Species of the Day: Lipped Snails

By James Duncan

Learning and Engagement Officer

There are a couple of species of Lipped Snails commonly found in Britain - they're cleverly named Brown (Cepaea nemoralis) and White-lipped (Cepaea hortensis) according to the colour of the band closest to the opening (or aperture) of the shell. Of course, in nature, things are rarely clear cut and it's not impossible that either species may have the opposite lip colour. General wear and tear to the shell may also make identification difficult. Both species are a type of land-based invertebrate known as a Gastropod, comprising both slugs and snails. This translates to an animal that essentially has its stomach and foot contained within the same body part. They may have a reputation as slow, slimy and somewhat distasteful but its worth remembering that Gastropods are one of the very few animals that have managed to conquer both land, sea and fresh water. 

To add to the ID challenge, these snails exhibit a huge amount of diversity to both their colour and patterning - this is known as polymorphism. In fact, these snails were used in early genetic studies on natural selection which continues to be researched even now. The morphology of the shells varies according to a number of external factors driving natural selection - predation, habitat type and climate. One of the top predators of the Lipped-snails is the Song Thrush, whose visual perception of the camouflage is pivotal as to which snails survive to pass on their genes. 

These snails (like most) are hermaphrodites, containing both male and female sex organs. This doesn't mean they have no requirement to mate, sexual reproduction is a requirement in the Lipped snails. Unfortunately for them, it's a long, tortuous and possibly painful process. During the courtship and prior to mating, they employ a 'love dart.' Now this isn't quite as romantic as it seems as it's essentially a weapon, used to pierce the skin of the other snail. The dart itself is a sharp, mucus coated calcareous object which unites the snails prior to copulation. Essentially it's a 'stabbing' with hormones to try and increase the chance of successful reproduction. Unfortunately there's no organ to receive such a thing and injury is a distinct possibility.  

White-lipped Snails © James Duncan