Superfamily:  Ampullarioidea (GRAY 1824)

Family:            Viviparidae (GRAY 1847)

Subfamily:      Viviparinae (GRAY 1847)

Genus:           Viviparus (MONTFORT 1810)

Species:        Viviparus acerosus (BOURGUIGNAT 1862)

Subspecies:  Viviparus acerosus acerosus (BOURGUIGNAT 1862)

Description:

The Danube river snail is the largest freshwater snail native to Central Europe. Its dextrous shell grow 30 to 57 mm long and 23 to 40 mm wide. Its dextrous shell grows to 30 to 57 mm in length and 23 to 40 mm in width. The up to 7 globose whorls are set off against each other by a deep suture. Starting at the pointed apex, they increase in size, at first slowly and flattish, then evenly and globose. The tiny apex looks like it had been added to the shell later on. Older snails often lose their apex due to corrosion, which can lead to confounding them with other related species.  Their navel is narrow and more than half-covered.

The aperture (and thus also the operculum) is teardrop-shaped with a moderate point. The growth rings of the corneous operculum are concentric around the excentric nucleus.

The males stay a little smaller and slimmer than the females when kept under the same conditions. Their shells have less and flatter whorls. The body whorls of the females can be extremely globose and show a short, shoulder-like flattening at the suture.

The shell surface is finely structured by stria. A characteristic for the species is said to be a spiralling sculpturation on the first three whorls and a cancellated or malleated structure on the further whorls. When growth stops, especially in winter, a clearly visible growth ring forms.

 The shell is of a dirty greyish yellow to a yellowish green and has three red-brown bands varying in width. The apex is mostly white.

The wide foot of this snail has a low bow at the front, is seamed with a glandular row and has a narrower bow at the back. The bristle-like tentacles are long, and the male's right tentacle is also a copulative organ and is thus significantly thicker. The eyes are located on short stubs at the bases of the tentacles. There is one lobe on each side behind the tentacles. The left one serves to bring fresh water to the gills, the right one houses the water outlet siphon and the food groove.

The body and foot of adult animals are of a medium grey, with contrasting bright yellowish-white dots. The young snails bodies are light grey with white dots.

Range/Habitat:

This species is prevalent in the catchment area of the Danube and its larger affluents:

Austria (Danube downriver of Vienna), the Czech Republic (e.g. in the area of Lednice; Moravì; Mokfiady dolního toku Dyje), Slovakia (e.g. at the confluence of Hron and Danube), Hungary (e.g. in eastern Hungary: borough of Nagymágocs; Thíza), Croata, Bosnia-Herzegovina, Serbia, Bulgaria, Romania (e.g.  Lake Matita/Danube delta, Bihor province), the Ukraine.

In Germany it has been known to exist as non-native species since 1966. So far it has only managed to advance to the Danube downriver of the Geislingen barrage.

This species prefers rivers and oxbow lakes with low currents as well as lakes and fish ponds. It lives on sand and mucky substrate.

Reproduction, life span:

In aquariums females ready to mate were observed crawling up the glass or a stone after pausing for several hours. They might give off pheromones to the water doing so, because soon the first males come with their right feeler outstretched. Before releasing the young snails the female digs into the substrate for 1 to 3 days.

In contrast to the pointy river snail (Viviparus contectus) the frontal mantle seam of the young snails is smooth or has tiny bulges at best. Accordingly, their shells are hairless or have only a few tiny hairs.

Apart from that, reproduction and life span can probably be compared to that of the common river snail (Viviparus viviparus).

Food:

In nature probably similar to that of the common river snail (Viviparus viviparus).

When adapting newly bought snails to an aquarium (wild-caught snails from trade) there can be losses not only due to transport damage but also to difficulties with the different food range. In a normally filtered tank this snail does not find anything to filter, and in a "tidy" tank muck and algae are also hard to come by.

After some time, however, the snails will also adapt to offered food like blanched spinach, sinking tablets with a high vegetable content, spirulina and vegetable tabs. When there are a lot of muck and algae in the tank in addition, and if powdered food high in spirulina is brought into the tank water as a suspension the snails will adapt a lot more easily to the aquarium.

Behavior:

In nature, probably very similar to the common river snail Stumpfen Flußdeckelschnecke (Viviparus viviparus).

Keeping in the aquarium:

The European Viviparidae species offered for ponds in the trade are more and more kept in aquariums together with their extraeuropean relatives.

They can be kept in unheated or little heated tanks from a lengt of 60 cm on. Also in very small containers from 20 l on they have been kept successfully. Experience on that over a longer period of time are not present to the editor, unfortunately.

As the snails dig in during resting periods there should be at least some sandy parts. Fine to coarse gravel can be put in as substrate in other areas. Wood as well as individual stones and lots of aquatic plants should be a part of the tank set-up. In order to provide for sufficient oxygen, aerating the tank is a must especially in summer. When they are kept in small containers outdoors, e.g. in a mortar bucket, aeration is also highly recommendable in summer. A current is not necessary; however, a small current is not of disadvantage. Basically, an artificial filtration is not required, in the contrary: Artificial filtering can lead to starving snails when the animals are new in the tank and there is not enough substitute food for them, as they are partial filter-feeders.

Socialization in the aquarium:

When keeping several of these snails together you should make sure that the males are not in the majority in order not to overstress the females.

They can be socialized with other snails without any objections. When co-housing them with apple snails, however, the young Viviparus snails seem to have no chance. We observed that a feeding Danube river snail defended itself successfully against an intrusive ramshorn snail by biting it away.

In the river snail tank you should abstain from keeping crayfish, large cichlids and other snail eaters. Moreover, the species should not be socialized with mussels like e.g. the zebra mussel (Dreissena polymorpha), as they are a serious food competitor due to the fact that they are filter feeders themselves.

Additional information:

The Danube river snail is classified as highly endangered in the Red List for Germany and Austria, endangered in that of the Czech Republic and Slovakia and as potentially endangered in the Red List of Romaina.

The river snails regularly offered in pet shops and hardware stores in spring as "pond snails" are mostly wild caught in Eastern Europe, mostly in Hungary and Poland. Very often these snails are not exclusively Viviparus acerosus, but also the related species Viviparus contectus and (rather seldomly) Viviparus viviparus. In order not to bastarize the fauna even more, those store-bought snails should not be set free in any case. Even putting them into garden ponds is highly questionable, as it cannot be ruled out that e.g. ducks do not take them to the wild. And apart from that we can safely assume that the Eastern European populations of Viviparus are not treated sustainably – which should not be supported by buying them as a general rule.

As recent subspecies in Europe

 Viviparus acerosus maritzanus (F. HAAS 1913)

 range: Bulgaria and

Viviparus acerosus rumaenicus ( ? )

range: Romania

have been described.

Literature:

GLÖER, P. (2002): Süßwassermollusken Nord und Mitteleuropas. Bestimmungsschlüssel, Lebensweise, Verbreitung. In: Die Tierwelt Deutschlands. Conchbooks, Hackenheim. ISBN 3-925919-60-0.

[Information about characteristics, range etc. - German book]

GLÖER, P & MEIER-BROOK, C. (2003): Süßwassermollusken. Ein Bestimmungsschlüssel für die Bundesrepublik Deutschland. Deutscher Jugendbund für Naturbeobachtung, Hamburg. ISBN 3-923376-02-2.

[Information about characteristics, range map for Germany – German book]

Web links:

Aquarienschnecken-Forum

[thread about Viviparus spec. - German page]

Aquarienschnecken-Forum

[Food thread Viviparus spec. - German page]

Aquarienschnecken-Forum

[thread about animals from the trade – German page]

CIOBOIU, O. (2003): Diversity of Gastropoda in the Romanian sector of the Danube lower hydrographic basin.

[Description of the ranges of V. acerosus and V. a. rumaenicus in Romania on river area levels]

Fauna Europaea

[European systematics, information about their range]

FISCHER, W.: Checklist to Austrian Mollusks / European Viviparidae.

[Color photos of shells]

SÎRBU, I. & BENEDIK, A. M. (2006): Freshwater Mollusca Fauna, Hydrocormoflora and Hygrocormoflora from Cefa Area (Bihor County Romania). In: Brukenthal. Acta Musei, I. 3. Ministeriul Culturii si Cultelor. Muzeul National Brukenthal. Sibiu / Hermannstadt.

[Information about ranges and habitats in Romania]

SLOBODNÍK, J. et al. (2005): Final report on sampling, chemical analysis and ecotoxicological studies.

[Information about some species locations of V. acerosus et.al. along the Danube]

WIESE, V: (Red.) (2007): Systematische Übersicht der Land- und Süßwassermollusken Nord- und Mitteleuropas.

[Systematis of European molluscs – German page]

Author: schneckli

Translator: Ulrike Bauer

This page was actualized on May 13, 2007

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