Chordata and Protochordates Classification
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Questions and Answers

What is the primary characteristic that defines all members of the phylum Chordata?

  • A notochord (correct)
  • A vertebral column
  • A dorsal fin
  • A complex nervous system
  • The notochord is a rigid structure that remains present in all adult chordates.

    False

    Name two of the fundamental characteristics of chordates.

    Notochord and nerve cord

    The nerve cord in chordates develops as a _____ tube lying just above the notochord.

    <p>hollow</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Notochord = An elongated, flexible skeletal structure Nerve cord = A fluid-filled hollow tube in chordates Pharyngeal gill slits = Paired structures perforating the pharyngeal wall Post-anal tail = Extension of the body behind the anus</p> Signup and view all the answers

    How many species are included in the phylum Chordata?

    <p>Roughly 45,000</p> Signup and view all the answers

    Cephalochordates are exclusively vertebrates.

    <p>False</p> Signup and view all the answers

    What are the soft and skeletal tissues between adjacent pharyngeal gill clefts called?

    <p>Visceral arches</p> Signup and view all the answers

    What distinguishes Urochordata from other sub-phylums?

    <p>They have a notochord that extends from just behind the head to the tail.</p> Signup and view all the answers

    All Urochordates are terrestrial organisms.

    <p>False</p> Signup and view all the answers

    What is the primary food source of tunicates?

    <p>plankton</p> Signup and view all the answers

    Urochordates are also known as _______ because their body is enclosed in a sac.

    <p>tunicates</p> Signup and view all the answers

    Which statement reflects the respiratory system of tunicates?

    <p>They have two to seven pairs of gill slits for respiration.</p> Signup and view all the answers

    Match each component of the tunicate anatomy with its function:

    <p>In-current siphon = Intake of food and water Ex-current siphon = Expulsion of waste and water Endostyle = Secretes mucus to trap food Ciliate cells = Help move food through the pharynx</p> Signup and view all the answers

    Most tunicates are hermaphrodites.

    <p>True</p> Signup and view all the answers

    What type of circulatory system do tunicates have?

    <p>open</p> Signup and view all the answers

    What is the primary function of the gill cleft?

    <p>To allow passage of water from the pharynx to outside</p> Signup and view all the answers

    All chordates possess a post-anal tail at all stages of their life cycle.

    <p>False</p> Signup and view all the answers

    What transformation occurs to the anterior most cleft in adult amphibians?

    <p>It transforms into the auditory tube and middle ear chamber.</p> Signup and view all the answers

    In non-vertebrate chordates, the clefts and arches are primarily involved in __________.

    <p>the capture of small food particles from water</p> Signup and view all the answers

    Match the subphylum with its characteristics:

    <p>Urochordata = Marine organisms with a gelatinous body Cephalochordata = Small, fish-like creatures with a notochord Agnatha = Jawless fish Gnathostomata = Vertebrates with jaws</p> Signup and view all the answers

    Which of the following is NOT a characteristic of chordates?

    <p>Vertebral column</p> Signup and view all the answers

    In fish-like vertebrates and juvenile amphibians, pharyngeal clefts develop into gills.

    <p>True</p> Signup and view all the answers

    What is the term for the membranous tissue that suspends internal organs in the coelomic cavity?

    <p>Mesentery</p> Signup and view all the answers

    What happens to tunicate larvae as they mature?

    <p>They undergo retrogressive metamorphosis.</p> Signup and view all the answers

    Cephalochordates have well-developed sense organs.

    <p>False</p> Signup and view all the answers

    What is the primary mode of respiration in cephalochordates?

    <p>through the general body surface</p> Signup and view all the answers

    The larval stage of tunicates compares to a ______ as it resembles a mobile form.

    <p>tadpole</p> Signup and view all the answers

    Match the following characteristics with their respective groups:

    <p>Tunicates = Undergo retrogressive metamorphosis Cephalochordates = Have a notochord throughout life Hemichordates = Sister group of echinoderms Ascidian Larvae = Mobile stage resembling a tadpole</p> Signup and view all the answers

    How do cephalochordates reproduce?

    <p>Sexually with external fertilization</p> Signup and view all the answers

    The digestive system of cephalochordates is incomplete.

    <p>False</p> Signup and view all the answers

    How many species of cephalochordates are estimated to exist?

    <p>about 30 species</p> Signup and view all the answers

    Study Notes

    Definition and Overview of Chordata

    • Chordata derives from Greek, "chorde" meaning cord and "ata" meaning bearing, indicating animals with a notochord.
    • Approximately 45,000 species fall under this phylum, including significant vertebrates and invertebrates like amphioxus and tunicates.

    Fundamental Characteristics

    • Chordates exhibit three core traits:
      • Notochord
      • Dorsal nerve cord
      • Pharyngeal gill slits
      • Post-anal tail

    Notochord

    • An elongated, flexible, cartilaginous structure located dorsally over the gut and ventrally beneath the nerve cord.
    • In most adults, it either disappears or transforms into the vertebral column, while some non-vertebrates retain it in a modified form.

    Nerve Cord

    • Develops as a fluid-filled, hollow longitudinal tube lying above the notochord.
    • Differentiates into the brain and spinal cord, forming the central nervous system connected to peripheral nerves.

    Pharyngeal Gill Slits

    • Present at various life stages, allowing water passage from the pharynx to outside, aiding in respiratory functions and filter feeding.
    • Fate varies across groups; non-vertebrates use them for feeding, while vertebrates develop them into gills or other structures.

    General Characteristics of Chordates

    • Possess bilateral symmetry, are triploblastic, and belong to a deuterostome group.
    • Have a complete digestive tract and well-developed coelom, with internal organs suspended in coelomic cavities via mesentery.
    • Reproduce sexually and feature a post-anal tail.

    Classification of Chordates

    • Phylum Chordata is divided into:
      • Acraniata (Protochordata)
      • Craniata (vertebrates)
    • Subphyla include:
      • Urochordata (tunicates)
      • Cephalochordata (lancelets)
      • Agnatha (jawless fish)
      • Gnathostomata (jawed vertebrates)

    Group Acraniata (Protochordata)

    • Characterized by the absence of a cranium and a less prominent brain than in Craniata.
    • Notochord does not evolve into a vertebral column.

    Sub-Phylum Urochordata

    • Known as tunicates; have a notochord extending only in the tail.
    • Body encased in a tunic, mainly composed of tunicine, similar to cellulose.
    • Adaptations for feeding include two siphons for water intake and waste expulsion.
    • Primarily filter-feeders, consuming plankton trapped by mucous secreted from the endostyle.

    Urochordate Physiology

    • Respiratory process involves gill slits capturing water and facilitating gas exchange; lacks kidney-like organs.
    • Simple blood vascular system containing high levels of vanadium and specialized proteins.
    • Most tunicates are hermaphrodites with a larval stage that exhibits chordate characteristics but undergo metamorphosis into a sedentary adult.

    Sub-Phylum Cephalochordata

    • Comprised of small, eel-like marine animals that retain the notochord and nerve cord throughout life.
    • Have a complete digestive system and filter feed using pharyngeal slits.
    • Respiration occurs through the body's surface; no specialized respiratory organs.
    • Reproduction is sexual with separate sexes, and fertilization happens externally.
    • Approximately 30 recognized species within this sub-phylum.

    Additional Information

    • Hemichordata is recognized as a sister group to echinoderms; they are marine, bilaterally symmetrical, and triploblastic animals.

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    Description

    Explore the fascinating world of Phylum Chordata and Protochordates through this quiz. Gain insights into their definitions, fundamental characters, and classification across various groups such as Urochordata and Cephalochordata. Test your understanding of the systems and general characteristics that define these unique organisms.

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