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Raja Erinacea
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 parts ... [...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 Rotherham. ... [...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, 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, just below the eyes, and includes the dog's nose and mouth. In the domestic dog, most of the upper muzzle contains organs for ... [...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 as a function of time, independent of its time and magnitude scales and of any displacement in time.David Crecraft, David Gorham, ''Electronics'', 2nd ed., , CRC Press, 2002, p. 62 In electronics, the term is usually applied to periodically varying voltages, currents, or electromagnetic fields. In acoustics, it is usually applied to steady periodic sounds—variations of 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 term can also be used for non-periodic signals, like chirps and pulses. The waveform of an electrical signal can be visualized in an oscilloscope or any other device that can capture and plot its value at various times, with a suitable scales in the time and value axes. The electrocardiograph is a medical device to record the waveform of the ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase (waves)
In physics and mathematics, the phase of a 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 denoted \phi(t) and 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 \phi(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 \phi(t) is also a periodic function, with the same period as F, that repeatedly scans the same range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Organ (biology)
An electric ray (Torpediniformes) showing location of paired electric organs in the head, and electrocytes stacked within it">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 that an electric fish uses to create an electric field. Electric organs are derived from modified muscle or in some cases nerve tissue, and have evolved at least six times among the 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 ... [...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 was na ... [...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 to stun prey. The capabilities are found almost exclusively in aquatic or amphibious animals, since water is a much better 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 Gymnotiformes (knifefishes) and the Mormyridae (elephantfishes), and by ''Gymnarchus niloticus'', the African knifefish. An electric fish generates an electric field using an electric organ, modified from muscles in its tail. The field is ca ... [...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 a 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. This increases the energy needed to pump fluid through a pipe. The onset of turbulence can be predicted by the dimensionless Rey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Punt (boat)
A punt is a flat-bottomed boat with a square-cut bow, designed for use in small rivers or other shallow water. Punting is boating in a punt. The punter generally propels the punt by pushing against the river bed with a pole. A punt should not be confused with a gondola, a shallow draft vessel that is structurally different, and which is propelled by an oar rather than a pole. Punts were originally built as cargo boats or platforms for fowling and angling, but in modern times their use is almost exclusively confined to pleasure trips with passengers. The term ''punt'' has also been used to indicate a smaller version of a regional type of long shore working boat, for example the Deal Galley Punt. This derives from the wide usage in coastal communities of the name "punt" for any small clinker-built open-stem general purpose boat. In Canada, the term ''punt'' can also refer to any small flat-bottomed boat with a square-cut bow, regardless of purpose, building material, or propuls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leucoraja Ocellata
The winter skate (''Leucoraja ocellata'') is a globally-endangered species of skate found in the surrounding waters of northeastern North America. They inhabit shallow shelf waters and are prone to bycatch during commercial fishing. Description The winter skate can reach a maximum size of 109 cm. It reaches maturity around 12 years of age, depending on the sex and area. Distribution and habitat This skate can be found in the northwest Atlantic Ocean, ranging from North of the Gulf of St. Lawrence to South of Newfoundland and Labrador. Winter skates prefer sand and gravel habitats. They are primarily found in depths below 111 m and up to 371 m and in temperatures ranging between -1.2 and -15 C. The local populations of the winter skate are not all evenly distributed. They are facing extirpation Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still ex ... [...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 scales, which can also provide effective camouflage through the use of reflection and 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 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 bony fishes are covered with the cycloid scales of salmon and carp, or the ctenoid scales of perch, or the ganoid scales of sturgeons and gars. Cartilaginous fishes (sharks and rays) are covered with placoid scales. Some species ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorsal Fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through convergent evolution they have independently evolved external superficial fish-like body plans adapted to their marine environments, including most numerously fish, but also mammals such as cetaceans (whales, dolphins, and porpoises), and even extinct ancient marine reptiles such as various known species of ichthyosaurs. Most species 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 large cetaceans to identify individuals in the field. The bony or cartilaginous bones that support the base of the dorsal fin in fish are called ''pterygiophores''. Functions The main purpose of the dorsal fin is to stabilize the animal against rollin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
