Section outline

  • A sea cucumber displayed on ocean floor, showcasing spines characteristic of echinoderms.

    What is a sea cucumber?
    ::什么是海参?

    A sea cucumber is not a vegetable! It is an invertebrate animal found in the ocean. Note the spines on this sea cucumber. The spines are a key feature of echinoderms.
    ::海黄瓜不是蔬菜,而是在海洋中发现的无脊椎动物。注意这个海黄瓜的脊椎。脊椎是大肠杆菌的关键特征。

    What are Echinoderms?
    ::什么是精密药?

    You're probably familiar with starfish and sand dollars ( Figure ). They are both echinoderms . Sea urchins and sea cucumbers are also echinoderms. What's similar between these three organisms ? They all have radial symmetry . This means that the body is arranged around a central point.
    ::你可能很熟悉海星和沙币(图 ) 。 它们都是电离层。 海胆和海参也是电离层。 这三种生物之间有什么相似之处? 它们都有线性对称性。 这意味着身体是围绕一个中心点排列的。

    Echinoderms belong to the phylum Echinodermata . This phylum includes 7,000 living species . It is the largest animal phylum without freshwater or land-living members.
    ::这种植物包括7 000种活物种,是没有淡水或陆地生物成员的最大动物植物。

    A starfish on the left and a keyhole sand dollar on the right, demonstrating radial symmetry.
    A starfish (left) and a keyhole sand dollar (right), showing the radial symmetry characteristic of the echinoderms. Starfish are also known as sea stars.

    Characteristics of Echinoderms
    ::近效药的特征

    As mentioned earlier, echinoderms show radial symmetry. Other key echinoderm features include an internal skeleton and spines, as well as a few organs and organ systems . Although echinoderms look like they have a hard exterior, they do not have an external skeleton. Instead, a thin outer skin covers an internal skeleton made of tiny plates and spines. This provides rigid support. Some groups of echinoderms, such as sea urchins ( Figure ), have spines that protect the organism. Sea cucumbers use these spines to help them move.
    ::如前所述,脑外皮显示的是线性对称。其他关键的脑外皮特征包括内骨和脊椎,以及一些器官和器官系统。虽然脑外皮看上去像硬外皮,但没有外部骨骼。相反,薄外皮覆盖了由小板块和脊椎组成的内骨。这提供了僵硬的支持。一些脑外皮群,如海胆(Figure ) , 有保护有机体的脊椎。海参利用这些脊椎帮助它们移动。

    A sea urchin displaying spines, illustrating key characteristics of echinoderms.
    Another echinoderm, a sea urchin (Echinus esculentus), showing its spines.

    Echinoderms have a unique water vascular system . This network of fluid-filled tubes helps them to breathe, eat, and move. Therefore, they can function without gill slits. Echinoderms also have a very simple , circulatory system, and . The digestive system often leads directly from the mouth to the anus. The echinoderms have an open circulatory system, meaning that fluid moves freely in the body cavity. But echinoderms have no heart. This may be due to their simple radial symmetry - a heart is not needed to pump the freely moving fluid. The echinoderm nervous system is a nerve net , or interconnected neurons with no central brain .
    ::精密的血管系统是独特的水体系统。 这个装满液体的管子网络可以帮助他们呼吸、吃饭和移动。 因此, 它们可以在没有刺断的情况下运作。 精密的系统也非常简单, 循环系统, 并且。 消化系统通常从嘴直接到肛门。 精密的循环系统是开放的, 意指液体在体腔中自由移动。 但是, 精密的管子没有心脏。 这可能是因为它们简单的辐射对称性, 不需要心脏来抽动自由移动的流体。 精密的神经系统是一个神经网, 或者是没有中央大脑的相互连接的神经。

    Many echinoderms have amazing powers of regeneration . For example, some sea stars (starfish) are capable of regenerating lost arms. In some cases, lost arms have been observed to regenerate a second complete sea star! Sea cucumbers often release parts of their internal organs if they perceive danger. The released organs and tissues are then quickly regenerated.
    ::许多电离层具有惊人的再生能力,例如,一些海星(海星)能够再生失去的手臂。在某些情况下,已经观察到丢失的手臂可以再生第二颗完整的海洋恒星。海参如果察觉到危险,往往会释放部分内脏器官。然后,释放的器官和组织会迅速再生。

    How do Echinoderms Eat?
    ::如何使用近效药物?

    Feeding strategies vary greatly among the different groups of echinoderms. There's no one food or technique that's shared by all echinoderms. Different eating-methods include:
    ::不同的脑电图组群的喂养策略差异很大。没有一种食物或技术是所有脑电图组共有的。不同的饮食方法包括:

    1. Passive filter feeders , which are organisms that absorb suspended nutrients from passing water. Some echinoderms use their long arms to capture food particles floating past in the currents.
      ::被动过滤过滤器是吸收通过水中悬浮养分的有机体,有些脑电极利用长臂捕捉漂浮在水流中的粮食颗粒。
    2. Grazers, such as sea urchins, are organisms that feed on available plants. Sea urchins are omnivorous, eating both plant and animals. The sea urchin mainly feeds on on the coral and rocks, along with decomposing matter such as dead , mussels, , and barnacles.
      ::海胆(例如海胆)是食用现有植物的有机体。 海胆(sea urchins)是无孔不入的,既食用植物,也食用动物。 海胆(sea urchin)主要食用珊瑚和岩石,同时分解物质,如死亡物质、贝类和谷仓。
    3. Deposit feeders, which are organisms that feed on small pieces of organic matter, usually in the top layer of soil . Sea cucumbers are deposit feeders, living on the ocean floor. They eat the tiny scrap particles that are usually abundant in the environments that they inhabit.
      ::海参是海参是海参的食肉动物,生活在洋底,它们食用在它们居住的环境中通常富含的微小碎粒。
    4. Active hunters, which are organisms that actively hunt their prey . Many sea stars are predators , feeding on like clams by prying apart their shells and actually placing their stomach inside the mollusk shell to digest the meat.
      ::活跃的猎人是积极捕猎猎物的有机体。 许多海星都是捕食者,它们像蛤一样食用蛤类食物,将贝壳隔开,并实际将胃放在软体壳中消化肉类。

    How do Echinoderms Reproduce?
    ::精密药物是如何复制的?

    Echinoderms reproduce sexually. In most echinoderms, eggs and cells are released into open water, and takes place when the eggs and sperm meet. This is called external fertilization , and is typical of many marine animals. The release of sperm and eggs often occurs when organisms are in the same place at the same time. Internal fertilization takes place in only a few species. Some species even take care of their offspring , like parents!
    ::蛋和细胞被放入开阔的水中,在卵子和精子交汇时发生。这被称为外部施肥,是许多海洋动物的典型现象。精子和卵子的释放往往是当生物同时处于同一位置时发生的。内部施肥只在少数物种中发生。有些物种甚至像父母一样照顾他们的后代。

    Summary
    ::摘要

    • Echinoderms show radial symmetry and have an endoskeleton and a unique water vascular system. Some have spines.
      ::Echinoderms 显示对称辐射,并有一个内骨骨骼和一个独特的水血管系统,有些有脊椎。
    • Echinoderms generally reproduce by external fertilization; regeneration is fairly common among echinoderms.
      ::精密药通常通过外部施肥而繁殖;再生在精密体中相当常见。

    Explore More
    ::探索更多

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

    • Echinoderms: The Ultimate Animal at (13:54)
      ::近效药:最后动物(13:54)

     

     

    1. What can sea star muscles do that our muscles cannot? How would this trait help sea stars living in the intertidal zone?
      ::海洋恒星的肌肉能做什么,而我们的肌肉却不能做?这一特性如何帮助生活在潮间带的海洋恒星呢?
    2. How are deep-sea sea cucumbers like earthworms?
      ::深海海参像蚯蚓怎么样?
    3. Why are brittle stars often found with their arms raised in the water current?
      ::为什么经常在水流中 怀着手臂 发现易碎的恒星呢?
    4. What organ system do echinoderms possess that is not seen in any other animal group?
      ::在任何其他动物组别中看不到的,哪些脑器官系统拥有哪些器官系统?
    5. Where do sea stars have their "eyes"? How does this arrangement help them coordinate movement?
      ::海星的“眼眼”在哪里?这一安排如何帮助它们协调运动?
    6. Some sea stars evert their stomachs to digest their prey, but Pycnopodia can do something else as well. What does Pycnopodia do to some of its prey?
      ::一些海洋恒星曾用胃来消化它们的猎物,但Pycnopodia也可以做其他事情。Pycnopodia对它的猎物做了什么?

    Review
    ::回顾

    1. List three examples of echinoderms.
      ::列举三例脑电图。
    2. What is radial symmetry?
      ::什么是辐射对称?
    3. What are two important characteristics of echinoderms (other than radial symmetry)?
      ::电子电离层(除辐射对称法外)的两个重要特征是什么?
    4. How do sea urchins eat?
      ::海胆怎么吃?
    5. Give an example of an echinoderm that is an active hunter.
      ::举个例子来说明一个活跃猎手的脑电图。