Animal Development and Symmetry
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Animal Development and Symmetry

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Questions and Answers

Which characteristic applies to acoelomates?

  • Possession of three embryonic tissue layers.
  • No cavity enclosing the gut. (correct)
  • Cavity lining the outer side only.
  • Cavity lining both sides of the gut.

    • All animals with bilateral symmetry have a coelom.

    False

    What is the primary body symmetry of Phylum Cnidaria?

    Radial symmetry

    The first opening in the embryo of protostomes becomes the ______.

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

    Match the following groups with their characteristics:

    <p>Ctenophora = Comb jellies with bilateral symmetry Porifera = Asymmetrical, sessile filter feeders Cnidaria = Radial symmetry, diploblastic Triploblastic = Three embryonic tissue layers</p> Signup and view all the answers

    What characteristic is primarily responsible for choanoflagellates filtering bacteria?

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

    Choanoflagellates are motile organisms that show self-directed movement.

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

    What is the dominant stage in the life cycle of multicellular eukaryotes?

    <p>Diploid stage</p> Signup and view all the answers

    ___ is a monophyletic group composed only of taxa that share common ancestors.

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

    Match the following terms with their definitions:

    <p>Asymmetric = No major axis of symmetry Radial symmetry = Body can be cut into identical pie segments Diploid = Organism with two sets of chromosomes Haploid = Organism with one set of chromosomes</p> Signup and view all the answers

    Which of the following characteristics is NOT associated with choanoflagellates?

    <p>Presence of cell wall</p> Signup and view all the answers

    All animals have a cell wall.

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

    What role do homeotic genes play in animal development?

    <p>They regulate the development of anatomical structures.</p> Signup and view all the answers

    Which of the following is a characteristic of Ecdysozoans?

    <p>Growth through ecdysis of the cuticle</p> Signup and view all the answers

    All Lophotrochozoans possess a circulatory system.

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

    What is the primary function of the water vascular system found in Echinodermata?

    <p>Movement and feeding</p> Signup and view all the answers

    Members of the phylum Nematoda are classified as __________ because their body wall is lined with mesoderm, but their gut lacks a mesoderm envelope.

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

    Match the following phyla with their key characteristics:

    <p>Platyhelminthes = Acoelomates with no circulatory systems Mollusca = Body organized into foot, mantle, and viscera Annelida = Well-defined segments with metamerism Arthropoda = Jointed chitinous exoskeleton and segmented body</p> Signup and view all the answers

    What type of body symmetry is exhibited by animals in the phylum Porifera?

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

    All triploblastic animals possess three embryonic tissue layers.

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

    What is the defining characteristic of protostomes regarding the fate of the embryonic opening?

    <p>The first opening becomes the mouth.</p> Signup and view all the answers

    Cnidarians have __________ bodies, which allow them to capture prey effectively.

    <p>radial symmetry</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Acoelomate = No cavity enclosing the gut Pseudocoelomate = Cavity lined with mesoderm on the outer side only Coelomate = Gut suspended in a cavity lined with mesoderm on both sides Diploblastic = Two embryonic tissue layers, endoderm and ectoderm</p> Signup and view all the answers

    What is a characteristic of Ecdysozoans?

    <p>Undergo ecdysis to grow</p> Signup and view all the answers

    Members of the phylum Platyhelminthes have a well-defined circulatory system.

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

    What type of symmetry do Echinodermata exhibit as adults?

    <p>Pentaradiate symmetry</p> Signup and view all the answers

    The body plan of Mollusca consists of a foot, ______, and viscera.

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

    Match the following phyla with their characteristics:

    <p>Nematoda = Pseudocoelomate and unsegmented Arthropoda = Jointed limbs and chitinous exoskeleton Echinodermata = Pentaradiate symmetry as adults Chordata = Notochord and dorsal hollow nerve cord</p> Signup and view all the answers

    What type of reproduction do choanoflagellates primarily use?

    <p>Asexual reproduction</p> Signup and view all the answers

    Choanoflagellates are the only unicellular eukaryotes known to exist.

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

    What is the primary characteristic that distinguishes animals from choanoflagellates?

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

    Animals that lack a major axis of symmetry are described as __________.

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

    Which of the following is NOT a characteristic of multicellular eukaryotes?

    <p>Have a cell wall</p> Signup and view all the answers

    Match each term with its description:

    <p>Choanoflagellates = Unicellular filter feeders Extracellular digestion = Process of breaking down food outside of cells Homeotic genes = Regulate anatomical structures during development Monophyletic group = A clade with a common ancestor</p> Signup and view all the answers

    Which type of symmetry allows an organism's body to be divided into identical sections from a central point?

    <p>Radial symmetry</p> Signup and view all the answers

    All animals possess a nervous system.

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

    What type of body cavity do pseudocoelomates possess?

    <p>Cavity lined with mesoderm on the outer side only</p> Signup and view all the answers

    All animals in the phylum Cnidaria have radial symmetry.

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

    What is the primary function of choanocytes in sponges?

    <p>Filter feeding</p> Signup and view all the answers

    Organisms with three embryonic tissue layers are classified as __________ animals.

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

    Match the following phyla with their characteristics:

    <p>Ctenophora = Comb jellies Porifera = Sponges with no symmetry Cnidaria = Jellyfish and corals with radial symmetry Annelida = Segmented worms</p> Signup and view all the answers

    Which characteristic is specific to Ecdysozoans?

    <p>External cuticle that is shed to grow</p> Signup and view all the answers

    Members of the phylum Mollusca have segmented bodies.

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

    What is the primary feeding structure found in some Lophotrochozoans?

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

    The body plan of Nematoda is described as __________ due to the presence of a body wall lined with mesoderm while the gut lacks a mesoderm envelope.

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

    Match the following phyla with their key characteristics:

    <p>Annelida = Metamerism and well-defined segments Echinodermata = Pentaradiate symmetry in adults Platyhelminthes = Acoelomate body structure Chordata = Presence of a notochord</p> Signup and view all the answers

    What is the primary mode of reproduction for choanoflagellates?

    <p>Binary fission</p> Signup and view all the answers

    All multicellular eukaryotes have a cell wall.

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

    Define what a clade is in terms of evolutionary biology.

    <p>A monophyletic group composed only of taxa with common ancestors sharing synapomorphies.</p> Signup and view all the answers

    Choanoflagellates are known to be __________ feeders.

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

    Match the following characteristics with the corresponding animal groups:

    <p>Porifera = Have choanocytes and filter feed Cnidaria = Exhibit radial symmetry Ecdysozoa = Possess an exoskeleton and undergo molting Lophotrochozoa = Commonly have a larval stage called trochophore</p> Signup and view all the answers

    Which of the following is NOT a characteristic of choanoflagellates?

    <p>They possess a true nervous system.</p> Signup and view all the answers

    All animals are photoautotrophic.

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

    What type of symmetry does an organism exhibit if it can be divided into identical sections from a central point?

    <p>Radial symmetry</p> Signup and view all the answers

    Study Notes

    Choanoflagellates

    • Unicellular eukaryote
    • Closest relative to animals
    • Have a collar around a flagellum
    • Filter feeders
    • Consume bacteria

    Animal Characteristics

    • Multicellular eukaryotes
    • Chemoheterotrophic
    • Obtain food through extracellular digestion
    • No cell wall
    • Motile
    • Produce ATP through oxidative phosphorylation
    • Sense and respond to the environment
    • Diploid stage is dominant
    • Have a blastula stage during development
    • Undergo gastrulation during development
    • Cell membranes contain cholesterol
    • Have an extracellular matrix containing collagen
    • Have cell-cell junctions (tight, anchoring, and gap junctions)

    Plant Characteristics

    • Multicellular eukaryotes
    • Photoautotrophic
    • Have cell walls
    • Sessile
    • Alternate between haploid (gametophyte) and diploid (sporophyte) stages
    • Cell wall provides shape and protection
    • Large vacuoles provide turgor pressure against the cell wall
    • Have chloroplasts
    • Can move through growth, pollen/seed dispersal, or being moved by external forces

    Animal Mobility

    • Most are mobile to acquire food
    • Motility characteristics:
      • Muscles
      • Sense organs and cephalization
      • Nervous, digestive, excretory, and skeletal systems
      • Locomotory structures
      • High metabolic rate
    • Some animals can be sessile

    Clades

    • A monophyletic group composed only of taxa with a common ancestor
    • Represents the most likely evolutionary pathway

    Cambrian Explosion

    • First diverse fauna of large, complex multicellular animals
    • First animals with eyes and jaws
    • Represents a rapid evolutionary radiation of Animalia

    Animal Classification

    • Symmetry
      • Asymmetric: No major axis of symmetry
      • Radial: Body can be cut into identical sections, with no left/right or front/back distinction
      • Bilateral: Body has a mirror-image left-right symmetry

    Animal Body Cavities

    • Coelom: Internal body cavity
      • Acoelomate: No cavity enclosing the gut
      • Pseudocoelomate: Cavity enclosing the gut lined with mesoderm on the outer side, but not the inner side
      • Coelomate: Cavity enclosing the gut lined with mesoderm on both sides

    Embryonic Tissue Layers

    • Diploblastic: Two embryonic tissue layers: endoderm and ectoderm
    • Triploblastic: Three embryonic tissue layers: endoderm, mesoderm, and ectoderm

    Bilaterian Divisions

    • Protostomes: The first opening in the embryo develops into the mouth
    • Deuterostomes: The first opening in the embryo develops into the anus

    Metamerism

    • Metameric segmentation: Repeating segments
      • Found in chordates, arthropods, and annelids

    Phylum Ctenophora (Comb Jellies)

    • Bilateral symmetry

    Phylum Porifera (Sponges)

    • Asymmetrical
    • Sessile as adults
    • No nerves
    • Filter feeders
    • Choanocytes provide flagellar action

    Phylum Cnidaria (Jellyfish, Coral)

    • Radial symmetry
    • Diploblastic
    • Cnidocytes are a shared derived character, used to capture prey

    Lophotrochozoans

    • Have a trochophore larva
    • Some have a lophophore feeding structure

    Ecdysozoans

    • External cuticle that is shed to grow (ecdysis)

    Lophotrochozoans: Phylum Platyhelminthes (Flatworms)

    • Acoelomates: No cavity between the body walls and the gut
    • No circulatory system

    Lophotrochozoans: Phylum Mollusca

    • Body organized into a foot, mantle, and visceral mass
    • Unsegmented

    Lophotrochozoans: Phylum Annelida (Segmented Worms)

    • Metamerism: Well-defined segments

    Ecdysozoans: Phylum Nematoda (Roundworms)

    • Pseudocoelomate: Body wall lined with mesoderm, but the gut is not
    • Unsegmented

    Ecdysozoans: Phylum Arthropoda

    • Jointed chitinous exoskeleton
    • Segmented body
    • Jointed limbs
    • Tagmatization: Fusion of body segments

    Deuterostomes: Phylum Echinodermata (Starfish, Sea Urchins)

    • Bilaterally symmetrical larvae
    • Pentaradial symmetry as adults
    • Water vascular system and tube feet

    Deuterostomes: Phylum Hemichordata

    • Pharyngeal gill slits
    • Dorsal nerve cord
    • Stomochord: A structure similar, but not homologous, to a notochord

    Deuterostomes: Phylum Chordata

    • Notochord
    • Dorsal hollow nerve cord
    • Pharyngeal gill slits - perforated pharynx
    • Post-anal tail
    • Segmented muscles

    Choanoflagellates

    • Unicellular eukaryotes most closely related to animals.
    • Sessile, meaning they don't move on their own.
    • Reproduce asexually.
    • Possess a collar surrounding a flagellum with contractile microfibrils.
    • Closely related to choanocytes found in sponges.
    • Filter feed on bacteria.

    Animals

    • Multicellular eukaryotes.
    • Chemoheterotrophic: They obtain energy by consuming organic molecules.
    • Extracellular digestion: Break down food outside of the cell.
    • Lack a cell wall.
    • Motile: Have some type of self-directed movement.
    • Utilize oxidative phosphorylation for ATP production.
    • Can sense and respond to their environment.
    • Have a dominant diploid stage.
    • Develop from a blastula and undergo gastrulation.
    • Cell membranes contain cholesterol.
    • Contain extracellular matrices like collagen.
    • Possess cell-cell junctions, such as tight, anchoring, and gap junctions.

    Plants

    • Multicellular eukaryotes.
    • Photoautotrophic: They produce their own food through photosynthesis.
    • Have a cell wall.
    • Mostly sessile - they don't move on their own.
    • Alternate between haploid (gametophyte) and diploid (sporophyte) stages.
    • Possess cell walls for shape, protection, and turgor pressure.
    • Large vacuoles help maintain turgor pressure.
    • Contain chloroplasts.
    • Can be moved (mobility) or move themselves (motility).

    Fungi

    • Chemoheterotrophic.
    • Mostly require mobility for food acquisition.
    • Lack a cell wall.
    • Can be motile.

    Animals (Motility & Other Characteristics)

    • Motility characteristics include muscles, sensory organs, cephalization, nervous, digestive, excretory, and skeletal systems.
    • High metabolic rate.
    • Some can be sessile.
    • Dominant diploid stage.

    Clade

    • A monophyletic group consisting of taxa with a common ancestor that share synapomorphies (shared derived traits).
    • Represents the phylogeny that requires the least evolutionary change.

    Animal Classification

    • Asymmetrical: No major axis of symmetry.
    • Radial symmetry: Body can be cut into identical pie segments.
    • Bilateral symmetry: Body has mirror-image left-right symmetry.

    Body Cavities (Coelom)

    • Acoelomate: No cavity enclosing the gut.
    • Pseudocoelomate: Cavity enclosing the gut is lined with mesoderm on the outer side, but not the inner.
    • Coelomate: Gut suspended in a cavity lined with mesoderm on both sides.

    Embryonic Tissue Layers

    • Diploblastic: Two embryonic tissue layers - endoderm and ectoderm.
    • Triploblastic: Three embryonic tissue layers - endoderm, ectoderm, and mesoderm.

    Bilaterian Divisions

    • Protostomes: First opening in the embryo becomes the mouth.
    • Deuterostomes: First opening becomes the anus.

    Metameric Segmentation (Repeating)

    • Chordates, arthropods, and annelids.

    Phylum Ctenophora (Comb Jellies)

    • Bilateral symmetry.

    Phylum Porifera (Sponges)

    • Asymmetrical.
    • Sessile as adults.
    • No nerves, filter feeders.
    • Use choanocyte flagella for movement.
    • Suspension feeders.

    Phylum Cnidaria (Jellyfish, Coral)

    • Radial symmetry.
    • Diploblastic.
    • Possess cnidocytes with nematocysts for capturing prey.

    Colonial Cnidarians

    • Siphonophores.

    Protostomes

    • Lophotrochozoans: Have trochophore larvae and some possess a lophophore feeding structure.
    • Ecdysozoans: Possess an outer cuticle that is shed to grow (ecdysis).

    Lophotrochozoans - Phylum Platyhelminthes (Flatworms)

    • Acoelomate - no cavity between the body wall and gut.
    • No circulatory system.

    Lophotrochozoans - Phylum Mollusca (Mollusks)

    • Body organized into foot, mantle, and visceral mass.
    • Unsegmented.

    Lophotrochozoans - Phylum Annelida (Segmented Worms)

    • Metameric segmentation.
    • Well-defined segments.

    Ecdysozoans

    • Growth through ecdysis, shedding of the cuticle.
    • Acellular cuticle: Secreted by epidermal cells.

    Ecdysozoans - Phylum Nematoda (Roundworms)

    • Pseudocoelomate: Body wall lined with mesoderm, but the gut has no mesoderm envelope.
    • Unsegmented.

    Ecdysozoans - Phylum Arthropoda (Arthropods)

    • Jointed chitinous exoskeleton.
    • Segmented body with specialized body parts.
    • Jointed limbs.
    • Tagmatization: Fusion of body segments.

    Deuterostomes - Phylum Echinodermata (Echinoderms)

    • Bilaterally symmetrical larvae.
    • Pentaradial symmetry as adults.
    • Water vascular system and tube feet.
    • Examples: Starfish, sea urchins, sea cucumbers.

    Deuterostomes - Phylum Hemichordata (Hemichordates)

    • Pharyngeal gill slits.
    • Dorsal nerve cord.
    • Stomochord, a structure similar to but not a notochord (rod-like).

    Deuterostomes - Phylum Chordata (Chordates)

    • Notochord, a flexible rod for support.
    • Dorsal, hollow nerve cord.
    • Pharyngeal slits, openings in the throat that can be used for filter feeding or gas exchange.
    • Post-anal tail, an extension of the body beyond the anus.
    • Segmented muscles: Muscles arranged in repeating blocks along the body.

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