求翻译：目前已知全世界的企鹅共有十八种。特征为不能飞翔；脚生于身体最下部，故呈直立姿势；趾间有蹼；跖行性（其他鸟类以趾着地）；前肢成鳍状；羽毛短，以减少摩擦和湍流；羽毛间存留一层空气，用以绝热。背部黑色，腹部白色。各个种的主要区别在于头部色型和个体大小。是什么意思？

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It is known throughout the world there are a total of 18 of the penguins. Character is unable to fly; the body was born, it is peace-keeping operations in an upright position, with a row of fins; inflation rates (other birds to peace-keeping operations in the forelimbs); a short fin, feather, so as

At present the known world penguin altogether has 18 kinds.The characteristic for cannot soar; The foot had been born in the bodily foot, therefore assumes the erectness posture; Between the foot has the web; The plantigrade (other birds are well-grounded by foot); The foreleg becomes finny; The fea

Penguins total 18 kinds of known all over the world. Features cannot fly; foot was born in lower part of body, it is upright posture; between the toes webbed; Plantar (other birds to toe); arms into fins; short feathers, to reduce friction and turbulence; left a layer of air between the feathers, fo

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