Chapter 32

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  1. Animal Characteristics
    • Defined by being:
    • multicellular
    • Eukaryotic
    • Heterotrophic
    • Diplontic life cycle
    •      Diploid multicellular body, haploid gametes, produced by meiosis
  2. Animal Reproduction and Development
    • Diploid body creates gametes (meiosis)
    • Haploid gametes create diploid zygote
    •      n+n-->2n (fertilization)
    • Zygote undergoes cell division
    •      Creates blastula (often a hollow ball of cells)
    • Gastrulation folds embryo inward
    •      Leads to the formation of gastrula
    •      Infolding creates the blastopore
    • Grastula has:
    •      Outer ectoderm
    •      inner ectoderm
    •      Inner pouch called the archenteron
    •          Archenteron will become the digestive tract
    • Gastrulation does not occur in sponges
  3. Animal Body Plans.
    Animals can be categorized by many features of their body structures
    • Symmetry
    • Tissues
    • Body Cavity
    • Developmental mode
  4. Symmetry
    • assymetry
    •      no symmetry in body plan
    • radial symmetry
    •      multiple planes create a mirror immage
    • bilateral symmetry
    •      Only one plane creates a mirror image
  5. Tissue Origin
    • Tissues are specialized cells grouped together with a unified function
    • Tissues arise from germ layers of gastrula
    •      Ectoderm-->outer covering of animal
    •      Endoderm--> digestive tract
    •      Mesoderm --> muscles, internal organs
    •            Other organs can arise from ectodern/endoderm
    • Some animals lack tissues (sponges)
    • Diploblastic animals have 2 germ layers (ectoderm and endoderm--ex. Jellies)
    • Triploblastic animals have 3 germ layers
    •      Ectoderm, endoderm, and mesoderm
    •      Ex. all bilaterally symmetrical animals
  6. Body Cavities
    • Fluid or air-filled space
    •      Seperates digestive tract from outer body wall
    •      Found in most triploblastic animals
    •      Allows organs to be suspended independently
    • Body cavity also called coelom
    • A true coelom develops from mesoderm
    •      True coelom completely lined with epithelium
  7. Developmental Modes
    • Two developmental modes:
    •      Protostome development
    •      Deuterostome development
    • Defined by differences in:
    •      Fate of blastopore
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Chapter 32
2012-10-13 22:05:48
Animal Diversity

Exam 2
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