Common heather snail
| Common heather snail | ||||||||||||
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Common heather snail ( Helicella itala ) |
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| Scientific name | ||||||||||||
| Helicella itala | ||||||||||||
| ( Linnaeus , 1758) |
The common heather snail , also Western heather snail ( Helicella itala , syn .: Helicella ericetorum (OF Müller)) is a species of snail from the family of Geomitridae , which belongs to the order of land snails (Stylommatophora). It is a very locally occurring species, but it tends to multiply in these locations.
features
The housing is flattened with a low thread, almost like a disk. It measures 5 to 12 × 9 to 25 mm. 5½ – 6½ vaulted, regularly increasing whorls are formed; these form a flat seam. The wide umbilicus takes up about a third of the total diameter. The last turn is initially light, and towards the mouth it is strongly lowered from the turn axis. The mouth is elliptical and is inclined to the winding axis. Usually no lip is formed, the edge is hardly bent, rather sharp and only slightly expanded at the sides and below.
The skin is whitish, slightly brownish, yellowish or very slightly reddish. The drawing consists of light to dark brown ribbons, the ribbon pattern being very variable. The surface is only provided with fine, somewhat irregular growth stripes.
The soft body of the animal is yellowish-white to brownish-yellow with slightly darker antennae. In the hermaphroditic genitalia, the spermatic duct (vas deferens) penetrates the epiphallus at an acute angle. The flagellum is slender, less than a third the length of the epiphallus. The epiphallus is about three times as long as the penis. The penis is spindle-shaped with a large brim and a central pore; the pore is surrounded by two to three short lobes. The penis sheath is comparatively thin. The penile retractor muscle attaches to the distal end of the epiphallus near the transition to the penis. The two arrow bags are relatively large and are attached to the vagina, well in front of the confluence of the penis in the genital atrium. Both arrow sacks open into protuberances in the vagina and each contain a love arrow. The two glandulae mucosae each have about four arms. The free fallopian tube is up to four times shorter than the vagina. The comparatively long stem of the spermathec is sub-cylindrical, the bladder ( bursa ) lies against the upper half of the egg duct.
Geographical occurrence and habitat
The common heather snail is found in the British Isles, France, Belgium, the Netherlands, Switzerland, Denmark, Germany, Austria, the Czech Republic and Poland. It is also widespread in Australia today. It was first detected there in 1891.
The animals live on dry, exposed habitats, such as roadsides and embankments, overgrown dunes and boulders as well as short limestone grasslands. In the Alps and Pyrenees , the species rises up to 2000 m above sea level.
Way of life
The common heather snail can reach an age of 2½ to 3 years. It does not keep a pronounced hibernation and is also active on mild winter days. There are usually two breeding seasons, in March / April and in late August to November. In mild winters, reproduction can start earlier. Eggs are laid 6 to 22 days after copulation. The eggs are deposited in a self-dug cavity in the ground. The number of eggs varies from 26 to 68 eggs per clutch. After the eggs are laid, the cavity is not closed. The slightly elliptical eggs measure 1.2 to 1.6 mm in diameter. They are whitish and have lime crystals embedded in the shell. The juvenile snails hatch as miniature adults after approx. 28 to 36 days. After a few days they leave the cavity in which the eggs were laid.
The common heather snail feeds on moldy substances and wilted plant parts.
Taxonomy
The taxon was set up as Helix itala by Carl von Linné as early as 1758 . It is the type species of the genus Helicella Férussac, 1821.
Danger
The species is not endangered in terms of distribution area. In Germany, however, the species is on the red list as endangered . The causes of risk are loss of habitat and changes or abandonment of agricultural practice (less sheep grazing, succession-related change from open grassland to wooded areas, etc.). These contribute to the fact that the H. itala populations are in decline. In order to draw attention to this threat from habitat loss and to raise awareness that certain snails are also adapted to dry habitats, the common heather snail was named mollusk of the year 2019.
supporting documents
literature
- Klaus Bogon: Land snails biology, ecology, biotope protection. 404 p., Natur Verlag, Augsburg 1990, ISBN 3-89440-002-1 (p. 318/9)
- Rosina Fechter, Gerhard Falkner: Mollusks. 287 p., Mosaik Verlag, Munich 1990 (Steinbach's natural guide 10.) ISBN 3-570-03414-3 (p. 210)
- Ewald Frömming: Biology of the Central European Landgastropods. 404 p., Duncker & Humblot, Berlin 1954 (as Helicella ericetorum ).
- Michael P. Kerney, RAD Cameron, Jürgen H. Jungbluth: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg / Berlin 1983, ISBN 3-490-17918-8 (p. 248/9).
- Francisco W. Welter-Schultes: European non-marine molluscs, a guide for species identification = identification book for European land and freshwater mollusks. A1-A3 S., 679 S., Q1-Q78 S., Göttingen, Planet Poster Ed., 2012 ISBN 3-933922-75-5 , ISBN 978-3-933922-75-5 (S. ***)
On-line
Individual evidence
- ↑ Harold E. Quick: Emigrant British Sbails. Proceedings of the Malacological Society of London, 181-189, 1952 PDF .
- ↑ Carolus Linnaeus: Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. 824 S., Salvius, Holmiae / Stockholm, 1758 Online at Göttinger Digitization Center (p. **).
- ↑ Helicella itala in the IUCN Red List of Threatened Species 2013.2. Posted by: Pall-Gergely, B., 2011. Retrieved December 12, 2013.
- ^ Vollrath Wiese: The land snails of Germany. 352 pp., Quelle & Meyer, Wiebelsheim 2014 ISBN 978-3-494-01551-4 , p. 271.
- ↑ Byrne, AW; Moorkens, EA; Anderson, R .; Killeen, IJ & E. Regan: Ireland Red List No. 2 - Non-marine molluscs. Ed .: National Parks and Wildlife Service, Department of the Environment, Heritage and Local Government. Dublin, Ireland. 2009.
- ^ Mollusc of the year. Retrieved August 29, 2019 .
