Lymnaea stagnalis

Lymnaea stagnalis, better known as the great pond snail, is a species of large air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Lymnaeidae.

Distribution
The distribution of this species is Holarctic. It is widely distributed, and is common in many countries and islands including:


 * British Isles: Great Britain and Ireland
 * Canada (Alberta province,Ottawa valley)
 * Cambodia
 * Czech Republic - least concern (LC)
 * Germany - distributed in whole Germany but in 2 states in red list (Rote Liste BRD)
 * Netherlands
 * Poland
 * Russia - Sverdlovsk oblast
 * Slovakia
 * Sweden (Skåne)
 * Switzerland
 * Ukraine

Shell description
The height of an adult shell of this species ranges from 45–60 mm. The width of an adult shell ranges from 20-30 (34) mm.

Nervous system
Lymnaea stagnalis is widely used for the study learning, memory and neurobiology.

Lymnaea stagnalis has a relatively simple central nervous system (CNS) consisting of a total of ~20,000 neurons, many of them individually identifiable, organized in a ring of interconnected ganglia. Most neurons of the Lymnaea stagnalis central nervous system are large in size (diameter: up to ~100 μm), thus allowing electrophysiological dissection of neuronal networks that has yielded profound insights in the working mechanisms of neuronal networks controlling relatively simple behaviors such as feeding, respiration, locomotion, and reproduction. Studies using the central nervous system of Lymnaea stagnalis as a model organism have also identified novel cellular and molecular mechanisms in neuronal regeneration, synapse formation, synaptic plasticity, learning and memory formation, the neurobiology of development and aging, the modulatory role of neuropeptides, and adaptive responses to hypoxic stress.

Habitat
This large snail lives only in freshwater: it prefers slowly running water, and standing water bodies.



Life cycle
Lymnaea stagnalis is a simultaneously hermaphroditic species and can mate in the male and female role, but within one copulation only one sexual role is performed at a time. Lymnaea stagnalis perform more inseminations in larger groups and prefer to inseminate novel over familiar partners. Such higher motivation to copulate when a new partner is encountered is known as the Coolidge effect and has been demonstrated in hermaphrodites firstly in 2007.

Parasites
Lymnaea stagnalis is an intermediate host for:
 * Moliniella anceps (Molin, 1859) Hubner, 1939

Other parasites of Lymnaea stagnalis include:
 * Echinoparyphium recurvatum
 * Opisthioglyphe ranae
 * Plagiorchis elegans
 * Diplostomum pseudospathaceum
 * Echinostoma revolutum
 * Trichobilharzia szidati

Lymnaea stagnalis has been experimentally infected with Elaphostrongylus rangiferi.