Isavar's picture

Snail

Observed: 20th October 2012 By: IsavarIsavar’s reputation in InvertebratesIsavar’s reputation in Invertebrates
P1010715
P1010714
Description:
Identifications
Species interactions

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Comments

BDeed's picture

Snail Lip

I have put the id as white lip as, well it lacks the Brown lip... However, i understand that rarely both species may show the opposites character but am not aware of other distinguishing features that can be relied on?

Martin Harvey's picture

Cepaea

I think the first question is whether or not this is an adult snail. Adult Cepaea snails have a thickened edge or 'lip' around the mouth opening (as do most snails when adult), and for Cepaea you can also check the 'umbilicus' in the centre of the shell underside - if this is an open hole then you have a juvenile, while adults should have the umbilicus completely closed off (for details see the links at end of this comment).

I can't quite make up my mind whether the photos here show an adult snail: the underside photo doesn't quite show the opening of the umbilicus (if there is an opening) and the snail's body is obscuring the lip inside the shell mouth opening. But there does seem to be some thickening of the shell opening, so I think it probably is an adult.

In which case the fact that the lip of the shell opening is pale makes it very likely to be White-lipped Banded Snail. The two banded snail species are extremely variable, and Ben is correct that there is a form of the Brown-lipped that has a white lip and vice-versa, but according to the Conchological Society these unusual forms are "very rare exceptions", see:
http://www.conchsoc.org/node/5468

Brown-lipped Banded Snail is usually larger than White-lipped, but again this can vary and the largest White-lipped snails are larger than the smallest Brown-lipped.

As far as I know the only way to be 100% certain of any one individual snail is to dissect it, in which case there are differences in the mucus glands and sex organs of the two species. But usually it is easier to have a look around for more snails: if you are looking at a population of Brown-lipped snails then larger shells with brown lips will predominate, and vice-versa for White-lipped.

For more on Cepaea snails see The Open University's "Evolution Megalab" project:
http://www.evolutionmegalab.org/en_GB/

and in particular these guides to identifying Cepaea snails:
http://www.evolutionmegalab.org/file_downloads/en/Adult_vs_juvenile.pdf

http://www.evolutionmegalab.org/file_downloads/en/How_to_hunt_banded_sna...

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Entomologist and biological recorder

BDeed's picture

Cheers for that Martin, i

Cheers for that Martin, i certainly wasn't aware of how to tell Adult and Immature snails apart so that's especially useful, as is the tip for looking for more snails in the population, i know when i've seen banded snails in the past there are often a lot of them together but i never thought of using that to aid in the identification..

dejayM's picture

deserves

Ben, I think you deserve some support. It is no great risk (for me) because there are some VERY doubtful agreements in other White-lipped posts.
Sometimes, when you are NOT an expert, it is worth having a punt, as it were; I see a white lipped banded snail here!
Have you thoughts as to why the ID Panel is incomplete (Wiki etc.)?
Isabel, it shows, doesn't it, that more and closer pictures and a scale or some measurements are sometimes necessary. Nice pics nevertheless.
ðj

BDeed's picture

Thanks Derek. I am not sure

Thanks Derek. I am not sure what you mean by incomplete id panel. The links seem to be working from my end?

dejayM's picture

name issue

Oh, you're welcome Ben.. The ID panel is pink and where the ID is 'held'; in the Brown lipped one, the panel is compete with links to NBN and Wiki etc. This should be worrying because it often suggests a mistake or a misspell. Your 'White Lipped Snail (Cepaea (Cepaea) hortensis)' has not been recognised by the iSpot master database - maybe because it prefers, simply, Capaea capaea, like in http://www.ispotnature.org/node/370146. But notice there that the ID panel changed it!

Note that many of the white lipped postings (search) have the same outcome but a few, like mine here http://www.ispotnature.org/node/350763 make it all the way, Can you spot the difference?
As a Mentor, Isabel (whose post it is) should take an interest in this anomaly. I dare say that we will quickly hear from Martin. I find it frustrating NOT being able to explain it.

Martin Harvey's picture

name links

I rather fear that the lack of links is simply the result of a glitch on iSpot, of which we have had a few in the last week or two. The name "Cepaea (Cepaea) hortensis" is entirely correct and the links to Wikipedia etc. should have appeared.

Ben, if you want to add the ID again it will hopefully work second time around, but up to you.

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Entomologist and biological recorder