Aspidogastrea
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Aspidogastrea
The Aspidogastrea (Ancient Greek: ' “shield”, ' “stomach/pouch”) is a small group of flukes comprising about 80 species. It is a subclass of the trematoda, and sister group to the Digenea. Species range in length from approximately one millimeter to several centimeters. They are parasites of freshwater and marine molluscs and vertebrates (cartilaginous and bony fishes and turtles). Maturation may occur in the mollusc or vertebrate host. None of the species has any economic importance, but the group is of very great interest to biologists because it has several characters which appear to be archaic. Morphology Shared characteristics Shared characteristics of the group are a large ventral disc with a large number of small alveoli ("suckerlets") or a row of suckers and a tegument with short protrusions, so-called "microtubercles". Aspidogastreans are an understudied class of parasitic flatworms that possess unique anterior attachment structures and are found exclusi ...
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Trematode
Trematoda is a Class (biology), class of flatworms known as trematodes, and commonly as flukes. They are obligate parasite, obligate Endoparasites, internal parasites with a complex biological life cycle, life cycle requiring at least two Host (biology), hosts. The intermediate host, in which asexual reproduction occurs, is a Mollusca, mollusk, usually a snail. The definitive host, where the flukes Sexual reproduction, sexually reproduce, is a vertebrate. Infection by trematodes can cause disease in all five vertebrate classes: mammals, birds, amphibians, reptiles, and fish. Etymology Trematodes are commonly referred to as flukes. This term can be traced back to the Old English name for flounder, and refers to the flattened, rhomboidal shape of the organisms. The etymology of trematode stems from the Ancient Greek, Greek word ''trēmatṓdēs'', which means "pierced with holes", and refers to the worm's sucker (zoology), sucker, which pierces a hole in the host while the worm is ...
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Trematoda
Trematoda is a class of flatworms known as trematodes, and commonly as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is a mollusk, usually a snail. The definitive host, where the flukes sexually reproduce, is a vertebrate. Infection by trematodes can cause disease in all five vertebrate classes: mammals, birds, amphibians, reptiles, and fish. Etymology Trematodes are commonly referred to as flukes. This term can be traced back to the Old English name for flounder, and refers to the flattened, rhomboidal shape of the organisms. The etymology of trematode stems from the Greek word ''trēmatṓdēs'', which means "pierced with holes", and refers to the worm's sucker, which pierces a hole in the host while the worm is attached and feeding. Taxonomy There are 18,000 to 24,000 known species of trematodes, divided into two subclasses — the Aspidogastrea and t ...
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Aspidogastrida
Aspidogastrida is an order of trematodes in the subclass Aspidogastrea The Aspidogastrea (Ancient Greek: ' “shield”, ' “stomach/pouch”) is a small group of flukes comprising about 80 species. It is a subclass of the trematoda, and sister group to the Digenea. Species range in length from approximately on .... Families *Superfamily Aspidogastrioidea Poche, 1907Poche, F. (1907). Einige Bemerkungen zur Nomenklatur der Trematoden. ''Zoologischer Anzeiger'', 31, 124-126. ** Aspidogastridae Poche, 1907 ** Multicalycidae Gibson & Chinabut, 1984Gibson, D. & Chinabut, S. (1984). ''Rohdella siamensis'' gen. et sp. nov. (Aspidogastridae: Rohdellinae subfam. nov.) from fresh water fishes in Thailand, with a reorganization of the classification of the subclass Aspidogastrea. ''Parasitology'', 88(3), 383–393. ** Rugogastridae Schell, 1973Schell, S. C. (1973). ''Rugogaster hydrolagi'' gen. et sp. n. (Tremtoda: Aspidobothrea: Rugogastridae fam. n.) from the ratfish ''Hydrolagus ...
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Platyhelminthes
Platyhelminthes (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called flatworms or flat worms. Being acoelomates (having no body cavity), and having no specialised circulatory and respiratory organs, they are restricted to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food can not be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non- parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematoda and Monogenea; however, since the turbellarians have since been proven not to be monophyletic, this classification i ...
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Digenea
Digenea (Gr. ''Dis'' – double, ''Genos'' – race) is a class of trematodes in the Platyhelminthes phylum, consisting of parasitic flatworms (known as ''flukes'') with a syncytial tegument and, usually, two suckers, one ventral and one oral. Adults commonly live within the digestive tract, but occur throughout the organ systems of all classes of vertebrates. Once thought to be related to the Monogenea, it is now recognised that they are closest to the Aspidogastrea and that the Monogenea are more closely allied with the Cestoda. Around 6,000 species have been described to date. Morphology Key features Characteristic features of the Digenea include a syncytial tegument; that is, a tegument where the junctions between cells are broken down and a single continuous cytoplasm surrounds the entire animal. A similar tegument is found in other members of the Neodermata; a group of platyhelminths comprising the Digenea, Aspidogastrea, Monogenea and Cestoda. Digeneans possess a ...
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Multicalyx Elegans
Multicalycidae is a family of trematodes in the order Aspidogastrida. It consists of one genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ..., ''Multicalyx'' Faust & Tang, 1936.Faust, E. & Tang, C. (1936). Notes on new aspidogastrid species, with a consideration of the phylogeny of the group. ''Parasitology'', 28(4), 487–501. Species *'' Multicalyx cristata'' Faust & Tang, 1936 *'' Multicalyx elegans'' (Olsson, 1869)Olsson, P. (1869). Nova genera parasitantia Copepodorum et Platyhelminthum. ''Lunds Universitets Arsskrift'', 6, 1–6. References Further reading *Thoney, D. A. & Burreson, E. M. (1988). Revision of the Multicalycidae (Aspidocotylea) with comments on postlarval development. ''Proceedings of the Helminthological Society of Washington'', 55(1), 62–67. Aspi ...
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Stichocotylida
''Stichocotyle'' is a monospecific genus of trematodes, in the monospecific family Stichocotylidae, which is itself in the monotypic order Stichocotylida. It comprises the single species ''Stichocotyle nephropis'', which is an internal parasite of elasmobranch fishes. It was originally described from the Norway lobster, ''Nephrops norvegicus'', by J. T. Cunningham in 1884. This flatworm is distinguished by a single ventral row of well separated suckers. ''Stichocotyle'' has not been seen since 1986, and it is possible that it is extinct. Like many parasites, it relied on multiple hosts, and its disappearance is hypothesized to be associated with declines in some of these hosts. The thornback ray ''Raja clavata'' and the barndoor skate ''Dipturus laevis'' were hosts for the adult form, and have declined because they are killed as bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific sp ...
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Flame Cell
A flame cell is a specialized excretory cell found in simple invertebrates, including flatworms ( Platyhelminthes), rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia. The flame cell has a nucleated cell body, with a "cup-shaped" projection, with flagella covering the inner surface of the cup. The beating of these flagella resemble a flame, giving the cell its name. The cup is attached to a tube cell, whose inner surface is also coated in cilia, which help to move liquid through the tube cell. The tube opens externally through a ''nephropore'', or, in the trematoda, into an excretory bladder. The function of these cells is to regulate the osmotic pressure of the worm, and maintain its ionic balance. Microvilli in the tube cell may be used to reabsorb some ions. Molecules enter the tubule in tube cells through the gap betw ...
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Excretion
Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, Kidney (vertebrates), kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the Cell (biology), cell. For example, placental mammals expel urine from the bladder through the urethra, which is part of the excretory system. Unicellular organisms discharge waste products directly through the surface of the cell. During life activities such as cellular respiration, several chemical reactions take place in the body. These are known as metabolism. These chemical reactions produce waste products such as carbon dioxide, water, Salt (chemistry), salts, urea and uric acid. Accumulation of these wastes beyond a level inside the body is harmful to the body. The excretory organs remove these wastes. This process of removal of metabolic waste from the body is known as excretion. Proce ...
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Gas Bladder
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift via swimming, which expends more energy. Also, the dorsal position of the swim bladder means that the expansion of the bladder moves the center of mass downwards, allowing it to act as a stabilizing apparatus. Additionally, the swim bladder functions as a resonating chamber to produce or receive sound. The swim bladder is evolutionarily homologous to the lungs of tetrapods and lungfish, and some ray-finned fish such as bowfins have also evolved similar respiratory functions in their swim bladders. Charles Darwin remarked upon this in ''On the Origin of Species'', and reasoned that the lung in air-breathing vertebrates had derived from a more primitive swim bladder as a specialized form of enteral respiration. Some species, such as mostly bottom dw ...
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Biologists
A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual cell, a multicellular organism, or a community of interacting populations. They usually specialize in a particular branch (e.g., molecular biology, zoology, and evolutionary biology) of biology and have a specific research focus (e.g., studying malaria or cancer). Biologists who are involved in basic research have the aim of advancing knowledge about the natural world. They conduct their research using the scientific method, which is an empirical method for testing hypotheses. Their discoveries may have applications for some specific purpose such as in biotechnology, which has the goal of developing medically useful products for humans. In modern times, most biologists have one or more academic degrees such as a bachelor's degree, as well as an advanced degree such as a master's degree or a doctorate. Like other scientists, biologists ...
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Posterior (anatomy)
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes, axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. ...
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