Brown-lipped Snail

Brown-lipped snail

The key thing about the brown lipped snail is calcium. They make their shells out of calcium carbonate with a small amount of protein. Snails get eaten by predators that like to obtain the calcium carbonate. At rannoch the brown-lipped snails are most common where there is limestone and limestone is basically calcium carbonate in the form of the mineral calcite. When the snail makes its shell it does so turning the mineral calcite into the mineral aragonite but it is still calcium carbonate.

If you visit the Schiehallion Limestone pavement you will find plenty of snails and wherever the Dalradian Limestone outcrops there you will find the brown-lipped snail (Cepaea nemoralis). Some of the snail shells will be empty as the snails have departed this life or the shell may be sealed up as in hot weather the snail may need to aestivate and does not want to lose water. You may find broken shells where a bird has broken the shell on a rock called an anvil in order to extract the snail. Song thrushes are renowned for this but not necessarily at the limestone pavement.

To the east of the Schiehallion limestone pavement there is a south facing limestone slope adorned with the usual lime-loving flowers such as rock rose and here there are hundreds of brown-lipped snails to be found.

Brown-lipped snails lay about 100 gelatinous eggs most of which get eaten, but if they do hatch, the young snail emerges with a transparent shell and needs to feed quickly and find calcium to get a thicker shell that will be an effective defence.

Brown-lipped snails are renowned for their polymorphism. In this case the polymorphism is the colour of the shell which is very variable. One suggestion is that the different colours provide camouflage against different backgrounds and thus hide the snails from birds.

Snails are gastropod molluscs. They have spiral shells and slide along on a mucus lubricated foot. They are hermaphrodites which means they have both sexes in one individual. In spite of this they still need to find a mate to fertilise and then both of the snails go off and lay eggs. They are plant eaters and have a ridged tongue called a radula with which they rasp their food, somewhat favouring dead or decaying vegetation.

(3rd January 2020)