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33-718: The weatherfish ( Misgurnus fossilis ) is a species of true loach that has a wide range in Europe and some parts of Asia . It is an omnivorous scavenger bottom feeder, using its sensitive barbels to find edible items. The diet mostly consists of small aquatic invertebrates along with some detritus . The weatherfish is long and thin which allows it to burrow through the substrate and navigate through places that deeper bodied fish would have trouble with. It grows up to 30 cm (12 in) in total length , though there are fishermen who say they have caught longer, up to 45 cm (17.7 in). If true, this would make Misgurnus fossilis

66-424: A danger to weatherfish populations. The weatherfish is listed as least concern but is protected in most of its range. They are able to survive in habitats that many other fish would be unable to because of their ability to breathe atmospheric oxygen. In low oxygen conditions, the weatherfish will swim to the surface and gulp air. The air then goes through the intestines where a complex system of blood vessels extracts

99-463: A family in their own right - Balitoridae . And as it seems the "sucking Cobitoidea" are quite distant indeed, perhaps even markedly closer to the Cyprinidae , thus the old superfamily Catostomoidea warrants revalidation. Finally, the puzzling mountain carps were most often considered the distinct family Psilorhynchidae in recent times. In a number of systematic schemes, though, they were placed in

132-709: A moon of Saturn, and Triton , a moon of Neptune, have atmospheres mainly of nitrogen . When in the part of its orbit closest to the Sun, Pluto has an atmosphere of nitrogen and methane similar to Triton's, but these gases are frozen when it is farther from the Sun. Other bodies within the Solar System have extremely thin atmospheres not in equilibrium. These include the Moon ( sodium gas), Mercury (sodium gas), Europa (oxygen), Io ( sulfur ), and Enceladus ( water vapor ). The first exoplanet whose atmospheric composition

165-508: A planet from atmospheric escape and that for some magnetizations the presence of a magnetic field works to increase the escape rate. Other mechanisms that can cause atmosphere depletion are solar wind -induced sputtering, impact erosion, weathering , and sequestration—sometimes referred to as "freezing out"—into the regolith and polar caps . Atmospheres have dramatic effects on the surfaces of rocky bodies. Objects that have no atmosphere, or that have only an exosphere, have terrain that

198-577: A single row of pharyngeal (throat) teeth . True loaches are mostly scavengers and are omnivorous, usually not very picky about their food. They may eat aquatic crustaceans , insects , and other small invertebrates , as well as scraps of organic detritus . Many live in eutrophic waters of generally poor quality and feed on tubifex worms and similar benthos associated with such habitat. Some of these loaches have adapted to low oxygen levels in warm, muddy rivers or dirty ponds by being able to gulp up atmospheric oxygen . Some species, particularly from

231-451: A variable amount of water vapor is also present, on average about 1% at sea level. The low temperatures and higher gravity of the Solar System's giant planets — Jupiter , Saturn , Uranus and Neptune —allow them more readily to retain gases with low molecular masses . These planets have hydrogen–helium atmospheres, with trace amounts of more complex compounds. Two satellites of the outer planets possess significant atmospheres. Titan ,

264-464: A wide range of velocities, there will always be some fast enough to produce a slow leakage of gas into space. Lighter molecules move faster than heavier ones with the same thermal kinetic energy , and so gases of low molecular weight are lost more rapidly than those of high molecular weight. It is thought that Venus and Mars may have lost much of their water when, after being photodissociated into hydrogen and oxygen by solar ultraviolet radiation,

297-443: Is also introduced in a few different areas, but not to the extent of the pond loach ( Misgurnus anguillicaudatus ). Adult weatherfish live in dense patches of aquatic vegetation while juveniles prefer to live near the shoreline in very shallow water where there is a lot of detritus ; neither adults nor juveniles are found in open areas without vegetation. Because of their habitat preferences, dredging and aquatic weed removal poses

330-423: Is covered in craters . Without an atmosphere, the planet has no protection from meteoroids , and all of them collide with the surface as meteorites and create craters. For planets with a significant atmosphere, most meteoroids burn up as meteors before hitting a planet's surface. When meteoroids do impact, the effects are often erased by the action of wind. Wind erosion is a significant factor in shaping

363-625: Is originally determined by the stellar nebula's chemistry and temperature, but can also by a product processes within the astronomical body outgasing a different atmosphere. The atmospheres of the planets Venus and Mars are principally composed of carbon dioxide and nitrogen , argon and oxygen . The composition of Earth's atmosphere is determined by the by-products of the life that it sustains. Dry air (mixture of gases) from Earth's atmosphere contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and traces of hydrogen, helium, and other "noble" gases (by volume), but generally

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396-401: Is the lowest layer of the atmosphere. This extends from the planetary surface to the bottom of the stratosphere . The troposphere contains 75–80% of the mass of the atmosphere, and is the atmospheric layer wherein the weather occurs; the height of the troposphere varies between 17 km at the equator and 7.0 km at the poles. The stratosphere extends from the top of the troposphere to

429-499: Is used to make nucleotides and amino acids ; plants , algae , and cyanobacteria use carbon dioxide for photosynthesis . The layered composition of the atmosphere minimises the harmful effects of sunlight , ultraviolet radiation, solar wind , and cosmic rays and thus protects the organisms from genetic damage. The current composition of the atmosphere of the Earth is the product of billions of years of biochemical modification of

462-588: The fisheries or being raised in aquaculture . Small species may occasionally be caught for bait . Many of the more brightly colored species are popular with freshwater aquarists , so are therefore of importance in the aquarium trade. Some Cobitidae often encountered in aquarium trade include: Atmospheric The atmosphere of Earth is composed of nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and trace gases. Most organisms use oxygen for respiration ; lightning and bacteria perform nitrogen fixation which produces ammonia that

495-892: The genera Cobitis and especially Misgurnus , are sensitive to changing air pressure . They change their behavior accordingly, and as these changes in activity are usually followed by a change in weather, they are commonly known as "weather fishes" or "weather loaches". Some Cobitidae have been introduced to foreign lands, where they may pose problems to local wildlife as invasive species . Other true loaches, many of them migratory fish , have been seriously affected by habitat destruction , chemical pollution , and damming , and are considered threatened species today. Some migratory species are popular aquarium fish and since they are very hard to raise in captivity, overfishing has seriously depleted once-common stocks in several cases. The other " loaches " used to be included in this family, but nowadays are recognized as well-distinct members of

528-405: The order Cypriniformes . Together with the suckers (Catostomidae), the "loaches" made up the superfamily Cobitoidea. However, the sucking loaches (Gyrinocheilidae) were easily recognizable as relatives of the suckers. Eventually, the hillstream loaches , though more similar to the true loaches than the other two presumed Cobitoidea, were recognized as distinct enough to be better regarded

561-477: The paleoatmosphere by living organisms. Atmospheres are clouds of gas bound to and engulfing an astronomical focal point of sufficiently dominating mass , adding to its mass, possibly escaping from it or collapsing into it. Because of the latter, such planetary nucleus can develop from interstellar molecular clouds or protoplanetary disks into rocky astronomical objects with varyingly thick atmospheres, gas giants or fusors . Composition and thickness

594-713: The Balitoridae (or Balitorinae, when these were included in the Cobitidae). In fact, they seem to be loach-like carps and belong in the Cyprinidae . In 2012, Maurice Kottelat reviewed the loaches and elevated the former subfamily Botiinae to its own family, Botiidae , and established the family Serpenticobitidae for the genus Serpenticobitis . Cobitidae has the following genera classified within it: Some true loaches are popular as food fish in East Asian countries such as Japan . These are of importance in

627-460: The Cobitidae tend to be vermiform – worm-shaped, long and thin. Most true loaches do not have true scales , and like many other Cypriniformes or catfishes , they have barbels at their mouths (usually three to six pairs). Some other traits typically found in this family are a small bottom-facing mouth suited to their scavenging benthic lifestyle, an erectile spine below the eye, and

660-438: The atmosphere can transport thermal energy from the higher temperature interior up to the surface. From the perspective of a planetary geologist , the atmosphere acts to shape a planetary surface. Wind picks up dust and other particles which, when they collide with the terrain, erode the relief and leave deposits ( eolian processes). Frost and precipitations , which depend on the atmospheric composition, also influence

693-411: The base of the exosphere at 690 km and contains the ionosphere , where solar radiation ionizes the atmosphere. The density of the ionosphere is greater at short distances from the planetary surface in the daytime and decreases as the ionosphere rises at night-time, thereby allowing a greater range of radio frequencies to travel greater distances. The exosphere begins at 690 to 1,000 km from

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726-428: The bottom of the mesosphere , and contains the ozone layer , at an altitude between 15 km and 35 km. It is the atmospheric layer that absorbs most of the ultraviolet radiation that Earth receives from the Sun. The mesosphere ranges from 50 km to 85 km and is the layer wherein most meteors are incinerated before reaching the surface. The thermosphere extends from an altitude of 85 km to

759-426: The diminishing mass of the gas above the point of barometric measurement. The units of air pressure are based upon the standard atmosphere (atm), which is 101,325  Pa (equivalent to 760  Torr or 14.696  psi ). The height at which the atmospheric pressure declines by a factor of e (an irrational number equal to 2.71828) is called the scale height ( H ). For an atmosphere of uniform temperature,

792-431: The distance from the Sun determines the energy available to heat atmospheric gas to the point where some fraction of its molecules' thermal motion exceed the planet's escape velocity , allowing those to escape a planet's gravitational grasp. Thus, distant and cold Titan , Triton , and Pluto are able to retain their atmospheres despite their relatively low gravities. Since a collection of gas molecules may be moving at

825-442: The hydrogen escaped. Earth's magnetic field helps to prevent this, as, normally, the solar wind would greatly enhance the escape of hydrogen. However, over the past 3 billion years Earth may have lost gases through the magnetic polar regions due to auroral activity, including a net 2% of its atmospheric oxygen. The net effect, taking the most important escape processes into account, is that an intrinsic magnetic field does not protect

858-921: The largest species of true loach . This loach has a very wide range, especially in Europe. It occurs north of the Alps , from the Meuse River in western Europe all the way to the Neva River in northwestern Russia . It also occurs in the northern part of the Black Sea basin from the Danube River to the Kuban River , and in the Caspian Sea in the River Volga and River Ural drainages. It

891-601: The oxygen, before expelling the air from the anus. This Cobitidae -related article is a stub . You can help Misplaced Pages by expanding it . Cobitidae see text Cobitidae , also known as the true loaches , is a family of Old World freshwater fish . They occur throughout Eurasia and in Morocco , and inhabit riverine ecosystems. Today, most " loaches " are placed in other families (see below ). The family includes about 260 described species . New species are being described regularly. The body forms of

924-406: The past. The circulation of the atmosphere occurs due to thermal differences when convection becomes a more efficient transporter of heat than thermal radiation . On planets where the primary heat source is solar radiation, excess heat in the tropics is transported to higher latitudes. When a planet generates a significant amount of heat internally, such as is the case for Jupiter , convection in

957-416: The relief. Climate changes can influence a planet's geological history. Conversely, studying the surface of the Earth leads to an understanding of the atmosphere and climate of other planets. For a meteorologist , the composition of the Earth's atmosphere is a factor affecting the climate and its variations. For a biologist or paleontologist , the Earth's atmospheric composition is closely dependent on

990-468: The scale height is proportional to the atmospheric temperature and is inversely proportional to the product of the mean molecular mass of dry air, and the local acceleration of gravity at the point of barometric measurement. Surface gravity differs significantly among the planets. For example, the large gravitational force of the giant planet Jupiter retains light gases such as hydrogen and helium that escape from objects with lower gravity. Secondly,

1023-413: The surface, and extends to roughly 10,000 km, where it interacts with the magnetosphere of Earth. Atmospheric pressure is the force (per unit-area) perpendicular to a unit-area of planetary surface, as determined by the weight of the vertical column of atmospheric gases. In said atmospheric model, the atmospheric pressure , the weight of the mass of the gas, decreases at high altitude because of

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1056-417: The terrain of rocky planets with atmospheres, and over time can erase the effects of both craters and volcanoes . In addition, since liquids cannot exist without pressure, an atmosphere allows liquid to be present at the surface, resulting in lakes , rivers and oceans . Earth and Titan are known to have liquids at their surface and terrain on the planet suggests that Mars had liquid on its surface in

1089-461: Was determined is HD 209458b , a gas giant with a close orbit around a star in the constellation Pegasus . Its atmosphere is heated to temperatures over 1,000 K, and is steadily escaping into space. Hydrogen, oxygen, carbon and sulfur have been detected in the planet's inflated atmosphere. The atmosphere of Earth is composed of layers with different properties, such as specific gaseous composition, temperature, and pressure. The troposphere

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