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A tripod stance is a behaviour in which quadruped animals rear up on their hind legs and use their tail to support this position. Several animals use this behaviour to improve observation or surveillance, and during feeding, grooming, thermoregulation, or fighting. ==In mammals== The common dwarf mongoose (''Helogale parvula'') adopts a tripod stance when being vigilant for predators. In a similar mammal, the thirteen-lined ground squirrel (''Spermophilus tridecemlineatus''), vigilance behaviour includes four postures: (1) quadrupedal alert (all four feet on the ground with head above the horizontal); (2) semiupright alert (on hind feet with a distinctive slouch); (3) upright alert (on hind feet with back straight and mostly perpendicular to the ground); (4) extended upright alert (similar to upright alert except that the squirrel extends its hind legs, (see image of meerkats). In meerkats (''Suricata suricatta''), the tripod stance may be adopted relatively briefly during foraging, in which case it is termed guarding behaviour, or for substantially longer periods when the animal is not foraging, in which case it is termed sentinel behaviour. Macropods can stand erect on their hind legs, supported by their tail as the third leg of the tripod. Macropods also engage in "pentapedal locomotion," an energy-inefficient gait used at slow speed, in which "the tail is used, with the forelimbs, as the third leg of a tripod to support the animal while the large hind limbs are moved forward." Giant armadillos (''Priodontes maximus'') have a well-developed sense of smell but poor eyesight. When approached by a potential threat, they rise up onto their hind legs, supported by the tail and begin to sniff from side to side. This tripod stance is similar to the defensive position adopted by anteaters and enables them to strike out with their sharply-hooked claws if suddenly attacked. It has been reported that the desert woodrat (''Neotoma lepida'') gives birth "...in a bipedal position supported by the tail." 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「Tripod stance」の詳細全文を読む スポンサード リンク
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