Photo of the day (69): Vitrina pellucida

Vitrina pellucida is a small land snail in the family Vitrinidae. It is widely distributed in the Holarctic and it is very common species.

There is visible mantle appendix (extension of the mantle that slightly cover the shell) and open pneumostome (breathing pore) on the photo:

Vitrina pellucidaYou can find them in autumn much more easily. They are fully grown up to 10 mm in body length in autumn. Then they will lay eggs and die. The next generation will hatch out from eggs at spring. Therefore you can not usually find adult Vitrina pellucida at (late) spring (depending on country).

I was mushroom hunting in Moravia on October 14, 2017. I found this snail altogether with two juvenile Lehmannia marginata slugs on a Xerocomellus chrysenteron mushroom.

Vitrina pellucida and two Lehmannia marginataVitrina pellucidaDoes the Vitrina pellucida eat mushrooms? I do not know. But what does it eat?

British malacologist John William Taylor (1845-1931) wrote in 1914: “Vitrina pellucida has an almost omnivorous appetite, and is credited with feeding upon Liverwort (Jungermannia platyphylla), mosses, fallen leaves, and decaying vegetable matter. It is also carnivorous, being said by Dr. Baudon to voraciously devour raw mutton, and will also feast upon the bodies of dead or dying worms and animals of its own or other species.”

Falkner et al. wrote in their dataset in 2001:
Deciduous forest litter 2
Lichens (gen.) 1
Epilithic/epiphytic 1
Living algae 1
Higher plants (gen.) 2
Dead 2
Carnivorous/saprophagous 2

This can be read (approximately) in human language: Vitrina pellucida eat sometimes deciduous forest litter and dead plants. It is sometimes carnivorous and/or saprophagous. Rarely it also feeds on epilithic and/or epiphytic lichens and on living algae.

Both authors does not mention fungi. Falkner at al. ignored information, that it eats mosses (although mosses have its own column in the dataset and although they cited Taylor in the reference section), but they listed lichens. Among hundreds of references listed at the end on the book only, it impossible to practically detect where informations comes from.


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

Horsák M., Juřičková L. & Picka J. 2013: Měkkýši České a Slovenské republiky. Molluscs of the Czech and Slovak Republics. Kabourek, Zlín, 264 pp. (in Czech and English). page 112 and page 34.

Taylor J. W. 1914″ Monograph of the land and freshwater Mollusca of the British Isles. Zonitidae, Endodontidae, Helicidae. Leeds, page 7.

Photo of the day (59): Semilimax semilimax

Semilimax semilimax is a semi-slug with central European and Alpine distribution. It lives in moist forests. It is from the family Vitrinidae.

Left side view:
Semilimax semilimaxRight side view:
Semilimax semilimaxWhen I found those gastropods, I though, that I found two different species. Unfortunately all of them are the same species – Semilimax semilimax. I realized that in the lab some time later.

Six semi-slugs, five dark grey, one light grey and all of them are Semilimax semilimax:
Semilimax semilimaxIt is exactly as Welter Schultes wrote: “Animal light to dark grey”. They can vary in color even in one population as it is documented in this my record from central Moravia.


Horsák M., Juřičková L. & Picka J. (2013) Měkkýši České a Slovenské republiky. Molluscs of the Czech and Slovak Republics. Kabourek, Zlín, 264 pp. (in Czech and English). page 34 and page 111.

Welter Schultes F. (2013) Species summary for Semilimax semilimax. AnimalBase, last change 11 December 2013, accessed 28 November 2016.

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.