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''Viviparus viviparus'' is a
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of large
freshwater snail Freshwater snails are gastropod mollusks that 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 t ...
with a
gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...
and an operculum, an aquatic
gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...
mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000  extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...
in the family
Viviparidae Summary Viviparidae, commonly called river snails or mystery snails, are a family of freshwater snails with gills and a protective lid (operculum). Recent studies show that their family tree is messier than expected, with genetic evidence sugg ...
, the river snails. This species is a viviparous (
ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...
) snail.


Description

The height of the
shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...
is 25–35 mm. The width of the shell is 20–26 mm. Males are 2 mm smaller than females of the same age. The shell colour is dark greenish brown or greyish yellow, with three reddish brown spiral bands. The shell is striated but has no hammer pattern. The shell
apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics) A-Bomb Abomination Absorbing Man Abraxas Abyss Abyss is the name of two characters appearing in Ameri ...
is blunt (more pointed in other '' Viviparus'' species). The shell has 5.5-6 weakly convex whorls. The last whorl is relatively large compared to that of other ''Viviparus'' species. The umbilicus is narrow. The animal can lock itself in behind a round lid which shows concentric striations (the operculum). This allows it to protect itself from dehydration, for several months if necessary. Once closed the operculum is flush with the opening of the shell. The operculum is attached to the dorsal surface of the rear of the foot of this gastropod, the body of which is wide and T-shaped, and the colour of which varies from spotted grey to greenish to orange. The mouth has a
radula The radula (; : radulae or radulas) is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters ...
, and a respiratory siphon opens on the right side of the head, feeding gills which are located in front of the heart. This also allows the animal to filter the water. There are two short tentacles; the eyes are on the external side of each tentacle.


Distribution and habitat

This is a European species, which is found in Romania, Slovenia,
Croatia Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...
,
Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...
(in Bohemia only), Horsák M., Juřičková L., Beran L., Čejka T. & Dvořák L. (2010). "Komentovaný seznam měkkýšů zjištěných ve volné přírodě České a Slovenské republiky. nnotated list of mollusc species recorded outdoors in the Czech and Slovak Republics. '' Malacologica Bohemoslovaca'', Suppl. 1: 1-37
PDF
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
,
Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
,
Great Britain Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...
,
Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...
and other countries. ''Viviparus viviparus'' is largely confined to major, slow-moving, lowland rivers and to lakes and prefers calcareous (base-rich) waters. They are often found in deep water. They are sometimes found in dense clusters (reaching thousands of individuals) on submerged branches and on various man-made objects present under water. More rarely, they are present more scattered in bottom mud, and then are much more discreet. They are also found in canals, artificial ponds, the water behind dams and in reservoirs, but usually not in small isolated standing waters. They require high oxygen content.


Feeding

''Viviparus viviparus'' species feeds on
plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...
and organic microdebris in suspension in the water and picked up through the
siphon A siphon (; also spelled syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, abo ...
which allows the animal to breathe while filtering the water. This filter-feeding habit makes this snail popular with owners of ponds or aquariums where they are known to consume filamentous algae, some microalgae, cyanophytes and waste solids, and thus help to purify and clarify the water. This species may however carry some parasites.


Reproduction

As its Latin name suggests, it is a viviparous (
ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...
) snail, a rare phenomenon among snails. The female gives birth to live young, after producing eggs that hatch internally. The naturalist
Jan Swammerdam Jan or Johannes Swammerdam (February 12, 1637 – February 17, 1680) was a Dutch biologist and microscopist. His work on insects demonstrated that the various phases during the life of an insect—Egg (biology), egg, larva, pupa, and adult� ...
, was the first to recognize the viviparous character of this species to which he gave the name of ''Cochlea mirabilis'' and ''Cochlea vivipara'' but he seems not even have understood that there were males and females in this species (most other snails are hermaphroditic). Then in 1863 Émile Baudelot clearly states that among the paludines (river snails) there are two distinct sexes "The male system extends from the anterior end of the right tentacle to the top of the spire. We may consider it four distinct portions, which are going from top to bottom, the testis, vas deferens, seminal reservoir and the penis.'' .Baudelot E (1863) ''Recherches sur l'appareil générateur des Mollusques Gastéropodes'' (Thèse de zoologie), Imprimerie de L. Martinet. The male is distinguished by a shorter and round-tipped right tentacle, which also serves as a penis during fertilization:the female is usually slightly larger than the male at the same age, and it has two identical tentacles. Sexual maturity is reached after two years, when the snail is about 2 cm long. Each female bears eggs (up to 30 and at all stages of development) with a size of 3 to 7 mm in diameter and up to the full development of the embryo. At the time of their expulsion, the young are about 7 mm and their shell is already marked with the characteristic stripes of the river snails. After producing all its young, the female dies. In 1879 Mathias Duval made studies of
spermatogenesis Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testicle. This process starts with the Mitosis, mitotic division of the stem cells located close to the basement membrane of ...
in ''Viviparus viviparus'' Duval M (1879) ''Étude sur la spermatogenèse étudiée chez la Paludine vivipare''. Rev Sci Nat S, 2, 1.)


Other life

The principle predators of this species are fish and certain insects (Coleoptera, Hemiptera...) ''Viviparus viviparus'' is an intermediate host of several species of
trematode Trematoda is a Class (biology), class of flatworms known as trematodes, and commonly as flukes. They are obligate parasite, obligate Endoparasites, internal parasites with a complex biological life cycle, life cycle requiring at least two Host ( ...
s which finish their life cycles in mammals and birds.


References


External links


''Viviparus viviparus''
Species account and photograph at Mollusc Ireland. {{Taxonbar, from=Q1758969 Viviparidae Gastropods described in 1758 Taxa named by Carl Linnaeus