Biology: Deuterostomes and Echinoderms
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Questions and Answers

What is a characteristic of cleavage in protostomes?

  • Indeterminate cleavage
  • Radial cleavage
  • Determinate cleavage (correct)
  • Spiral cleavage

    • What is unique about the ossicles in echinoderms?

  • They are external and covered by muscle
  • They have a sponge-like microstructure called stereom (correct)
  • They are hollow and contain air
  • They are solid and contain collagen

    • What is the function of the water vascular system in echinoderms?

  • Regulates body temperature
  • Aids in sensing the environment
  • Performs many important functions including locomotion, respiration, and feeding (correct)
  • Supports the skeleton

    • What is the composition of the fluid in the water vascular system?

    <p>A solution similar to seawater with cells, proteins, and high potassium levels</p> Signup and view all the answers

    What is the characteristic symmetry of echinoderms?

    <p>5-sided symmetry</p> Signup and view all the answers

    What is the function of the ossicles in echinoderms?

    <p>Provides structural support and protection</p> Signup and view all the answers

    What is the name of the phylum that includes sea lilies and feather stars?

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

    What is the developmental origin of echinoderm ossicles?

    <p>Mesenchymal cells</p> Signup and view all the answers

    What is the location of the ossicles in echinoderms?

    <p>Just under the epidermis</p> Signup and view all the answers

    When did echinoderms first appear in the fossil record?

    <p>During the Cambrian period</p> Signup and view all the answers

    What is the unique microstructure found in echinoderm ossicles?

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

    What is the primary function of the water vascular system in echinoderms?

    <p>Aiding in locomotion and respiration</p> Signup and view all the answers

    What is the characteristic feature of Class Crinoidea?

    <p>Upwardly directed mouth with podia-bearing arms</p> Signup and view all the answers

    What is the function of the connective tissue in crinoids?

    <p>Altering stiffness in response to nervous impulses</p> Signup and view all the answers

    What is the characteristic feature of Class Ophiuroidea?

    <p>Thin, flexible, snake-like arms</p> Signup and view all the answers

    What is the function of the Cuvierian tubules in sea cucumbers?

    <p>Defence mechanism against predators</p> Signup and view all the answers

    What is the characteristic feature of Class Asteroidea?

    <p>Star-shaped body plan with radiating arms</p> Signup and view all the answers

    What is the function of the ambulacra in echinoderms?

    <p>Feeding and respiration</p> Signup and view all the answers

    What is the characteristic feature of Class Echinoidea?

    <p>Globose/discoidal test with spines</p> Signup and view all the answers

    Which phylum shares some morphological traits with chordates?

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

    What is unique about the body plan of crinoids compared to other echinoderms?

    <p>They have a upwardly directed mouth in the centre of a circle of arms.</p> Signup and view all the answers

    What is the function of the connective tissue in the stems of crinoids?

    <p>To alter the stiffness of the stems rapidly.</p> Signup and view all the answers

    What is a characteristic feature of asteroids?

    <p>A star-shaped body plan with radiating arms.</p> Signup and view all the answers

    What is the function of the cancerous ring in sea cucumbers?

    <p>To serve as an attachment point for muscles operating the oral tentacles.</p> Signup and view all the answers

    What is a characteristic feature of echinoids?

    <p>A skeleton composed of calcitic plates embedded in the skin.</p> Signup and view all the answers

    What is the function of the Cuvierian tubules in sea cucumbers?

    <p>To deter predators.</p> Signup and view all the answers

    What is a characteristic feature of hemichordates?

    <p>A tripartite division of the body.</p> Signup and view all the answers

    What is the name of the group that includes echinoderms and hemichordates?

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

    What is a characteristic feature of deuterostomes?

    <p>Indeterminate cleavage.</p> Signup and view all the answers

    What is the name of the phylum that includes acorn worms and pterobranchs?

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

    What is the primary function of the ambulacra in echinoderms?

    <p>filtering food from the water</p> Signup and view all the answers

    What is the characteristic body plan of crinoids?

    <p>upwardly directed mouth in the centre of a circle of podia-bearing arms</p> Signup and view all the answers

    What is the function of the cancerous ring in sea cucumbers?

    <p>attachment point for muscles operating the oral tentacles</p> Signup and view all the answers

    What is the characteristic feature of Class Ophiuroidea?

    <p>snake-like arms with a single row of large calcite plates</p> Signup and view all the answers

    What is the name of the group that includes echinoderms and hemichordates?

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

    What is the characteristic feature of echinoids?

    <p>globose/discoidal test with spines</p> Signup and view all the answers

    What is the characteristic feature of asteroids?

    <p>star-shaped body plan with multiple radiating arms</p> Signup and view all the answers

    What is the function of the Cuvierian tubules in sea cucumbers?

    <p>expelling white, sticky, toxic threads from the anus</p> Signup and view all the answers

    What is the characteristic feature of hemichordates?

    <p>pharyngeal slits and a tripartite body division</p> Signup and view all the answers

    What is the characteristic feature of deuterostomes?

    <p>indeterminate cleavage</p> Signup and view all the answers

    What is the primary difference between determinate and indeterminate cleavage in developmental biology?

    <p>The developmental potential of each cell produced during cleavage</p> Signup and view all the answers

    What is the primary function of the ossicles in echinoderms?

    <p>Providing structural support and protection</p> Signup and view all the answers

    What is unique about the water vascular system in echinoderms?

    <p>It is only found in echinoderms</p> Signup and view all the answers

    What is the characteristic shape of echinoderm radial symmetry?

    <p>5-sided</p> Signup and view all the answers

    What is the name of the class of echinoderms that includes sea lilies and feather stars?

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

    When did echinoderms first appear in the fossil record?

    <p>Cambrian period</p> Signup and view all the answers

    What is the unique microstructure found in echinoderm ossicles?

    <p>Sponge-like</p> Signup and view all the answers

    What is the developmental origin of echinoderm ossicles?

    <p>Mesenchymal cells</p> Signup and view all the answers

    What is the primary function of the water vascular system in echinoderms?

    <p>All of the above</p> Signup and view all the answers

    What is the characteristic feature of deuterostomes?

    <p>Indeterminate cleavage</p> Signup and view all the answers

    What is the primary function of the ossicles in echinoderms?

    <p>To provide a rigid shell</p> Signup and view all the answers

    Which class of echinoderms is characterized by a flexible, snake-like body plan?

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

    What is unique about the symmetry of irregular echinoids?

    <p>They have a combination of radial and bilateral symmetry</p> Signup and view all the answers

    What is the function of the pharyngeal slits in hemichordates?

    <p>To facilitate respiration</p> Signup and view all the answers

    Which class of echinoderms has a characteristic feature of a cancerous ring that encircles the pharynx?

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

    What is the name of the microstructure found in echinoderm ossicles?

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

    What is the function of the ambulacra in echinoderms?

    <p>To divide the body into three regions</p> Signup and view all the answers

    Which class of echinoderms has a characteristic feature of a globose or discoidal test?

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

    What is the function of the Cuvierian tubules in sea cucumbers?

    <p>To defend against predators</p> Signup and view all the answers

    What is the characteristic feature of the arms of asteroids?

    <p>They have a broad-based attachment to the disc</p> Signup and view all the answers

    Study Notes

    Determinate vs Indeterminate Cleavage

    • Protostomes: determinate cleavage, cannot take one cell away and have a visible embryo
    • Deuterostomes: indeterminate cleavage, up to a certain point, any one cell still has the ability to become a whole embryo
    • Deuterostomes that are not vertebrates: Echinoderms, Hemichordates, Cephalochordates, Urochordates

    Echinoderms

    • Skeletons containing pieces of calcite called ossicles covered by skin
    • Ossicles are not solid, but have a sponge-like microstructure called stereom unique to the phylum
    • Embryonically, echinoderm ossicles are a true endoskeleton, produced by mesenchymal cells and usually covered by epidermis
    • Functionally, however, the majority of ossicles act more like an exoskeleton, lying just under the epidermis and enclosing most other tissues in a flexible but tough covering
    • First appeared in the Cambrian
    • Water-vascular system with extensions emerging through the skeleton to the outside as tube feet or podia
    • Water vascular system performs many important functions including locomotion, respiration, and feeding
    • Echinoderms are unique in having a water vascular system

    Classes of Echinoderms

    Class Crinoidea

    • Sea lilies look like flowers
    • Feather stars are mobile
    • Each arm is an articulated series of ossicles extending outwards from the body
    • Cricoids are the only surviving echinoderm to have retained the ancestral body plan of an upwardly directed mouth in the centre of a circle of mucociliary, suspension-feeding, podia-bearing arms

    Class Ophiuroidea

    • 5 thin, flexible, snake-like arms
    • Arms clearly demarcated from central disks and made up of a single row of large calcite plates
    • Filter feeding/predatory

    Class Asteroidea

    • Characteristic star-shaped body plan consisting of a central disc and multiple radiating arms
    • Mostly generalist predators, few detritivores
    • Asteroids are most easily distinguished from other asterozoa by the structure of the arms

    Class Echinoidea

    • Skeleton composed of calcitic plates embedded in their skin
    • Echinoderms with globose/discoidal test
    • Typically with spines
    • Diverse feeding strategies from generalists to deposit feeders
    • Irregular echinoids have secondarily acquired bilateral symmetry superimposed upon the radial symmetry

    Class Holothuroidea

    • Generally scavengers
    • Distinguishing characteristic - cancerous ring that encircles the pharynx or throat
    • The ring serves as an attachment point for muscles operating the oral tentacles and for the anterior ends of other muscles that contract the body longitudinally
    • Sea cucumbers have few ossicles and may seem vulnerable to predation, but possess an arsenal of weapons
    • Expel white, sticky, toxic threats called Cuvierian tubules from their anus

    Phylum Hemichordata

    • Hemichordates share some morphological traits with chordates: pharyngeal slits, nerve cord
    • Bilateral symmetry
    • Tripartite division of body: proboscis, collar, and trunk
    • Two extant sub-phyla: Enteropneusts - acorn worms, Pterobranchia
    • Echinoderms + Hemichordates form the sister group to chordates - Ambulacraria
    • Echinodermata + Hemichordata are grouped as Ambulacraria
    • The phylum Chordata is grouped with Echinodermata + Hemichordata within the Deuterostomes

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    Description

    This quiz covers the characteristics and classification of Deuterostomes, including Echinoderms and Hemichordates. Learn about the different classes of Echinoderms, their unique features, and their evolutionary relationships.

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