Slugs
| Slugs | ||||||||||||
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Spanish slug ( Arion vulgaris ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Arionidae | ||||||||||||
| Gray , 1840 |
The family of slugs (Arionidae) belongs to the order of the lung snails . They are defined by similarities in the genital apparatus. Some species can only be distinguished by genital morphological studies.
features
The slugs have over the evolution of their original housing greatly reduced and are slugs become or "semi-slugs". Slugs are not a taxonomic group (see below). From the shell of their ancestors, into which the snails were originally able to withdraw completely, only lime grains or lime flakes remain, which are also covered by the mantle. However, young animals can still completely withdraw into an enclosure. When developing into adult animals, the housing is rudimented. In slugs, the oval mantle only covers the front part of the body. The breathing hole ( pneumostom ) sits a little in front of the middle of the mantle on the right side. The "jaw" is ribbed transversely ( odontognath ). The sole of the foot is uniformly or indistinctly divided longitudinally into three zones. A mucous gland on the front end of the foot may be present or absent. Depending on the type, the slime can also be colored. When threatened, the animals can pull together (contract) their longitudinal muscles. The back pressure of the blood makes the severely shrunk body tough and hard. Slugs can curl up. All species are hermaphrodites (hermaphrodites) that usually mate with each other. Spermatophores are transferred in the process. In extreme situations, they can mate themselves. In the male part of the genital system, the penis is usually greatly reduced or absent entirely. On the other hand, an epiphallus is usually present. The vagina is simple, the atrium more or less swollen. The atrium usually has thick, glandular walls. The spermatophore, when present, is usually relatively thin, with a serrated, elongated back.
differences
Nudibranchs are not a taxonomic group. In various groups of terrestrial snails the shell was more or less reduced and the animals converged to nudibranchs or half- slugs . These groups often look very similar. In contrast to the Schnegel family (Limacidae), the breathing hole is in front of the middle of the mantle shield when viewed from the head. In the otherwise very similar snails, it is located behind the middle of the mantle shield. In contrast to the slugs, the snails have a keel-shaped rear part that extends to about the middle of the back. They cannot curl up like slugs.
Distribution and way of life
The slugs are or were originally distributed Holarctic , i. H. in Europe, North Asia and North America. In the meantime, many species have been anthropogenically transported to other regions and are now distributed almost worldwide. They are mainly herbivores that feed on living and also withered plant material. Some species can have a noticeable harmful effect on cultivated plants in corresponding population sizes, e.g. B. the Spanish slug ( Arion vulgaris ).
Systematics
The family of slugs (Arionidae) has been severely restricted in its scope and therefore contains only a few genera compared to the previous scope:
- Slugs family (Arionidae J. Gray, 1840)
- Subfamily Arioninae J. Gray, 1840
- Genus Arion Férussac, 1819 (with five subgenera A. (Arion) Férussac, 1819, A. (Carinarion) Hesse, 1926, A. (Mesarion) Hesse, 1926, A. (Microarion) Hesse, 1926 and A. (Kobeltia) Seibert, 1873)
- Genus Carinacauda Leonard et al., 2011
- Genus Geomalacus Allman 1843 (with two subgenera Geomalacus (Geomalacus) Allman, 1843 and Geomalacus (Arrudia) Pollonera, 1890)
- Genus Ichnusarion Pollonera, 1890
- Genus Letourneuxia Bourguignat, 1866
- Genus Nipponarion Yamaguchi & Habe, 1955
- Genus Securicauda Leonard et al., 2011
supporting documents
literature
- MP Kerney among others: The land snails of Northern and Central Europe. Hamburg 1983, ISBN 3-490-17918-8 .
- L. Buse, D. Godan: Slugs - On quiet feet through the world. Georgsmarienhütte 1999, ISBN 3-923792-44-1 .
- J. Pinceel et al .: Extreme mtDNA divergences in a terrestrial slug (Gastropoda, Pulmonata, Arionidae): accelerated evolution, allopatric divergence and secondary contact. In: J Evol Biol. 18/2005, pp. 1264-1280. PMID 16135122
- H. Reise ua: Penis-biting slugs: wild claims and confusions. In: Trends in Ecology & Evolution. 17/2002, p. 163.
- Anatolij A. Schileyko: Treatise on Recent terrestrial pulmonate molluscs, Part 15 Oopeltidae, Anadenidae, Arionidae, Philomycidae, Succineidae, Athoracophoridae. In: Ruthenica. Supplement 2, Moscow 2007, pp. 2049-2210 ISSN 0136-0027
- Andrzej Wiktor: The Polish Nudibranchs. Arionidae, Milacidae, Limacidae (Gastropoda, Stylommatophora). Polska Akademia Zakład Zoologii Systematycznej i Doświadczalnej Monograph Fauny Polski, I, Kraków 1973, DNB 770325319 .
Individual evidence
- ^ A b William P. Leonard, Lyle Chichester, Casey H. Richart, Tiffany A. Young: Securicauda hermani and Carinacauda stormi, two new genera and species of slug from the Pacific Northwest of the United States (Gastropoda: Stylommatophora: Arionidae), with notes on Gliabates oregonius Webb 1959. In: Zootaxa. 2746, 2011, pp. 43-56. (PDF)
