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Little Skate
The little skate (''Leucoraja erinacea'') is a species of skate in the family Rajidae, found from Nova Scotia to North Carolina on sand or gravel habitats. They are one of the dominant members of the demersal fish community in the northwestern Atlantic. This species is of minimal commercial importance and is mostly used as bait for lobster traps, though its wings are also marketed for food. It is also important as a model organism for biological and medical research. Distribution and habitat This skate is native to the western Atlantic Ocean, from Nova Scotia, Canada, to Cape Hatteras, North Carolina, USA. They are most abundant in the northern Mid-Atlantic Bight and the Georges Bank. Little skates prefer sandy or gravelly habitats from the shore to a depth of , though they have been caught as deep as . They can tolerate temperatures of and salinities of 27–33.8 ppt (though the optimum is 29–33 ppt). They do not undertake long migrations, but at the inshore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samuel Latham Mitchill
Samuel Latham Mitchill (August 20, 1764September 7, 1831) was an American physician, naturalist, and politician who lived in Plandome, New York. Early life Samuel Mitchill was born in Hempstead in the Province of New York, the son of Robert Mitchill and his wife, Mary Latham, both Quakers. He was sent to Scotland and graduated in 1786 from the University of Edinburgh Medical School with an M.D., his education being paid for by a wealthy uncle. Returning to the United States after medical school, Mitchill also completed law school. As a lawyer, he oversaw the purchase of lands in western New York from the Iroquois Indians in 1788. Career Mitchill taught chemistry, botany, and natural history at Columbia College from 1792 to 1801 and was a founding editor of '' The Medical Repository'', the first medical journal in the United States. In 1793, he was elected a Foreign Fellow of the Royal Society of Edinburgh. His proposers were James Gregory, Dugald Stewart, and John Rother ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snout
A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, Rostrum (anatomy), rostrum, beak or proboscis. The wet furless surface around the nostrils of the nose of many mammals is called the rhinarium (colloquially this is the "cold wet snout" of some mammals). The rhinarium is often associated with a stronger sense of olfaction. Variation Snouts are found on many mammals in a variety of shapes. Some animals, including ursines and great cats, have box-like snouts, while others, like shrews, have pointed snouts. Pig snouts are flat and cylindrical. Primates Strepsirrhine primates have muzzles, as do baboons. Great apes have reduced muzzles, with the exception being human beings, whose face does not have protruding jaws nor a snout but merely a human nose. Dogs The muzzle begins at the Stop (dog), stop, just below the eyes, and includes the dog's nose and mouth. In the domestic dog, most of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waveform
In electronics, acoustics, and related fields, the waveform of a signal is the shape of its Graph of a function, graph as a function of time, independent of its time and Magnitude (mathematics), magnitude Scale (ratio), scales and of any displacement in time.David Crecraft, David Gorham, ''Electronics'', 2nd ed., , CRC Press, 2002, p. 62 ''Periodic waveforms'' repeat regularly at a constant wave period, period. The term can also be used for non-periodic or aperiodic signals, like chirps and pulse (signal processing), pulses. In electronics, the term is usually applied to time-varying voltages, electric current, currents, or electromagnetic fields. In acoustics, it is usually applied to steady periodic sounds — variations of air pressure, pressure in air or other media. In these cases, the waveform is an attribute that is independent of the frequency, amplitude, or phase shift of the signal. The waveform of an electrical signal can be visualized with an oscilloscope or an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase (waves)
In physics and mathematics, the phase (symbol φ or ϕ) of a wave or other periodic function F of some real variable t (such as time) is an angle-like quantity representing the fraction of the cycle covered up to t. It is expressed in such a scale that it varies by one full turn as the variable t goes through each period (and F(t) goes through each complete cycle). It may be measured in any angular unit such as degrees or radians, thus increasing by 360° or 2\pi as the variable t completes a full period. This convention is especially appropriate for a sinusoidal function, since its value at any argument t then can be expressed as \varphi(t), the sine of the phase, multiplied by some factor (the amplitude of the sinusoid). (The cosine may be used instead of sine, depending on where one considers each period to start.) Usually, whole turns are ignored when expressing the phase; so that \varphi(t) is also a periodic function, with the same period as F, that repeatedly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Organ (biology)
An Torpediniformes.html" ;"title="electric ray (Torpediniformes">electric ray (Torpediniformes) showing location of paired electric organs in the head, and electrocytes stacked within it In biology, the electric organ is an organ (biology), organ that an electric fish uses to create an electric field. Electric organs are derived from modified muscle or in some cases nerve tissue, called electrocytes, and have evolved at least six times among the Elasmobranchii, elasmobranchs and teleosts. These fish use their electric discharges for navigation, communication, mating, defence, and in strongly electric fish also for the incapacitation of prey. The electric organs of two strongly electric fish, the torpedo ray and the electric eel, were first studied in the 1770s by John Walsh, Hugh Williamson, and John Hunter. Charles Darwin used them as an instance of convergent evolution in his 1859 ''On the Origin of Species''. Modern study began with Hans Lissmann's 1951 study of electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copeia
''Ichthyology & Herpetology'' (formerly ''Copeia'') is a quarterly peer-reviewed scientific journal covering research in ichthyology and herpetology that was originally named after Edward Drinker Cope, a prominent American researcher in these fields. It is the official journal of the American Society of Ichthyologists and Herpetologists. According to the ''Journal Citation Reports'', ''Copeia'' has a 2021 impact factor of 1.857, ranking it 65th out of 176 journals in the category "Zoology". History On December 27, 1913, John Treadwell Nichols published the first issue of ''Copeia''. This issue consisted of a single piece of paper folded to form four pages of information with five articles. The cover of the pamphlet bore the inscription: "Published by the contributors to advance the science of coldblooded vertebrates." In 2020, the American Society of Ichthyologists and Herpetologists voted to rename the journal, ''Ichthyology & Herpetology''. Name change The journal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electroreception
Electroreception and electrogenesis are the closely related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes, such as the electric eel, to stun prey. The capabilities are found almost exclusively in aquatic or amphibious animals, since water is a much better Conductor (material), conductor of electricity than air. In passive electrolocation, objects such as prey are detected by sensing the electric fields they create. In active electrolocation, fish generate a weak electric field and sense the different distortions of that field created by objects that conduct or resist electricity. Active electrolocation is practised by two groups of weakly electric fish, the order Gymnotiformes (knifefishes) and family Mormyridae (elephantfishes), and by the monotypic genus ''Gymnarchus'' (African knifefish). An electric fish generates an electric field using an Elect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between those layers. Turbulence is commonly observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney, and most fluid flows occurring in nature or created in engineering applications are turbulent. Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid's viscosity. For this reason, turbulence is commonly realized in low viscosity fluids. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases. The onset of turbulence can be predicted by the dimensionless Reynolds number, the ratio of kinetic energy to viscous damping ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Punt (boat)
A punt is a flat-bottomed boat with a square-cut bow (ship), bow, designed for use in small rivers and shallow water. Punting is boating in a punt; the punter propels the punt by pushing against the river bed with a pole. Punts were originally built as cargo boats and as platforms for fowling and for fishing, such as angling; whereas now punting is boating for pleasure. The term ''punt'' also refers to smaller versions of regional types of long shore work boats, such as the Deal galley punt, a square-sterned, lapstrake open-boat rigged with a single dipping lugsail, used for salvage and rescue work off a beach. In coastal communities, ''punt'' refers to any small Clinker (boat building), clinker-built, open-stem, general-purpose boat. In Canada, the term ''punt'' refers to any small, flat-bottomed boat with a square-cut bow, regardless of navigational purpose, building material, or means of propulsion. In Australia, the term ''punt'' is used to refer to cable ferry, cable ferrie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leucoraja Ocellata
''Leucoraja'' is a genus of hardnose skates in the family Rajidae, commonly known as the rough skates. They occur mostly on continental shelves and slopes in the north-western and eastern Atlantic Ocean, the Mediterranean Sea, the south-western Indian Ocean, and Australia. Species There are currently 16 species in this genus: * ''Leucoraja caribbaea'' ( McEachran, 1977) (Maya skate) * ''Leucoraja circularis'' (Couch, 1838) (sandy ray) * ''Leucoraja compagnoi'' ( Stehmann, 1995) (tigertail skate) * ''Leucoraja erinacea'' ( Mitchill, 1825) (little skate) * ''Leucoraja fullonica'' (Linnaeus, 1758) (shagreen skate) * ''Leucoraja garmani'' ( Whitley, 1939) (rosette skate) * ''Leucoraja lentiginosa'' ( Bigelow & Schroeder, 1951) (freckled skate) * ''Leucoraja leucosticta'' (Stehmann, 1971) (whitedappled skate) * ''Leucoraja longirostris'' Weigmann, Stehmann, Séret & Ishihara, 2024 (brown longnose skate) * ''Leucoraja melitensis'' ( R. S. Clark, 1926) (Maltese skate) * ''Leucoraja ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermal Denticle
A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scale (zoology), scales, which can also provide effective Underwater camouflage, camouflage through the use of animal reflectors, reflection and animal coloration, colouration, as well as possible hydrodynamic advantages. The term ''scale'' derives from the Old French , meaning a shell pod or husk. Scales vary enormously in size, shape, structure, and extent, ranging from strong and rigid armour plates in fishes such as shrimpfishes and boxfishes, to microscopic or absent in fishes such as eels and anglerfishes. The morphology (biology), morphology of a scale can be used to identify the species of fish it came from. Scales originated within the jawless ostracoderms, ancestors to all jawed fishes today. Most Osteichthyes, bony fishes are covered with the cycloid scales of salmon and carp, or the ctenoid scales of perch, or the ganoid scales of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorsal Fin
A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found in most fish, in mammals such as whales, and in extinct ancient marine reptiles such as ichthyosaurs. Most have only one dorsal fin, but some have two or three. Wildlife biologists often use the distinctive nicks and wear patterns which develop on the dorsal fins of whales to identify individuals in the field. The bones or cartilages that support the dorsal fin in fish are called pterygiophores. Functions The main purpose of the dorsal fin is usually to stabilize the animal against rolling and to assist in sudden turns. Some species have further adapted their dorsal fins to other uses. The sunfish uses the dorsal fin (and the anal fin Fins are moving appendages protruding from the body of fish that interact with water to ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
