Water snail
| Water snail | ||||||||||||
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Water snail ( Deroceras laeve ) |
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| Scientific name | ||||||||||||
| Deroceras laeve | ||||||||||||
| ( OV Müller , 1774) |
The water snail ( Deroceras laeve ) is a species of slug from the family of the field slugs ( Agriolimacidae), which is placed in the subordination of the land snails (Stylommatophora). The species lives in permanently moist biotopes and is said to be able to stay under water for days.
features
The adult water snail becomes 15 to 25 mm long when stretched out. The coat is relatively large and takes up about 50% of the body length. The keel is blunt and short. The edge of the breathing opening is slightly lighter in color than the coat. The color varies from dark brown to light gray to almost black, mostly with indistinct, somewhat darker spots that are arranged in groups. The mucus is colorless and the sole is uniformly pale brown in color. In this species the penis is often reduced; these animals reproduce by self-fertilization.
Reproduction
The water snail has an extremely short life cycle, under favorable conditions of about a month. In Central Europe, up to five generations are formed each year. The animals are hermaphrodites, but in some of the animals the penis is largely reduced. They reproduce through self-fertilization. The eggs are laid several times in groups of about 7 to 22 pieces. The eggs are colorless and transparent. They measure around 1.1 to 2 mm. Size and shape vary greatly throughout life. Usually small and more rounded eggs are laid first, later the eggs become larger and usually have somewhat elongated shapes. The number of eggs also decreases somewhat. The development of the eggs takes about 18 to 21 days (in Central Europe), but is strongly temperature-dependent. At the time of hatching, the animals are already 3 to 4 mm long. Under particularly favorable circumstances, the animals can be sexually mature after just one month. In Central Europe, they are sexually mature at nine to eleven weeks. As a rule, the animals live to be around 1 year old, or 1.5 years under laboratory conditions.
Way of life, occurrence and distribution
The species was originally distributed in the Holarctic. In the meantime, however, it has been abducted worldwide, with the exception of Antarctica. The species lives in permanently humid biotopes, such as the edges of waters, swamps, swamp forests, but also in greenhouses. As a rule, the species is restricted to the lowlands and low mountain ranges. In the Alps, the species rises up to 1800 m. It has a high tolerance to cold and heat and occurs today from the subpolar regions to the tropics. Due to the rapid succession of generations, new biotopes can be populated quickly. The water snail is a common species in suitable biotopes. In greenhouses it can sometimes be perceived as a pest.
The water snail is one of the few land snails that are said to voluntarily go into the water and can live submerged for days. Fromming doubts this behavior. He considers submerged animals to be animals that have accidentally fallen into the water and then crawl back onto the bank. The eggs should also occasionally be laid in the water and also be able to develop under water. The animals often rope themselves down by hanging from a thread of mucus in order to escape excessive sun exposure and possible dehydration. They are active animals that crawl relatively quickly. The animals are omnivores, but fresh and dead plant material is preferred. Cannibalism was also observed.
The water snail has also been identified as the egg predator of Pegomyia betae Curtis ( real flies = Muscidae) and Epilachna varivestis Mulsant ( ladybirds = Coccinellidae).
Individual evidence
- ↑ cf. Kerney et al., P. 191, Falkner & Fechter, p. 192
- ^ Fromming, p. 208
- ↑ U. Röttger and F. Klingauf: Deroceras laeve garbage. (Mollusca: Limacidae), an egg predator from Pegomyia betae Curt. (Muscidae). Journal of Pest Science, 49 (4): 49-51, Berlin & Heidelberg 1976 doi: 10.1007 / BF01986516
literature
- Klaus Bogon: Land snails biology, ecology, biotope protection. 404 p., Natur Verlag, Augsburg 1990 ISBN 3-89440-002-1
- Rosina Fechter and Gerhard Falkner: molluscs. 287 pp., Munich, Mosaik-Verlag 1990 (Steinbach's Nature Guide 10) ISBN 3-570-03414-3
- Ewald Frömming: Biology of the Central European Landgastropods. 404 p., Duncker & Humblot, Berlin 1954.
- Michael P. Kerney, RAD Cameron & Jürgen H. Jungbluth: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg
