Section outline

  • Close-up of a brown tarantula on wood with greenery; illustrates arachnid characteristics.

    Is a spider a type of ?
    ::蜘蛛是一种类型的吗?

    Although spiders and insects are both , a spider is not an insect. One key difference is that insects have six legs, while spiders have eight legs.
    ::虽然蜘蛛和昆虫是两者,但蜘蛛不是昆虫。 关键区别之一是昆虫有六条腿,而蜘蛛有八条腿。

    Arachnids
    ::喷火剂

    Arachnids are a class of joint-legged invertebrates in the subphylum Chelicerata. They live mainly on land but are also found in fresh and in all environments, except for the open ocean. There are over 100,000 named , including many species of spiders, scorpions, daddy-long-legs, ticks, and mites ( Figure ). There may be up to 600,000 species in total, including unknown ones.
    ::Arachnids是切列斯拉塔亚植物类中一条双腿无脊椎动物,主要居住在陆地上,但除了开阔的海洋外,在各种环境中都是新鲜的,除开阔的海洋外,还存在于各种环境中。有超过10万个被点名的物种,包括许多蜘蛛、蝎子、长腿、长腿、小滴和米特(图 ) 。可能共有多达600,000种物种,包括未知物种。

    A daddy-long-legs spider on a leaf and a tick on grass.

    ( left ) A daddy-long-legs spider. ( right ) Various diseases are caused by bacteria that are spread to humans by arachnids, like the tick shown here.
    :sad左) 长腿蜘蛛。 (右) 各种疾病是由细菌引起的,这些细菌通过虫子传播到人类,如此处显示的滴子。

    Characteristics of Arachnids
    ::Arachnids 的特征

    Arachnids have the following characteristics:
    ::喷火具有以下特性:

    1. Four pairs of legs (eight total). You can tell the difference between an arachnid and an insect because insects have three pairs of legs (six total).
      ::四双腿(共八条)。你可以分辨出一只野兽和一只昆虫的区别,因为昆虫有三双腿(共六条腿)。
    2. Arachnids also have two additional pairs of appendages . The first pair, the chelicerae , serve in feeding and defense. The next pair, the pedipalps , help the organisms feed, move, and reproduce.
      ::Arachnids 也有另外两对附着物。第一对, , 用于喂养和防御。 下一对, , 帮助生物进食、 移动和繁殖。
    3. Arachnids do not have antennae or wings.
      ::Arachnids没有天线或翅膀。
    4. The arachnid body is organized into the cephalothorax , a fusion of the head and thorax, and the abdomen.
      ::气管体被组织成脑膜 头部和胸部的聚变 还有腹部
    5. To adapt to living on land, arachnids have internal systems, like a trachea or a book lung .
      ::为了适应在陆地上的生活,arachnids有内部系统,如气管或书本肺。
    6. Arachnids are mostly carnivorous, feeding on the pre-digested bodies of insects and other small .
      ::食肉动物大多是食肉动物,
    7. Several groups are venomous. They release the venom from specialized glands to kill prey or enemies.
      ::有几个群体有毒,它们从特殊腺中释放毒液,杀死猎物或敌人。
    8. Several mites are parasitic, and some of those are carriers of disease.
      ::几只是寄生虫,其中一些是疾病的传播者。
    9. Arachnids usually lay eggs , which hatch into immature arachnids that are similar to adults. Scorpions, however, give birth to live young.
      ::Arachnids通常产卵,它们孵化成与成年人相似的不成熟的arachnids。 然而,蝎子生下活生的青春。

    Arachnid Subgroups
    ::Arachnid 分组

    The arachnids are divided into eleven subgroups. Below are the four most familiar subgroups, with a description of each ( Table ).
    ::Arachnids分为11个分组,以下是4个最熟悉的分组,每个分组都有说明(表)。

    Subgroup Representative Organisms Approximate Number of Species Characteristics
    Araneae Spiders 40,000
    • Found all over the world, ranging from tropics to the , some in extreme environments.
      ::从热带到热带,有些是在极端环境中发现的。
    • All produce silk , which is used for trapping insects in webs, aiding in climbing, producing egg sacs, and wrapping prey.
      ::所有产品都生产丝绸,用于在网中捕捉昆虫、协助攀爬、生产蛋囊和包装猎物。
    • Nearly all spiders inject venom to protect themselves or to kill prey. Only about 200 species have bites that can be harmful to humans.
      ::几乎所有蜘蛛都注入毒液来保护自己或杀死猎物。 只有大约200种物种的咬痕可能对人类有害。
    Opiliones Daddy-long-legs 6,300
    • Known for extremely long walking legs. No silk nor poison glands.
      ::长长的步行腿,没有丝绸和毒液
    • Many are omnivores , eating small insects, plant material, and . Some are scavengers , eating decaying animal and other matter.
      ::许多人是食用小昆虫、植物材料的全食动物,有些人是拾荒者,食用腐烂的动物和其他物质。
    • Mostly nocturnal (come out at night) and colored in hues of brown. A number of diurnal (come out during the day) species have vivid patterns of yellow, green, and black.
      ::黄黄、绿和黑的活生生的形态。 黄、绿和黑的物种大多在夜间出现(晚上出来 ) , 染色在棕色的粗体中。 一些黑黄物种(白天出来 ) 。 黄、 绿和黑的活生生的形态是黄、 绿色和黑色的。
    Scorpiones Scorpions 2,000
    • Characterized by a tail with six segments, the last bearing a pair of venom glands and a venom-injecting barb.
      ::由尾巴和6个区段的特征 最后一个带有一对毒液腺 和毒液注射棒
    • Predators of small arthropods and insects. They use pincers to catch prey. Then they either crush it or inject it with a fast-acting venom, which is used to kill or paralyze the prey. Only a few species are harmful to humans.
      ::小节肢动物和昆虫的捕食者,他们用针刺来捕食猎物,然后或粉碎它,或注射一种快速作用的毒液,用来杀死猎物或使其麻痹,只有少数物种对人类有害。
    • Nocturnal; during the day, they find shelter in holes or under rocks.
      ::夜间;白天,他们在洞穴或岩石下找到栖身之所。
    • Unlike the majority of arachnids, scorpions produce live young. The young are carried about on the mother’s back until they have molted at least once. They reach an age of between four to 25 years.
      ::与大多数阿拉克尼特人不同的是,蝎子活生生的年青。 幼子背在母亲的背上,直到他们至少磨过一次。 他们的年龄在4至25岁之间。
    Acarina Mites and ticks 30,000
    • Most are small (no more than 1.0 mm in length), but some ticks, and one species of mite, may grow to be 10-20 mm in length.
      ::多数是小的(长度不超过1.0毫米),但有些小块和一种微小的微粒,长可能长为10-20毫米。
    • Live in nearly every habitat , including and .
      ::几乎生活在每一个栖息地, 包括和。
    • Many are parasitic, affecting both invertebrates and vertebrates . They may transmit diseases to humans and other mammals . Those that feed on plants may damage crops.
      ::许多人是寄生虫,影响无脊椎动物和脊椎动物,他们可能把疾病传染给人类和其他哺乳动物,那些靠植物为生的哺乳动物可能会破坏作物。

    Summary
    ::摘要

    • Arachnids have four pairs of legs, specialized appendages, and a fused head and thorax.
      ::Arachnids有四双腿, 专门附着物, 和一个装有引信的头部和胸部。
    • Arachnids include spiders, daddy-long-legs, scorpions, and ticks.
      ::青蛙包括蜘蛛、长腿、蝎子和虱子。

    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。

    • Spiders at (4:03)
      ::蜘蛛在(4:03)
    1. How do spiders differ from insects?
      ::蜘蛛和昆虫有什么不同?
    2. What are some of the uses of their silk?
      ::他们的丝绸有什么用?
    3. How do spiders keep from becoming stuck in their own webs?
      ::蜘蛛如何避免被困在自己的网络里?
    4. What role do spiders play in their ecosystem?
      ::蜘蛛在其生态系统中发挥什么作用?

    Review
    ::回顾

    1. List three types of arachnids.
      ::列出三种型号的Arachnids。
    2. What are two key features of arachnids?
      ::Arachnids的两个关键特征是什么?
    3. Arachnids also have two additional pairs of appendages. Describe these two pairs.
      ::Arachnids也有另外两对附件。描述这两对附件。
    4. List two specific features of spiders.
      ::列出蜘蛛的两个具体特征。
    5. List two specific features of scorpions.
      ::列出蝎子的两个具体特征。