''Anisus vorticulus'' (lesser ramshorn snail or little whirlpool ramshorn snail) is a species of minute, air-breathing,

freshwater snail Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs ...

, an aquatic gastropod

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is es ...

in the family Planorbidae, the ramshorn snails.

Description

The lesser ramshorn snail is a very small species growing to a maximum diameter of . The shell lacks a keel and the peripheral angle is relatively prominent, with a slender, narrow periostracal fringe.

Distribution

''Anisus vorticulus'' occurs in

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. Th ...

- critically endangered (CR). Its Conservation status in 2004–2006 is bad (U2) in report for

European commission The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body ...

in accordance with Habitats Directive.

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

- vulnerable (VU), listed in List of endangered species in the British Isles. It is currently the focus of a

Back from the Brink Back from the Brink may refer to: * ''Back from the Brink: Pre-Revolution Psychedelic Rock from Iran: 1973–1979'', a 2011 album by Kourosh Yaghmaei * ''Back from the Brink'', a 1983 book by Michael Edwardes * ''Back from the Brink'', a 2006 autob ...

project.

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

- critically endangered (''vom Aussterben bedroht''),

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

Poland Poland, officially the Republic of Poland, , is a country in Central Europe. Poland is divided into Voivodeships of Poland, sixteen voivodeships and is the fifth most populous member state of the European Union (EU), with over 38 mill ...

Slovakia Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the ...

- critically enangered,

Latvia Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic of Latvia ( lv, Latvijas Republika, links=no, ltg, Latvejas Republika, links=no, liv, Leţmō Vabāmō, links=no), is a country in the Baltic region of ...

and

Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...

- in the

Krka National Park Krka National Park ( hr, Nacionalni park Krka) is one of the Croatian national parks, named after the river Krka (ancient Greek: ''Kyrikos'') that it encloses. It is located along the middle-lower course of the Krka River in central Dalmatia, i ...

. First finding of this species in Croatia was in 2009. In the British Isles, this species is restricted to a small number of sites in the Norfolk Broads and the

Pevensey Levels Pevensey Levels is a biological Site of Special Scientific Interest between Bexhill-on-Sea and Hailsham in East Sussex. It is a Nature Conservation Review site, Grade I, a Ramsar site and a Special Area of Conservation. An area of is a nati ...

and Arun Valley in Sussex and Surrey.

Habitat

This small snail lives in pools with standing water and in

oxbow lake An oxbow lake is a U-shaped lake or pool that forms when a wide meander of a river is cut off, creating a free-standing body of water. In South Texas, oxbows left by the Rio Grande are called '' resacas''. In Australia, oxbow lakes are cal ...

s, but these biotopes are threatened because of

sedimentation Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to t ...

and

ecological succession Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire) or more or less. Bacteria allows for the cycling of nutrients such as car ...

. It favours ditches with much aquatic flora but little emergent vegetation. Invasive plants such as floating

marsh pennywort ''Hydrocotyle vulgaris'', the marsh pennywort, common pennywort, water naval, money plant, lucky plant or copper coin, is a small creeping aquatic perennial plant native to North Africa, Europe, the Caucasus and parts of the Levant. Description ...

, (''Hydrocotyle ranunculouides''), that sometimes chokes ditches, and the

Himalayan balsam ''Impatiens glandulifera'', Himalayan balsam, is a large annual plant native to the Himalayas. Via human introduction it is now present across much of the Northern Hemisphere and is considered an invasive species in many areas. Uprooting or cut ...

(''Impatiens glandulifera'') are particularly harmful. This species often lives in places where there is abundant duckweed ''

Lemna ''Lemna'' is a genus of free-floating aquatic plants referred to by the common name "duckweed". They are morphologically divergent members of the arum family Araceae. These rapidly growing plants have found uses as a model system for studies in ...

'' spp..

Water quality Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through ...

that is suitable for ''Anisus vorticulus'' is water without

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids ...

, with a high pH and a low level of nutrients. The main threats to this snail include land drainage, poor habitat management and

eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...

References

External links

''Anisus vorticulus''
at

Animalbase AnimalBase is a project brought to life in 2004 and is maintained by the University of Göttingen, Germany. The goal of the AnimalBase project is to digitize early zoological literature, provide copyright-free open access to zoological works, and p ...

distribution of ''Anisus vorticulus''
at

European Environment Agency The European Environment Agency (EEA) is the agency of the European Union (EU) which provides independent information on the environment. Definition The European Environment Agency (EEA) is the agency of the European Union (EU) which provides ...

webpage *
''Anisus vorticulus'' and its distribution in the Czech Republic with map
{{Taxonbar, from=Q199130 Planorbidae Gastropods described in 1834