Thursday, January 1, 2009

Evolution MegaLab - you can study the evolution of snails in your garden

Evolution MegaLab background

Scientists have been studying the banded snail for many years and have found that the darker shell types tend to be more common in woodland where the background colour is brown, while in grass the banded snails tend to be lighter-coloured, yellow and more stripy. This camouflage is an example of adaptation.

Birds eat banded snails

We want your help to find out whether this pattern can still be found, because there has been a big decrease in the numbers of song thrushes in some places over the last 30 years. If there are fewer song thrushes about, you would expect the different snails to be less faithful to their particular habitats than they used to be.

Climate change

There is also a geographical pattern in the colour of shells that we think may have changed in response to the warming of the climate over the last 30 years. Darker shells used to be more common in the north than in the south. We think this was because darker shells warm up more quickly in sunlight, enabling the animals to be more active than light-coloured snails in colder areas.

Help us find out whether lighter coloured shells are more common further north than they used to be, now that the climate has become warmer.


We have collected together all the historical records of banded snail shell patterns that we can find. There are many thousands of them, mainly collected at least 30 years ago. Do a survey of your own and when you register and enter your data the website will automatically search our historical database and show you any changes that have occurred in your area. Visit the Instructions page to get started.

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