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Tardigrada
Tardigrades (), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär ("little water bear"). In 1777, the Italian biologist Lazzaro Spallanzani named them Tardigrada (), which means "slow steppers". They have been found in diverse regions of Earth's biospheremountaintops, the deep sea, tropical rainforests, and the Antarctic. Tardigrades are among the most resilient animals known, with individual species able to survive extreme conditions – such as exposure to extreme temperatures, extreme pressures (both high and low), air deprivation, radiation, dehydration, and starvation – that would quickly kill most other known forms of life. Tardigrades have survived exposure to outer space. There are about 1,300 known species in the phylum Tardigrada, a part of the superphylum Ecdysozoa consisting of animal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecdysozoa
Ecdysozoa () is a group of protostome animals, including Arthropoda (insects, chelicerata, crustaceans, and myriapods), Nematoda, and several smaller phyla. They were first defined by Aguinaldo ''et al.'' in 1997, based mainly on phylogenetic trees constructed using 18S ribosomal RNA genes. A large study in 2008 by Dunn ''et al.'' strongly supported the Ecdysozoa as a clade, that is, a group consisting of a common ancestor and all its descendants. The group is also supported by morphological characters, and includes all animals that grow by ecdysis, moulting their cuticle. The group was initially contested by a significant minority of biologists. Some argued for groupings based on more traditional taxonomic techniques, while others contested the interpretation of the molecular data. Etymology The name ''Ecdysozoa'' stems etymologically . Characteristics The most notable characteristic shared by ecdysozoans is a three-layered cuticle (four in Tardigrada) composed of orga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milnesium Tardigradum
''Milnesium tardigradum'' is a cosmopolitan species of tardigrade that can be found in a diverse range of environments. It has also been found in the sea around Antarctica. ''M. tardigradum'' was described by Louis Michel François Doyère in 1840. It contains unidentified osmolytes that could potentially provide important information in the process of cryptobiosis. Description Morphology ''M. tardigradum'' has a symmetrical body with a total of eight legs; it uses claws—a distinctive feature for this tardigrade species. The total length of the body varies, with some measuring up to 0.7 mm in length. ''M. tardigradum'' have been found to possess a high level of radioresistance. In 2007, individuals of two tardigrade species, '' Richtersius coronifer'' and ''M. tardigradum'', were subject to the radiation, near-vacuum, and near-absolute zero conditions of outer space as part of the European Space Agency's Biopan-6 experiment. Three specimens of ''M. tardigradum'' survive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arthropod cuticle, cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. Arthropods are bilaterally symmetrical and their body possesses an exoskeleton, external skeleton. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. Some species have wings. They are an extremely diverse group, with up to 10 million species. The haemocoel, an arthropod's internal cavity, through which its haemolymph – analogue of blood – circulates, accommodates its interior Organ (anatomy), organs; it has an open circulatory system. Like their exteriors, the internal or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echiniscus
''Echiniscus'' is a genus of tardigrades in the family Echiniscidae. The genus was named and described by Karl August Sigismund Schultze in 1840. Species The genus includes the following species: * ''Echiniscus africanus'' Murray, 1907 * ''Echiniscus aliquantillus'' Grigarick, Schuster & Nelson, 1983 * ''Echiniscus angolensis'' da Cunha & do Nascimento Ribeiro, 1964 * ''Echiniscus apuanus'' Bertolani, 1946 * ''Echiniscus arcangelii'' Maucci, 1973–74 * ''Echiniscus arctomys'' Ehrenberg, 1853 * ''Echiniscus arthuri'' Pilato, Binda & Lisi, 2005 * ''Echiniscus azoricus'' Fontoura, Pilato & Lisi, 2008 * ''Echiniscus baius'' Marcus, 1928 * ''Echiniscus baloghi'' Iharos, 1973 * ''Echiniscus barbarae'' Kaczmarek & Michalczyk, 2002 * ''Echiniscus batramiae'' Iharos, 1936 * ''Echiniscus becki'' Schuster & Grigarick, 1966 * ''Echiniscus bigranulatus'' Richters, 1907 * ''Echiniscus bisculptus'' Maucci, 1983 * ''Echiniscus blumi'' Richters, 1903 * ''Echiniscus calcaratus'' Richters, 190 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lazzaro Spallanzani
Lazzaro Spallanzani (; 12 January 1729 – 11 February 1799) was an Italian Catholic priest (for which he was nicknamed Abbé Spallanzani), biologist and physiologist who made important contributions to the experimental study of bodily functions, animal reproduction, and animal echolocation. His research on biogenesis paved the way for the downfall of the theory of spontaneous generation, a prevailing idea at the time that organisms develop from inanimate matters, though the final death blow to the idea was dealt by French scientist Louis Pasteur a century later. His most important works were summed up in his book ''Experiencias Para Servir a La Historia de La Generación De Animales y Plantas'' (''Experiences to Serve to the History of the Generation of Animals and Plants''), published in 1786. Among his contributions were experimental demonstrations of fertilisation between ova and spermatozoa, and ''in vitro'' fertilisation''.'' Biography Spallanzani was born in Scandian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesotardigrada
Mesotardigrada is one of three classes of tardigrades, consisting of a single species, ''Thermozodium esakii''. The animal reportedly has six claws of equal length at each foot. This species was described in 1937 by German zoologist Gilbert Rahm from a hot spring near Nagasaki, Japan. The inability of taxonomists to replicate Rahm's finding has cast doubt on the accuracy of the description, making ''T. esakii'', and by extension the entire class Mesotardigrada, a ''taxon inquirendum''. Taxonomic ambiguity The type specimen Rahm used as the basis of his description has either been lost or it was never preserved in the first place, which Grothman ''et al''. (2017) suggest is consistent with the lax taxonomic standards of the 1930s. Thus, re-examination of the original specimen is not possible. Complicating matters further, the type locality from which Rahm collected his specimen may have been destroyed by an earthquake and subsequent searches for additional specimens matching ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eutardigrade
Eutardigrada are a class of tardigrades (Tardigrada) without lateral appendices. Primarily freshwater bound, some species have secondarily gained the ability to live in marine environments (''Halobiotus''). By cryptobiosis many species are able to live temporarily in very dry environments. More than 700 species have been described. The order Apochela consists of only one family, Milnesiidae, with two genera: ''Milnesium'' and ''Limmenius''. ''Milnesium tardigradum'' can be found worldwide and is one of the biggest species among tardigrades (up to 1.4 mm); similar-looking species have been found in Cretaceous amber. The mouth of this predator has a wide opening, so the animal can eat rotifers and larger protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...s. Other eutardi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eutardigrada
Eutardigrada are a class of tardigrades (Tardigrada) without lateral appendices. Primarily freshwater bound, some species have secondarily gained the ability to live in marine environments (''Halobiotus''). By cryptobiosis many species are able to live temporarily in very dry environments. More than 700 species have been described. The order Apochela consists of only one family, Milnesiidae, with two genera: ''Milnesium'' and ''Limmenius''. ''Milnesium tardigradum'' can be found worldwide and is one of the biggest species among tardigrades (up to 1.4 mm); similar-looking species have been found in Cretaceous amber. The mouth of this predator has a wide opening, so the animal can eat rotifers and larger protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...s. Other eutardi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylum
In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering the relationships between phyla, which are contained in larger clades, like Ecdysozoa and Embryophyta. General description The term phylum was coined in 1866 by Ernst Haeckel from the Greek (, "race, stock"), related to (, "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy transformation, and reproduction. Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. Biology is the science that studies life. The gene is the unit of heredity, whereas the Cell (biology), cell is the structural and functional unit of life. There are two kinds of cells, prokaryotic and eukaryotic, both of which consist of cytoplasm enclosed within a membrane and contain many biomolecules such as proteins and nucleic acids. Cells reproduce through a process of cell division, in which the parent cell divides into two or more daughter cells and passes its genes onto a new generation, sometimes producing genetic variation. Organisms, or the individual entities of life, are generally thought t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outer Space
Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is . The plasma between galaxies is thought to account for about half of the baryonic (ordinary) matter in the universe, having a number density of less than one hydrogen atom per cubic metre and a kinetic temperature of millions of kelvins. Local concentrations of matter have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces. Observations s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecdysis
Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed. The remnants of the old, empty exoskeleton are called exuviae. After moulting, an arthropod is described as ''teneral'', a ''callow''; it is "fresh", pale and soft-bodied. Within one or two hours, the cuticle hardens and darkens following a tanning process analogous to the production of leather. During this short phase the animal expands, since growth is otherwise constrained by the rigidity of the exoskeleton. Growth of the limbs and other parts normally covered by the hard exoskeleton is achieved by transfer of body fluids from soft parts before the new skin hardens. A spider with a small abdomen may be undernourished but more probably has recently undergone ecdysis. Some arthropods, especially large insects with tracheal respiration, expand thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
