98-399: Seisonacea (for order) Seisonidae is a family of rotifers , found on the gills of Nebalia , a marine crustacean . Peculiar among rotifers, males and females are both present and equal in size. Males and females are similar with paired gonads . It is considered to have diverged from the other rotifers early on, and in one treatment is placed in a separate class Seisonoidea . They have
196-428: A Neo-Latin word meaning ' wheel -bearer' due to the corona around the mouth that in concerted sequential motion resembles a wheel (although the organ does not actually rotate). Rotifers have bilateral symmetry and a variety of different shapes. The body of a rotifer is divided into a head, trunk, and foot, and is typically somewhat cylindrical. There is a well-developed cuticle , which may be thick and rigid, giving
294-628: A penis . The gonopore is homologous to the cloaca of females, but in most species has no connection to the vestigial digestive system, which lacks an anus . In the genus Asplanchna also the females lacks an anus, but have kept the cloacal opening for excretion and the release of eggs. The phylum Rotifera encloses three classes that reproduce by three different mechanisms: Seisonidea only reproduce sexually; Bdelloidea reproduce exclusively by asexual parthenogenesis; Monogononta reproduce alternating these two mechanisms ("cyclical parthenogenesis" or "heterogony"). Parthenogenesis (amictic phase) dominates
392-540: A woolly rhinoceros from the Kolyma , and bison and horses from Yukagir have been found. Remote Wrangel Island and the Taymyr Peninsula are believed to have been the last places on Earth to support woolly mammoths as isolated populations until their extinction around 2000 BC. At least three species of humans lived in southern Siberia around 40,000 years ago: H. sapiens , H. neanderthalensis , and
490-635: A bdelloid rotifer, Adineta vaga , was reported to be around 244 Mb. The genomes of Monogononts seem to be significantly smaller than those of Bdelloids. In Monogononta the nuclear DNA content (2C) in eight different species of four different genera ranged almost fourfold, from 0.12 to 0.46 pg. Haploid "1C" genome sizes in Brachionus species range at least from 0.056 to 0.416 pg. Siberia Siberia ( / s aɪ ˈ b ɪər i ə / sy- BEER -ee-ə ; Russian : Сибирь , romanized : Sibir' , IPA: [sʲɪˈbʲirʲ] )
588-399: A characteristic chewing pharynx (called the mastax ), sometimes via a ciliated tube, and sometimes directly. The pharynx has a powerful muscular wall and contains tiny, calcified, jaw-like structures called trophi , which are the only fossilizable parts of a rotifer. The shape of the trophi varies between different species, depending partly on the nature of their diet. In suspension feeders,
686-440: A few hours. Bdelloids can survive the dry state for long periods, with the longest well-documented dormancy being nine years. Rotifers can also undergo other forms of cryptobiosis, notably cryobiosis which results from decreased temperatures. In 2021, researchers collected samples from remote Arctic locations containing rotifers which when thawed revealed living specimens around 24,000 years old. While in other anhydrobionts, such as
784-459: A large and elongate body with reduced corona. Their muscular system is similar to that of other rotifers: they have longitudinal muscles as well as open annular muscles. Being attached for most of their life, they are semi-sessile, but are capable of detaching and crawl short distances if required. Feeding has never been observed directly, but the stomach in Seison nebaliae contained bacteria, while
882-547: A larger clade called Syndermata . In June 2021, biologists reported the restoration of bdelloid rotifers after being frozen for 24,000 years in the Siberian permafrost . Early purported fossils of rotifers have been suggested in Devonian and Permian fossil beds. John Harris first described the rotifers (in particular a bdelloid rotifer ) in 1696 as "an animal like a large maggot which could contract itself into
980-524: A major foodsource and with many species also contributing to the decomposition of soil organic matter. Most species of the rotifers are cosmopolitan , but there are also some endemic species, like Cephalodella vittata to Lake Baikal . Recent barcoding evidence, however, suggests that some 'cosmopolitan' species, such as Brachionus plicatilis , B. calyciflorus , Lecane bulla , among others, are actually species complexes . In some recent treatments, rotifers are placed with acanthocephalans in
1078-521: A million years and some scientists consider it a possible cause of the " Great Dying " about 250 million years ago, – estimated to have killed 90% of species existing at the time. The region has paleontological significance, as it contains bodies of prehistoric animals from the Pleistocene Epoch , preserved in ice or permafrost . Specimens of Goldfuss cave lion cubs , Yuka the mammoth and another woolly mammoth from Oymyakon ,
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#17328020083171176-445: A recessive allele. Resting eggs enclose an embryo encysted in a three-layered shell that protects it from external stressors. They are able to remain dormant for several decades and can resist adverse periods (e.g., pond desiccation or presence of antagonists). When favourable conditions return and after an obligatory period of diapause which varies among species, resting eggs hatch releasing diploid amictic females that enter into
1274-707: A region extending eastward from the Ural Mountains to the watershed between Pacific and Arctic drainage basins, and southward from the Arctic Ocean to the hills of north-central Kazakhstan and the national borders of both Mongolia and China. By this definition, Siberia includes the federal subjects of the Siberian Federal District , and some of the Ural Federal District , as well as Sakha (Yakutia) Republic , which
1372-400: A series of tube-like secretions with a highly filamentous framework. This is highly suggestive of a glycosaminoglycan structure- proteins with negatively charged polysaccharide chains forming proteoglycan molecules. These molecules are standard in vertebrate and invertebrate gelatins such as mucus . Despite recent advancements in understanding RCO organ and secretion ultrastructure,
1470-404: A short intestine that terminates in a cloaca on the posterior dorsal surface of the animal. Up to seven salivary glands are present in some species, emptying to the mouth in front of the oesophagus, while the stomach is associated with two gastric glands that produce digestive enzymes . A pair of protonephridia open into a bladder that drains into the cloaca. These organs expel water from
1568-436: A spherical figure and then stretch itself out again; the end of its tail appeared with a forceps like that of an earwig ". In 1702, Antonie van Leeuwenhoek gave a detailed description of Rotifer vulgaris and subsequently described Melicerta ringens and other species. He was also the first to publish observations of the revivification of certain species after drying. Other forms were described by other observers, but it
1666-505: A substance that probably represents hemolymph of the Nebalia host was found in the stomach of Paraseison annulatus . The latter prefer to settle beneath the carapace on the gills of the host's legs, and the former is usually found on the host's carapase, trunk or legs. Their host often lives in tidal puddles with decomposing algae for a limited period of time, with oxygen content so low it sometimes reaches anoxia, which doesn't seem to bother
1764-505: Is a part of the Far Eastern Federal District . Geographically, this definition includes subdivisions of several other subjects of Urals and Far Eastern federal districts, but they are not included administratively. This definition excludes Sverdlovsk Oblast and Chelyabinsk Oblast , both of which are included in some wider definitions of Siberia. Other sources may use either a somewhat wider definition that states
1862-424: Is about 0.5 °C (32.9 °F). January averages about −20 °C (−4 °F) and July about +19 °C (66 °F), while daytime temperatures in summer typically exceed 20 °C (68 °F). With a reliable growing season, an abundance of sunshine and exceedingly fertile chernozem soils, southern Siberia is good enough for profitable agriculture , as was demonstrated in the early 20th century. By far
1960-602: Is an extensive geographical region comprising all of North Asia , from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states since the centuries-long conquest of Siberia , which began with the fall of the Khanate of Sibir in the late 16th century and concluded with the annexation of Chukotka in 1778. Siberia
2058-655: Is culturally and politically considered European, since it is a part of Russia. Major geographical zones within Siberia include the West Siberian Plain and the Central Siberian Plateau . Eastern and central Sakha comprises numerous north–south mountain ranges of various ages. These mountains extend up to almost 3,000 metres (9,800 ft), but above a few hundred metres they are almost completely devoid of vegetation. The Verkhoyansk Range
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#17328020083172156-573: Is derived from a Mongolic word sibir , cognate with modern Buryat sheber 'dense forest'. Siberia in Paleozoic times formed the continent of Siberia/Angaraland , which fused to Euramerica during the Late Carboniferous , as part of the formation of Pangea . The Siberian Traps were formed by one of the largest-known volcanic events of the last 251 million years of Earth's geological history . Their activity continued for
2254-429: Is different and found on a different chromosome excluding the possibility of homozygous sexual reproduction . Rotifers eat particulate organic detritus, dead bacteria, algae, and protozoans. They eat particles up to 10 micrometres in size. Like crustaceans , rotifers contribute to nutrient recycling. For this reason, they are used in fish tanks to help clean the water, to prevent clouds of waste matter. Rotifers affect
2352-530: Is doubtful that the total early modern Siberian population exceeded 300,000 persons". The first mention of Siberia in chronicles is recorded in the year 1032. The city-state of Novgorod established two trade routes to the Ob River , and laid claim to the lands the Russians called Yugra . The Russians were attracted by its furs in particular. Novgorod launched military campaigns to extract tribute from
2450-427: Is further modified, with the upper band splitting into two rotating wheels, raised up on a pedestal projecting from the upper surface of the head. The trunk forms the major part of the body, and encloses most of the internal organs. The foot projects from the rear of the trunk, and is usually much narrower, giving the appearance of a tail. The cuticle over the foot often forms rings, making it appear segmented, although
2548-425: Is high also in most of Primorye in the extreme south, where monsoonal influences can produce quite heavy summer rainfall. Researchers, including Sergei Kirpotin at Tomsk State University and Judith Marquand at Oxford University , warn that Western Siberia has begun to thaw as a result of global warming . The frozen peat bogs in this region may hold billions of tons of methane gas , which may be released into
2646-483: Is internal. The male either inserts his penis into the female's cloaca or uses it to penetrate her skin, injecting the sperm into the body cavity. The egg secretes a shell, and is attached either to the substratum, nearby plants, or the female's own body. A few species, such as members of the Rotaria , are ovoviviparous , retaining the eggs inside their body until they hatch. Most species hatch as miniature versions of
2744-612: Is no longer visible. The Central Siberian Plateau is an ancient craton (sometimes named Angaraland ) that formed an independent continent before the Permian (see the Siberian continent ). It is exceptionally rich in minerals, containing large deposits of gold , diamonds , and ores of manganese , lead , zinc , nickel , cobalt , and molybdenum . Much of the area includes the Siberian Traps —a large igneous province . A massive eruptive period approximately coincided with
2842-603: Is several degrees warmer than in the East ( Irkutsk , or Chita ) where in the north an extreme winter subarctic climate (Köppen Dfd , Dwd , or Dsd ) prevails. But summer temperatures in other regions can reach +38 °C (100 °F). In general, Sakha is the coldest Siberian region, and the basin of the Yana has the lowest temperatures of all, with permafrost reaching 1,493 metres (4,898 ft). Nevertheless, Imperial Russian plans of settlement never viewed cold as an impediment. In
2940-605: Is the Monogononta, with about 1,500 species, followed by the Bdelloidea, with about 350 species. There are only two known genera with three species of Seisonidea. The Acanthocephala , previously considered to be a separate phylum, have been demonstrated to be modified rotifers. The exact relationship to other members of the phylum has not yet been resolved. One possibility is that the Acanthocephala are closer to
3038-473: Is the active volcano Klyuchevskaya Sopka , on the Kamchatka Peninsula . Its peak reaches 4,750 metres (15,580 ft). The West Siberian Plain, consisting mostly of Cenozoic alluvial deposits, is somewhat flat. In the mid-Pleistocene, many deposits on this plain resulted from ice dams which produced a large glacial lake . This mid- to late- Pleistocene lake blocked the northward flow of
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3136-626: Is the city of Novosibirsk . Present-day Novosibirsk is an important business, science, manufacturing and cultural center of the Asian part of Russia. Omsk played an important role in the Russian Civil War serving as a provisional Russian capital, as well in the expansion into and governing of Central Asia . In addition to its cultural status, it has become a major oil-refining, education, transport and agriculture hub. Other historic cities of Siberia include Tobolsk (the first capital and
3234-431: Is vast and sparsely populated, covering an area of over 13.1 million square kilometres (5,100,000 sq mi), but home to roughly a quarter of Russia's population. Novosibirsk , Krasnoyarsk , and Omsk are the largest cities in the area. Because Siberia is a geographic and historic concept and not a political entity, there is no single precise definition of its territorial borders. Traditionally, Siberia spans
3332-623: The Ainu people ). Evidence from full genomic studies suggests that the first people in the Americas diverged from Ancient East Asians about 36,000 years ago and expanded northwards into Siberia, where they encountered and interacted with Ancient North Eurasians, giving rise to both Paleosiberian peoples and Ancient Native Americans , which later migrated towards the Beringian region, became isolated from other populations, and subsequently populated
3430-746: The Denisovans . In 2010, DNA evidence identified the last as a separate species. Late Paleolithic southern Siberians appear to be related to Paleolithic Europeans and the paleolithic Jōmon people of Japan. Ancient DNA analysis has revealed that the oldest fossil known to carry the derived KITLG allele, which is responsible for blond hair in modern Europeans, is a 17,000 year old Ancient North Eurasian specimen from Siberia. Ancient North Eurasian populations genetically similar to Mal'ta–Buret' culture and Afontova Gora were an important genetic contributor to Native Americans, Europeans, Ancient Central Asians, South Asians, and some East Asian groups (such as
3528-676: The Late Carboniferous through Jurassic Verkhoyansk foldbelt , on the northwest by the Paleozoic Taymr foldbelt, and on the southeast, south and southwest by the Middle Silurian to Middle Devonian Baykalian foldbelt. A regional geologic reconnaissance study begun in 1932 and followed by surface and subsurface mapping revealed the Markova-Angara Arch ( anticline ). This led to the discovery of
3626-636: The Ob and Yenisey rivers, resulting in a redirection southwest into the Caspian and Aral seas via the Turgai Valley . The area is very swampy, and soils are mostly peaty histosols and, in the treeless northern part, histels . In the south of the plain, where permafrost is largely absent, rich grasslands that are an extension of the Kazakh Steppe formed the original vegetation, most of which
3724-573: The Permian–Triassic extinction event . The volcanic event is one of the largest known volcanic eruptions in Earth's history . Only the extreme northwest was glaciated during the Quaternary , but almost all is under exceptionally deep permafrost, and the only tree that can thrive, despite the warm summers, is the deciduous Siberian Larch ( Larix sibirica ) with its very shallow roots. Outside
3822-622: The Siberian sub-ethnic group), and Eastern Slavic cultural influences predominate throughout the region. Nevertheless, there exist sizable ethnic minorities of Asian lineage, including various Turkic communities—many of which, such as the Yakuts , Tuvans , Altai , and Khakas , are Indigenous —along with the Mongolic Buryats , ethnic Koreans , and smaller groups of Samoyedic and Tungusic peoples (several of whom are classified as Indigenous small-numbered peoples by
3920-672: The Siberian Tatar word for 'sleeping land' ( Sib-ir ). A different hypothesis claims that the region was named after the Sibe people . The Polish historian Jan Chyliczkowski has proposed that the name derives from the Proto-Slavic word for 'north' (cf. Russian север sever ), as in Severia . Anatole Baikaloff has dismissed this explanation. He said that the neighboring Chinese, Turks, and Mongolians, who have similar names for
4018-684: The Soviet Union (especially in the 1930s and 1940s), the government used the Gulag state agency to administer a system of penal labour camps , replacing the previous katorga system. According to semi-official Soviet estimates, which did not become public until after the fall of the Soviet government in 1991, from 1929 to 1953 more than 14 million people passed through these camps and prisons, many of them in Siberia. Another seven to eight million people were internally deported to remote areas of
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4116-419: The anterior end of the gland where they undergo homotypic fusion to create larger granules with numerous "mesh-like" contents. These contents gradually fuse into tubular secretions that accumulate in the reservoir, awaiting secretion. Cross-striated longitudinal muscles form a partial sleeve around the reservoir and may function to squeeze the secretions through the gland's duct that often penetrates through
4214-727: The brine shrimp , this desiccation tolerance is thought to be linked to the production of trehalose , a non-reducing disaccharide ( sugar ), bdelloids apparently cannot synthesise trehalose. In bdelloids, a major cause of the resistance to desiccation, as well as resistance to ionizing radiation, is a highly efficient mechanism for repairing the DNA double-strand breaks induced by these agents. This repair mechanism likely involves mitotic recombination between homologous DNA regions. Rotifers fall prey to many animals, such as copepods , fish (e.g. herring , salmon ), bryozoa , comb jellies , jellyfish , starfish , and tardigrades . The genome size of
4312-418: The cloaca . Males do not usually have a functional digestive system, and are therefore short-lived, often being sexually fertile at birth. They have a single testicle and sperm duct , associated with a pair of glandular structures referred to as prostates (unrelated to the vertebrate prostate ). The sperm duct opens into a gonopore at the posterior end of the animal, which is usually modified to form
4410-843: The Americas. During past millennia, different groups of nomads – such as the Enets , the Nenets , the Huns , the Xiongnu , the Scythians , and the Yugur – inhabited various parts of Siberia. The Afanasievo and Tashtyk cultures of the Yenisey valley and Altay Mountains are associated with the Indo-European migrations across Eurasia. The proto-Mongol Khitan people also occupied parts of
4508-458: The Bdelloidea and Monogononta than to the Seisonidea; the corresponding names and relationships are shown in the cladogram below. Seisonida Bdelloidea Monogononta Acanthocephala The Rotifera, strictly speaking, are confined to the Bdelloidea and the Monogononta. Rotifera, Acanthocephala and Seisonida make up a clade called Syndermata. The word rotifer is derived from
4606-1147: The Markovo Oil Field in 1962 with the Markovo—1 well, which produced from the Early Cambrian Osa Horizon bar - sandstone at a depth of 2,156 metres (7,073 ft). The Sredne-Botuobin Gas Field was discovered in 1970, producing from the Osa and the Proterozoic Parfenovo Horizon. The Yaraktin Oil Field was discovered in 1971, producing from the Vendian Yaraktin Horizon at depths of up to 1,750 metres (5,740 ft), which lies below Permian to Lower Jurassic basalt traps . The climate of Siberia varies dramatically, but it typically has warm but short summers and long, brutally cold winters. On
4704-652: The North-East Camps ) along the Kolyma and Norillag near Norilsk , where 69,000 prisoners lived in 1952. Major industrial cities of Northern Siberia, such as Norilsk and Magadan , developed from camps built by prisoners and run by former prisoners. Siberia spans an area of 13.1 million square kilometres (5,100,000 sq mi), covering the vast majority of Russia's total territory, and almost 9% of Earth's land surface (148,940,000 km , 57,510,000 sq mi). It geographically falls in Asia, but
4802-557: The Pacific coast, not the watershed, is the eastern boundary (thus including the whole Russian Far East), as well as all Northern Kazakhstan is its subregion in the south-west or a somewhat narrower one that limits Siberia to the Siberian Federal District (thus excluding all subjects of other districts). In Russian, 'Siberia' is commonly used as a substitute for the name of the federal district by those who live in
4900-678: The Russian Far East, and even Petropavlovsk in Kazakhstan and Harbin in China. Novosibirsk is the largest by population and the most important city for the Siberian economy; with an extra boost since 2000 when it was designated a regional center for the executive bureaucracy ( Siberian Federal District ). Omsk is a historic and currently the second largest city in the region, and since 1950s hosting Russia's largest oil refinery,
4998-559: The Russian government), among many others. The origin of the name is uncertain. The Russian name Yugra was applied to the northern lands east of the Urals , which had been known of since the 11th century or earlier, while the name Siberia is first mentioned in Russian chronicles at the start of the 15th century in connection with the death of the khan Tokhtamysh , in "the Siberian land". Some sources say that "Siberia" originates from
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#17328020083175096-905: The Seisonidae. Two genera with total four species belong to Seisonidae: This rotifer -related article is a stub . You can help Misplaced Pages by expanding it . Rotifer The rotifers ( / ˈ r oʊ t ɪ f ər z / , from Latin rota 'wheel' and -fer 'bearing'), sometimes called wheel animals or wheel animalcules , make up a phylum ( Rotifera / r oʊ ˈ t ɪ f ər ə / ) of microscopic and near-microscopic pseudocoelomate animals . They were first described by Rev. John Harris in 1696, and other forms were described by Antonie van Leeuwenhoek in 1703. Most rotifers are around 0.1–0.5 mm (0.0039–0.0197 in) long (although their size can range from 50 μm (0.0020 in) to over 2 mm (0.079 in)), and are common in freshwater environments throughout
5194-467: The Siberian Khanate in the 16th century. First, groups of traders and Cossacks began to enter the area. The Russian army was directed to establish forts farther and farther east to protect new Russian settlers who migrated from Europe. Towns such as Mangazeya , Tara , Yeniseysk , and Tobolsk developed, the last becoming the de facto capital of Siberia from 1590. At this time, Sibir was
5292-575: The Soviet Union (including entire nationalities or ethnicities in several cases). Half a million (516,841) prisoners died in camps from 1941 to 1943 during World War II . At other periods, mortality was comparatively lower. The size, scope, and scale of the Gulag slave-labour camps remain subjects of much research and debate. Many Gulag camps operated in extremely remote areas of northeastern Siberia. The best-known clusters included Sevvostlag (
5390-480: The adult. Sessile species, however, are born as free-swimming larvae , which closely resemble the adults of related free-swimming species. Females grow rapidly, reaching their adult size within a few days, while males typically do not grow in size at all. The life span of monogonont females varies from two days to about three weeks. ' Ancient asexuals': Bdelloid rotifers are assumed to have reproduced without sex for many millions of years. Males are absent within
5488-565: The ages. Historically, Siberia was defined as the whole part of Russia and North Kazakhstan to the east of Ural Mountains , including the Russian Far East . According to this definition, Siberia extended eastward from the Ural Mountains to the Pacific coast, and southward from the Arctic Ocean to the border of Central Asia and the national borders of both Mongolia and China. Soviet-era sources ( Great Soviet Encyclopedia and others) and modern Russian ones usually define Siberia as
5586-403: The animal a box-like shape, or flexible, giving the animal a worm-like shape; such rotifers are respectively called loricate and illoricate . Rigid cuticles are often composed of multiple plates, and may bear spines, ridges, or other ornamentation. Their cuticle is nonchitinous and is formed from sclerotized proteins. The two most distinctive features of rotifers (in females of all species) are
5684-465: The area between the Laptev Sea and East Siberian Sea . Since 1988, experimentation at Pleistocene Park has proposed to restore the grasslands of prehistoric times by conducting research on the effects of large herbivores on permafrost, suggesting that animals, rather than climate, maintained the past ecosystem. The nature reserve park also conducts climatic research on the changes expected from
5782-429: The asexual phase of the life cycle. Bdelloid rotifer females cannot produce resting eggs, but many can survive prolonged periods of adverse conditions after desiccation . This facility is termed anhydrobiosis , and organisms with these capabilities are termed anhydrobionts. Under drought conditions, bdelloid rotifers contract into an inert form and lose almost all body water; when rehydrated they resume activity within
5880-607: The atmosphere. Methane is a greenhouse gas 22 times more powerful than carbon dioxide . In 2008 a research expedition for the American Geophysical Union detected levels of methane up to 100 times above normal in the atmosphere above the Siberian Arctic , likely the result of methane clathrates being released through holes in a frozen "lid" of seabed permafrost around the outfall of the Lena and
5978-482: The body, helping to maintain osmotic balance . The coronal cilia pull the animal, when unattached, through the water. Like many other microscopic animals, adult rotifers frequently exhibit eutely —they have a fixed number of cells within a species, usually on the order of 1,000. Bdelloid rotifer genomes contain two or more divergent copies of each gene , suggesting a long-term asexual evolutionary history. For example, four copies of hsp82 are found. Each
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#17328020083176076-582: The brain, this organ usually consists of one or more glands and a sac or reservoir. The sac drains into a duct before opening through pores on the uppermost part of the head. Current data shows a wide diversity in structure and potential function. In some species it is reduced or may even be absent completely. Benthic species have larger RCO's than planktonic species. Despite this diversity, positional correspondence of RCOs strongly suggests homology . A 2023 study using transmission electron microscopy and confocal laser scanning microscopy has illuminated
6174-421: The bristles of the corona are sensitive to touch, and there are also a pair of tiny sensory pits lined by cilia in the head region. Despite over 100 years of research, rotifer anatomy still has many poorly understood components. One of the more mysterious organs in rotifers is the "retrocerebral organ" (RCO), which still remains very enigmatic in its morphology, function, development, and evolution. Lying close to
6272-423: The cerebral ganglion. Much like the organ itself, the precise function and biochemical makeup of the secretions is still unknown. The small size of rotifers and small volume of the secretions makes isolation immensely difficult. The secretions have some similarities to the hydrogel secretions that form gelatinous housings in some rotifer species. Ultrastructure analysis of T. similis secretions showed them to be
6370-635: The coldest inhabited point in the Northern hemisphere. Each town also frequently reaches 30 °C (86 °F) in the summer, giving them, and much of the rest of Russian Siberia, the world's greatest temperature variation between summer's highs and winter's lows, often well over 94–100+ °C (169–180+ °F) between the seasons. Southwesterly winds bring warm air from Central Asia and the Middle East. The climate in West Siberia (Omsk, or Novosibirsk)
6468-424: The corona include alteration of the cilia into bristles or large tufts, and either expansion or loss of the ciliated band around the head. In genera such as Collotheca , the corona is modified to form a funnel surrounding the mouth. In many species, such as those in the genus Testudinella , the cilia around the mouth have disappeared, leaving just two small circular bands on the head. In the bdelloids , this plan
6566-470: The definition of the territory of Siberia a potentially controversial subject. In the eastern extent of Siberia there are territories which are not clearly defined as either Siberia or the Far East , making the question of "what is Siberia?" one with no clear answer, and what is a "Siberian", one of self-identification . The most populous city of Siberia, as well as the third most populous city of Russia,
6664-403: The district itself, but less commonly used to denote the federal district by people residing outside of it. Due to the different interpretations of Siberia, starting from Tyumen , to Chita , the territory generally defined as 'Siberia', some people will define themselves as 'Siberian', while others not. A number of factors in recent years, including the fomenting of Siberian separatism have made
6762-594: The entire expanse of land from the Ural Mountains to the Pacific Ocean , with the Ural River usually forming the southernmost portion of its western boundary, and includes most of the drainage basin of the Arctic Ocean . It is further defined as stretching from the territories within the Arctic Circle in the north to the northern borders of Kazakhstan , Mongolia , and China in the south, although
6860-429: The exact function of the organ is still ultimately unclear. The leading hypotheses are that the RCO secretes a mucus-like substance that aids in benthic locomotion, adhesion, and/or reproduction (i.e., attachment of eggs to a substrate), although more research is needed to explore function and evaluate the homology between species. The coronal cilia create a current that sweeps food into the mouth. The mouth opens into
6958-413: The extreme northwest, the taiga is dominant, covering a significant fraction of the entirety of Siberia. Soils here are mainly turbels , giving way to spodosols where the active layer becomes thicker and the ice-content lower. The Lena-Tunguska petroleum province includes the Central Siberian platform (some authors refer to it as the "Eastern Siberian platform"), bounded on the northeast and east by
7056-487: The fine structure of this organ further. The study, the first of its kind, investigated the RCO in one species, Trichocerca similis . It was determined to be a syncytial organ , composed of a posterior glandular region, an expansive reservoir, and an anterior duct . The glandular portion has an active cytoplasm with paired nuclei , abundant rough ER , ribosomes , Golgi , and mitochondria . Secretion granules accumulate at
7154-456: The hills of north-central Kazakhstan are also commonly included. The Russian government divides the region into three federal districts (groupings of Russian federal subjects ), of which only the central one is officially referred to as " Siberian "; the other two are the Ural and Far Eastern federal districts, named for the Ural and Russian Far East regions that correspond respectively to
7252-430: The internal structure is uniform. Many rotifers can retract the foot partially or wholly into the trunk. The foot ends in from one to four toes, which, in sessile and crawling species, contain adhesive glands to attach the animal to the substratum. In many free-swimming species, the foot as a whole is reduced in size, and may even be absent. Rotifers have a small cerebral ganglion, effectively its brain, located just above
7350-474: The local population, but often met resistance, such as two campaigns in 1187 and 1193 mentioned in chronicles that were defeated. After Novgorod was annexed by Moscow , the newly emerging centralized Russian state also laid claim to the region, with Ivan III of Russia sending expeditionary forces to Siberia in 1483 and 1499–1500. The Russians received tribute, but contact with the tribes ceased after they left. The growing power of Russia began to undermine
7448-439: The mastax, from which a number of nerves extend throughout the body. The number of nerves varies among species, although the nervous system usually has a simple layout. The nervous system comprises about 25% of the roughly 1,000 cells in a rotifer. Rotifers typically possess one or two pairs of short antennae and up to five eyes. The eyes are simple in structure, sometimes with just a single photoreceptor cell . In addition,
7546-615: The mid-17th century, Russia had established areas of control that extended to the Pacific Ocean. Some 230,000 Russians had settled in Siberia by 1709. Siberia became one of the destinations for sending internal exiles . Exile was the main Russian punitive practice with more than 800,000 people exiled during the nineteenth century. The first great modern change in Siberia was the Trans-Siberian Railway , constructed during 1891–1916. It linked Siberia more closely to
7644-591: The monogonont life cycle, promoting fast population growth and colonization. In this phase males are absent and amictic females produce diploid eggs by mitosis which develop parthenogenetically into females that are clones of their mothers. Some amictic females can generate mictic females that will produce haploid eggs by meiosis. Mixis (meiosis) is induced by different types of stimulus depending on species. Haploid eggs develop into haploid dwarf males if they are not fertilized and into diploid "resting eggs" (or "diapausing eggs") if they are fertilized by males. Fertilization
7742-553: The most commonly occurring climate in Siberia is continental subarctic (Koppen Dfc , Dwc , or Dsc ), with the annual average temperature about −5 °C (23 °F) and an average for January of −25 °C (−13 °F) and an average for July of +17 °C (63 °F), although this varies considerably, with a July average about 10 °C (50 °F) in the taiga–tundra ecotone . The business -oriented website and blog Business Insider lists Verkhoyansk and Oymyakon , in Siberia's Sakha Republic , as being in competition for
7840-488: The name of a fortress at Qashliq , near Tobolsk. Gerardus Mercator , in a map published in 1595, marks Sibier both as the name of a settlement and of the surrounding territory along a left tributary of the Ob . Other sources contend that the Sibe , an Indigenous Tungusic people , offered fierce resistance to Russian expansion beyond the Urals. Some suggest that the term "Siberia" is a russification of their ethnonym. By
7938-400: The north coast, north of the Arctic Circle , there is a very short (about one month long) summer. Almost all the population lives in the south, along the route of the Trans-Siberian Railway . The climate in this southernmost part is humid continental climate (Köppen Dfa/Dfb or Dwa/Dwb ) with cold winters but fairly warm summers lasting at least four months. The annual average temperature
8036-462: The only kremlin in Siberia), Tomsk (formerly a wealthy merchant's town) and Irkutsk (former seat of Eastern Siberia's governor general, near lake Baikal). Other major cities include: Barnaul , Kemerovo , Krasnoyarsk , Novokuznetsk , Tyumen . Wider definitions of geographic Siberia also include the cities of: Chelyabinsk and Yekaterinburg in the Urals, Khabarovsk and Vladivostok in
8134-412: The presence of corona on the head, a structure ciliated in all genera except Cupelopagis and presence of mastax. In the more primitive species, the corona forms a simple ring of cilia around the mouth from which an additional band of cilia stretches over the back of the head. In the great majority of rotifers, however, this has evolved into a more complex structure. Modifications to the basic plan of
8232-406: The rapidly industrialising Russia of Nicholas II ( r. 1894–1917 ). Around seven million Russians moved to Siberia from Europe between 1801 and 1914. Between 1859 and 1917, more than half a million people migrated to the Russian Far East. Siberia has extensive natural resources: during the 20th century, large-scale exploitation of these took place, and industrial towns cropped up throughout
8330-466: The region, would not have known Russian. He suggested that the name might be a combination of two words with Turkic origin, su 'water' and bir 'wild land'. Another account sees the name as the ancient tribal ethnonym of the Sihirtia or Sirtya (also Syopyr [sʲɵpᵻr])), a hypothetical Paleo-Asiatic ethnic group assimilated by the Nenets . Mongolist György Kara posits that the toponym Siberia
8428-557: The region. At 7:15 a.m. on 30 June 1908, the Tunguska Event felled millions of trees near the Podkamennaya Tunguska River (Stony Tunguska River) in central Siberia. Most scientists believe this resulted from the air burst of a meteor or a comet. Even though no crater has ever been found, the landscape in the (sparsely inhabited) area still bears the scars of this event. In the early decades of
8526-751: The region. In the 13th century, during the period of the Mongol Empire , the Mongols conquered a large part of this area. With the breakup of the Golden Horde , the autonomous Khanate of Sibir was formed in the late-15th century. Turkic-speaking Yakut migrated north from the Lake Baikal region under pressure from the Mongol tribes from the 13th to 15th centuries. Siberia remained a sparsely populated area. Historian John F. Richards wrote: "it
8624-558: The reintroduction of grazing animals or large herbivores, hypothesizing that a transition from tundra to grassland would lead to a net change in energy emission to absorption ratios. According to Vasily Kryuchkov, approximately 31,000 square kilometers of the Russian Arctic has subjected to severe environmental disturbance. The term "Siberia" has both a long history and wide significance, and association. The understanding, and association of "Siberia" have gradually changed during
8722-408: The size of the male. In parthenogenetic species, males may be present only at certain times of the year, or absent altogether. The female reproductive system consists of one or two ovaries , each with a vitellarium gland that supplies the eggs with yolk . Together, each ovary and vitellarium form a single syncitial structure in the anterior part of the animal, opening through an oviduct into
8820-413: The species composition of algae in ecosystems through their choice in grazing. Rotifers may compete with cladocera and copepods for planktonic food sources. Rotifers are dioecious and reproduce sexually or parthenogenetically . They are sexually dimorphic , with the females always being larger than the males. In some species, this is relatively mild, but in others the female may be up to ten times
8918-701: The species, and females reproduce only by parthenogenesis . However, a new study provided evidence for interindividual genetic exchange and recombination in Adineta vaga , a species previously thought to be anciently asexual. Recent transitions: Loss of sexual reproduction can be inherited in a simple Mendelian fashion in the monogonont rotifer Brachionus calyciflorus : This species can normally switch between sexual and asexual reproduction (cyclical parthenogenesis), but occasionally gives rise to purely asexual lineages (obligate parthenogens). These lineages are unable to reproduce sexually due to being homozygous for
9016-478: The title of the Northern Hemisphere's Pole of Cold . Oymyakon is a village which recorded a temperature of −67.7 °C (−89.9 °F) on 6 February 1933. Verkhoyansk , a town further north and further inland, recorded a temperature of −69.8 °C (−93.6 °F) for three consecutive nights: 5, 6 and 7 February 1933. Each town is alternately considered the Northern Hemisphere's Pole of Cold –
9114-431: The trophi are covered in grinding ridges, while in more actively carnivorous species, they may be shaped like forceps to help bite into prey. In some ectoparasitic rotifers, the mastax is adapted to grip onto the host, although, in others, the foot performs this function instead. Behind the mastax lies an oesophagus , which opens into a stomach where most of the digestion and absorption occurs. The stomach opens into
9212-425: The western and eastern thirds of Siberia in the broader sense. Siberia is known for its long, harsh winters, with a January average of −25 °C (−13 °F). Although it is geographically in Asia, Russian sovereignty and colonization since the 16th century has led to perceptions of the region as culturally and ethnically European. Over 85% of its population are of European descent , chiefly Russian (comprising
9310-567: The winter, southern Siberia sits near the center of the semi-permanent Siberian High , so winds are usually light in the winter. Precipitation in Siberia is generally low, exceeding 500 millimetres (20 in) only in Kamchatka , where moist winds flow from the Sea of Okhotsk onto high mountains – producing the region's only major glaciers , though volcanic eruptions and low summer temperatures allow only limited forests to grow. Precipitation
9408-417: The world with a few saltwater species. Some rotifers are free swimming and truly planktonic , others move by inchworming along a substrate, and some are sessile , living inside tubes or gelatinous holdfasts that are attached to a substrate. About 25 species are colonial (e.g., Sinantherina semibullata ), either sessile or planktonic. Rotifers are an important part of the freshwater zooplankton , being
9506-486: Was extensively glaciated in the Pleistocene, but the climate was too dry for glaciation to extend to low elevations. At these low elevations are numerous valleys, many of them deep and covered with larch forest, except in the extreme north where the tundra dominates. Soils are mainly turbels (a type of gelisol ). The active layer tends to be less than one metre deep, except near rivers. The highest point in Siberia
9604-438: Was not until the publication of Christian Gottfried Ehrenberg 's Die Infusionsthierchen als vollkommene Organismen in 1838 that the rotifers were recognized as being multicellular animals. About 2,200 species of rotifers have been described. Their taxonomy is currently in a state of flux. One treatment places them in the phylum Rotifera, with three classes: Seisonidea , Bdelloidea and Monogononta . The largest group
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