tang(redirected from blue tangs)
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tang, in zoology
tang,common name for certain members of the Acanthuridae, a family of mostly small, mainly reef-dwelling tropical fishes with compressed bodies and small mouths and teeth. Other members of the family are known as surgeonfishes and unicornfishes. They have sharp spines on either side of the tail, and many are brightly colored. The tangs include the blue-gray to dark-brown doctorfish, several species known as blue tangs, and the larger and more abundant ocean tang of deep waters. The unicornfishes are named after the hornlike projection found in some species; the whitemargin unicornfish is among the largest members of the family, reaching 39 in. (1 m) in length. The allied spadefishes, which include the batfishes of the Indo-Pacific region, are generally large than the tangs and belong to the family Ephippidae. They are barred in black and white. The Atlantic spadefish, also called angelfish or white angelfish, is valued both as a food and a game fish. The tangs and spadefishes are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
..... Click the link for more information. , subphylum Vertebrata, class Actinopterygii, order Perciformes, families Acanthuridae and Ephippidae, respectively.
a Chinese imperial dynasty that reigned from 618 to 907. The T’ang Dynasty was founded by Li Yuan. His son, Li Shih-min, united the country in 628, after subduing peasant insurgents and separatist feudal forces. He also strengthened the central authority and improved the organization of the military by instituting the fuping system.
During the reigns of the first T’ang emperors, a system of competitive state examinations was developed, which permitted the rise among the feudal class of an estate of scholars loyal to the imperial court; it was from this estate that members of the bureaucracy and the military elite were chosen. The same era saw the establishment of a system of allotment landowning called the equal-field system, which made it possible for the central government to regulate taxation.
A growing internal struggle among feudal groups resulted in a palace coup at the end of Emperor Li Chih’s reign (650–683). The emperor’s wife, Wu Tse-t’ien, seized power and ruled the country herself from 684 to 705. Until the middle of the eighth century, the T’ang Dynasty carried out an aggressive foreign policy that led to war and the seizure of neighboring lands. Later, the empire encountered resistance from the states of Nan Chao and T’ufan (Tibet) and the Uighur Khanate.
As the power of the dynasty waned in the middle of the eighth century, the power of the military governors (the chieh-tu-shih) increased—to the point where one governor, An Lu-shan, openly revolted. The dynasty’s dominance was ultimately broken by a peasant uprising led by Huang Ch’ao and his successors and by a struggle among various groups of the ruling class. Li Chu (904–907), the last T’ang emperor, was overthrown by the military commander Chu Wen. Earlier, Chu Wen, one of the leaders of the peasant uprising, had betrayed Huang Ch’ao by aligning himself with the emperor.
L. I. DUMAN