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Ichthyopsida
The anamniotes are an informal group of craniates comprising all fishes and amphibians, which lay their eggs in aquatic environments. They are distinguished from the amniotes (reptiles, birds and mammals), which can reproduce on dry land either by laying shelled eggs or by carrying fertilized eggs within the female. Older sources, particularly before the 20th century, may refer to anamniotes as "lower vertebrates" and amniotes as "higher vertebrates", based on the antiquated idea of the evolutionary great chain of being. The name "anamniote" is a back-formation word created by adding the prefix ''an-'' to the word ''amniote'', which in turn refers to the amnion, an extraembryonic membrane present during the amniotes' embryonic development which serves as a biochemical barrier that shields the embryo from environmental fluctuations by regulating the oxygen, carbon dioxide and metabolic waste exchanges and secreting a cushioning fluid. As the name suggests, anamniote embryos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchocephalians ( tuatara). As of March 2022, the Reptile Database includes about 11,700 species. In the traditional Linnaean classification system, birds are considered a separate class to reptiles. However, crocodilians are more closely related to birds than they are to other living reptiles, and so modern cladistic classification systems include birds within Reptilia, redefining the term as a clade. Other cladistic definitions abandon the term reptile altogether in favor of the clade Sauropsida, which refers to all amniotes more closely related to modern reptiles than to mammals. The study of the traditional reptile orders, historically combined with that of modern amphibians, is called herpetology. The earliest known proto-reptiles originated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trout
Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salmonid fish such as ''Cynoscion nebulosus'', the spotted seatrout or speckled trout. Trout are closely related to salmon and char (or charr): species termed salmon and char occur in the same genera as do fish called trout (''Oncorhynchus'' – Pacific salmon and trout, ''Salmo'' – Atlantic salmon and various trout, ''Salvelinus'' – char and trout). Lake trout and most other trout live in freshwater lakes and rivers exclusively, while there are others, such as the steelhead, a form of the coastal rainbow trout, that can spend two or three years at sea before returning to fresh water to spawn (a habit more typical of salmon). Arctic char and brook trout are part of the char genus. Trout are an important food source for humans and wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Land
Land, also known as dry land, ground, or earth, is the solid terrestrial surface of the planet Earth that is not submerged by the ocean or other bodies of water. It makes up 29% of Earth's surface and includes the continents and various islands. Earth's land surface is almost entirely covered by regolith, a layer of rock, soil, and minerals that forms the outer part of the crust. Land plays important roles in Earth's climate system and is involved in the carbon cycle, nitrogen cycle, and water cycle. One-third of land is covered in trees, 15% is used for crops, and 10% is covered in permanent snow and glaciers. Land terrain varies greatly and consists of mountains, deserts, plains, plateaus, glaciers, and other landforms. In physical geology, the land is divided into two major categories: mountain ranges and relatively flat interiors called cratons. Both are formed over millions of years through plate tectonics. A major part of Earth's water cycle, streams shape the lan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amniotic Fluid
The amniotic fluid is the protective liquid contained by the amniotic sac of a gravid amniote. This fluid serves as a cushion for the growing fetus, but also serves to facilitate the exchange of nutrients, water, and biochemical products between mother and fetus. For humans, the amniotic fluid is commonly called water or waters (Latin liquor amnii). Development Amniotic fluid is present from the formation of the gestational sac. Amniotic fluid is in the amniotic sac. It is generated from maternal plasma, and passes through the fetal membranes by osmotic and hydrostatic forces. When fetal kidneys begin to function around week 16, fetal urine also contributes to the fluid. In earlier times, it was believed that the amniotic fluid was composed entirely of fetal urine. The fluid is absorbed through the fetal tissue and skin. After 22 to 25 week of pregnancy, keratinization of an embryo's skin occurs. When this process completes around the 25th week, the fluid is primarily absor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metabolic Waste
Metabolic wastes or excrements are substances left over from metabolic processes (such as cellular respiration) which cannot be used by the organism (they are surplus or toxic), and must therefore be excreted. This includes nitrogen compounds, water, CO2, phosphates, sulphates, etc. Animals treat these compounds as excretes. Plants have chemical "machinery" which transforms some of them (primarily the nitrogen compounds) into useful substances. All the metabolic wastes are excreted in a form of water solutes through the excretory organs ( nephridia, Malpighian tubules, kidneys), with the exception of CO2, which is excreted together with the water vapor throughout the lungs. The elimination of these compounds enables the chemical homeostasis of the organism. Nitrogen wastes The nitrogen compounds through which excess nitrogen is eliminated from organisms are called nitrogenous wastes () or nitrogen wastes. They are ammonia, urea, uric acid, and creatinine. All of these s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transparent to visible light but absorbs infrared radiation, acting as a greenhouse gas. It is a trace gas in Earth's atmosphere at 421 parts per million (ppm), or about 0.04% by volume (as of May 2022), having risen from pre-industrial levels of 280 ppm. Burning fossil fuels is the primary cause of these increased CO2 concentrations and also the primary cause of climate change.IPCC (2022Summary for policy makersiClimate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA Carbon dioxide is soluble in water and is found in groundwater, lakes, ice ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula . Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres are arranged as a solid ball that when reaching a certain size, called a morula, takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb. Once implanted the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis. Gastrulation is the formation of the three germ layers that will form all of the different parts of the body. Neurulation forms the ner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryonic Development
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres are arranged as a solid ball that when reaching a certain size, called a morula, takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb. Once implanted the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis. Gastrulation is the formation of the three germ layers that will form all of the different parts of the body. Neurulation forms the nervous s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extraembryonic Membrane
The extraembryonic membranes are four membranes which assist in the development of an animal's embryo. Such membranes occur in a range of animals from humans to insects. They originate from the embryo, but are not considered part of it. They typically perform roles in nutrition, gas exchange, and waste removal. There are four standard extraembryonic membranes in birds, reptiles, and mammals: the yolk sac which surrounds the yolk, the amnion which surrounds and cushions the embryo, the allantois which among avians stores embryonic waste and assists with the exchange of carbon dioxide with oxygen as well as the resorption of calcium from the shell, and the chorion which surrounds all of these and in avians successively merges with the allantois in the later stages of egg development to form a combined respiratory and excretory organ called the chorioallantois. The extraembryonic membranes in insects include a serous membrane originating from blastoderm cells, an amnion or amnioti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amnion
The amnion is a membrane that closely covers the human and various other embryos when first formed. It fills with amniotic fluid, which causes the amnion to expand and become the amniotic sac that provides a protective environment for the developing embryo. The amnion, along with the chorion, the yolk sac and the allantois protect the embryo. In birds, reptiles and monotremes, the protective sac is enclosed in a shell. In marsupials and placental mammals, it is enclosed in a uterus. The term is from Ancient Greek ἀμνίον 'little lamb', diminutive of ἀμνός 'lamb'. it is cognate with the English verb 'yean', bring forth young (usually lambs). The amnion is a feature of the vertebrate clade ''Amniota'', which includes reptiles, birds, and mammals. Amphibians and fish are not amniotes and thus lack the amnion. The amnion stems from the extra-embryonic somatic mesoderm on the outer side and the extra-embryonic ectoderm or trophoblast on the inner side. In humans In th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-formation
In etymology, back-formation is the process or result of creating a new word via inflection, typically by removing or substituting actual or supposed affixes from a lexical item, in a way that expands the number of lexemes associated with the corresponding root word.Crystal, David. ''A Dictionary of Linguistics and Phonetics, Sixth Edition'', Blackwell Publishers, 2008. The resulting is called a ''back-formation'', a term coined by James Murray in 1889. ('' Oxford English Dictionary Online'' preserves its first use of 'back-formation' from 1889 in the definition of ''to burgle''; from ''burglar''.) For example, the noun ''resurrection'' was borrowed from Latin, and the verb ''resurrect'' was then back-formed hundreds of years later from it by removing the ''-ion'' suffix. This segmentation of ''resurrection'' into ''resurrect'' + ''ion'' was possible because English had examples of Latin words in the form of verb and verb+''-ion'' pairs, such as ''opine/opinion''. These becam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
