Mud Snails (Hydrobiidae)

Spring snails are a very diverse family of small to tiny snails inhabiting fresh or brackish water, also appearing on humid ground near the coast. Very few species also actually are found in the sea, on muddy ground among seaweed. It is estimated there are about 300 species in North and South Europe, about 1000 species worldwide, in Australia alone 280 species are mentioned. In Central Europe many spring snail species inhabiting ground water, caves or springs are limited to one single geographic finding site, which means a very large ecological threat to those species.

Systematics of Gastropoda: Clade Caenogastropoda: Hydrobiidae.

Mud Snails (Hydrobiinae)

 
  Superfamily Rissooidea
  Family Amnicolidae (Spring snails)
  Subfamily Amnicolinae (Spring snails)
Genus Bythinella (Spring snails)
Genus Marstoniopsis
  Subfamily Emmericiinae (Spring snails)
Genus Emmericia (Spring snails)
  Family Hydrobiidae (Mud snails)
  Subfamily Hydrobiinae
Genus Peringia (Laver spire snails)

  Subfamily Belgrandiinae (Spring snails)
Genus Belgrandiella (Spring snails)
Genus Sadleriana (Spring snails)
Genus Bythiospeum (Fountain snails)

  Subfamily Tateinae
Genus Potamopyrgus (New Zealand mud snails)

  Subfamily Pyrgulinae
Genus Pyrgulina
  Family Lithoglyphidae (Gravel snails)
  Subfamily Lithoglyphinae
Genus Lithoglyphus (Gravel snails)
  Family Bithyniidae
Table: Summary of the described families.

Laver Spire Snail - Peringia ulvae (Pennant 1777).

Laver spire snail (Peringia ulvae).

Spring Snails (Belgrandiinae)


Spring snail (Belgrandiella wawrai).
Picture: © Alexander Mrkvicka, Vienna (mrkvicka.at).
 

Spring snails (Belgrandiella) in Austria

Belgrandiella aulaei Haase, Weigand & Haseke 2000
Belgrandiella austriana (Radoman 1975)
Belgrandiella boetersi Reischütz & Falkner 1998
Belgrandiella fuchsi (Boeters 1970)
Belgrandiella ganslmayri Haase 1993
Belgrandiella kreisslorum Reischütz 1997
Belgrandiella mimula Haase 1996
Belgrandiella multiformis Fischer & Reischütz 1995
Belgrandiella parreyssii (L. Pfeiffer 1841)
Belgrandiella pelerei Haase 1994
Belgrandiella styriaca Stojaspal 1978
Belgrandiella wawrai Haase 1996

Source: Wolfgang Fischer: Checklist of Austrian Mollusca.

Among the spring snails of the Belgrandiella genus there is also the thermal spring snail Belgrandiella pareyssii, which shares the thermal springs of Bad Vöslau in Lower Austria with the thermal spring nerite (Theodoxus prevostianus) and the thermal spring pitch snail (Esperiana daudebartii).

 
Another group of spring snails are the Sadleriana genus (this
is Sadleriana schmidtii from Slovenia).
Picture: © Alexander Mrkvicka, Vienna (mrkvicka.at).

Spring snails (Sadleriana) from Slovenia and Croatia.

Fountain Snails (Bythiospeum)

Fountain snails not only live in fountains. There are many cave-dwelling species among them, as are species living in the ground water. Some attention the snail Husmann's fountain snail received by being elected mollusc of the year 2009.


Husmann's fountain snail (Bythiospeum husmanni).
Picture: © Vollrath Wiese, Haus der Natur, Cismar.
 

The snail with the scientific name Bythiospeum husmanni at the current state of knowledge exclusively is to be found in the ground water flow accompanying the river Ruhr in North Rhine-Westphalia. It is only able to survive in extremely clean and constantly cool ground water. Its appearance therefore also is valued as an indicator for the innocuousness of this area's ground water as a resource for drinking water. In the rear part of the snail's head two kidney shaped red spots are recognizable, those are the odontophores, where the muscles are attached, moving the rasp tongue (radula) armed with numerous rows of seven toothlets each.

Fountain snails are known from France, Germany, the Netherlands, Switzerland, Austria, Hungary, Slovenia and Northern Italy. There are 50 scientific names of fountain snails of this widely unresearched genus in Germany alone.

Research group molluscs NRW: Mollusc of the year 2009 - Husmanns Brunnenschnecke (Bythiospeum husmanni BOETTGER 1963). (In German)
Tierdoku.com: Husmanns Brunnenschnecke. (In German)
NABU: Bakterienweide im Grundwasserstrom - Husmanns Brunnenschnecke. (In German)
Franz Brümmer, Gerhard Falkner, Hans-Jörg Niederhöfer, Michael Schopper & Rainer Straub: Brunnenschnecken aus Karstquellen. (In German)

New Zealand Mud snails (Tateinae)

New Zealand mud snail - Potamopyrgus antipodarum (Gray 1843)


New Zealand mud snail (Potamopyrgus antipodarum).
Picture: © Alexander Mrkvicka, Vienna (mrkvicka.at).
 

The New Zealand mud snail, apart from the Lusitanian slug (Arion lusitanicus or vulgaris) and the wandering mussel (Dreissena polymorpha), may be one of the best known neozoa in Central Europe. Around 1850 it was introduced by ship from New Zealand to Great Britain, from where it has spread through almost all of Europe.

 
Potamopyrgus antipodarum.
Picture: © Alexander Mrkvicka, Vienna.

Description: Potamopyrgus antipodarum has an erect conical shell with strong walls, a pointed apex and slightly rounded whorls. The shell mouth is pointedly oval, the shell navel (umbilicus) is closed. The shell is glossy, yellowish to reddish brown in colour. The relation between height and width is variable, by parasitic castration there may be more whorls, and as a consequence larger specimens.

Dimensions: H: 4 - 6 mm; W: 2 - 3 mm; N: 5½. (Abbreviations).

Habitat and Distribution: The New Zealand mud snail lives in brackish and fresh water, it tolerates a salinity of up to 1.7%. Potamopyrgus antipodarum is usually found in the surf zone of rivers, as well as in ditches, where it also serves as food source for fish.

Of the most native water snail groups the New Zealand mud snail is different in its high tolerance against eutrophic conditions. It also tolerates temperatures between 0 and 34 °C, periods of dryness of up to 24 hours, up to 50 days on a humid surface. It is able to pass the digestive system of birds and so be additionally distributed.

Partly, appearances in high numbers have been recorded, such as 100,000 specimens per square metre (in some places Potamopyrgus antipodarum takes 95% of the overall invertebrate biomass). This is ecologically problematic, as so the spring snail replaces not only other molluscs species, but also the fish species feeding on them.

Potamopyrgus antipodarum, to a large extent, reproduces parthenogenetically. While in the beginning it had been assumed exclusively so, in the meantime male specimens have been found, so sexual reproduction is possible.


Picture: © Alexander Mrkvicka, Vienna.
 

New Zealand mud snail (Potamopyrgus antipodarum) from the Timavo springs near Trieste, Italy.

 
Pyrgula annulata from Lake Garda (Italy).
Picture: © Alexander Mrkvicka, Vienna.

Pyrgulinae

Pyrgula annulata Linnaeus 1758

Description: Pyrgula annulata is a relative of spring snails. Its shell can be recognized by the conspicuous sharp keels running ring-like along the whorls, one along the periphery and one weaker keel below.

Dimensions: H: 4 - 10 mm; W: 2.5 - 4 mm.

Habitat and Distribution: The ringed spring snail (according to the approximate translation of the species' scientific name) can be found in Lakes between Northern Italy and Northern Albania. In Dalmatia, the species is also found in springs.

Francisco Welter-Schultes: Pyrgula annulata species homepage.