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The Amblyopsidae are a fish family commonly referred to as cavefish, blindfish, or swampfish. They are small freshwater fish found in the dark environments of swamps, caves, and deep lakes in the eastern half of the United States. Like other troglobites, amblyopsids exhibit adaptations to these dark environments, including the lack of functional eyes and, in some species, the absence of pigmentation. About 170 species of cavefishes are known,〔Rantin B., and M.E. Bichuette (2013). ''Phototactic behaviour of subterranean Copionodontinae Pinna, 1992 catfishes (Siluriformes, Trichomycteridae) from Chapada Diamantina, central Bahia, northeastern Brazil.'' International Journal of Speleology 41(1): 57-63〕 but only six of these are in the family Amblyopsidae. ==Description== Blindfish are generally small, ranging up to in length. Cavefish are probably ancient in origin. Adaptations common to many cavefish include reduced susceptibility to light, pigment loss, or reduction in skin scales, as well as development of chemoreceptors in the sensory organs of the body surface and the lateral line. Three species exhibit efficient metabolism during swimming, as compared with a group of non-cave fish,〔 and many cavefish species exhibit slender bodies adapted to swimming in fast-flowing waters.〔 Their bodies lack pigment and are translucent. They have a naked, moderately depressed head and an elongated body, covered with small cycloid irregular flakes, with tiny or absent pelvic fins. The anal opening is so far forward that it is in the throat region. The premaxilla, a bone of the upper jaw, is segmented, and the vomer has no teeth. They have no ventral fins. The lateral line is incomplete, but well developed in some species. Its spine has between 27 and 35 vertebrae. Externally, they resemble killifishes in many respects, although their internal anatomy more closely resembles the trout-perches, with which they are currently classified. Cavefish have an unusual body clock that does not respond to light. The period of their circadian rhythm has grown to 47 hours.〔(Cavefish Keep Time Without the Sun ), SINDYA N. BHANOO, September 12, 2011, nytimes.com〕〔(Blind Cave Fish Can Tell Time ), Sunday, 11 September 2011, livescience.com〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Amblyopsidae」の詳細全文を読む スポンサード リンク
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