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81-458: Entomobryidae , sometimes called "slender springtails", is a family of springtails characterised by having an enlarged fourth abdominal segment and a well-developed furcula . Species in this family may be heavily scaled and can be very colourful. The scale-less Entomobryidae are commonly caught in pitfall traps around the planet, and also occur in canopy faunas high up in trees (notably Entomobrya nivalis , very common throughout Europe if not

162-449: A behavioural dimension to this still poorly understood vertical segregation. Experiments with peat samples turned upside down showed two types of responses to disturbance of this vertical gradient, called "stayers" and "movers". As a group, springtails are highly sensitive to desiccation , because of their tegumentary respiration , although some species with thin, permeable cuticles have been shown to resist severe drought by regulating

243-529: A biological warfare effort. The alleged associated diseases included anthrax , cholera , dysentery , fowl septicemia , paratyphoid , plague , scrub typhus , small pox , and typhoid . China created an international scientific commission for investigating possible bacterial warfare, eventually ruling that the United States probably did engage in limited biological warfare in Korea. The US government denied all

324-617: A ringtest , on the biology and ecotoxicology of Folsomia candida and comparison with the sexual nearby species Folsomia fimetaria (sometimes preferred to Folsomia candida ) are given in a document written by Paul Henning Krogh. Care should be taken that different strains of the same species may be conducive to different results. Avoidance tests have been also performed. They have been standardized, too. Avoidance tests are complementary to toxicity tests, but they also offer several advantages: they are more rapid (thus cheaper), more sensitive and they are environmentally more reliable, because in

405-412: A background of snow. In addition, a few species routinely climb trees and form a dominant component of canopy fauna, where they may be collected by beating or insecticide fogging. These tend to be the larger (>2 mm) species, mainly in the genera Entomobrya and Orchesella , though the densities on a per square meter basis are typically 1–2 orders of magnitude lower than soil populations of

486-642: A clasping organ located on their antenna . Many springtails, mostly those living in deeper soil horizons, are parthenogenetic, which favors reproduction to the detriment of genetic diversity and thereby to population tolerance of environmental hazards . Parthenogenesis (also called thelytoky ) is under the control of symbiotic bacteria of the genus Wolbachia , which live, reproduce and are carried in female reproductive organs and eggs of Collembola. Feminizing Wolbachia species are widespread in arthropods and nematodes , where they co-evolved with most of their lineages . Abdominal In humans,

567-430: A continuous change in species assemblages can be observed from tree canopies to ground vegetation then to plant litter down to deeper soil horizons . This is a complex factor embracing both nutritional and physiological requirements, together with behavioural trends, dispersal limitation and probable species interactions . Some species have been shown to exhibit negative or positive gravitropism , which adds

648-403: A food source for spiders and harvestmen in the same environment, such as the endangered harvestman Texella reyesi . To protect themselves, some species have evolved chemical defenses. Springtails are cryptozoa frequently found in leaf litter and other decaying material, where they are primarily detritivores and microbivores , and one of the main biological agents responsible for

729-421: A full set of ocelli (photoreceptors). Epedaphic species inhabit upper litter layers and fallen logs. They are slightly smaller and have less pronounced pigments, as well as less developed limbs and ocelli than the atmobiotic species. Hemiedaphic species inhabit the lower litter layers of decomposing organic material. They are 1-2 millimeters (about 1/16") in length, have dispersed pigmentation, shortened limbs, and

810-735: A negative effect on mesofauna biomass and diversity in drier parts and a positive effect in moist sub-areas. Furthermore, a study with 20 years of experimental warming in three contrasting plant communities found that small scale heterogeneity may buffer springtails to potential climate warming. Sexual reproduction occurs through the clustered or scattered deposition of spermatophores by male adults. Stimulation of spermatophore deposition by female pheromones has been demonstrated in Sinella curviseta . Mating behavior can be observed in Symphypleona . Among Symphypleona, males of some Sminthuridae use

891-654: A neurological problem, such as delusional parasitosis , a psychological rather than entomological problem. Researchers themselves may be subject to psychological phenomena. For example, a publication in 2004 claiming that springtails had been found in skin samples was later determined to be a case of pareidolia ; that is, no springtail specimens were actually recovered, but the researchers had digitally enhanced photos of sample debris to create images resembling small arthropod heads, which then were claimed to be springtail remnants. However, Steve Hopkin reports one instance of an entomologist aspirating an Isotoma species and in

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972-444: A newborn, it may represent a diaphragmatic hernia . In general, it is indicative of malnutrition . Many gastrointestinal diseases affect the abdominal organs. These include stomach disease , liver disease , pancreatic disease , gallbladder and bile duct disease; intestinal diseases include enteritis , coeliac disease , diverticulitis , and irritable bowel syndrome . Different medical procedures can be used to examine

1053-431: A patchwork of closed ( woodland ) and open ( meadows , cereal crops ) environments, most soil -dwelling species are not specialized and can be found everywhere, but most epigeal and litter -dwelling species are attracted to a particular environment, either forested or not. As a consequence of dispersal limitation, landuse change, when too rapid, may cause the local disappearance of slow-moving, specialist species ,

1134-562: A phenomenon the measure of which has been called colonisation credit. Springtails are well known as pests of some agricultural crops. Sminthurus viridis , the lucerne flea, has been shown to cause severe damage to agricultural crops, and is considered as a pest in Australia. Onychiuridae are also known to feed on tubers and to damage them to some extent. However, by their capacity to carry spores of mycorrhizal fungi and mycorrhiza helper bacteria on their tegument, soil springtails play

1215-514: A positive role in the establishment of plant-fungal symbioses and thus are beneficial to agriculture. They also contribute to controlling plant fungal diseases through their active consumption of mycelia and spores of damping-off and pathogenic fungi. It has been suggested that they could be reared to be used for the control of pathogenic fungi in greenhouses and other indoor cultures. Various sources and publications have suggested that some springtails may parasitize humans, but this

1296-447: A reduced number of ocelli. Euedaphic species inhabit upper mineral layers known as the humus horizon. They are smaller than hemiedaphic species; have soft, elongated bodies; lack pigmentation and ocelli; and have reduced or absent furca. Poduromorphs are characterized by their elongated bodies and conspicuous segmentation – three thoracic segments, six abdominal segments, including a well-developed prothorax with tergal chaetae, while

1377-421: A separate evolutionary line from the other Hexapoda , but others disagree; this seems to be caused by widely divergent patterns of molecular evolution among the arthropods . The adjustments of traditional taxonomic rank for springtails reflect the occasional incompatibility of traditional groupings with modern cladistics : when they were included with the insects, they were ranked as an order ; as part of

1458-691: Is a muscular sphincter. Malpighian tubules are absent. Traditionally, the springtails were divided into the orders Arthropleona , Symphypleona , and occasionally also Neelipleona . The Arthropleona were divided into two superfamilies , the Entomobryoidea and the Poduroidea . However, recent phylogenetic studies show Arthropleona is paraphyletic . Thus, the Arthropleona are abolished in modern classifications, and their superfamilies are raised in rank accordingly, being now orders Entomobryomorpha and

1539-500: Is also becoming a genomic model organism for soil toxicology. With microarray technology the expression of thousands of genes can be measured in parallel. The gene expression profiles of Folsomia candida exposed to environmental toxicants allow fast and sensitive detection of pollution, and additionally clarifies molecular mechanisms causing toxicology. Collembola have been found to be useful as bio-indicators of soil quality. Laboratory studies have been conducted that validated that

1620-402: Is believed to be associated with fluid uptake and balance, excretion, and orientation of the organism itself. Most species have an abdominal, tail-like appendage known as a furcula (or furca). It is located on the fourth abdominal segment of springtails and is folded beneath the body, held under tension by a small structure called the retinaculum (or tenaculum). When released, it snaps against

1701-437: Is entirely inconsistent with their biology, and no such phenomenon has ever been scientifically confirmed, though it has been documented that the scales or hairs from springtails can cause irritation when rubbed onto the skin. They may sometimes be abundant indoors in damp places such as bathrooms and basements, and incidentally found on one's person. More often, claims of persistent human skin infection by springtails may indicate

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1782-407: Is fixed, they can pull up the pelvis and finally, they can bend the vertebral column sideways and assist in the trunk's rotation. The transverse abdominis muscle is the deepest muscle; therefore, it cannot be touched from the outside. It can greatly affect the body's posture. The internal obliques are also deep and also affect body posture. Both of them are involved in rotation and lateral flexion of

1863-435: Is flat and triangular, with its fibers running horizontally. It lies between the internal oblique and the underlying transverse fascia . It originates from the inguinal ligament, costal cartilages 7-12, the iliac crest and thoracolumbar fascia. Inserts into the conjoint tendon, xiphoid process , linea alba and the pubic crest. The rectus abdominis muscles are long and flat. The muscle is crossed by three fibrous bands called

1944-417: Is important to properly exercise the abdominal muscles together with the back muscles because when these are weak or overly tight they can suffer painful spasms and injuries . When properly exercised, abdominal muscles contribute to improved posture and balance, reduce the likelihood of back pain episodes, reduce the severity of back pain, protect against injury, help avoid some back surgeries, and help with

2025-402: Is more inclusive. Though taxonomic rank cannot be used for absolute comparisons, it is notable that nematodes are a phylum and crustaceans a subphylum . Most springtails are small and difficult to see by casual observation, but one springtail, the so-called snow flea ( Hypogastrura nivicola ), is readily observed on warm winter days when it is active and its dark color contrasts sharply with

2106-467: Is small and has one or two teeth. In more general terms, Entomobryidae tend to be relatively large springtails, reaching 2 mm or more. They may have stripes, bands or streaks of blue, red or purple. Some species are all blue or all white, the latter tending to also have reduced ocelli . Cave-dwelling species have long appendages and the claws are often modified. On humid mornings, many entomobryid species climb herbaceous plants to feed on pollen and

2187-417: Is the abdominal wall in the front and the peritoneal surface at the rear. In vertebrates, the abdomen is a large body cavity enclosed by the abdominal muscles, at the front and to the sides, and by part of the vertebral column at the back. Lower ribs can also enclose ventral and lateral walls. The abdominal cavity is continuous with, and above, the pelvic cavity. It is attached to the thoracic cavity by

2268-408: Is the muscle that very fit people develop into "six-pack" abs, though there are five vertical sections on each side. The two bottom sections are just above the pubic bone and usually not visible. The rectus abdominals' function is to bend one's back forward (flexion). The main work of the abdominal muscles is to bend the spine forward when contracting concentrically. Social and cultural perceptions of

2349-453: Is to draw three horizontal and two vertical lines. The two vertical or mid-Poupart lines are drawn from the point midway between the anterior superior spine and the pubic symphysis on each side, vertically upward to the costal margin. The right subcostal margin corresponds to the lower limit of the liver , while the right nipple is about half an inch above its upper limit. The abdomen can be divided into quadrants or regions to describe

2430-842: The Early Devonian . The fossil from 400  million years ago , Rhyniella praecursor , is the oldest terrestrial arthropod, and was found in the famous Rhynie chert of Scotland . Given its morphology resembles extant species quite closely, the radiation of the Hexapoda can be situated in the Silurian , 420  million years ago or more. Additional research concerning the coprolites (fossilized feces) of ancient springtails allowed researchers to track their lineages back some 412 million years. Fossil Collembola are rare. Instead, most are found in amber. Even these are rare and many amber deposits carry few or no collembola. The best deposits are from

2511-562: The Krubera Cave . The horizontal distribution of springtail species is affected by environmental factors which act at the landscape scale, such as soil acidity , moisture and light . Requirements for pH can be reconstructed experimentally. Altitudinal changes in species distribution can be at least partly explained by increased acidity at higher elevation. Moisture requirements, among other ecological and behavioural factors, explain why some species cannot live aboveground, or retreat in

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2592-527: The Lepidoptera and the Symphyta (sawflies) have fleshy appendages called prolegs on their abdominal segments (as well as their more familiar thoracic legs), which allow them to grip onto the edges of plant leaves as they walk around. In arachnids (spiders, scorpions and relatives), the term "abdomen" is used interchangeably with " opisthosoma " ("hind body"), which is the body section posterior to that bearing

2673-648: The Poduromorpha . Technically, the Arthropleona are thus a partial junior synonym of the Collembola. The term "Neopleona" is essentially synonymous with Symphypleona + Neelipleona. The Neelipleona was originally seen as a particularly advanced lineage of Symphypleona, based on the shared global body shape, but the global body of the Neelipleona is realized in a completely different way than in Symphypleona. Subsequently,

2754-437: The digestive system , including the stomach , the small intestine , and the colon with its attached appendix . Other digestive organs are known as the accessory digestive organs and include the liver , its attached gallbladder , and the pancreas , and these communicate with the rest of the system via various ducts. The spleen , and organs of the urinary system including the kidneys , and adrenal glands also lie within

2835-407: The hip . All of their fibers merge towards the midline and surround the rectus abdominis in a sheath before joining up on the opposite side at the linea alba . Strength is gained by the criss-crossing of fibers, such that the external oblique runs downward and forward, the internal oblique upward and forward, and the transverse abdominal horizontally forward. The transverse abdominal muscle

2916-414: The linea alba in the abdominal wall. At about its midpoint sits the umbilicus or navel . The rectus abdominis on each side of the linea alba stands out in muscular people. The outline of these muscles is interrupted by three or more transverse depressions indicating the tendinous intersections . There is usually one about the xiphoid process, one at the navel, and one in between. It is the combination of

2997-435: The navel . Functionally, the human abdomen is where most of the digestive tract is placed and so most of the absorption and digestion of food occurs here. The alimentary tract in the abdomen consists of the lower esophagus , the stomach , the duodenum , the jejunum , ileum , the cecum and the appendix , the ascending , transverse and descending colons , the sigmoid colon and the rectum . Other vital organs inside

3078-406: The spine and are used to bend and support the spine from the front. The external obliques are more superficial and are also involved in rotation and lateral flexion of the spine. They also stabilize the spine when upright. The rectus abdominis muscle is not the most superficial abdominal muscle. The tendonous sheath extending from the external obliques cover the rectus abdominis. The rectus abdominis

3159-413: The tendinous intersections . The rectus abdominis is enclosed in a thick sheath, formed as described above, by fibers from each of the three muscles of the lateral abdominal wall. They originate at the pubis bone , run up the abdomen on either side of the linea alba, and insert into the cartilages of the fifth, sixth, and seventh ribs. In the region of the groin , the inguinal canal , is a passage through

3240-933: The Canadian Cretaceous specimens. There are about 3,600 different species. Specific feeding strategies and mechanisms are employed to match specific niches. Herbivorous and detritivorous species fragment biological material present in soil and leaf litter, supporting decomposition and increasing the availability of nutrients for various species of microbes and fungi. Carnivorous species maintain populations of small invertebrates such as nematodes, rotifers, and other collembolan species. Springtails commonly consume fungal hyphae and spores, but also have been found to consume plant material and pollen, animal remains, colloidal materials, minerals and bacteria. Springtails are consumed by mesostigmatan mites in various families, including Ascidae , Laelapidae , Parasitidae , Rhodacaridae and Veigaiidae . Cave-dwelling springtails are

3321-483: The Entognatha, they are ranked as a subclass . If they are considered a basal lineage of Hexapoda, they are elevated to full class status. Members of the Collembola are normally less than 6 mm (0.24 in) long, have six or fewer abdominal segments , and possess a tubular appendage (the collophore or ventral tube) with reversible, sticky vesicles, projecting ventrally from the first abdominal segment. It

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3402-546: The Korean War were Isotoma (Desoria) negishina (a local species) and the "white rat springtail" Folsomia candida . Captive springtails are often kept in a terrarium as part of a clean-up crew . Springtails are currently used in laboratory tests for the early detection of soil pollution . Acute and chronic toxicity tests have been performed by researchers, mostly using the parthenogenetic isotomid Folsomia candida . These tests have been standardized. Details on

3483-673: The Neelipleona were considered as being derived from the Entomobryomorpha. Analysis of 18S and 28S rRNA sequence data, though, suggests that they form the most ancient lineage of springtails, which would explain their peculiar apomorphies . This phylogenetic relationship was also confirmed using a phylogeny based on mtDNA and whole-genome data . The latest whole-genome phylogeny supporting four orders of Collembola: Neelipleona [REDACTED] Poduromorpha [REDACTED] Symphypleona [REDACTED] Entomobryomorpha [REDACTED] Springtails are attested to since

3564-589: The Northern Hemisphere). There are more than 1700 described species in Entomobryidae. This family has a reduced prothorax that lacks setae. The antennae are longer than the head diagonal. A mandibular plate is present. The abdominal segments are not fused. The body has trichobothria and thick clavate setae , and often scales as well. The dens is longer than the manubrium, tapering and annulated. The dentes are roughly parallel and distally curved. The mucro

3645-431: The abdomen include the liver , the kidneys , the pancreas and the spleen . The abdominal wall is split into the posterior (back), lateral (sides), and anterior (front) walls. The abdominal muscles have different important functions. They assist as muscles of exhalation in the breathing process during forceful exhalation . Moreover, these muscles serve as protection for the inner organs. Furthermore, together with

3726-399: The abdomen stretches from the thorax at the thoracic diaphragm to the pelvis at the pelvic brim . The pelvic brim stretches from the lumbosacral joint (the intervertebral disc between L5 and S1 ) to the pubic symphysis and is the edge of the pelvic inlet . The space above this inlet and under the thoracic diaphragm is termed the abdominal cavity. The boundary of the abdominal cavity

3807-423: The abdomen, along with many blood vessels including the aorta and inferior vena cava . The urinary bladder , uterus , fallopian tubes , and ovaries may be seen as either abdominal organs or as pelvic organs. Finally, the abdomen contains an extensive membrane called the peritoneum . A fold of peritoneum may completely cover certain organs, whereas it may cover only one side of organs that usually lie closer to

3888-412: The abdominal organs. This is associated with a higher risk of heart disease , asthma and type 2 diabetes. Abdominal trauma is an injury to the abdomen and can involve damage to the abdominal organs. There is an associated risk of severe blood loss and infection . Injury to the lower chest can cause injuries to the spleen and liver. A scaphoid abdomen is when the abdomen is sucked inwards. In

3969-407: The abdominal wall. This is called the retroperitoneum , and the kidneys and ureters are known as retroperitoneal organs. There are three layers of muscles in the abdominal wall . They are, from the outside to the inside: external oblique , internal oblique , and transverse abdominal . The first three layers extend between the vertebral column , the lower ribs, the iliac crest and pubis of

4050-459: The allegations, and instead proposed that the United Nations send a formal inquiry committee to China and Korea, but China and Korea refused to cooperate. U.S. and Canadian entomologists further claimed that the accusations were ridiculous and argued that anomalous appearances of insects could be explained through natural phenomena. Springtail species cited in allegations of biological warfare in

4131-407: The back muscles they provide postural support and are important in defining the form. When the glottis is closed and the thorax and pelvis are fixed, they are integral in the cough , urination , defecation , childbirth , vomit , and singing functions. When the pelvis is fixed, they can initiate the movement of the trunk in a forward motion. They also prevent hyperextension . When the thorax

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4212-495: The bulbous gaster . The petiole and gaster (abdominal segments 2 and onward) are collectively called the metasoma . Unlike other arthropods, insects possess no legs on the abdomen in adult form, though the Protura do have rudimentary leg-like appendages on the first three abdominal segments, and Archaeognatha possess small, articulated "styli" which are sometimes considered to be rudimentary appendages. Many larval insects including

4293-458: The common honey bee . In the Collembola (springtails), the abdomen has only six segments. The abdomen is sometimes highly modified. In Apocrita (bees, ants and wasps), the first segment of the abdomen is fused to the thorax and is called the propodeum . In ants , the second segment forms the narrow petiole . Some ants have an additional postpetiole segment, and the remaining segments form

4374-440: The concavity of the ileum. However, the term is in common usage. Abdominal organs can be highly specialized in some mammals. For example, the stomach of ruminants , (a suborder of mammals that includes cattle and sheep ), is divided into four chambers – rumen , reticulum , omasum and abomasum . In arthropods , the abdomen is built up of a series of upper plates known as tergites and lower plates known as sternites ,

4455-692: The control and the dissemination of soil microorganisms . In a mature deciduous woodland in temperate climate, leaf litter and vegetation typically support 30 to 40 species of springtails, and in the tropics the number may be over 100. In sheer numbers, they are reputed to be one of the most abundant of all macroscopic animals, with estimates of 100,000 individuals per square meter of ground, essentially everywhere on Earth where soil and related habitats ( moss cushions, fallen wood , grass tufts, ant and termite nests) occur. Only nematodes , crustaceans , and mites are likely to have global populations of similar magnitude, and each of those groups except mites

4536-481: The decomposition of organic matter, but contribute to it indirectly through the fragmentation of organic matter and the control of soil microbial communities. The word Collembola is from the ancient Greek κόλλα kólla "glue" and ἔμβολος émbolos "peg"; this name was given due to the existence of the collophore , which was previously thought to stick to surfaces to stabilize the creature. Early DNA sequence studies suggested that Collembola represent

4617-495: The diaphragm. Structures such as the aorta , inferior vena cava and esophagus pass through the diaphragm. Both the abdominal and pelvic cavities are lined by a serous membrane known as the parietal peritoneum . This membrane is continuous with the visceral peritoneum lining the organs. The abdomen in vertebrates contains a number of organs belonging to, for instance, the digestive system , urinary system , and muscular system . The abdominal cavity contains most organs of

4698-563: The early Eocene of Canada and Europe, Miocene of Central America, and the mid-Cretaceous of Burma and Canada. They display some unexplained characteristics: first, all but one of the fossils from the Cretaceous belong to extinct genera, whereas none of the specimens from the Eocene or the Miocene are of extinct genera; second, the species from Burma are more similar to the modern fauna of Canada than are

4779-635: The family Entomobryidae: Data sources: i = ITIS, c = Catalogue of Life, g = GBIF, b = Bugguide.net Springtail Springtails (class Collembola ) form the largest of the three lineages of modern hexapods that are no longer considered insects . Although the three orders are sometimes grouped together in a class called Entognatha because they have internal mouthparts , they do not appear to be any more closely related to one another than they are to all insects, which have external mouthparts. Springtails are omnivorous , free-living organisms that prefer moist conditions. They do not directly engage in

4860-413: The first springtails to have been described by Carl Linnaeus ), spends its entire life at the surface of water, its wettable eggs dropping in water until the non-wettable first instar hatches then surfaces. A few genera are capable of being submerged, and after molting young springtails lose their water repellent properties and are able to survive submerged under water. In a variegated landscape, made of

4941-466: The first thoracic segment in Entomobryomorpha is clearly reduced and bears no chaetae. The digestive tract of springtails consists of three main components: the foregut, midgut, and hindgut. The midgut is surrounded by a network of muscles and lined with a monolayer of columnar or cuboidal cells. Its function is to mix and transport food from the lumen into the hindgut through contraction. Many species of syntrophic bacteria, archaea, and fungi are present in

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5022-696: The head and the thorax , leading to a rudimentary, although fully functional, tracheal system. The anatomical variance present between different species partially depends on soil morphology and composition. Surface-dwellers are generally larger, have darker pigments, have longer antennae and functioning furcula. Sub-surface-dwellers are usually unpigmented, have elongated bodies, and reduced furcula. They can be categorized into four main forms according to soil composition and depth: atmobiotic, epedaphic, hemiedaphic, and euedaphic. Atmobiotic species inhabit macrophytes and litter surfaces. They are generally 8-10 millimeters (about ⅓") in length, pigmented, have long limbs, and

5103-418: The healing of back problems, or after spine surgery. When strengthened, the abdominal muscles provide flexibility as well. The abdominal muscles can be worked by strength and fitness exercises, and through practicing disciplines of general body strength such as Pilates , yoga , tai chi , and jogging . Abdominal obesity is a condition where abdominal fat or visceral fat, has built up excessively between

5184-408: The ilium to the spine of the pubis . These lower limits are marked by visible grooves. Just above the pubic spines on either side are the external abdominal rings, which are openings in the muscular wall of the abdomen through which the spermatic cord emerges in the male, and through which an inguinal hernia may rupture. One method by which the location of the abdominal contents can be appreciated

5265-587: The jumping ability of springtails can be used to evaluate the soil quality of Cu- and Ni-polluted sites. In polar regions that are expected to experience among the most rapid impact from climate warming, springtails have shown contrasting responses to warming in experimental warming studies. There are negative, positive and neutral responses reported. Neutral responses to experimental warming have also been reported in studies of non-polar regions. The importance of soil moisture has been demonstrated in experiments using infrared heating in an alpine meadow, which had

5346-405: The layers. This gap is where the testes can drop through the wall and where the fibrous cord from the uterus in the female runs. This is also where weakness can form, and cause inguinal hernias . The pyramidalis muscle is small and triangular. It is located in the lower abdomen in front of the rectus abdominis. It originates at the pubic bone and is inserted into the linea alba halfway up to

5427-424: The linea alba and the tendinous intersections which form the abdominal "six-pack" sought after by many people. The upper lateral limit of the abdomen is the subcostal margin (at or near the subcostal plane ) formed by the cartilages of the false ribs (8, 9, 10) joining one another. The lower lateral limit is the anterior crest of the ilium and Poupart's ligament , which runs from the anterior superior spine of

5508-406: The location of an organ or structure. Classically, quadrants are described as the left upper, left lower, right upper, and right lower. Quadrants are also often used in describing the site of an abdominal pain. The abdomen can also be divided into nine regions. These terms stem from "hypo" meaning "below" and "epi" means "above", while "chondron" means "cartilage" (in this case, the cartilage of

5589-404: The lumen. These different digestive regions have varying pH to support specific enzymatic activities and microbial populations. The anterior portion of the midgut and hindgut is slightly acidic (with a pH of approximately 6.0) while the posterior midgut portion is slightly alkaline (with a pH of approximately 8.0). Between the midgut and hindgut is an alimentary canal called the pyloric region, which

5670-436: The organs of the gastrointestinal tract. These include endoscopy , colonoscopy , sigmoidoscopy , enteroscopy , oesophagogastroduodenoscopy and virtual colonoscopy . There are also a number of medical imaging techniques that can be used. Surface landmarks are important in the examination of the abdomen . In the mid-line, a slight furrow extends from the xiphoid process above to the pubic symphysis below, representing

5751-963: The osmotic pressure of their body fluid. The gregarious behaviour of Collembola, mostly driven by the attractive power of pheromones excreted by adults, gives more chance to every juvenile or adult individual to find suitable, better protected places, where desiccation could be avoided and reproduction and survival rates (thereby fitness ) could be kept at an optimum. Sensitivity to drought varies from species to species and increases during ecdysis . Given that springtails moult repeatedly during their entire life (an ancestral character in Hexapoda ) they spend much time in concealed micro-sites where they can find protection against desiccation and predation during ecdysis, an advantage reinforced by synchronized moulting. The high humidity environment of many caves also favours springtails and there are numerous cave adapted species, including one, Plutomurus ortobalaganensis living 1,980 metres (6,500 ft) down

5832-440: The outward appearance of the abdomen has varying significance around the world. Depending on the type of society, excess weight can be perceived as an indicator of wealth and prestige due to excess food, or as a sign of poor health due to lack of exercise. In many cultures, bare abdomens are distinctly sexualized and perceived similarly to breast cleavage . Being key elements of spinal support, and contributors to good posture, it

5913-599: The process accidentally inhaling some of their eggs, which hatched in his nasal cavity and made him quite ill until they were flushed out. In 1952, China accused the United States military of spreading bacteria-laden insects and other objects during the Korean War by dropping them from P-51 fighters above rebel villages over North Korea . In all, the U.S. was accused of dropping ants, beetles, crickets, fleas, flies, grasshoppers, lice, springtails, and stoneflies as part of

5994-488: The real world Collembola move actively far from pollution spots. It may be hypothesized that the soil could become locally depauperated in animals (and thus improper to normal use) while below thresholds of toxicity. Contrary to earthworms , and like many insects and molluscs, Collembola are very sensitive to herbicides and thus are threatened in no-tillage agriculture, which makes a more intense use of herbicides than conventional agriculture. The springtail Folsomia candida

6075-414: The reduction in body size is advantageous to their survival. The Poduromorpha and Entomobryomorpha have an elongated body, while the Symphypleona and Neelipleona have a globular body. Collembola lack a tracheal respiration system, which forces them to respire through a porous cuticle , except for the two families Sminthuridae and Actaletidae, which exhibit a single pair of spiracles between

6156-486: The rib) and "gaster" means stomach. The reversal of "left" and "right" is intentional, because the anatomical designations reflect the patient's own right and left .) The "right iliac fossa" (RIF) is a common site of pain and tenderness in patients who have appendicitis . The fossa is named for the underlying iliac fossa of the hip bone , and thus is somewhat imprecise. Most of the anatomical structures that will produce pain and tenderness in this region are not in fact in

6237-425: The same species. In temperate regions, a few species (e.g. Anurophorus spp., Entomobrya albocincta , Xenylla xavieri , Hypogastrura arborea ) are almost exclusively arboreal. In tropical regions a single square meter of canopy habitat can support many species of Collembola. The main ecological factor driving the local distribution of species is the vertical stratification of the environment: in woodland

6318-420: The soil during dry seasons, but also why some epigeal springtails are always found in the vicinity of ponds and lakes, such as the hygrophilous Isotomurus palustris . Adaptive features, such as the presence of a fan-like wettable mucro, allow some species to move at the surface of water in freshwater and marine environments. Podura aquatica , a unique representative of the family Poduridae (and one of

6399-418: The spores of fungi. Entomobryids have been found in brood galleries of bark beetles , where they are presumed to feed on fungi or act as saprophages . Some species live in intertidal habitats. Springtails of this family are prey for a range of predators, including various ground beetles , the shore bug Saldula saltatoria , lady beetle larvae, ants and crab spiders . These 38 genera belong to

6480-443: The substrate, flinging the springtail into the air and allowing for rapid evasion and travel. All of this takes place in as little as 18 milliseconds. Springtails also possess the ability to reduce their body size by as much as 30% through subsequent ecdyses (moulting) if temperatures rise high enough. The shrinkage is genetically controlled. Since warmer conditions increase metabolic rates and energy requirements in organisms,

6561-415: The whole being held together by a tough yet stretchable membrane. In insects , the abdomen contains the insect's digestive tract and reproductive organs, it consists of eleven segments in most orders of insects though the eleventh segment is absent in the adult of most higher orders. The number of these segments does vary from species to species with the number of segments visible reduced to only seven in

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