Photo of the day (27): three gastropods from the family Vitrinidae

These are three gastropods from the family Vitrinidae on a human hand. Each of them belong to a different genus. All of them shows a different level of a reduction of its shell.

Vitrina pellucidae and Eucobresia diaphana and Semilimax semilimaxThe upper one is Vitrina pellucida. This gastropod can completely withdraw into its shell and therefore it is called a snail.

Two others can not fully withdraw into their shells. They are semi-slugs.

The lower left is Eucobresia diaphana. Mantle covers apical part of the shell.

The lower right is Semilimax semilimax. Quite big mantle lobe is covering an apex. The reduction of the shell of Semilimax semilimax is the highest among these three species.

Genera in the family Vitrinidae shows the complete example of the shell reduction from the snails through semi-slugs to slugs.

Examples of snails: Phenacolimax, Vitrina.

Examples of semi-slugs: Eucobresia, Semilimax, Vitrinobrachium.

Example of a slug in Vitrinidae is Plutonia atlantica. It is a slug with an internal shell living on Azores.


Species summary for Plutonia atlantica. AnimalBase, accessed 2 January 2014.

Species summary for Vitrina pellucida. AnimalBase, accessed 2 January 2014.

How to (not) transport Eucobresia diaphana

(This post was released on 28th October 2011 and I have changed one of its photos and some  texts on 9th December 2011.)

Eucobresia diaphana is a semi-slug with Alpine-central European distribution that occur in wet cold places.

My specimen comes from Hrubý Jeseník Mountains, the Czech Republic, from altitude 764 m above sea level. In the surrounding Poland it lives only in Lower Silesia.

This semi-slug can not withdraw into its very small shell. According to Falkner et al. (2001) it will survive desiccation of its habitat for hours or for days only. This land semi-slug is even less adapted for drought than some freshwater snails. For example freshwater snail Planorbis planorbis will survive desiccation of its habitat for weeks or months.

Eucobresia diaphana requires wet environment always. I have highly underestimated this requirements. I have placed the semi-slug to dry paper box. Eucobresia diaphana did not survive transport in such conditions in less than two hours. The semi-slug was completelly dried in less than two hours and it was fixed to the box, so when I have tried to take it, the dried body has broken! I had to use at least moist paper box when I had no other box.

The photo of dead Eucobresia diaphana placed in water with its tail removed. The mantle normally cover the whole apex in live Eucobresia diaphana, but here is the apex visible on this dead specimen:


This embarrassing example shows, how some gastropods are very sensitive to environmental conditions.

The photo of the shell is from the same specimen. Apical view of the shell:


Umbilical view of the shell:


The umbilical view of the shell enables view of apex because columella is curved in such way, that all preceeding whorls are visible. Such shells are called “strofostylní” in the Czech language.

I have taken these photos of the fresh shell in water to show the shell undamaged including undamaged apertural membrane. You can compare these photos with photos of dried shells at AnimalBase.

I have taken these photos of translucent shell on white background (white paper). There were not seen much details on the shell in direct light, so I made these photos in a shadow with reflected light. A little bit red color on the second photo is a shadow or the light, that moved through my own hand (I have used very strong light source).


Falkner G., Obrdlík P., Castella E. & Speight M. C. D. (2001). Shelled Gastropoda of Western Europe. München: Friedrich-Held-Gesellschaft, 267 pp.

Pokryszko B. M. & Maltz T. K. (2007). Rare and endangered terrestrial gastropods of Lower Silesia (SW. Poland) – current status and perspectives. Acta Universitatis Latviensis 723: 7-20.