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    A cheetah running at high speed across a dry landscape, showcasing its agility and design.

    What allows this cheetah to be so fast?
    ::是什么让这只猎豹这么快?

    Do you think it has something to do with the placement of the limbs? Well, it does. Look closely at the cheetah's body. Can you describe why it is so fast?
    ::你觉得这和四肢的放置有关吗?

    Social Living in Mammals
    ::哺乳动物的社会生活

    Many mammals live in social groups. Social living evolved because it is adaptive. Consider these two examples:
    ::许多哺乳动物生活在社会群体中,社会生活因为适应性而演变。

    1. Herbivores such as zebras and elephants live in herds . Adults in the herd surround and protect the young, who are most vulnerable to predators .
      ::食草动物(如斑马和大象)等食草动物生活在牧群中,牧群中的成年人包围并保护最易受食肉动物伤害的年轻人。
    2. Lions live in social groups called prides . Adult females in the pride hunt cooperatively, which is more efficient than hunting alone. Then they share the food with the rest of the pride. For their part, adult males defend the pride’s territory from other predators.
      ::狮子生活在称为自豪感的社会团体中。 成年女性在骄傲感中合作打猎,这比单独打猎更有效。 然后,她们与其余的骄傲者分享食物。 而成年男性则保护自豪感不受其他掠食者的侵袭。

    Locomotion in Mammals
    ::哺乳动物的劳动

    Mammals are noted for the many ways they can move about. Generally, their limbs are very mobile. Often, they can be rotated. Many mammals are also known for their speed. The fastest land is a predatory mammal. Can you guess what it is? Racing at speeds of up to 112 kilometers (70 miles) per hour, the cheetah wins hands down. In addition, the limbs of mammals let them hold their body up above the ground. That’s because the limbs are attached beneath the body, rather than at the sides as in (see Figure ).
    ::哺乳动物的行走方式很多,通常它们的四肢非常移动。通常,它们可以旋转。许多哺乳动物也因其速度而闻名。最快的陆地是食肉哺乳动物。你能猜到它是什么吗?以每小时112公里(70英里)的速度赛跑,猎豹赢得了双手。此外,哺乳动物的四肢让它们把身体放在地面之上。这是因为四肢附在身体下面,而不是侧面(见图 ) 。

    Comparison of a reptile's sprawling limb position and a mammal's upright stance.
    Limb Positions in Reptiles and Mammals. The sprawling limbs of a reptile keep it low to the ground. A mammal has a more upright stance.

    Mammals may have limbs that are specialized for a particular way of moving. They may be specialized for running, jumping, climbing, flying, or swimming. Mammals with these different modes of locomotion are pictured in Figure .
    ::哺乳动物的四肢可能专门用于某种特定的移动方式。它们可能专门用于跑步、跳跃、攀登、飞跃或游泳。 图中描绘了这些不同运动模式的哺乳动物。

    Examples of various mammals specialized for different forms of locomotion.
    Mammalian Locomotion. Mammals have many different modes of locomotion.

    The deer in the Figure is specialized for running. Why? It has long legs and hard hooves. Can you see why the other animals in the figure are specialized for their particular habitats ? Notice how arboreal , or tree-living animals, have a variety of different specializations for moving in trees. For example, they may have:
    ::图中的鹿是专门用来跑的。 为什么? 它有长腿和坚固的蹄子。 你可以看到为什么图中的其他动物是专门用于其特定栖息地的吗? 注意亚马星或活树动物如何在树上移动有各种不同的专业。 例如,它们可能有:

    • A prehensile tail (or grasping tail). This is used for climbing and hanging from branches.
      ::尾巴( 或抓尾巴) 。 用于从树枝上攀爬和悬吊 。
    • Very long arms for swinging from branch to branch. This way of moving is called brachiation .
      ::从树枝到树枝的臂弯很长,这种移动方式叫做断裂。
    • Sticky pads on their fingers. The pads help them cling to tree trunks and branches.
      ::他们的手指上有粘粘的垫子,这些垫子帮助他们粘在树干和树枝上。

     

     

     

     

    Summary
    ::摘要

    • Mammals live in social groups, which are an adaptive beneficial trait.
      ::哺乳动物生活在社会团体中,是适应性的有益特征。
    • Mammals have many ways of moving about and may move very quickly.
      ::哺乳动物有多种移动方式 并且可以快速移动

    Review
    ::回顾

    1. Name five types of movement found in mammals?
      ::列出在哺乳动物体内发现的五种运动类型?
    2. A certain mammal has very long forelimbs. What does that suggest about where the animal lives and how it moves?
      ::某种哺乳动物有很长的时间来生长。这说明动物的栖息地和移动方式是什么?
    3. What type of movement is found in the above question.
      ::在上述问题中发现了何种类型的转移。
    4. What is the purpose of a prehensile tail?
      ::预发性尾巴的目的是什么?