|
The hourglass dolphin (''Lagenorhynchus cruciger'') is a small dolphin in the family Delphinidae that inhabits Antarctic and subantarctic waters. The dolphin has rarely been seen. It was identified as a new species by Qouy and Galmard in 1824 from a drawing made in the South Pacific in 1820. It is the only cetacean to have been widely accepted as a species solely on witness accounts. By 1960, despite decades of whaling in the Southern Ocean, only three specimens had been recovered. As of 2010 only 6 complete and 14 partial specimens had been examined. Further information was obtained from 4 strandings and boats which searched for the dolphins in areas rarely visited by ships. Though it is traditionally placed in the genus ''Lagenorhynchus'', recent molecular analyses indicate that the hourglass dolphin is actually more closely related to the dolphins of the genus ''Cephalorhynchus''. ==Description== The hourglass dolphin is colored black and white and sometimes variations of dark grey. For this reason was colloquially known by whalers as a "sea cow". Each flank has a white patch at the front, above the beak, eye and flipper, and a second patch at the rear. These two patches are connected by a thin white strip, creating, loosely speaking, an hourglass shape and hence the common name of the dolphin. The scientific name ''cruciger'' is Latin for "cross-carrier". This refers to the area of black coloration, which, viewed from above, vaguely resembles a Maltese cross or cross pattée. In its usual range the dolphin is easily identifiable. Only the southern right whale dolphin is of comparable size and lives as far south. The right whale dolphin does not have a dorsal fin, so the two species are easily distinguished. The fin considerably varies across individuals. It is generally tall and curved, and the curve may be particularly pronounced in older animals. A fully grown adult is about length and weighs . Males are thought to be slightly smaller and lighter than females, although the small number of specimens does not permit a firm conclusion. 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「hourglass dolphin」の詳細全文を読む スポンサード リンク
|