Goldsmith, MD

Musings on skin and the universe


Thailand's amazing insects photographed in the forests around Chiang Mai

Tangled Bank

The natural world, inclusive bushcraft, evidence-based environmentalism

The Quagga

Science Blog of the SciComm Students @ Natural History Museum, Zoological Society of London & University College London

Exploring Colour

New Zealand

Gwen Pearson

Entomologist. Educator. Writer. Nerd.

Davina's observations

Observations of nature and science

Michael Whitehead

Plants, pollination, evolution, ecology, natural history.

The year of the fly

Exploring the families of British Diptera

Jonathan Pomroy

Wildlife & Landscape Artist

the glyptodon

Stories of natural history


Research blog of Renee Rossini

Notes on a Spanish Valley

Award-winning blog - Living in rural Andalucia

The Art of Blogging

For bloggers who aspire to inspire

walter sanford's photoblog

Showcasing some of my digital photography and videography.


Science, skepticism and dragonflies

Paths Unwritten

Lost Cities. Forgotten Spaces. Curious Places.

Q13 FOX News

Seattle and Western Washington's source for breaking news, weather, and sports. Home of Washington’s Most Wanted and the Seattle Seahawks.

Spanish Linguist

a linguist writes about Spanish

%d bloggers like this: