Limnaea

Scientific name: Limnaea stagnalis

Family: Lymnaeidae

Sub-family: Lymnaea

Origin: Europe

Size: 5 to 6 cm for the biggest

Breathing: aerial, through lungs

Temperature:  0 to 25°C

Utility: major algae eater

Remark: hermaphrodite, two specimens are sufficient to make a colony.

Particularity: has no operculum, becomes a major victim of other aquaria population if there is a food shortage.  When it dies, the brown color of the shell soon "disolves" to become translucid (see above picture).

 

Its big shell with 7 spires, dextrogyrous, fragile, is often covered with algae that assure its camouflage when, curiously, it moves under the surface with its head down by spreading its oval foot and showing its two triangular flat tentacles.

It mostly eats microscopic algae that infest aquatic plants and the glasse of the aquarium.  It also eats the organic waste, and aquatic plants if there is a shortage of algae. This may be avoided by giving spirulina tabs or boiled lettuce.

To mate, limnaea superpose and each one inseminates the one which is placed immediately below.  Each limnaea lays a 3 to 5 cm long clutch of some fifty adhesive and transparent eggs.  This egg laying may occur every two days during summer.

Ten days afterwards, the young limnaea break the membrane that is holding them. They scatter and grow quite quickly if the environment is propicious.  Their shell grows by one spire each month, until they reach the adult size.

 

Other limnaea may be  handled as limnaea stagnalis, the species Limnaea palustris, Limnaea trunculata and Limnaea trunculata. In general they prefer slow, fresh and well planted waters.  The small limnaea (Limnaea trunculata) may be considered as additional food for big cichlids (as for example tilapias) and aquatic turtles. 

It is important to obtain the first specimens from known breeders, as it transmits  a form of Hepatites.

The  ovale limnaea (limnaea ovata), what breeding is easy in aquarium, is very useful as it eats the algae that stick to the aquarium glass.

 

Mating is not reciprocal, a single limnaea is acting as a "male".  View on the "male" organ after mating. View of the eggs, protected by the jello-like membrane. These eggs are about to eclode.
This snail torsion and extension capacity proves it is quite evolved.  It has a single weakness: no operculum to protect itself if threatened.

 

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