The Negev is a desert and semidesert region of southern Israel. The region's largest city and administrative capital is Beersheba, in the north. At its southern end is the Gulf of Aqaba and the resort city of Eilat, it contains several development towns, including Dimona and Mitzpe Ramon, as well as a number of small Bedouin cities, including Rahat and Tel as-Sabi and Lakyah. There are several kibbutzim, including Revivim and Sde Boker; the desert is home to the Ben-Gurion University of the Negev, whose faculties include the Jacob Blaustein Institutes for Desert Research and the Albert Katz International School for Desert Studies, both located on the Midreshet Ben-Gurion campus adjacent to Sde Boker. Although a separate region, the Negev was added to the proposed area of Mandatory Palestine to become Israel, on 10 July 1922, having been conceded by British representative St John Philby ”in Trans-Jordan’s name”. In October 2012, global travel guide publisher Lonely Planet rated the Negev second on a list of the world's top ten regional travel destinations for 2013, noting its current transformation through development.
The origin of the word'negev' is from the Hebrew root denoting'dry'. In the Bible, the word Negev is used for the direction'south'. In Arabic, the Negev is known as al-Naqab or an-Naqb, though it was not thought of as a distinct region until the demarcation of the Egypt-Ottoman frontier in the 1890s and has no traditional Arabic name. During the British Mandate, it was called Beersheba sub-district; the Negev covers more than half of Israel, over some 13,000 km² or at least 55% of the country's land area. It forms an inverted triangle shape whose western side is contiguous with the desert of the Sinai Peninsula, whose eastern border is the Arabah valley; the Negev has a number of interesting geological features. Among the latter are three enormous, craterlike makhteshim, which are unique to the region: Makhtesh Ramon, HaMakhtesh HaGadol, HaMakhtesh HaKatan; the Negev is a rocky desert. It is a melange of brown, dusty mountains interrupted by wadis and deep craters, it can be split into five different ecological regions: northern and central Negev, the high plateau and the Arabah Valley.
The northern Negev, or Mediterranean zone, receives 300 mm of rain annually and has fertile soils. The western Negev receives 250 mm of rain per year, with light and sandy soils. Sand dunes can reach heights of up to 30 metres here. Home to the city of Beersheba, the central Negev has an annual precipitation of 200 mm and is characterized by impervious soil, known as loess, allowing minimum penetration of water with greater soil erosion and water runoff; the high plateau area of Negev Mountains/Ramat HaNegev stands between 370 metres and 520 metres above sea level with extreme temperatures in summer and winter. The area gets 100 mm of rain per year, with inferior and salty soils; the Arabah Valley along the Jordanian border stretches 180 km from Eilat in the south to the tip of the Dead Sea in the north. The Arabah Valley is arid with 50 mm of rain annually, it has inferior soils. Vegetation in the Negev is sparse, but certain trees and plants thrive there, among them Acacia, Retama, Urginea maritima and Thymelaea.
A small population of Arabian leopards, an endangered animal in the Arabian peninsula, survives in the southern Negev. The Negev Tortoise is a critically endangered species that lives only in the sands of the western and central Negev Desert; the Negev shrew is a species of mammal of the family Soricidae found only in Israel. Hyphaene thebaica or doum palm can be found in the Southern Negev. Evrona is the most northerly point in the world; the Negev region is arid, receiving little rain due to its location to the east of the Sahara, extreme temperatures due to its location 31 degrees north. However the northernmost areas of the Negev, including Beersheba, are semi-arid; the usual rainfall total from June through October is zero. Snow and frost are rare in the northern Negev, snow and frost are unknown in the vicinity of Eilat in the southernmost Negev. Nomadic life in the Negev dates back at least 4,000 years and as much as 7,000 years; the first urbanized settlements were established by a combination of Canaanite, Amorite and Edomite groups circa 2000 BC.
Pharaonic Egypt is credited with introducing copper mining and smelting in both the Negev and the Sinai between 1400 and 1300 BC. In the Bible, the term Negev only relates to the northern, semiarid part of what we call Negev today, located in the general area of the Arad-Beersheba Valley. According to the Book of Genesis chapter 13, Abraham lived for a while in the Negev after being banished from Egypt. During the Exodus journey to the promised land, Moses sent twelve scouts into the Negev to assess the land and population; the northern part of biblical Negev was inhabited by the Tribe of Judah and the southern part of biblical Negev by the Tribe of Simeon. The Negev was part of the Kingdom of Solomon, with varied extension to the s
Mollusca is the second largest phylum of invertebrate animals. The members are known as mollusks. Around 85,000 extant species of molluscs are recognized; the number of fossil species is estimated between 100,000 additional species. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs live in freshwater and terrestrial habitats, they are diverse, not just in size and in anatomical structure, but in behaviour and in habitat. The phylum is divided into 8 or 9 taxonomic classes, of which two are extinct. Cephalopod molluscs, such as squid and octopus, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species; the gastropods are by far the most numerous molluscs and account for 80% of the total classified species. The three most universal features defining modern molluscs are a mantle with a significant cavity used for breathing and excretion, the presence of a radula, the structure of the nervous system.
Other than these common elements, molluscs express great morphological diversity, so many textbooks base their descriptions on a "hypothetical ancestral mollusc". This has a single, "limpet-like" shell on top, made of proteins and chitin reinforced with calcium carbonate, is secreted by a mantle covering the whole upper surface; the underside of the animal consists of a single muscular "foot". Although molluscs are coelomates, the coelom tends to be small; the main body cavity is a hemocoel. The "generalized" mollusc's feeding system consists of a rasping "tongue", the radula, a complex digestive system in which exuded mucus and microscopic, muscle-powered "hairs" called cilia play various important roles; the generalized mollusc has three in bivalves. The brain, in species that have one, encircles the esophagus. Most molluscs have eyes, all have sensors to detect chemicals and touch; the simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur.
All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults. The coelomic cavity is reduced, they have kidney-like organs for excretion. Good evidence exists for the appearance of gastropods and bivalves in the Cambrian period, 541 to 485.4 million years ago. However, the evolutionary history both of molluscs' emergence from the ancestral Lophotrochozoa and of their diversification into the well-known living and fossil forms are still subjects of vigorous debate among scientists. Molluscs still are an important food source for anatomically modern humans. There is a risk of food poisoning from toxins which can accumulate in certain molluscs under specific conditions and because of this, many countries have regulations to reduce this risk. Molluscs have, for centuries been the source of important luxury goods, notably pearls, mother of pearl, Tyrian purple dye, sea silk, their shells have been used as money in some preindustrial societies. Mollusc species can represent hazards or pests for human activities.
The bite of the blue-ringed octopus is fatal, that of Octopus apollyon causes inflammation that can last for over a month. Stings from a few species of large tropical cone shells can kill, but their sophisticated, though produced, venoms have become important tools in neurological research. Schistosomiasis is transmitted to humans via water snail hosts, affects about 200 million people. Snails and slugs can be serious agricultural pests, accidental or deliberate introduction of some snail species into new environments has damaged some ecosystems; the words mollusc and mollusk are both derived from the French mollusque, which originated from the Latin molluscus, from mollis, soft. Molluscus was itself an adaptation of Aristotle's τὰ μαλάκια ta malákia, which he applied inter alia to cuttlefish; the scientific study of molluscs is accordingly called malacology. The name Molluscoida was used to denote a division of the animal kingdom containing the brachiopods and tunicates, the members of the three groups having been supposed to somewhat resemble the molluscs.
As it is now known these groups have no relation to molluscs, little to one another, the name Molluscoida has been abandoned. The most universal features of the body structure of molluscs are a mantle with a significant cavity used for breathing and excretion, the organization of the nervous system. Many have a calcareous shell. Molluscs have developed such a varied range of body structures, it is difficult to find synapomorphies to apply to all modern groups; the most general characteristic of molluscs is they are bilaterally symmetrical. The following are present in all modern molluscs: The dorsal part of the body wall is a mantle which secretes calcareous spicules, plates or shells, it overlaps the body with enough spare room to form a mantle cavity. The anus and genitals open into the mantle cavity. There are two pairs of main nerve cords. Other characteristics that appear in textbooks have significant exceptions: Estimates of accepted described living species of molluscs vary from 50,000 to a maximum of 120,000 species.
In 1969 David Nicol estimated the probable total number of living mollusc species at 107,000 of which were ab
Orthurethra is a clade of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Stylommatophora. In the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005, Orthurethra is treated as an informal group and subclade of Stylommatophora. Superfamilies and families within the clade Orthurethra: Superfamily Partuloidea Family Partulidae Family Draparnaudiidae Superfamily Achatinelloidea Family Achatinellidae Superfamily Cochlicopoidea Family Cochlicopidae Family Amastridae Superfamily Pupilloidea Family Pupillidae Family Argnidae Family Chondrinidae † Family Cylindrellinidae Family Lauriidae Family Orculidae Family Pleurodiscidae Family Pyramidulidae Family Spelaeodiscidae Family Strobilopsidae Family Valloniidae Family Vertiginidae Superfamily Enoidea Family Enidae Family Cerastidae
Panpulmonata is a taxonomic clade of snails and slugs in the clade Heterobranchia within the clade Euthyneura. Panpulmonata was established as a new taxon by Jörger et al. in October 2010. The older name "Pulmonata" referred to a group of gastropods which were considered to be "air-breathers"; this meaning does not apply to the panpulmonate groups Acochlidia and Pyramidelloidea, was inaccurate when applied to some of the more traditional pulmonate taxa such as Siphonarioidea or Hygrophila, most members of which lack permanently air-filled lungs. However, the term Panpulmonata was chosen by Jörger et al. to provide some continuity in the terminology. Panpulmonata consists of following taxa: Siphonarioidea Sacoglossa Glacidorboidea Amphiboloidea Pyramidelloidea Hygrophila Acochlidiacea Eupulmonata: Stylommatophora, Systellommatophora, Otinoidea, Trimusculoidea; this cladogram shows phylogenic relations within the Heterobranchia, as proposed by Jörger et al.: Changes in the taxonomy of gastropods since 2005#Heterobranchia Heterobranchia#2010 taxonomy Acochlidiacea#2010 taxonomy This article incorporates CC-BY-2.0 text from the reference
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more they represent problematic species concepts. For example, the boundaries between related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, in a ring species. Among organisms that reproduce only asexually, the concept of a reproductive species breaks down, each clone is a microspecies. All species are given a two-part name, a "binomial"; the first part of a binomial is the genus.
The second part is called the specific epithet. For example, Boa constrictor is one of four species of the genus Boa. None of these is satisfactory definitions, but scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties. If species were fixed and distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, to grade into one another. Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped. Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection; that understanding was extended in the 20th century through genetics and population ecology. Genetic variability arises from mutations and recombination, while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures.
Genes can sometimes be exchanged between species by horizontal gene transfer. Viruses are a special case, driven by a balance of mutation and selection, can be treated as quasispecies. Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics. Early taxonomists such as Linnaeus had no option but to describe what they saw: this was formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or impossible to test. Biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: agamospecies for asexual organisms biospecies for reproductively isolated sexual organisms ecospecies based on ecological niches evolutionary species based on lineage genetic species based on gene pool morphospecies based on form or phenotype and taxonomic species, a species as determined by a taxonomist.
A typological species is a group of organisms in which individuals conform to certain fixed properties, so that pre-literate people recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens would differentiate the species; this method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, different phenotypes are not different species. Species named in this manner are called morphospecies. In the 1970s, Robert R. Sokal, Theodore J. Crovello and Peter Sneath proposed a variation on this, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms, it differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species is a group of sexually reproducing organisms that recognize one another as potential mates.
Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms. A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology, genes can move even between distantly related bacteria extending to the whole bacterial domain; as a rule of thumb, microbiologists have assumed that kinds of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA-DNA hybridisation to decide if they belong to the same species or not. This concept was narrowed in 2006 to a similarity of 98.7%. DNA-DNA hybri
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
Stylommatophora is an order of air-breathing land snails and slugs, terrestrial pulmonate gastropod molluscs. This taxon includes the majority of land slugs; the two strong synapomorphies of Stylommatophora are a long pedal gland placed beneath a membrane and two pairs of retractile tentacles. Several families in this group contain species of slugs that create love darts. Stylommatophora are known from the Cretaceous to the Recent periods. According to the taxonomy of the Gastropoda by Bouchet & Rocroi based on evolutionary ancestry is the clade Stylommatophora in clade Eupulmonata within informal group Pulmonata, it uses unranked clades for taxa above the rank of superfamily and the traditional Linnaean approach for all taxa below the rank of superfamily. The clade Stylommatophora contains the subclades Elasmognatha and the informal group Sigmurethra; the term "informal group" has been used to indicate whenever monophyly has not been tested, or where a traditional taxon of gastropods has now been discovered to be paraphyletic or polyphyletic.
Clade Elasmognatha Superfamily Succineoidea Superfamily Athoracophoroideaclade Orthurethra Superfamily Partuloidea Superfamily Achatinelloidea Superfamily Cochlicopoidea Superfamily Pupilloidea Superfamily Enoideainformal group Sigmurethra Superfamily Clausilioidea Superfamily Orthalicoidea Superfamily Achatinoidea Superfamily Aillyoidea Superfamily Testacelloidea Superfamily Papillodermatoidea Superfamily Streptaxoidea Superfamily Rhytidoidea Superfamily Acavoidea Superfamily Punctoidea Superfamily Sagdoidea"limacoid clade" Superfamily Staffordioidea Superfamily Dyakioidea Superfamily Gastrodontoidea Superfamily Parmacelloidea Superfamily Zonitoidea Superfamily Helicarionoidea Superfamily Limacoidea Superfamily Arionoidea Superfamily Helicoidea Subinfraorder Orthurethra Superfamily Achatinelloidea Gulick, 1873 Superfamily Cochlicopoidea Pilsbry, 1900 Superfamily Partuloidea Pilsbry, 1900 Superfamily Pupilloidea Turton, 1831 Subinfraorder Sigmurethra Superfamily Acavoidea Pilsbry, 1895 Superfamily Achatinoidea Swainson, 1840 Superfamily Aillyoidea Baker, 1960 Superfamily Arionoidea J.
E. Gray in Turnton, 1840 Superfamily Buliminoidea Clessin, 1879 Superfamily Camaenoidea Pilsbry, 1895 Superfamily Clausilioidea Mörch, 1864 Superfamily Dyakioidea Gude & Woodward, 1921 Superfamily Gastrodontoidea Tryon, 1866 Superfamily Helicoidea Rafinesque, 1815 Superfamily Helixarionoidea Bourguignat, 1877 Superfamily Limacoidea Rafinesque, 1815 Superfamily Oleacinoidea H. & A. Adams, 1855 Superfamily Orthalicoidea Albers-Martens, 1860 Superfamily Plectopylidoidea Moellendorf, 1900 Superfamily Polygyroidea Pilsbry, 1894 Superfamily Punctoidea Morse, 1864 Superfamily Rhytidoidea Pilsbry, 1893 Superfamily Sagdidoidera Pilsbry, 1895 Superfamily Staffordioidea Thiele, 1931 Superfamily Streptaxoidea J. E. Gray, 1806 Superfamily Strophocheiloidea Thiele, 1926 Superfamily Trigonochlamydoidea Hese, 1882 Superfamily Zonitoidea Mörch, 1864