''Sphincterochila zonata zonata'' is a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. Not all specie ...

of 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 gastropod mollusks that have shells (those without shells are known ...

, a

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

pulmonate Pulmonata or pulmonates, is an informal group (previously an Order (biology), order, and before that a Class (biology), subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a Respiratory system of gastro ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the family Sphincterochilidae. MolluscaBase eds. (2022). MolluscaBase. Sphincterochila zonata zonata (Bourguignat, 1853). Accessed through: World Register of Marine Species at: https://marinespecies.org/aphia.php?p=taxdetails&id=1259809 on 2022-06-19 This species lives in

desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...

s in Israel and Egypt. ''Helix boissieri'' is the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ...

of the genus '' Sphincterochila''. The type species was subsequently designated by

Henry Augustus Pilsbry Henry Augustus Pilsbry (7 December 1862 – 26 October 1957) was an American biologist, malacologist and carcinologist, among other areas of study. He was a dominant presence in many fields of invertebrate taxonomy for the better part of a cent ...

in 1895. It is named after botanist

Pierre Edmond Boissier Pierre Edmond Boissier (25 May 1810 Geneva – 25 September 1885 Valeyres-sous-Rances) was a Swiss prominent botanist, explorer and mathematician. He was the son of Jacques Boissier (1784-1857) and Caroline Butini (1786-1836), daughter of Pie ...

. ''Sphincterochila zonata zonata'' lives in the

Negev The Negev or Negeb (; he, הַנֶּגֶב, hanNegév; ar, ٱلنَّقَب, an-Naqab) is a desert and semidesert region of southern Israel. The region's largest city and administrative capital is Beersheba (pop. ), in the north. At its sout ...

desert (

Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...

), and the Sinai desert in the

Sinai Peninsula The Sinai Peninsula, or simply Sinai (now usually ) (, , cop, Ⲥⲓⲛⲁ), is a peninsula in Egypt, and the only part of the country located in Asia. It is between the Mediterranean Sea to the north and the Red Sea to the south, and is a ...

(

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a List of transcontinental countries, transcontinental country spanning the North Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via a land bridg ...

Shell description

Shell is cretaceous, white; consists of five convex whorls and a deflected ultimate whorl. The aperture is thickened, projecting internally in two subconcrescent denticles (described by Tryon as "tubercles"). The average diameter of the shell is 25 mm.

Anatomy and physiology

The average body mass of ''Sphincterochila zonata zonata'' is around 4.3 g. Such mass is approximately divided in an even manner between the shell itself and the animal's soft parts. Schmidt-Nielsen et al., in 1971, found that 56% of the animals body mass was contained in its shell. About 80 to 90% of the mass of the soft body parts is composed of water (according to the Yom-Tov 1970). In average, soft body parts contain 81% of water (nearly 1400 mg of water), 11% of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

s, 4% of

ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non-gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...

, and little other organic matter. ''Sphincterochila zonata zonata'' has no energy reserves and the amount of lipids it contains is a fraction of 1%, which is considered to be extremely low.

Ecology

Habitat

''Sphincterochila zonata zonata'' lives in

environments. This snail is common in areas with

loess Loess (, ; from german: Löss ) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loess or similar deposits. Loess is a periglacial or aeoli ...

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

soils, and uncommon in areas that have a

flint Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Flint was widely used historically to make stone tools and start ...

substrate. Yom-Tov measured the maximum

demographic Demography () is the statistical study of populations, especially human beings. Demographic analysis examines and measures the dimensions and dynamics of populations; it can cover whole societies or groups defined by criteria such as ed ...

density for ''Sphincterochila zonata zonata'', encountering a value of 0.2-0.3 specimens/m² in the area of the

desert he investigated in 1970. The snail '' Xerocrassa seetzeni'' was found to be more abundant there. On the other hand, in the Northern Negev area investigated by Steinberger et al. In 1981 ''Sphincterochila zonata zonata'' was the most abundant snail. ''Sphincterochila zonata zonata'' along with other snail species and algae are the most significant faunal and floral components of the Negev and Sinai deserts

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

Adaptations for arid conditions

This species presents adaptations to

arid A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ...

conditions which significantly improve its

desiccation tolerance Desiccation tolerance refers to the ability of an organism to withstand or endure extreme dryness, or drought-like conditions. Plants and animals living in arid or periodically arid environments such as temporary streams or ponds may face the challe ...

. Some of those adaptations include a thick shell and a relatively reduced

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

Luchtel D. L. & Deyrup-Olsen: ''Body Wall Form and Function''. in Barker G. M. (ed.):
The biology of terrestrial molluscs
'. CABI Publishing, Oxon, UK, 2001, . 1-146, cited pages: 159. (see also Machin 1967), a thick

epiphragm An epiphragm (from the Ancient Greek ἐπί, '' epi '' " upon, on, over " and φράγμα, '' -phrágma '' "fence") is a temporary structure which can be created by many species of shelled, air-breathing land snails, terrestrial pulmonate gast ...

, and slow body surface

heat conduction Conduction is the process by which heat is transferred from the hotter end to the colder end of an object. The ability of the object to conduct heat is known as its ''thermal conductivity'', and is denoted . Heat spontaneously flows along a te ...

. About 90% of its shell surface reflects the visible portion of the solar spectrum, and much over 90% of the solar

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

itself. ''Sphincterochila zonata zonata'' also produces a new epiphragm after every period of activity (see also Yom-Tov 1971). These snails dig themselves into the soil to depths from 1 to 5 cm while they aestivate during summer in the Negev Desert. In the vicinity of the

Dead Sea The Dead Sea ( he, יַם הַמֶּלַח, ''Yam hamMelaḥ''; ar, اَلْبَحْرُ الْمَيْتُ, ''Āl-Baḥrū l-Maytū''), also known by other names, is a salt lake bordered by Jordan to the east and Israel and the West Ban ...

, they usually either burrow to depths of up to 10 cm, or aestivate hidden under stones. All dormant snails of this species can resist

ambient temperature Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...

s up to 50 °C, but temperatures of 55 °C and above are usually lethal. The soft parts of the animal's body shelter inside the second and the third

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

of its shell, where the temperature can reach up to 50.3 °C. Temperatures of up to 56.2 °C were measured and are known to occur inside the shell's

body whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the ...

, which is mostly filled with air during aestivation. Dormant snails experience water loss of 0.5 mg per day per snail in summer, with a very low oxygen consumption rate. For these reasons, dormant ''Sphincterochila zonata zonata'' can survive severe

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

s for several years.

Life cycle

''Sphincterochila zonata zonata'' is active for a few days only after rainfall during the winter season, from November to March. At this time of the year they feed, mate, and lay eggs. Thus these snails are active for only 5-7% of the year (nearly 18 to 26 days), and

aestivate Aestivation ( la, aestas (summer); also spelled estivation in American English) 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 ...

during all the rest of the time. Dormant snails are known to have survived in museum collections for up to 6 years. Schmidt-Nielsen et al. in 1971 estimated their life span according to their oxygen consumption as being nearly 8 years.

Feeding habits

''Sphincterochila zonata zonata'' feeds on

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...

, especially

mud after rains,

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...

and surface of

directly. It does not eat higher plants.

Predators

The known predators of ''Sphincterochila zonata zonata'' are

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

s, namely the

Cairo Spiny Mouse The Cairo spiny mouse (''Acomys cahirinus''), also known as the common spiny mouse, Egyptian spiny mouse, or Arabian spiny mouse, is a nocturnal species of rodent in the family Muridae. It is found in Africa north of the Sahara, where its natur ...

(''

Acomys cahirinus The Cairo spiny mouse (''Acomys cahirinus''), also known as the common spiny mouse, Egyptian spiny mouse, or Arabian spiny mouse, is a nocturnal species of rodent in the family Muridae. It is found in Africa north of the Sahara, where its natur ...

''),

Wagner's Gerbil Wagner's gerbil (''Dipodillus dasyurus'') is a gerbil that is native mainly to the Nile Delta, Israel, the Sinai, Syria, Iraq and the Arabian Peninsula The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَب� ...

(''

Dipodillus dasyurus Wagner's gerbil (''Dipodillus dasyurus'') is a gerbil that is native mainly to the Nile Delta, Israel, the Sinai, Syria, Iraq Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, trans ...

'') and the

Asian Garden Dormouse The Asian garden dormouse or large-eared garden dormouse, (''Eliomys melanurus'') is a species of rodent in the family Gliridae. It is found in Egypt, Iraq, Israel, Jordan, Lebanon, Libya, Saudi Arabia, Syria and Turkey. Its natural h ...

('' Eliomys melanurus'').

References

This article incorporates public domain text from the reference.

George Washington Tryon George Washington Tryon Jr. (20 May 1838 – 5 February 1888) was an American malacologist who worked at the Academy of Natural Sciences in Philadelphia. Biography George Washington Tryon was the son of Edward K. Tryon and Adeline Savidt ...

, Jr. 1887. Manual of Conchology. Second series: Pulmonata
Volume 3
Helicidae - Volume I
page 14–15