martinjohnbishop's picture

Identification of juvenile snails from the shell

This topic has been raised a number of times in iSpot observations so this post may be of wider interest.

Identification of terrestrial juvenile snail shells is important for ecological, archaeological and pleistocene geological studies.

It is fortunate that the whole development of a snail shell remains visible in the adult. To know what a juvenile snail shell looks like you only need to examine larger immature or adult specimens.
The embryonic whorl (the shell possessed when the snail emerged from the egg) is particularly important in this regard. Note the size, shape and texture. It may not be so easy from photographs, but with a suitable reference collection and a stereomicroscope much is possible and the difficulties are well documented.

A good starting point is the work by John G. Evans Land snails in archaeology; with special reference to the British Isles. London, New York, Seminar Press, 1972. xii, 436 p. illus. 24 cm. ISBN: 0128295503

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Martin Harvey's picture

juveniles

Thanks for that Martin, very helpful.

I must admit that when I see a small snail I always struggle to know whether I'm looking at a small adult or a juvenile of a larger species. Am I right in thinking that the lip of the shell is usually (always?) soft and flexible in the juvenile, while in the adult it is usually (always?) thicker and more solid?

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Entomologist and biological recorder

martinjohnbishop's picture

Shell lips

Yes, the shell is always soft and flexible in juveniles.

There are many species where the shell is reduced or even internal. In an adult Vitrina pellucida, for example, the shell is small relative to the body and remains soft and flexible. So yes, the shell lip is usually thicker and more solid in the adult but there are species where this is not the case.