Bats are mammals of the order Chiroptera. Bats are more manoeuvrable than birds, flying with their long spread-out digits covered with a thin membrane or patagium; the smallest bat, arguably the smallest extant mammal, is Kitti's hog-nosed bat, 29–34 mm in length, 15 cm across the wings and 2–2.6 g in mass. The largest bats are the flying foxes and the giant golden-crowned flying fox, Acerodon jubatus, which can weigh 1.6 kg and have a wingspan of 1.7 m. The second largest order of mammals, bats comprise about 20% of all classified mammal species worldwide, with over 1,200 species; these were traditionally divided into two suborders: the fruit-eating megabats, the echolocating microbats. But more recent evidence has supported dividing the order into Yinpterochiroptera and Yangochiroptera, with megabats as members of the former along with several species of microbats. Many bats are insectivores, most of the rest are frugivores. A few species feed on animals other than insects. Most bats are nocturnal, many roost in caves or other refuges.
Bats are present throughout the world, with the exception of cold regions. They are important in their ecosystems for dispersing seeds. Bats provide humans at the cost of some threats. Bat dung has been used as fertiliser. Bats consume insect pests, they are sometimes numerous enough to serve as tourist attractions, are used as food across Asia and the Pacific Rim. They are natural reservoirs such as rabies. In many cultures, bats are popularly associated with darkness, witchcraft and death. An older English name for bats is flittermouse, which matches their name in other Germanic languages, related to the fluttering of wings. Middle English had bakke, most cognate with Old Swedish natbakka, which may have undergone a shift from -k- to -t- influenced by Latin blatta, "moth, nocturnal insect"; the word "bat" was first used in the early 1570s. The name "Chiroptera" derives from Ancient Greek: χείρ – cheir, "hand" and πτερόν – pteron, "wing"; the delicate skeletons of bats do not fossilise well, it is estimated that only 12% of bat genera that lived have been found in the fossil record.
Most of the oldest known bat fossils were very similar to modern microbats, such as Archaeopteropus. The extinct bats Palaeochiropteryx tupaiodon and Hassianycteris kumari are the first fossil mammals whose colouration has been discovered: both were reddish-brown. Bats were grouped in the superorder Archonta, along with the treeshrews and primates. Modern genetic evidence now places bats in the superorder Laurasiatheria, with its sister taxon as Fereuungulata, which includes carnivorans, odd-toed ungulates, even-toed ungulates, cetaceans. One study places Chiroptera as a sister taxon to odd-toed ungulates; the phylogenetic relationships of the different groups of bats have been the subject of much debate. The traditional subdivision into Megachiroptera and Microchiroptera reflected the view that these groups of bats had evolved independently of each other for a long time, from a common ancestor capable of flight; this hypothesis recognised differences between microbats and megabats and acknowledged that flight has only evolved once in mammals.
Most molecular biological evidence supports the view that bats form a monophyletic group. Genetic evidence indicates that megabats originated during the early Eocene, belong within the four major lines of microbats. Two new suborders have been proposed. Yangochiroptera includes the other families of a conclusion supported by a 2005 DNA study. A 2013 phylogenomic study supported the two new proposed suborders. In the 1980s, a hypothesis based on morphological evidence stated the Megachiroptera evolved flight separately from the Microchiroptera; the flying primate hypothesis proposed that, when adaptations to flight are removed, the Megachiroptera are allied to primates by anatomical features not shared with Microchiroptera. For example, the brains of megabats have advanced characteristics. Although recent genetic studies support the monophyly of bats, debate continues about the meaning of the genetic and morphological evidence; the 2003 discovery of an early fossil bat from the 52 million year old Green River Formation, Onychonycteris finneyi, indicates that flight evolved before echolocative abilities.
Onychonycteris had claws on all five of its fingers, whereas modern bats have at most two claws on two digits of each hand. It had longer hind legs and shorter forearms, similar to climbing mammals that hang under branches, such as sloths and gibbons; this palm-sized bat had short, broad wings, suggesting that it could not fly as fast or as far as bat species. Instead of flapping its wings continuously while flying, Onychonycteris alternated between flaps and
Skinks are lizards belonging to the family Scincidae and the infraorder Scincomorpha. With more than 1,500 described species, the Scincidae are one of the most diverse families of lizards; the word "skink" comes from classical Greek skinkos, a name that referred to various specific lizards of the region. Skinks look like true lizards, but most species have no pronounced neck, their legs are small; the skink skull is covered by substantial bony scales matching up in shape and size, while overlapping. Other genera, such as Neoseps, have with fewer than five toes on each foot. In such species, their locomotion resembles that of snakes more than that of lizards with well-developed limbs; as a general rule, the longer the digits, the more arboreal the species is to be. A biological ratio can determine the ecological niche of a given skink species; the Scincidae ecological niche index is a ratio based on anterior foot length at the junction of the ulna/radius-carpal bones to the longest digit divided by the snout-to-vent length.
Most species of skinks have tapering tails they can shed if predators grab onto them. Such species can regenerate the lost part of a tail, though imperfectly. Species with stumpy tails have no special regenerative abilities; some species of skinks are quite small. Most skinks, are medium-sized, with snout-to-vent lengths around 12 cm, although some grow larger. Skinks in the genus Prasinohaema have green blood because of a buildup of the waste product biliverdin. Skink-like lizards first appear in the fossil record about 140 million years ago, during the early Cretaceous jawbones that appear skink-like. Definitively skink fossils appear during the Miocene period. Skink genera known from fossils include the following: A trait apparent in nearly all species of skink is digging and burrowing. Most spend their time underground where they are safe from predators, sometimes digging out tunnels for easy navigation, they use their tongues to sniff the air and track their prey. When they encounter their prey, they chase it down until they corner it or manage to land a bite and swallow it whole.
Skinks are carnivorous and in particular insectivorous. Typical prey include flies, grasshoppers and caterpillars. Various species eat earthworms, snails, isopods, other lizards, small rodents; some species those favored as home pets, have more varied diets and can be maintained on a regimen of 60% vegetables/leaves/fruit and 40% meat. Although most species of skinks are oviparous, laying eggs in clutches, some 45% of skink species are viviparous in one sense or another. Many species are ovoviviparous, the young developing lecithotrophically in eggs that hatch inside the mother's reproductive tract, emerging as live births. In some genera, such as Tiliqua and Corucia, the young developing in the reproductive tract derive their nourishment from a mammal-like placenta attached to the female – unambiguous examples of viviparous matrotrophy. Furthermore, an example described in Trachylepis ivensi is the most extreme to date: a purely reptilian placenta directly comparable in structure and function, to a eutherian placenta.
Such vivipary has developed independently in the evolutionary history of the Scincidae and the different examples are not ancestral to the others. In particular, placental development of whatever degree in lizards is phylogenetically analogous, rather than homologous, to functionally similar processes in mammals. Skinks seek out sheltered environments out of the elements, such as thick foliage, underneath man-made structures, ground-level buildings such as garages and first-floor apartments; when two or more skinks are seen in a small area, it is typical to find a nest nearby. Skinks are considered to be territorial and are seen standing in front of or "guarding" their nest area. If a nest is nearby, one can expect to see 10-30 lizards within the period of a month. In parts of the southern United States, nests are found within houses and apartments along the coast; as a family, skinks are cosmopolitan. Various species occur in ecosystems ranging from mountains to grasslands. Many species are good burrowers.
More species are fossorial than arboreal or aquatic species. Some are "sand swimmers" the desert species, such as the mole skink or sand skink in Florida; some use a similar action in moving through grass tussocks. Most skinks are diurnal and bask on rocks or logs during the day. Raccoons, possums, coatis, cats, herons, hawks and other predators of small land vertebrates prey on various skinks; this can be troublesome, given the long gestation period for some skinks, making them an easy target to predators such as the mongoose, which threaten the species to at least near extinction, such as the Anguilla Bank skink. Many large genera, Mabuya for example, are still insufficiently studied, their systematics are at times controversial, see for example the taxonomy of the western skink, Eumeces skiltonianus. Mabuya in particular, is being split, many species being allocated to new genera such as Trachylepis, Chionini
Stencilling produces an image or pattern by applying pigment to a surface over an intermediate object with designed gaps in it which create the pattern or image by only allowing the pigment to reach some parts of the surface. The stencil is pattern and the intermediate object. In practice, the stencil is a thin sheet of material, such as paper, wood or metal, with letters or a design cut from it, used to produce the letters or design on an underlying surface by applying pigment through the cut-out holes in the material; the key advantage of a stencil is that it can be reused to and produce the same letters or design. Although aerosol or painting stencils can be made for one-time use they are made with the intention of being reused. To be reusable, they must remain intact after a design is produced and the stencil is removed from the work surface. With some designs, this is done by connecting stencil islands to other parts of the stencil with bridges. Stencil technique in visual art is referred to as pochoir.
A related technique is aerography, in which spray-painting is done around a three-dimensional object to create a negative of the object instead of a positive of a stencil design. This technique was used in cave paintings dating to 10,000 BC, where human hands were used in painting handprint outlines among paintings of animals and other objects; the artist sprayed pigment around his hand by using a hollow bone, blown by mouth to direct a stream of pigment. Screen printing uses a stencil process, as does mimeography; the masters from which mimeographed pages are printed are called "stencils". Stencils can be made with one or many colour layers using different techniques, with most stencils designed to be applied as solid colours. During screen printing and mimeography, the images for stenciling are broken down into color layers. Multiple layers of stencils are used on the same surface to produce multi-colored images. Hand stencils, made by blowing pigment over a hand held against a wall, are found from over 35,000 years ago in Asia and Europe, prehistoric dates in other continents.
After that stenciling has been used as a historic painting technique on all kinds of materials. Stencils may have been used to color cloth for a long time. In Europe, from about 1450 they were used to color old master prints printed in black and white woodcuts; this was the case with playing-cards, which continued to be colored by stencil long after most other subjects for prints were left in black and white. Stencils were used for mass publications. Stencils were popular as a method of book illustration, for that purpose, the technique was at its height of popularity in France during the 1920s when André Marty, Jean Saudé and many other studios in Paris specialized in the technique. Low wages contributed to the popularity of the labor-intensive process; when stencils are used in this way they are called "pochoir". In the pochoir process, a print with the outlines of the design was produced, a series of stencils were used through which areas of color were applied by hand to the page. To produce detail, a collotype could be produced which the colors were stenciled over.
Pochoir was used to create prints of intense color and is most associated with Art Nouveau and Art Deco design. Aerosol stencils have many practical applications and the stencil concept is used in industrial, artistic and recreational settings, as well as by the military and infrastructure management. A template is used to create an outline of the image. Stencils templates can be made from any material which will hold its form, ranging from plain paper, plastic sheets and wood. Stencils are used by official organizations, including the military, utility companies, governments, to and label objects and locations. Stencils for an official application can be customized, or purchased as individual letters and symbols; this allows the user to arrange words and other labels from one set of templates, unique to the item being labeled. When objects are labeled using a single template alphabet, it makes it easier to identify their affiliation or source. Stencils have become popular for graffiti, since stencil art using spray-paint can be produced and easily.
These qualities are important for graffiti artists where graffiti is illegal or quasi-legal, depending on the city and stenciling surface. The extensive lettering possible with stencils makes it attractive to political artists. For example, the anarcho-punk band Crass used stencils of anti-war, anarchist and anti-consumerist messages in a long-term graffiti campaign around the London Underground system and on advertising billboards. There has been a semi-recent trend in making multi-layered stencils with different shades of grey for each layer creating a more detailed stenciled image. Well known for their use of stencil art is Blek le Rat and Jef aerosol from France, British artist Banksy, New York artist, world traveling artist Tavar Zawacki f.k.a.'ABOVE', Shepard Fairey's OBEY, Pirate & Acid from Hollywood, California. A common tradition for stencils is in home decorating and arts & crafts
The Holocene is the current geological epoch. It began 11,650 cal years before present, after the last glacial period, which concluded with the Holocene glacial retreat; the Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1, it is considered by some to be an interglacial period within the Pleistocene Epoch. The Holocene has seen the growth and impacts of the human species worldwide, including all its written history, development of major civilizations, overall significant transition toward urban living in the present. Human impacts on modern-era Earth and its ecosystems may be considered of global significance for future evolution of living species, including synchronous lithospheric evidence, or more hydrospheric and atmospheric evidence of human impacts. In July 2018, the International Union of Geological Sciences split the Holocene epoch into three distinct subsections, Greenlandian and Meghalayan, as proposed by International Commission on Stratigraphy.
The boundary stratotype of Meghalayan is a speleothem in Mawmluh cave in India, the global auxiliary stratotype is an ice core from Mount Logan in Canada. The name Holocene comes from the Ancient Greek words ὅλος and καινός, meaning "entirely recent", it is accepted by the International Commission on Stratigraphy that the Holocene started 11,650 cal years BP. The Subcommission on Quaternary Stratigraphy quotes Gibbard and van Kolfschoten in Gradstein Ogg and Smith in stating the term'Recent' as an alternative to Holocene is invalid and should not be used and observe that the term Flandrian, derived from marine transgression sediments on the Flanders coast of Belgium has been used as a synonym for Holocene by authors who consider the last 10,000 years should have the same stage-status as previous interglacial events and thus be included in the Pleistocene; the International Commission on Stratigraphy, considers the Holocene an epoch following the Pleistocene and the last glacial period. Local names for the last glacial period include the Wisconsinan in North America, the Weichselian in Europe, the Devensian in Britain, the Llanquihue in Chile and the Otiran in New Zealand.
The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations: Preboreal, Atlantic and Subatlantic. Note: "ka" means "kilo-annum" Before Present, i.e. 1,000 years before 1950 The Blytt–Sernander classification of climatic periods defined by plant remains in peat mosses, is being explored. Geologists working in different regions are studying sea levels, peat bogs and ice core samples by a variety of methods, with a view toward further verifying and refining the Blytt–Sernander sequence, they find a general correspondence across Eurasia and North America, though the method was once thought to be of no interest. The scheme was defined for Northern Europe, but the climate changes were claimed to occur more widely; the periods of the scheme include a few of the final pre-Holocene oscillations of the last glacial period and classify climates of more recent prehistory. Paleontologists have not defined any faunal stages for the Holocene. If subdivision is necessary, periods of human technological development, such as the Mesolithic and Bronze Age, are used.
However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world. Climatically, the Holocene may be divided evenly into the Neoglacial periods. According to some scholars, a third division, the Anthropocene, has now begun; the International Commission on Stratigraphy Subcommission on Quaternary Stratigraphy’s working group on the'Anthropocene' note this term is used to denote the present time interval in which many geologically significant conditions and processes have been profoundly altered by human activities. The'Anthropocene' is not a formally defined geological unit. Continental motions due to plate tectonics are less than a kilometre over a span of only 10,000 years. However, ice melt caused world sea levels to rise about 35 m in the early part of the Holocene. In addition, many areas above about 40 degrees north latitude had been depressed by the weight of the Pleistocene glaciers and rose as much as 180 m due to post-glacial rebound over the late Pleistocene and Holocene, are still rising today.
The sea level rise and temporary land depression allowed temporary marine incursions into areas that are now far from the sea. Holocene marine fossils are known, from Vermont and Michigan. Other than higher-latitude temporary marine incursions associated with glacial depression, Holocene fossils are found in lakebed and cave deposits. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any tectonic uplift of non-glacial origin. Post-glacial rebound in the Scandinavia region resulted in the formation of the Baltic Sea; the region continues to rise, still causing weak earthquakes across Northern Europe. The equivalent event in North America was the rebound of Hudson Bay, as it shrank from its larger, immediate post-glacial Tyrrell Sea phase, to near its present boundaries. Climate has been stable over the Holocene. Ice core
A spring is a point at which water flows from an aquifer to the Earth's surface. It is a component of the hydrosphere. A spring may be the result of karst topography where surface water has infiltrated the Earth's surface, becoming part of the area groundwater; the groundwater travels through a network of cracks and fissures—openings ranging from intergranular spaces to large caves. The water emerges from below the surface, in the form of a karst spring; the forcing of the spring to the surface can be the result of a confined aquifer in which the recharge area of the spring water table rests at a higher elevation than that of the outlet. Spring water forced to the surface by elevated sources are artesian wells; this is possible if the outlet is in the form of a 300-foot-deep cave. In this case the cave is used like a hose by the higher elevated recharge area of groundwater to exit through the lower elevation opening. Non-artesian springs may flow from a higher elevation through the earth to a lower elevation and exit in the form of a spring, using the ground like a drainage pipe.
Still other springs are the result of pressure from an underground source in the earth, in the form of volcanic activity. The result can be water at elevated temperature such as a hot spring; the action of the groundwater continually dissolves permeable bedrock such as limestone and dolomite, creating vast cave systems. Seepage or filtration spring; the term seep refers to springs with small flow rates in which the source water has filtered through permeable earth. Fracture springs, discharge from faults, joints, or fissures in the earth, in which springs have followed a natural course of voids or weaknesses in the bedrock. Tubular springs, in which the water flows from underground caverns. Spring discharge, or resurgence, is determined by the spring's recharge basin. Factors that affect the recharge include the size of the area in which groundwater is captured, the amount of precipitation, the size of capture points, the size of the spring outlet. Water may leak into the underground system from many sources including permeable earth and losing streams.
In some cases entire creeks disappear as the water sinks into the ground via the stream bed. Grand Gulf State Park in Missouri is an example of an entire creek vanishing into the groundwater system; the water emerges 9 miles away. Human activity may affect a spring's discharge—withdrawal of groundwater reduces the water pressure in an aquifer, decreasing the volume of flow. Springs are classified by the volume of the water they discharge; the largest springs are called "first-magnitude", defined as springs that discharge water at a rate of at least 2800 liters or 100 cubic feet of water per second. Some locations contain many first-magnitude springs, such as Florida where there are at least 27 known to be that size; the scale for spring flow is as follows: Minerals become dissolved in the water as it moves through the underground rocks. This may give the water flavor and carbon dioxide bubbles, depending on the nature of the geology through which it passes; this is why spring water is bottled and sold as mineral water, although the term is the subject of deceptive advertising.
Springs that contain significant amounts of minerals are sometimes called'mineral springs'. Springs that contain large amounts of dissolved sodium salts sodium carbonate, are called'soda springs'. Many resorts are known as spa towns. Water from springs is clear; however some springs may be colored by the minerals. For instance, water heavy with iron or tannins will have an orange color. In parts of the United States a stream carrying the outflow of a spring to a nearby primary stream may be called a spring branch or run. Groundwater tends to maintain a long-term average temperature of its aquifer; the cool water of a spring and its branch may harbor species such as certain trout that are otherwise ill-suited to a warmer local climate. Springs have been used for a variety of human needs including drinking water, domestic water supply, mills and electricity generation. Other modern uses include recreational activities such as fishing and floating. A sacred spring, or holy well, is a small body of water emerging from underground and revered either in a Christian, pagan or other religious context, sometimes both.
The lore and mythology of ancient Greece was replete with sacred and storied springs—notably, the Corycian and Castalian. In medieval Europe, holy wells were pagan sacred sites that became Christianized; the term "holy well" is employed to refer to any water source of limited size, which has some significance in local folklore. This can take the form of a particular name, an associated legend, the attribution of healing qualities to the water through the numinous presence of its guardian spirit or Christian saint, or a ceremony or ritual centred on the well site. In Christian legend, the spring water is said to have been made to flow by the action of a saint, a familiar theme in the hagiography of Celtic saints. LaMor
An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy is incorporated into plant tissue. By feeding on plants and on one-another, animals play an important role in the movement of matter and energy through the system, they influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be used by plants and other microbes. Ecosystems are controlled by internal factors. External factors such as climate, the parent material which forms the soil and topography, control the overall structure of an ecosystem, but are not themselves influenced by the ecosystem. Ecosystems are dynamic entities—they are subject to periodic disturbances and are in the process of recovering from some past disturbance.
Ecosystems in similar environments that are located in different parts of the world can end up doing things differently because they have different pools of species present. Internal factors not only control ecosystem processes but are controlled by them and are subject to feedback loops. Resource inputs are controlled by external processes like climate and parent material. Resource availability within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Although humans operate within ecosystems, their cumulative effects are large enough to influence external factors like climate. Biodiversity affects ecosystem functioning, as do the processes of disturbance and succession. Ecosystems provide a variety of services upon which people depend; the term ecosystem was first used in 1935 in a publication by British ecologist Arthur Tansley. Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment.
He refined the term, describing it as "The whole system... including not only the organism-complex, but the whole complex of physical factors forming what we call the environment". Tansley regarded ecosystems not as natural units, but as "mental isolates". Tansley defined the spatial extent of ecosystems using the term ecotope. G. Evelyn Hutchinson, a limnologist, a contemporary of Tansley's, combined Charles Elton's ideas about trophic ecology with those of Russian geochemist Vladimir Vernadsky; as a result, he suggested. This would, in turn, limit the abundance of animals. Raymond Lindeman took these ideas further to suggest that the flow of energy through a lake was the primary driver of the ecosystem. Hutchinson's students, brothers Howard T. Odum and Eugene P. Odum, further developed a "systems approach" to the study of ecosystems; this allowed them to study the flow of material through ecological systems. Ecosystems are controlled both by internal factors. External factors called state factors, control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem.
The most important of these is climate. Climate determines the biome. Rainfall patterns and seasonal temperatures influence photosynthesis and thereby determine the amount of water and energy available to the ecosystem. Parent material determines the nature of the soil in an ecosystem, influences the supply of mineral nutrients. Topography controls ecosystem processes by affecting things like microclimate, soil development and the movement of water through a system. For example, ecosystems can be quite different if situated in a small depression on the landscape, versus one present on an adjacent steep hillside. Other external factors that play an important role in ecosystem functioning include time and potential biota; the set of organisms that can be present in an area can significantly affect ecosystems. Ecosystems in similar environments that are located in different parts of the world can end up doing things differently because they have different pools of species present; the introduction of non-native species can cause substantial shifts in ecosystem function.
Unlike external factors, internal factors in ecosystems not only control ecosystem processes but are controlled by them. They are subject to feedback loops. While the resource inputs are controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other factors like disturbance, succession or the types of species present are internal factors. Primary production is the production of organic matter from inorganic carbon sources; this occurs through photosynthesis. The energy incorporated through this process supports life on earth, while the carbon makes up much of the organic matter in living and dead biomass, soil carbon and fossil fuels, it drives the carbon cycle, which influences global climate via the greenhouse effect. Through the process of photosynthesis, plants capture energy from light and use it to combine carbon dioxide and water to produce carbohydrates and oxygen.
The photosynthesis carried out by all the plants in an ecosystem is called the gross primary production. About half of the GPP is consumed in plant respiration; the remainder, that portion of GPP, not used up by respirati