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  • 虫类

    A roundworm coiled against a dark background, highlighting its elongated, cylindrical shape.

    When most people picture a worm, do they picture a roundworm?
    ::当大多数人想象虫子的时候, 他们想象的是圆虫吗?

    Actually, they do not. Whereas are flat, roundworms obviously appear round. With over 80,000 , there are plenty of different types of roundworms. But these are still not the types of worms most people picture when they think of worms.
    ::事实上,它们没有。虽然它们平坦,但圆虫显然在周围出现。有超过8万只圆虫,它们有多种不同的圆虫。但是,当人们想到虫子的时候,它们仍然不是多数人所想象的虫子类型。

    Roundworms
    ::虫类

    Roundworms make up the phylum Nematoda . This is a very diverse phyla. It has more than 80,000 known species.
    ::圆虫组成了牛毛。这是一个非常多样化的植物。 它有超过80,000种已知物种。

    Structure and Function of Roundworms
    ::圆虫的结构和功能

    Roundworms range in length from less than 1 millimeter to over 7 meters (23 feet) in length. As their name suggests, they have a round body. This is because they have a pseudocoelom . This is one way they differ from flatworms. Another way is their complete digestive system . It allows them to take in food , digest food, and eliminate wastes all at the same time.
    ::圆虫的长度从不到1毫米到超过7米(23英尺)不等。按照它们的名字,它们有一个圆形体。这是因为它们有一个假蛋黄。这是它们与扁虫不同的一种方式。另一种方法是它们完整的消化系统。它允许它们食用食物,消化食物,同时消除废料。

    Roundworms have a tough covering of cuticle on the surface of their body. It prevents their body from expanding. This allows the buildup of fluid pressure in the pseudocoelom. As a result, roundworms have a hydrostatic skeleton . This provides a counterforce for the contraction of lining the pseudocoelom. This allows the worms to move efficiently along solid surfaces.
    ::圆虫在身体表面有坚硬的圆柱盖。 它阻止了它们的身体扩张。 这使得假蛋白的液体压力增加。 结果, 圆虫有静水骨骼。 这为假蛋白的内衬收缩提供了抗力。 这使得蠕虫能够有效地沿着固体表面移动。

    Roundworm Reproduction
    ::圆虫繁殖

    Roundworms reproduce sexually. and eggs are produced by separate male and female adults. takes place inside the female organism . Females lay huge numbers of eggs, sometimes as many as 100,000 per day! The eggs hatch into larvae , which develop into adults. Then the cycle repeats.
    ::女性产卵数量巨大,有时每天多达10万个! 卵子会孵化成幼虫,而幼虫会发展成成人。然后循环重复。

    Ecology of Roundworms
    ::圆虫的生态学

    Roundworms may be free-living or parasitic. Free-living worms are found mainly in freshwater habitats . Some live in soil . They generally feed on , , protozoans, or decaying organic matter. By breaking down organic matter, they play an important role in the .
    ::可能是自由生存的,也可能是寄生虫。自由生存的蠕虫主要存在于淡水生境中,有些生活在土壤中,一般食用原生动物或腐烂的有机物。通过分解有机物,它们起着重要的作用。

    Parasitic roundworms may have plant, vertebrate , or invertebrate hosts. Several species have human hosts. For example, hookworms, like the one in Figure , are human parasites . They infect the human intestine. They are named for the hooks they use to grab onto the host’s tissues . Hookworm larvae enter the host through the skin. They migrate to the intestine, where they mature into adults. Adults lay eggs, which pass out of the host in feces . Then the cycle repeats.
    ::寄生虫可能会有植物、脊椎动物或无脊椎动物宿主。 一些物种有人类宿主。 例如, 钩虫, 如图中的寄生虫, 是人类寄生虫。 它们感染了人类肠。 它们被命名为它们用来抓捕宿主组织上的钩子。 幼虫通过皮肤进入宿主。 它们迁移到肠部, 长大成成人。 成人产卵, 卵在粪便中通过宿主。 然后循环重复 。

    Close-up view of a hookworm highlighting its mouthparts used for attachment.

    Hookworm Parasite. Hookworms like this one are common human parasites.
    ::钩虫寄生虫 像这样的钩虫是普通的人类寄生虫

    Tiny pinworms are the most common roundworm parasites of people in the U.S. In some areas, as many as one out of three children are infected. Humans become infected when they ingest the nearly microscopic pinworm eggs. The eggs hatch and develop into adults in the host’s digestive tract. Adults lay eggs that pass out of the host’s body to continue the cycle. Pinworms have a fairly simple with only one host.
    ::幼虫是美国人最常见的寄生虫。 在一些地区,每三个儿童中就有一个被感染。 人类在吞食接近微缩的寄生虫蛋时就会被感染。 卵在宿主的消化道中孵化并发展成成年人。 成年人产出卵,从宿主的身体中传出,以继续这种循环。 寄生虫只拥有一个宿主,因此相当简单。

       

     

    Summary
    ::摘要

    • Roundworms make up the phylum Nematoda.
      ::圆形虫组成了 植物的Nematoda。
    • Roundworms have a pseudocoelom and hydrostatic skeleton. Their body is covered with tough cuticle.
      ::圆虫有假蛋白和静水骨骼,身体上被坚硬的切片覆盖。
    • Free-living roundworms are found mainly in freshwater habitats.
      ::在淡水生境中,主要发现有非活性圆虫。
    • Parasitic roundworms have a variety of hosts, including humans.
      ::寄生虫的圆虫有各种各样的宿主,包括人类。

    Review
    ::回顾

    1. How do free-living nematodes contribute to the carbon cycle?
      ::自由生存线虫如何促进碳循环?
    2. Apply what you know about pinworms to develop one or more recommendations for preventing pinworm infections in humans.
      ::运用你所了解的关于虫子的知识,制定一项或多项建议,预防人类中虫虫感染。
    3. Platyhelminthes and nematodes are both worms. Justify classifying them in different invertebrate phyla.
      ::等离子元素和线虫都是蠕虫。 将它们分类为不同的无脊椎植物。