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Pistol Shrimp
Alpheidae is a family of caridean snapping shrimp, characterized by having asymmetrical claws, the larger of which is typically capable of producing a loud snapping sound. Other common names for animals in the group are pistol shrimp or alpheid shrimp. The family is diverse and worldwide in distribution, consisting of about 1,119 species within 38 or more genera. The two most prominent genera are ''Alpheus'' and ''Synalpheus'', with species numbering well over 250 and 100, respectively. Most snapping shrimp dig burrows and are common inhabitants of coral reefs, submerged seagrass flats, and oyster reefs. While most genera and species are found in tropical and temperate coastal and marine waters, ''Betaeus'' inhabits cold seas and ''Potamalpheops'' is found only in freshwater caves. When in colonies, the snapping shrimp can interfere with sonar and underwater communication. The shrimp are considered a major source of sound in the ocean. Description The "Pistol Shrimp" grows to o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpheus Digitalis
''Alpheus digitalis'' is a species of pistol shrimp in the family Alpheidae. The species was first discovered after a taxonomic study of a snapping shrimp from the genus Alpheus from Japan and the Gulf of Thailand, of which, it was found that two species was confounded under ''A.digitalis'', which was originally described based on a single specimen possessing abnormal chelipeds. Differences between ''A. digitalis'' & ''A.longiforceps'' Between the two species, the most unique difference is coloration and morphology. ''A.longiforceps,'' the new species, can be differentiated from ''A.digitalis'' by the more slender (rather than connex), flexor margin, the longer male minor chela, more elongate dactylus, possession of a single (rather than two), obliquely transverse white bands on the spot which is located on the lateral surface of the fourth abdominal region. The present day new species is referred to the ''Alpheus brevirostris'' species group, mainly because of the compressed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synalpheus
''Synalpheus'' is a genus of snapping shrimp of the family Alpheidae, presently containing more than 100 species; new ones are described on a regular basis, and the exact number even of described species is disputed. ''Zuzalpheus'' The genus ''Zuzalpheus'' was established for ''S. gambarelloides'', ''S. brooksi'', and their closest relatives, which contain several notably eusocial species. While these do seem to form a clade, it is not fully resolved whether or not they are indeed the sister taxon of all the remaining ''Synalpheus''. However, a detailed cladistic study of morphological characters found well marked differences between the proposed two genera and concluded that the supposed species groups around ''S. biunguiculatus''/''S. coutierei'', ''S. brevicarpus'' and ''S. neomeris'' are neither clearly defined nor, as it seems, monophyletic, while the group separated in ''Zuzalpheus'' was clearly distinct in characters of the minor first walki ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science (journal)
''Science'', also widely referred to as ''Science Magazine'', is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. ''Science'' is based in Washington, D.C., United States, with a second office in Cambridge, UK. Contents The major focus of the journal is publishing important original scientific research and research reviews, but ''Science'' also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals, which focus on a specific field, ''Science'' and its rival ''Nature (journal), Nature'' c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Pressure
Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit of sound pressure is the pascal (Pa). Mathematical definition A sound wave in a transmission medium causes a deviation (sound pressure, a ''dynamic'' pressure) in the local ambient pressure, a ''static'' pressure. Sound pressure, denoted ''p'', is defined by p_\text = p_\text + p, where * ''p''total is the total pressure, * ''p''stat is the static pressure. Sound measurements Sound intensity In a sound wave, the complementary variable to sound pressure is the particle velocity. Together, they determine the sound intensity of the wave. ''Sound intensity'', denoted I and measured in W· m−2 in SI units, is defined by \mathbf I = p \mathbf v, where * ''p'' is the sound pressure, * v is the particle velocity. Acoustic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavitation
Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble, but rapidly weaken as they propagate away from the implosion. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal causing a type of wear also called "cavitation". The most common examples of this kind of wear are to pump impellers, and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior: inertial (or transient) cavitation and non-inertial c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beluga Whale
The beluga whale () (''Delphinapterus leucas'') is an Arctic and sub-Arctic cetacean. It is one of two members of the family Monodontidae, along with the narwhal, and the only member of the genus ''Delphinapterus''. It is also known as the white whale, as it is the only cetacean to regularly occur with this colour; the sea canary, due to its high-pitched calls; and the melonhead, though that more commonly refers to the melon-headed whale, which is an oceanic dolphin. The beluga is adapted to life in the Arctic, with anatomical and physiological characteristics that differentiate it from other cetaceans. Amongst these are its all-white colour and the absence of a dorsal fin, which allows it to swim under ice with ease. It possesses a distinctive protuberance at the front of its head which houses an animal echolocation, echolocation organ called the Melon (whale), melon, which in this species is large and deformable. The beluga's body size is between that of a dolphin and a true ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sperm Whale
The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus ''Kogia''. The sperm whale is a pelagic mammal with a worldwide range, and will migrate seasonally for feeding and breeding. Females and young males live together in groups, while mature males (bulls) live solitary lives outside of the mating season. The females cooperate to protect and nurse their young. Females give birth every four to twenty years, and care for the calves for more than a decade. A mature sperm whale has few natural predators, although calves and weakened adults are sometimes killed by pods of killer whales (orcas). Mature males average in length, with the head representing up to one-third of the animal's length. Plunging to , it is the third deep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pistol Shrimp Claw Mechanism
A pistol is a handgun, more specifically one with the chamber integral to its gun barrel, though in common usage the two terms are often used interchangeably. The English word was introduced in , when early handguns were produced in Europe, and is derived from the Middle French ''pistolet'' (), meaning a small gun or knife. In colloquial usage, the word "pistol" is often used to describe any type of handgun, inclusive of revolvers (which have a single barrel and a separate cylinder housing multiple chambers) and the pocket-sized derringers (which are often multi-barrelled). The most common type of pistol used in the contemporary era is the semi-automatic pistol, while the older single-shot and manual repeating pistols are now rarely seen and used primarily for nostalgic hunting and historical reenactment, and the fully automatic machine pistols are uncommon in civilian usage due to generally poor recoil-controllability and strict laws and regulations governing their manu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacean Larva
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults (on the sea bed), more-so than where the larvae are planktonic, and thereby easily caught. Many crustacean larvae were not immediately recognised as larvae when they were discovered, and were described as new genera and species. The names of these genera have become generalised to cover specific larval stages across wide groups of crustaceans, such as ''zoea'' and ''nauplius''. Other terms described forms which are only found in particular groups, such as the ''glaucothoe'' of hermit crabs, or the ''phyllosoma'' of slippe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zoea
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults (on the sea bed), more-so than where the larvae are planktonic, and thereby easily caught. Many crustacean larvae were not immediately recognised as larvae when they were discovered, and were described as new genera and species. The names of these genera have become generalised to cover specific larval stages across wide groups of crustaceans, such as ''zoea'' and ''nauplius''. Other terms described forms which are only found in particular groups, such as the ''glaucothoe'' of hermit crabs, or the ''phyllosoma'' of slippe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nauplius (larva)
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a ecdysis, moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults (on the sea bed), more-so than where the larvae are planktonic, and thereby easily caught. Many crustacean larvae were not immediately recognised as larvae when they were discovered, and were described as new genera and species. The names of these genera have become generalised to cover specific larval stages across wide groups of crustaceans, such as ''zoea'' and ''nauplius''. Other terms described forms which are only found in particular groups, such as the ''glaucothoe'' of hermit crabs, or the ''phyllosoma'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustaceana
''Crustaceana'' is a peer-reviewed scientific journal specialising in carcinology. It was established in 1960 and is published monthly by Brill Publishers. The journal is abstracted and indexed by BIOSIS Previews, the Science Citation Index, The Zoological Record, and GeoRef. According to the ''Journal Citation Reports'', the journal has a 2011 impact factor of 0.464. The journal is edited by J.C. von Vaupel Klein. It charges an unspecified publication fee from authors of all regular papers, and an optional open access fee of USD 1830.CrustaceanaInstructions for Authors Brill Publishers Brill Academic Publishers (known as E. J. Brill, Koninklijke Brill, Brill ()) is a Dutch international academic publisher founded in 1683 in Leiden, Netherlands. With offices in Leiden, Boston, Paderborn and Singapore, Brill today publishes 27 ... References External links * *{{Official website, http://www.brill.nl/crustaceana Carcinology journals Publications established in 1960 Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
