Biology, 30.07.2019 22:30 monsterking4549

What are the characteristics of crustaceans, insects, and arachnids?

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Crustaceans have 3 main body parts head, thorax, and abdomen. insect bodies are divided in 3 main body parts. Legs: arachnids contain 4 pair of legs, Crustaceans have 6-14 pairs of jointed legs, insects have 3 pairs of jointed legs. Antenna: Arachnids have no antennas

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a fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis.[1] the age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years.[2] fossil fuels contain high percentages of carbon and include petroleum, coal, and natural gas.[3] other commonly used derivatives include kerosene and propane. fossil fuels range from volatile materials with low carbon to hydrogen ratios like methane, to liquids like petroleum, to nonvolatile materials composed of almost pure carbon, like anthracite coal. methane can be found in hydrocarbon fields either alone, associated with oil, or in the form of methane clathrates.

the theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the earth's crust over millions of years was first introduced by andreas libavius "in his 1597 alchemia [alchymia]" and later by mikhail lomonosov "as early as 1757 and certainly by 1763".[4] the first use of the term "fossil fuel" was by the german chemist caspar neumann, in english translation in 1759.[5]

in 2017 the world's primary energy sources consisted of petroleum (34%), coal (28%), natural gas (23%), amounting to an 85% share for fossil fuels in primary energy consumption in the world.[6] non-fossil sources in 2006 included nuclear (8.5%), hydroelectric (6.3%), and others (geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%.[7] world energy consumption was growing at about 2.3% per year. in 2015 about 18% of worldwide consumption was from renewable sources.[8]

Answer from: Quest

Mantle convection is the slow creepingmotion of earth's solid silicate mantle caused by convection currents carrying heat from the interior to the planet's surface.[1][2] the earth's surface lithosphere, which rides atop the asthenosphere (the two components of the upper mantle), is divided into a number of plates that are continuously being created and consumed at their opposite plate boundaries. accretion occurs as mantle is added to the growing edges of a plate, associated with seafloor spreading. this hot added material cools down by conduction and convection of heat. at the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of subduction usually at an ocean trench.[3]this subducted material sinks through the earth's interior. some subducted material appears to reach the lower mantle,[4] while in other regions, this material is impeded from sinking further, possibly due to a phase transition from spinel to silicate perovskiteand magnesiowustite, an endothermic reaction.[5]the subducted oceanic crust triggers volcanism, although the basic mechanisms are varied. volcanism may occur due to processes that add buoyancy to partially melted mantle causing an upward flow due to a decrease in density of the partial melt.secondary forms of convection that may result in surface volcanism are postulated to occur as a consequence of intraplate extension[6] and mantle plumes.[7]it is because the mantle can convect that the tectonic plates are able to move around the earth's surface.[8]mantle convection seems to have been much more active during the hadean period, resulting in gravitational sorting of heavier molten iron, and nickel elements and sulphides in the core, and lighter silicate minerals in the mantle.