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  • General

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  • 鸟鸟

    Three penguins standing on a beach, emphasizing their inability to fly.

    Can all birds fly?
    ::所有的鸟都能飞吗?

    No, not all birds can fly. And not all birds have wings. This penguin is a good example. Their wings have evolved into flippers, adapted for swimming instead of flying. The kiwi of New Zealand is another bird without wings.
    ::不,不是所有的鸟都能飞,也不是所有的鸟都有翅膀。这只企鹅就是一个很好的例子。它们的翅膀已经演化成脚掌,适合游泳而不是飞行。新西兰的kiwi鸟是另一只没有翅膀的鸟。

    Characteristics of Birds
    ::鸟类的特点

    How many different types of birds can you think of? Robins, ostriches, hummingbirds, chickens, and eagles. All of these are birds, but they are very different from one another. There is an amazingly wide variety of birds. Like , , mammals , and , birds are vertebrates . What does that mean? It means they have a backbone . Almost all birds have forelimbs modified as wings, but not all birds can fly. In some birds, the wings have evolved into other structures.
    ::你能想到多少种不同的鸟类? 罗宾、 、 蜂鸟、 鸡和鹰。 这些都是鸟类, 但它们彼此差异很大。 鸟类种类千差万别。 比如, 哺乳动物和, 鸟类是脊椎动物。 这意味着什么 ? 这意味着它们的脊椎。 几乎所有鸟类都有作为翅膀而变形的, 但不是所有的鸟类都能飞翔。 在有些鸟类中, 翅膀演变成其他结构 。

    Birds are in the class Aves. All birds have the following key features: they are endothermic (warm-blooded), have two legs, and lay eggs .
    ::鸟类在Aves类中,所有鸟类都具有以下关键特征:它们有热性(温血),有两条腿,还有产卵。

    Birds range in size from the tiny two-inch bee hummingbird to the nine-foot ostrich ( Figure ). With approximately 10,000 living species , birds are the most numerous vertebrates with four limbs. They live in diverse habitats around the globe, from the Arctic to the Antarctic.
    ::鸟类的大小从小蜂蜂蜂鸟的两英寸到九英尺长的鸟鸟鸟(图 ) 。 鸟类有大约10,000种活种,是最多有四肢的脊椎动物,分布在全球从北极到南极的不同生境中。

    An ostrich standing near its eggs and young chicks in a natural setting.
    The ostrich can reach a height of nine feet! Pictured here is an ostrich with her young.

    Features of Birds
    ::鸟类的特点

    The of birds is unique, with a gizzard that contains swallowed stones for grinding food. Birds do not have teeth. What do you think the stones do? They help them digest their food. Defining characteristics of modern birds also include:
    ::鸟是独有的,鸟是独有的,它有一只有吞咽的石块,用来研磨食物。鸟没有牙齿。你以为石头是做什么的?它们能帮助他们消化食物。界定现代鸟的特性还包括:

    • Feathers .
      ::羽毛 羽毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛 毛
    • High metabolism .
      ::高新陈代谢。
    • A four-chambered heart.
      ::一颗四分五裂的心
    • A beak with no teeth.
      ::没有牙齿的嘴唇
    • A lightweight but strong skeleton.
      ::轻量级但坚固的骨骼
    • Production of hard-shelled eggs.
      ::生产硬壳蛋。

    Which of the above traits do you think might be of importance to flight?
    ::你认为上述特征中哪些对飞行很重要?

    Adaptations for Flight
    ::飞行适应

    In comparing birds with other vertebrates, what do you think distinguishes them the most? In most birds, flight is the obvious difference. Birds have adapted their body plan for flight:
    ::将鸟类与其他脊椎动物相比,你认为它们有什么区别?在大多数鸟类中,飞行是明显的区别。鸟类调整了身体飞行计划:

    • Their skeleton is especially lightweight, with large, air-filled spaces connecting to their .
      ::他们的骨骼特别轻, 有着巨大的空隙 与他们的连接。
    • Their neck bones are flexible. Birds that fly have a bony ridge along the breastbone that the flight attach to ( Figure ). This allows them to remain stable in the air as they fly.
      ::它们的颈骨是柔软的。苍蝇在飞行附着的胸骨(图)上有一个皮脊。这样它们就可以在飞行时保持空中稳定。
    • Birds also have wings that function as an airfoil . The surface of the airfoil is curved to help the bird control and use the air currents to fly. Airfoils are also found on the wings of airplanes.
      ::鸟类也有翅膀,可以作为空气流,空气流的表面被弯曲,帮助鸟类控制,利用空气流飞翔,飞机的翅膀上也发现了空气流。
    A bird skeleton with a highlighted breastbone for muscle attachment.
    A bony ridge along the breastbone (green) allows birds to remain stable as they fly.

    What other traits do you think might be important for flight? Feathers help because they're more lightweight than scales or fur. A bird’s wing shape and size will determine how a species flies. For example, many birds have powered flight at certain times, requiring the flapping of their wings, while at other times they soar, using up less energy ( Figure ).
    ::你认为其他什么特征对飞行可能很重要? 羽毛有帮助,因为它们比天秤或毛皮轻。 鸟的翅膀形状和大小将决定一个物种如何飞翔。 比如,许多鸟类在某些时候为飞行提供动力,需要翅膀的拍拍,而在其他时候则会飞,消耗较少的能量(图 ) 。

    A bird in flight with wings extended against a cloudy sky, showcasing flight adaptations.
    One bird’s flight.

    About 60 living bird species are flightless, such as penguins, as were many extinct birds. Flightlessness often evolves when birds live on isolated islands. The absence of land predators might make flying no longer necessary. Other birds evolved into new niches where flying was no longer necessary. This may have been in response to limited resources . For example, the flightless cormorant can no longer fly, but its wings are now adapted to swim in the sea ( Figure ).
    ::大约60个活鸟类物种没有飞行能力,如企鹅和许多灭绝的鸟类一样。当鸟类生活在孤立的岛屿上时,无飞行能力往往会演变为无飞行能力。没有陆地捕食者可能就不再需要飞行了。其他鸟类可能因为资源有限而演变成新的位置,而不再需要飞行。这也许是为了应对有限的资源。例如,无飞行的幼鸟无法再飞行,但其翅膀现在已经适应了在海上游泳(图示 ) 。

    A flightless cormorant standing on rocks by the sea, wings spread for balance.
    A flightless cormorant can no longer fly, but it uses its wings for swimming.

    Summary
    ::摘要

    • Birds are endothermic (warm-blooded), have beaks, and lay eggs.
      ::鸟类是最后的热量(温血),有嘴和产卵。
    • Adaptations for flight include a lightweight skeleton and flexible neck bones.
      ::飞行调整包括轻量级骨架和弹性颈骨。

    Explore More
    ::探索更多

    Use the resources below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    Explore More I
    ::探索更多

    • Birds Vertebrates at (5:19)
      :sad5:19时)

     

     

    1. What benefits do birds gain from being able to fly?
      ::鸟类能够飞翔有什么好处?
    2. Where do you see scales on birds?
      ::你从哪看鸟的天平?
    3. What do scientists think was the first use of feathers?
      ::科学家们认为羽毛的第一用法是什么?
    4. How are the feathers of birds similar to the fur of mammals? Consider this question in terms of form and function.
      ::鸟类的羽毛如何与哺乳动物的毛皮相似?从形态和功能的角度考虑这个问题。
    5. How do the oxygen requirements of birds differ from the oxygen requirements of reptiles? Why does this difference exist?
      ::鸟类的氧气需求与爬行动物的氧气需求有何不同? 为什么存在这种差异?

    Explore More II
    ::探索更多情况二

    • Emperor Penguin at
      ::企鹅皇帝在
    1. Where do Emperor penguins live?
      ::企鹅皇帝住在哪里?
    2. How do they conserve warmth?
      ::他们如何保护温暖?
    3. What do they eat?
      ::他们吃什么?

    Review
    ::回顾

    1. Can all birds fly?
      ::所有的鸟都能飞吗?
    2. What are three key features of birds?
      ::鸟类的三个主要特征是什么?
    3. What is unique about a bird's digestive system?
      ::鸟的消化系统有什么独特之处?
    4. How are birds adapted for flight?
      ::鸟类如何适应飞行?