Theba pisana

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Theba pisana
Theba pisana 0109.JPG
A live and active individual of Theba pisana
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Heterobranchia
Order: Stylommatophora
Family: Helicidae
Genus: Theba
Species:
T. pisana
Binomial name
Theba pisana
(Müller, 1774) [1]
Synonyms [2]
  • Helix Albella Linnaeus, 1758
  • Helix pisana Müller, 1774
  • Eupharypha pisana (Müller)

Theba pisana, common names the white garden snail, sand hill snail, white Italian snail, Mediterranean coastal snail, and simply just the Mediterranean snail, is an edible species of medium-sized, air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Helicidae, the typical snails.

Contents

This species is native to the Mediterranean region, but it has become an invasive species in many other countries. Theba pisana is a well-known agricultural pest in numerous parts of the world. [3] The shell color varies from white to yellow-brown with light brown spiral markings. [3]

Distribution

The species is native to the Mediterranean region. The type locality is Italy. [1]

The distribution of Theba pisana includes the Mediterranean region and adjacent Atlantic coasts from central Morocco to north western Europe: [4]

The species has been introduced to numerous other areas, including:

In many of these places T. pisana has become a problematic invasive species and a serious agricultural pest.

This species is already established in the US, and is considered to represent a potentially serious threat as a pest, an invasive species which could negatively affect agriculture, natural ecosystems, human health or commerce. Therefore, it has been suggested that this species be given top national quarantine significance in the USA. [9]

Description

Apical and apertural view of a shell, with an arrow marking the half-colvered umbilicus Theba pisana Spain.jpg
Apical and apertural view of a shell, with an arrow marking the half-colvered umbilicus
Theba pisana Camargue fg11.jpg
Theba pisana

The shell background color is a creamy white. Different individuals may have shells with varying degrees of pale to dark brown markings. The markings, when present, may be in the form of uninterrupted spiral bands, spiral dotted lines, or small radial smudges.

The shell can be found in various colour variants, but is basically yellow or white with dark color bands or spots and often a dark bluish grey apex. [4] The shells of juveniles are sharply keeled, however the keel is not present on the final adult whorl. [4] The aperture often has a lip that is light reddish on the inside, and the lip margin is only reflected at columellar side. [4] The umbilicus is narrow and half covered by the reflected columellar margin. [4] The apex has a characteristic size in the eastern Mediterranean when compared with other species, where there are no other Theba species. [4] The umbilicus is also rarely seen in other species. [4] Juveniles of Eobania vermiculata have a considerably larger apex. [4]

The width of the shell is 12–25 mm, [4] but in Greece the adult shells are usually below 15 mm in width. [4] The height of the shell is 9–20 mm. [4] The visible soft parts are very light yellowish with dark colour bands running from the sides to the upper tentacles; the tentacles are very long. [4]

This snail is sometimes confused with Cernuella virgata , a species with a much smaller and less inflated shell.

Ecology

Theba pisana snails aestivate on fennel Foeniculum vulgare in Montbazin, France. Theba pisana on Foeniculum vulgare, Montbazin, Herault 03.jpg
Theba pisana snails aestivate on fennel Foeniculum vulgare in Montbazin, France.
Drawing of love dart of Theba pisana. Theba pisana dart.jpg
Drawing of love dart of Theba pisana.

Theba pisana usually lives in coastlands, in or near sandy habitats. In hot climates it aestivates often directly exposed to the sun, attached to grasses, shrubs or succulent plants, fence posts, tall weeds, and so on. It is common near beaches. In dunes it can live on nearly bare sand that is poorly fixed in place by grasses. In colder regions the snails do not aestivate, but they do climb on plants in dry weather. This snail does not survive serious winter frosts. [4]

Theba pisana is often associated with two other land snail species Cochlicella acuta and Cernuella virgata , but it can live slightly deeper inside pure sandy habitats, and is usually more common than Cochlicella acuta. [4] It is one of the most common snails in coastal regions from south Portugal to Greece. [4]

In South Africa, a study showed that these snails were most abundant along roadsides; densities decreased dramatically with distance from roads. [3] The snails were observed to be living on a variety of endemic and introduced plant species; these snails appear to be able to eat an unusually wide range of different food sources. [3] Theba pisana is also a significant pest of citrus, vines, legume crops and cereals in South Africa. [3] In Australia, it feeds on a range of agricultural plants. [3]

Most Theba pisana snails have an annual life cycle, breeding in summer and autumn, but a few also take 2 years to mature. [10] In aestivating T. pisana populations in Israel some individuals retain an immature size and shape and a rudimentary status of the genital system, defined as 'infantiles'; the populations of T. pisana may be self-regulated by the mechanism of infantilism or controlled by humidity or, perhaps, by both. [11] In South Africa, Theba pisana appear to have an annual lifecycle, breeding in autumn to winter and growing to adult size of about 14 mm diameter by the end of the following summer. [3] Maturity is reached at half maximum shell size after 1 year. [4] Maximum shell size is attained after 2 years. [4] This species of snail makes and uses love darts. The size of the egg is 2.2 mm. [12] In South Africa, the population density can reach up to 300-700 snails m2. [3]

In South Africa, these snails are active mostly at night and especially during periods of high humidity, irrespective of temperature. [3]

Parasites

Theba pisana is an intermediate host for the terrestrial trematode parasite Brachylaima cribbi . [13]

Impact of invasions

In addition to the direct negative effect of Theba pisana feeding on agricultural crops, it also has several other additional effects. It uses the stalks of cereals as aestivating sites, which in turn clogs machinery and fouls produce during mechanical harvesting. [3]

According to Quick (1952) [14] Theba pisana has been responsible for the extermination of native snail species as a result of competition for available food. [3]

In their report on the status and potential impacts of alien invasive organisms in the fynbos biome, MacDonald & Jarman (1984) [15] predicted that Theba pisana would have very little impact on ecosystem processes, such as nutrient cycling, energy flow and sediment dynamics or on the germination and succession processes of the plant community itself. [3] However, the snail could seriously impact directly on fynbos plants, by feeding on them, and also displace native herbivores by competing with them for resources, and these effects have not been studied. [3]

Related Research Articles

<span class="mw-page-title-main">Aestivation</span> State of animal dormancy taking place in the summer

Aestivation is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. It takes place during times of heat and dryness, which are often the summer months.

<span class="mw-page-title-main">Decollate snail</span> Species of gastropod

The decollate snail, scientific name Rumina decollata, is a medium-sized predatory land snail, a species of terrestrial pulmonate gastropod mollusk in the family Achatinidae. It is a European species that has been introduced in a number of areas worldwide.

<i>Cornu aspersum</i> Species of edible land snail

Cornu aspersum, known by the common name garden snail, is a species of land snail in the family Helicidae, which includes some of the most familiar land snails. Of all terrestrial molluscs, this species may well be the most widely known. It was classified under the name Helix aspersa for over two centuries, but the prevailing classification now places it in the genus Cornu.

<i>Brachylaima</i> Genus of flukes

Brachylaima is a genus of trematodes. It has recently been discovered that it can infect the gastrointestinal tract of human beings.

<i>Lissachatina fulica</i> Species of land snail

Lissachatina fulica is a species of large land snail that belongs in the subfamily Achatininae of the family Achatinidae. It is also known as the Giant African land snail. It shares the common name "giant African snail" with other species of snails such as Achatina achatina and Archachatina marginata. This snail species has been considered a significant cause of pest issues around the world. Internationally, it is the most frequently occurring invasive species of snail.

<span class="mw-page-title-main">Helicidae</span> Family of gastropods

Helicidae is a large, diverse family of western Palaearctic, medium to large-sized, air-breathing land snails, sometimes called the "typical snails." It includes some of the largest European land snails, several species are common in anthropogenic habitats, and some became invasive on other continents. A number of species in this family are valued as food items, including Cornu aspersum the brown or garden snail, and Helix pomatia. The biologies of these two species in particular have been thoroughly studied and documented.

<i>Arianta arbustorum</i> Species of gastropod

Arianta arbustorum, sometimes known as the copse snail, is a medium-sized species of pulmonate land snail in the family Helicidae.

<i>Helix lucorum</i> Species of gastropod

Helix lucorum is a species of large, edible, air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Helicidae, the typical snails.

<i>Cantareus apertus</i> Species of gastropod

Cantareus apertus, commonly known as the green garden snail, is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Helicidae, the typical snails.

<i>Xerolenta obvia</i> Species of gastropod

Xerolenta obvia is a species of air-breathing land snail, a terrestrial gastropod mollusk in the family Geomitridae, the hairy snails and their allies.

<i>Theba</i> Genus of gastropods

Theba is a taxonomic genus of air-breathing land snails, medium-sized pulmonate gastropod mollusks in the family Helicidae, the true snails.

<span class="mw-page-title-main">Land snail</span> Common name for many species of snail

A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. Land snail is the common name for terrestrial gastropod mollusks that have shells. However, it is not always easy to say which species are terrestrial, because some are more or less amphibious between land and fresh water, and others are relatively amphibious between land and salt water.

<i>Cernuella</i> Genus of gastropods

Cernuella is a genus of small air-breathing land snails, pulmonate gastropod mollusks in the family Geomitridae, the hairy snails and their allies.

<i>Cernuella virgata</i> Species of gastropod

Cernuella virgata, also known as Helicella virgata, common name, the "vineyard snail", is a species of small, air-breathing land snail, a pulmonate gastropod mollusc in the family Geomitridae.

<i>Cochlicella acuta</i> Species of gastropod

Cochlicella acuta, common name the pointed snail, is a species of small but very high-spired, air-breathing land snail, a pulmonate gastropod mollusk in the family Geomitridae.

<i>Brachylaima cribbi</i> Species of fluke

Brachylaima cribbi is a species of terrestrial trematode parasites in the family Brachylaimidae.

<i>Eobania vermiculata</i> Species of gastropod

Eobania vermiculata also known as Helix vermiculata, common name the "chocolate-band snail" is a species of large, air-breathing, land snail, a terrestrial pulmonate gastropod mollusk in the family Helicidae, the true snails or typical snails.

<i>Otala punctata</i> Species of gastropod

Otala punctata is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Helicidae.

Elisolimax flavescens is a species of air-breathing land snail or semislug, terrestrial pulmonate gastropod mollusks in the family Helicarionidae or Urocyclidae.

References

This article incorporates public domain text from the reference [4] and CC-BY-3.0 text from the reference [3]

  1. 1 2 Müller O. F. (1774). Vermivm terrestrium et fluviatilium, seu animalium infusoriorum, helminthicorum, et testaceorum, non marinorum, succincta historia. Volumen alterum. pp. I-XXXVI, 1-214. Havniae & Lipsiae. (Heineck & Faber). page 60-61.
  2. ↑ "Synonyms of Helix pisana". AnimalBase, accessed 11 May 2011.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Odendaal L. J., Haupt T. M. & Griffiths C. L. (2008). "The alien invasive land snail Theba pisana in the West Coast National Park: Is there cause for concern?". Koedoe - African Protected Area Conservation and Science 50(1): 93-98. abstract, doi : 10.4102/koedoe.v50i1.153.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 "Species summary for Theba pisana". AnimalBase, last modified 2 February 2011, accessed 11 May 2011.
  5. ↑ Kolouch, Luboš R. (2003-07-10). "Suchozemští, sladkovodní a brakičtí měkkýši ostrovů Malty [Terrestrial, freshwater and brackish mollusca of Malta islands]". Malacologica Bohemoslovaca (in Czech). 2: 43–50. doi: 10.5817/MaB2003-2-43 . ISSN   1336-6939.
  6. 1 2 Commonwealth of Australia. (April 2002). "Citrus Imports from the Arab Republic of Egypt. A Review Under Existing Import Conditions for Citrus from Israel" Archived 2009-01-09 at the Wayback Machine . Agriculture, Fisheries and Forestry, Australia. Caption: Gastropods, page 12 and Appendix 2.
  7. ↑ Kerney M. P. & Cameron R. A. D. (1979). A field guide to the land snails of Britain and northwestern Europe. - Collins, London.
  8. ↑ Clarke, G. M., Gross, S., Matthews, M., Catling, P. C., Baker, B., Hewitt, C. L., Crowther, D., & Saddler, S. R. 2000, Environmental Pest Species in Australia, Australia: State of the Environment, Second Technical Paper Series (Biodiversity), Department of the Environment and Heritage, Canberra.
  9. ↑ Cowie R. H., Dillon R. T., Robinson D. G. & Smith J. W. (2009). "Alien non-marine snails and slugs of priority quarantine importance in the United States: A preliminary risk assessment". American Malacological Bulletin27: 113-132. PDF Archived 2016-06-16 at the Wayback Machine .
  10. ↑ Cowie, Robert H. (1984). "The Life-Cycle and Productivity of the Land Snail Theba pisana (Mollusca: Helicidae)" . Journal of Animal Ecology. 53 (1): 311–325. doi:10.2307/4359. ISSN   0021-8790.
  11. ↑ Moran, Shmuel (1989-06-01). "Weather- and population density-induced infantilism in the landsnailTheba pisana in a semi-arid climate". International Journal of Biometeorology. 33 (2): 101–108. doi:10.1007/BF01686286. ISSN   1432-1254.
  12. ↑ Heller J.: Life History Strategies. in Barker G. M. (ed.): The biology of terrestrial molluscs . CABI Publishing, Oxon, UK, 2001, ISBN   0-85199-318-4. 1-146, cited page: 428.
  13. ↑ Butcher A. R. & Grove D. I. (2006). "Seasonal variation in rates of sporocyst and metacercarial infection by Brachylaima cribbi in helicid and hygromiid land snails on the Yorke Peninsula, South Australia". Australian Journal of Zoology 53(6): 375-382. abstract.
  14. ↑ Quick H. E. (1952). "Emigrant British snails". Proceedings of the Malacological Society of London 29(5): 181-189.
  15. ↑ MacDonald I. A. W. & Jarman M. L. (1984). "Invasive alien organisms in the terrestrial ecosystems of the fynbos biome, South Africa". South African National Scientific Programmes Report No. 85.

Further reading

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