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  • General

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  • 无脊椎动物

    A close-up of a sea squirt with red openings among coral and algae.

    Would you believe this animal eats its own brain?
    ::你相信这只动物会吃自己的大脑吗?

    This is a sea squirt, which is a . Many physical changes occur to the tunicate's body during metamorphosis into an adult, with one of the most interesting being the digestion of the cerebral ganglion, which controls movement and is the equivalent of the human brain . From this comes the common saying that the sea squirt "eats its own brain."
    ::这是一个海水喷口,它是一个。它的身体在变形成成人时发生了许多物理变化,其中最有趣的一个变化是大脑交织的消化,它控制着运动,相当于人类的大脑。从这个意义上说,海水喷口“吞食了自己的大脑 ” 。

    Invertebrate Chordates
    ::无脊椎动物

    Living of are classified into three major subphyla: Vertebrata, Urochordata, and Cephalochordata. Vertebrates are all chordates that have a backbone . The other two subphyla are invertebrate chordates that lack a backbone. Members of the subphylum Urochordata are tunicates (also called sea squirts). Members of the subphylum Cephalochordata are . Both tunicates and lancelets are small and primitive. They are probably similar to the earliest chordates that evolved more than 500 million years ago.
    ::活物分为三大类:Vertebrata、Urochordata和Cephalochordata。 Vertebrate都是有脊椎的染色体。另外两个亚类是缺乏脊椎的无脊椎染色体。 Urochordata的子系成员是受礼动物(也称为海沟),亚脊椎切色体数据的成员是受礼动物。亚脊椎动物和鼻梁都是小而原始的。它们可能与五亿多年前形成的最早的染色体相似。

    Tunicates
    ::受 教 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语 语

    There are about 3,000 living species of tunicates (see Figure ). They inhabit shallow waters. Larval tunicates are free-swimming. They have all four defining chordate traits (see the "Chordates" concept). Adult tunicates are sessile . They no longer have a notochord or post-anal tail .
    ::有大约3 000种受礼动物(见图 ) 。 它们居住在浅水水域。 拉尔瓦尔受礼动物是自由游荡的。 它们有四种定义的受礼动物特征(见“ 受礼动物” 概念 ) 。 成年受礼动物是沉默的, 它们不再有受礼动物或后肛门动物尾巴 。

    Colorful barrel-shaped tunicates grouped together, illustrating filter feeding in marine environments.

    Tunicates (Urochordata). Tunicates are one of two subphyla of invertebrate chordates.
    ::教育(Urochordata) 教育(Urochordata) 是两个无脊椎甲状腺的子植物之一。

    Adult tunicates are barrel-shaped. They have two openings that siphon into and out of the body. The flow of water provides food for filter feeding. Tunicates reproduce sexually. Each individual produces both male and female gametes . However, they avoid self- . Tunicates can also reproduce asexually by budding .
    ::成人义体是桶状的,有两处可以抽进和抽出身体的开口,水流为过滤食物提供食物,对性生殖进行调试,每个人生产男的和女的调子,但避免自相矛盾,教义也可以通过发芽进行性繁殖。

    Lancelets
    ::射子

    There are only about 25 living species of lancelets. They inhabit the ocean floor where the water is shallow. Lancelet larvae are free-swimming. The adults can swim but spend most of their time buried in the sand. Like tunicates, lancelets are filter feeders . They take in water through their mouth and expel it through an opening called the atriopore (see Figure ). Lancelets reproduce sexually and have separates sexes.
    ::只有大约25种活生生的长矛种类,它们居住在浅水的洋底。兰斯莱特幼虫是自由游泳的。成年人可以游泳,但大部分时间都埋在沙子里。像外衣一样,长矛是过滤器。它们从口中取水,通过一个叫做 " 亚特里奥波尔 " 的开口(见图 ) 将其排出。长矛是性繁殖的,有不同的性别。

    The anatomy of a lancelet, highlighting key structures and organs.

    Lancelet (Cephalochordata). Unlike tunicates, lancelets retain all four defining chordate traits in the adult stage. Can you find them?
    ::兰斯莱特( Cephalochordata ) 。 与外衣不同的是, 长袍保留了成人阶段所有四个定义的发色特征。 您能找到它们吗 ?

    Summary
    ::摘要

    • Chordates include vertebrates and invertebrates that have a notochord.
      ::和弦包括脊椎动物和无脊椎动物,这些无脊椎动物有非亚化物。
    • Invertebrate chordates do not have a backbone.
      ::无脊椎染色体没有脊椎骨。
    • Invertebrate chordates include tunicates and lancelets. Both are primitive marine organisms.
      ::无脊椎动物甲状腺染色体包括突尼黑和鼻梁,两者都是原始海洋生物。

    Review
    ::回顾

    1. Name and describe the two subphyla of invertebrate chordates.
      ::名称并描述无脊椎甲状腺的两个亚phyla。