Photo of the day (9): Arion obesoductus

Arion obesoductus Reischütz, 1973 is a small Arion species that lives in undistrurbed forests. Its synonym includes Arion alpinus auct. nec Pollonera, 1887. It lives in Austria, Germany, Slovenia, Croatia, Italy, Switzerland and France. It is found in Alps and around Alps, but its distribution is more wide: also in Central Europe. The first records of this species from the Czech Republic were published in 2006 under the name Arion alpinus. It is not very common in the Czech Republic, but it was found in various areas there. It was neither found in Poland, nor Slovakia and Hungary.


It is often found on mushrooms and I have found it on mushrooms also. My record comes from the forest near the Pateřín village in the Central Moravia, Czech Republic. It is spruce forest (Picea abies) with beech (Fagus sylvatica). Arion obesoductus cooccur with slugs Arion fuscus, Malacolomax tenellus and Lehmannia marginata there. It is similar to Arion fuscus, but its foot is orange:


The orange foot of Arion obesodusctus (two specimen on the right) is easily recognizable even trough plastic translucent test-tube in comaprison of Arion fuscus (on the left). The length of the tube is 58 mm.



Dvořák L., Backeljau T., Reischütz P. L., Horsák M., Breugelmans K. & Jordaens K. (2006): Arion alpinus Pollonera, 1887 in the Czech Republic (Gastropoda: Arionidae). Malacologica Bohemoslovaca 5: 51-55.

Horsák M., Juřičková L., Beran L., Čejka T. & Dvořák L. (2010). “Komentovaný seznam měkkýšů zjištěných ve volné přírodě České a Slovenské republiky. [Annotated list of mollusc species recorded outdoors in the Czech and Slovak Republics]. Malacologica Bohemoslovaca, Suppl. 1: 1-37.



Photo of the day (8): Anisus leucostoma

Anisus leucostoma is planorbid freshwater snail with Palearctic distribution. It occurs in standing water such as periodic marshes.


Its shell is flattened and it has dimensions of shell about 6.5 mm × 1.4 mm. Therefore it is not easy to get its sharp photo with such dimensions and moreover in water. Addtionally its brown shell can be covered with some coating, that gives to the shell very dark appearance.


Anisus leucostoma crawling below the water surface in natural light conditions. There is also visible for example mantle edge on the lip of the aperture:



Comparison with larva of Culex:


Anisus leucostoma extended from its shell:


There is periphyton attached on the shell:


Under bright artificial lighting and with white balance there is visible, that the periphyton consist of green algae:



Photo of the day (7): Monacha cartusiana

Monacha cartusiana is hygromiid land snail of Atlantic-Mediterranean origin. It lives for example also in the southern England and in France. Is is considered as non-indigenous in (some parts of) the Central Europe, where it has isolated localities. It appears that it is spreading northward.


Monacha cartusiana can be easily recognized according to the reddish margin of the lip and white lip. The shell is yellowish.


These photos are from Olomouc, Moravia, the Czech Republic.

It is usually sitting on vegetation like this:


Juvenile specimen:


Mapping project on also includes Monacha cartusiana.


There are about 80 species in the genus. Up to 2011 there have been found only this one Monacha species in the Czech Republic. Another species Monacha cantiana has been recently found in Bohemia, the Czech Republic in 2009. We will see, if it will be also spreading, but its spreading is expected.




Míkovcová A. & Juřičková L. (2008). “Hledá se tmavoretka bělavá. [The helicid snail wanted]”. Živa 2: 73. (Czech abstract), (English abstract)


Pech P. & Pechová H. (2009). “Monacha cartusiana (Gastropoda: Hygromiidae) in South Bohemia”. Malacologica Bohemoslovaca <> 8: 28.


Novák J. & Novák M. (2009). “Dvě nové lokality tmavoretky bělavé Monacha cartusiana (O.F. Müller, 1774) na Moravě”. Malacologica Bohemoslovaca 8: 29-30.


Horsák M., Juřičková L., Beran L., Čejka T. & Dvořák L. (2010). “Komentovaný seznam měkkýšů zjištěných ve volné přírodě České a Slovenské republiky. [Annotated list of mollusc species recorded outdoors in the Czech and Slovak Republics]. Malacologica Bohemoslovaca, Suppl. 1: 1-37.


Hlaváč J. Č. & Peltanová A. (2010). “First occurrence of the Kentish Snail Monacha cantiana (Mollusca: Gastropoda: Hygromiidae) in the Czech Republic”. Malacologica Bohemoslovaca 9: 11-15.


Peltanová A. & Novák J. (2011). “Map of distribution of Monacha cartusiana in the Czech Republic”. In: Zicha O. (ed.) Biological Library – BioLib. Retrieved on 2011-08-18. Available on: <>


How does Oxychilus hunt?

I wanted to see how the predaceous snail Oxychilus draparnaudi hunts and eats its prey. It is called to be typical predaceous species. But after 10 days of keeping it at home I have not seen it hunting yet.

3rd August – I have collected the snail Oxychilus draparnaudi (shell width 7.5 mm). Locality: Olomouc, Czech Republic.


4th August – no food

5th August – added 3 Trochulus hispidus. They have cucumber as a food source. Even when the predator was at least one day without the food and its prey has been crawling on the predator’s body, it has not been hunting them during the day.


6th August – found Trochulus hispidus (shell width 4.0 mm) eaten

7th August – found Trochulus hispidus (shell width 5.5 mm) eaten at 9:01 and I have taken the photo of Oxychilus above the empty shell.
–  added 6 Trochulus hispidus
– added 2 adult Laciniaria plicata. I have no idea if it will be able to eat them.


8th August – found Trochulus hispidus (shell width 5.0 mm) eaten

9th August – found Trochulus hispidus (shell width 3.5 mm) eaten

10th August – nothing

11th August – found Trochulus hispidus (shell width 3.5 mm) eaten

12th August – nothing

13th August – nothing, measured Oxychilus draparnaudi (shell width is still 7.5 mm)

All my controls when I have found empty shells, were during the day, but the Oxychilus draparnaudi is nocturnal. Some controls were at night.
It have eaten 5 snails during 10 days.
I found no damage on shells of the eaten Trochulus and shells were completely clean inside (but with water).

Any hints how to see it hunting?


Buccal mass of Arion vulgaris

Pharynx (as one of frontal parts of the digestive system of gastropods) in number of carnivourous gastropods can be everted to draw the prey easily into the predator’s body.


Arion vulgaris is omnivorous and it is not known to evert its pharynx during feeding (as far as I know). This photo of Arion vulgaris shows the dead or nearly dead specimen with buccal mass everted out of the body . I am not sure what exactly has stimulated to this specimen to evert its pharynx, but I think that it was caused by some deadly conditions such as drowning in water with mucus.


The buccal mass consist of mouth and buccal cavity (=pharynx). Mouth has lips. There are visible lips on the the photo (the left part of the white extended part). Behind the lips there is oral tube (not visible on this photo) leading to the buccal cavity (=pharynx, the right part of the white extended part). Inside the buccal cavity there is the jaw, the radula sac containing the cartilaginous odontophore and the radula on the odontophore (all of them are hidden inside the pharynx). The radula sac can be seen on the posterior part of the buccal cavity (on the top righ of this photo), but I do not know exactly how much is the radula sac extended into the buccal cavity.


The head of this slug is dirty dark brown in color. I think, that there is also visible frontal part of the oesophagus, that starts normally on the dorsal part of the buccal mass. Oesophagus is visible in light brown-reddish color before the frontal part of the head.


The slug has also two ducts from salivary glands leading to the buccal mass. They are on sides of the oesophagus, but they are not visible on the photo and I have not find these ducts on this specimen. There should be also buccal retractor, but I was unable to identify that muscle also.


This photo shows main parts of the digestive system of gastropods, that are responsible for reception of the food.


Further reading:


How slugs fight against dehydration

I have put nine Tandonia budapestensis into fully transparent plastic terrarium with internal dimensions: 17 cm long, 8.3 cm width and 2.8 cm high. This transparent box (or any other transparent terrarium) seems to be useful for watching the behaviour of gastropods. They received a piece of skin of watermelon as a food source. They also received some water from water sprayer, but not too much because I was afraid of drowning of slugs. Approximately only centre of the box was sprayed once. There was nothing else in this terrarium. No substrate except of some small pieces of soil that were stinged to slug’s bodies during transport. No ventilation, but probably no loss of water in this closed artificial environment.

About one day later they were “sleeping” and they were clustered like this:


Two of them are not on the photo, because they were on the cover. Those two were also next to each other.


Similar photo of aggregation of slugs (of Limacus flavus) is on the page 470 in the 2001 book The biology of terrestrial molluscs.


This aggregation of slugs is explained as behaviour against loosing of water in drier environment. They are tightly packed to each other and they reduce the area of evaporation. (Snails do not do that, because they can retract to shells.)


I have taken the first photo at 18:57:33 very soon after the removing the cover of the terrarium. All slugs were sleeping and one was eating. Slugs have swiftly found out, that something has changed. After 1 minute 22 seconds (at time 18:58:55) they started to extend their tentacles and started to move.


Next days they did not make similar aggregation. It seems, that instead of that, they “discovered”, that they can be sitting on the watermelon and receive water through the body wall.


You can not see such behaviour if you will keep one, or two slugs in the terrarium.

When I have started to doubt that they will agrregate again and six days later after taking the first photo, I have taken these photos:


Surviving poisonous fungi


Today I was mushroom hunting. One of the best findings was the death cap Amanita phalloides, that is the most poisonous fungus of the Northern Hemisphere. It is deadly poisonous for humans, but some animals, such as gastropods can eat them without any problems.

When you are mushroom hunting, yellow slug Malacolimax tenellus is one of the most common species you can find even in spruce monoculture plantings. It is strictly woodland species living in Europe. Coniferous forests are not suitable environment for many gastropods, especially for snails. Snails can not create their shells in acidic coniferous forest habitats easily. Therefore usualy only few slug speciess thrive there.


Although this time the slug has fallen down when trying to go up over the annulus, there are many markings how the fungus is damaged by this slug: on the top of the cap (not visible on these photos), on lamellae, on the stipe, the whole volva is eaten.


Gastropods are alo resistant to hallucinogenic alcaloids hyoscyamine and atropine that are available for example in mandrake plant Mandragora officinarum.




(in Czech) (15 May 2011) “Peyotl, mandragora a další: Ze světa halucinogenních rostlin” Český rozhlas [Czech Radio] – reference about the mandrake. It would be good to have more scientific reference for the resistence to mandrake. If you know some, let me to know.

Barker G. M. (ed.) (2001) The biology of terrestrial molluscs. page 263.


(in Slovak) Lisický M. J. (1991). Mollusca Slovenska [The Slovak molluscs]. VEDA vydavateľstvo Slovenskej akadémie vied, Bratislava, 344 pp.

Nature of Šumava in danger

Šumava National Park is the largest National Park in The Czech Republic. It is also among the largest forest in Central Europe and Special Protected Area within the Natura 2000.


The temporary director of the management of the Šumava National Park decided to extensive logging in core zone in habitats of rare birds and with other parts of its unique biota including gastropods. Czech Ministry of Environment tolerate this damage of the most valuable parts of nature in Central Europe. Logging activities in National Park are illegal in the Czech Republic, against law of European Union, against principles of conservation biology, and against scientific recommendations of Czech Ecological Society , Federation of Nature and National Parks of Europe and others.


The most rare gastropod species in Šumava include (with the conservation status in the Czech Republic):


Macrogastra badia – Endangered


Petasina edentula – Endangered


Vestia turgida – Endangered in Bohemia


Vitrea transsylvanica – Critically Endangered in Bohemia


Eucobresia nivalis – Endangered


Arion intermedius – Near Threatened


Vertigo ronnebyensis – Critically Endangered


Deroceras rodnae – Near Threatened


If you also think, that this unprecedented destruction of a National Park should be stopped, you can send a letter to Mr. Petr Nečas, Prime Minister of the Czech Republic.


Dvořák L. (2003). Nejvzácnější prvky šumavské malakofauny. In: Zoologické dny Brno 2003, Bryja J. & Zukal J. (eds.), Sborník abstraktů z konference 13.-14. února 2003: page 29.


Dvořák L. (2005). Notes on distribution of the Carpathian snail Vestia turgida in the Bohemian Forest. Silva Gabreta 11: 97–103.


Red List of the molluscs (Mollusca) of the Czech Republic


Further reading in English:


Further reading in Czech:


Photo of the day (6): Arion vulgaris – mating and ovotestis

Arion vulgaris is a serious agricultural pest in Europe. It is a hermaphroditic slug. They have gonad in male phase before and during mating. During the mating they “think”, that the other slug is female and they will exchange sperm reciprocally. Later, some time after mating, they will get to female phase, they will produce ova and they will use received and stored sperm to fertilize its ova.


That is not in ideal circle on the photo, because I have disturbed them to move them into glass to take photos.


Reproductive system is usually important in determination of species. There were usually black and white drawings of reproductive system of gastropods in scientific literature. Only sometimes there are photos of reproductive system in newer publications. I found no photos of reproductive system of Arion species on the internet.


End of visceral mass removed from tail end on the body of the slug. There are not parts, that could be useful in species identification in this photo. It shows hepatopancreas and ovotestis. The hepatopancreas is that brown mass. Maybe it shows the whole hepatopancreas, but I am not sure, because the whole part on the photo is roughly torned off the rest of the body. The grey part is ovotestis.


The most important part of the reproductive system in hermaphroditic pulmonate slugs is ovotestis (= gonad, = hermaphordite gland). Ovotestis consist of some lobes. Each lobe consist of number of acini. The ovotestis of Arion vulgaris (as far as I can see) has five lobes. Ovotestis produces sperm (spermatogenesis) in male phase and it produces ova (ovogenesis) in female phase. I do not know in which phase the ovotestis is on the photo. I think that it should be possible to identify histologically, but I do not know, if it is possible to identify macroscopically. Spermatozoa grows in the inner part of each acinus. Oocytes grows in cortex of each acinus.