''Theba pisana'',

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

s 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 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 molluscs, terrestrial gastropod mollusks that have gastropod shell, shel ...

, a terrestrial

pulmonate Pulmonata or pulmonates is an informal group (previously an order, and before that, a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group inclu ...

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the family

Helicidae 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 anthropoge ...

, the typical snails. This species is native to the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

region, but it has become an

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

in many other countries. ''Theba pisana'' is a well-known agricultural pest in numerous parts of the world. The shell color varies from white to yellow-brown with light brown spiral markings.

Distribution

The species is native to the

region. The type locality is Italy. The distribution of ''T. pisana'' includes the Mediterranean region and adjacent Atlantic coasts from central Morocco to north western Europe: *

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

* In

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

occasionally also in the interior. It is introduced to

Menorca Menorca or Minorca (from , later ''Minorica'') is one of the Balearic Islands located in the Mediterranean Sea belonging to Spain. Its name derives from its size, contrasting it with nearby Mallorca. Its capital is Maó, situated on the isl ...

. - A subspecies, ''T. pisana arietina'', from coastal habitats in Spain and Portugal, is on the Red List as Endangered. *

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

Malta Malta, officially the Republic of Malta, is an island country in Southern Europe located in the Mediterranean Sea, between Sicily and North Africa. It consists of an archipelago south of Italy, east of Tunisia, and north of Libya. The two ...

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

Commonwealth of Australia. (April 2002)
"Citrus Imports from the Arab Republic of Egypt. A Review Under Existing Import Conditions for Citrus from Israel"
. Agriculture, Fisheries and Forestry, Australia. Caption: Gastropods, page 12 and Appendix 2. * Belgium * Central Atlantic islands The species has been introduced to numerous other areas, including: * southwestern England and south Wales,

Great Britain Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...

: - introduced since at least the 1700s * eastern and southern

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

- introduced since at least the 1700s and it is still spreading along frost-free coastal localities. *

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

- non-indigenous * the United States in

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

* parts of

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

* southeastern Australia, southwestern Australia and

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

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. *

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

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
. - It was introduced into South Africa prior to 1881. It has invaded the

fynbos Fynbos (; , ) is a small belt of natural shrubland or heathland vegetation located in the Western Cape and Eastern Cape provinces of South Africa. The area is predominantly coastal and mountainous, with a Mediterranean climate. The fynbos ...

biome in South Africa. Given the very high densities that ''T. pisana'' can attain at some sites, plus their apparently not particular feeding habits, their potential impact on the vegetation is cause for concern and should be further investigated. In many of these places ''T. pisana'' has become a problematic

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

which could negatively affect agriculture, natural ecosystems, human health or commerce. Therefore, it has been suggested that this species be given top national

quarantine A quarantine is a restriction on the movement of people, animals, and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have bee ...

significance in the USA. File:Theba_pisana_02.JPG, Theba pisana pisana File:Theba_pisana_01.JPG, Theba pisana pisana File:Theba_pisana_ampullacea_02.JPG, Theba pisana ampullacea File:Theba_pisana_ampullacea_01.JPG, Theba pisana ampullacea File:Theba pisana carpiensis 01.JPG, Theba pisana carpiensis File:Theba_pisana_concolor_01.JPG, Theba pisana concolor File:Theba_pisana_dermoi_01.JPG, Theba pisana dermoi File:Theba pisana fauxrosea 01.JPG, Theba pisana fauxrosea File:Theba_pisana_ferruginea_01.JPG, Theba pisana ferruginea File:Theba pisana lineolata 01.JPG, Theba pisana lineolata File:Theba_pisana_major_01.JPG, Theba pisana major File:Theba_pisana_minor_01.JPG, Theba pisana minor File:Theba_pisana_musica_01.JPG, Theba pisana musica File:Theba_pisana_semifulva_01.JPG, Theba pisana semifulva File:Theba pisana sertum 01.jpg, Theba pisana sertum

Description

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 Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

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. The shells of juveniles are sharply keeled, however the keel is not present on the final adult whorl. The aperture often has a lip that is light reddish on the inside, and the lip margin is only reflected at columellar side. The umbilicus is narrow and half covered by the reflected columellar margin. The apex has a characteristic size in the eastern Mediterranean when compared with other species, where there are no other ''Theba'' species. The umbilicus is also rarely seen in other species. Juveniles of '' Eobania vermiculata'' have a considerably larger apex. The width of the shell is 12–25 mm, but in Greece the adult shells are usually below 15 mm in width. The height of the shell is 9–20 mm. 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. This snail is sometimes confused with ''

Cernuella virgata ''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.MolluscaBase eds. (2020). MolluscaBase. Cer ...

'', a species with a much smaller and less inflated shell.

Ecology

''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

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

s 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. ''Theba pisana'' is often associated with two other land snail species '' Cochlicella acuta'' and ''

'', but it can live slightly deeper inside pure sandy habitats, and is usually more common than ''Cochlicella acuta''. It is one of the most common snails in coastal regions from south Portugal to Greece. In South Africa, a study showed that these snails were most abundant along roadsides; densities decreased dramatically with distance from roads. 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. ''Theba pisana'' is also a significant pest of

citrus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is nativ ...

vine A vine is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas, or runners. The word ''vine'' can also refer to such stems or runners themselves, for instance, when used in wicker work.Jackson; Benjamin; Da ...

legume Legumes are plants in the pea family Fabaceae (or Leguminosae), or the fruit or seeds of such plants. When used as a dry grain for human consumption, the seeds are also called pulses. Legumes are grown agriculturally, primarily for human consum ...

crops and

cereal A cereal is a grass cultivated for its edible grain. Cereals are the world's largest crops, and are therefore staple foods. They include rice, wheat, rye, oats, barley, millet, and maize ( Corn). Edible grains from other plant families, ...

s in South Africa. In Australia, it feeds on a range of agricultural plants. Most ''T. pisana'' snails have an annual life cycle, breeding in summer and autumn, but a few also take 2 years to mature. 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. In South Africa, ''T. 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. Maturity is reached at half maximum shell size after 1 year. Maximum shell size is attained after 2 years. This species of snail makes and uses

love darts A love dart (also known as a gypsobelum, shooting darts, or just as darts) is a sharp, calcium carbonate, calcareous or chitinous Dart (missile), dart which some hermaphroditic land snails and slugs create. Love darts are both formed and stor ...

. The size of the egg is 2.2 mm.Heller J.: ''Life History Strategies''. in Barker G. M. (ed.):
The biology of terrestrial molluscs
'. CABI Publishing, Oxon, UK, 2001, . 1-146, cited page: 428. In South Africa, the

population density Population density (in agriculture: Standing stock (disambiguation), standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geog ...

can reach up to 300-700 snails m². In South Africa, these snails are active mostly at night and especially during periods of high humidity, irrespective of temperature.

Parasites

''Theba pisana'' is an intermediate host for the terrestrial

trematode Trematoda is a Class (biology), class of flatworms known as trematodes, and commonly as flukes. They are obligate parasite, obligate Endoparasites, internal parasites with a complex biological life cycle, life cycle requiring at least two Host ( ...

parasite '' Brachylaima cribbi''.

Impact of invasions

In addition to the direct negative effect of ''T. 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. According to Quick (1952)''Theba pisana'' has been responsible for the extermination of native snail species as a result of

competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indi ...

for available food. In their report on the status and potential impacts of alien invasive organisms in the

biome, MacDonald & Jarman (1984)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. predicted that ''T. pisana'' would have very little impact on

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

processes, such as

nutrient cycling A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyc ...

, energy flow and sediment dynamics or on the germination and succession processes of the plant community itself. 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.

References

This article incorporates public domain text from the reference"Species summary for ''Theba pisana''"

AnimalBase AnimalBase is a project brought to life in 2004 and is maintained by the University of Göttingen, Germany. The goal of the AnimalBase project is to digitize early zoological literature, provide copyright-free open access to zoological works, and p ...

, last modified 2 February 2011, accessed 11 May 2011. and CC-BY-3.0 text from the reference

External links

Animalbase.uni-goettingen.de: ''Theba pisana''
— ''at

Animalbase AnimalBase is a project brought to life in 2004 and is maintained by the University of Göttingen, Germany. The goal of the AnimalBase project is to digitize early zoological literature, provide copyright-free open access to zoological works, and p ...

: taxonomy, short description, distribution, biology, status (threats), images''.
Encyclopedia of Life—EOL.org ''Theba pisana'' images

Pestalert.org: ''Theba pisana'' (white garden snail)

— ''

University of Florida The University of Florida (Florida or UF) is a public university, public land-grant university, land-grant research university in Gainesville, Florida, United States. It is a senior member of the State University System of Florida and a preem ...

Institute of Food and Agricultural Sciences An institute is an organizational body created for a certain purpose. They are often research organisations (research institutes) created to do research on specific topics, or can also be a professional body. In some countries, institutes ca ...

"Featured Creatures website."''
Snailcream.in.th: White garden snail
- Images of shell variations in ''C. hortensis'' (Thai language translate). {{Authority control Helicidae Molluscs of Europe Agricultural pest molluscs Gastropods described in 1774 Taxa named by Otto Friedrich Müller Gastropods of Africa Molluscs of Egypt