Bio Animal Intro

  1. What Are the Features of Animals?
    • Multicellularity
    • Cells lack cell wall
    • Heterotrophs
    • Most reproduce sexually
    • They are motile at some point in the life
    • cycle
    • They are able to respond rapidly to
    • external stimuli
    • Early embryological development is
    • similar for all animal groups
  2. Anatomical Features of the Animal Evolutionary Tree
    • Most currentanimal phyla were present by the Cambrian period (544million years ago)
    • Prior to the “Cambrian Explosion” there are few fossils
    • Other evidence used to define groups
    • includes: (ADE)
    • Anatomy
    • DNA sequences
    • Embryological development
  3. Animal Clades
    • Metazoa – all multicellular animals
    • Sponges- no tissue level organization
    • Eumetazoans – animals with true tissues
    • Radiata
    • Radial symmetry, 2 tissue layers
    • Cnidarians
    • Bilateria
    • Bilateral symmetry, cephalization
    • Protostomes (Lophotrochozoa and
    • Ecdysozoa), Deuterostomes
    • (more on these later)
  4. Tissues
    • Tissues are groups of similar cells that carry
    • out a specific function (e.g., muscle)
    • Isolated from other tissues by membranes
    • Tissues form during embryological
    • development (germ layers)
    • Sponges are the only modern-day animals
    • that lack tissues
    • Individual cells in sponges
    • can be specialized, but they act
    • independently, are not organized into tissues
  5. Origin of Animals
    • Sponges and all tissue-containing phyla
    • arose from an ancient common ancestor without tissues (ancestral colonial choanoflagellate)

  6. Body Symmetry
    • Animals without tissues are asymmetrical (Sponges)
    • Symmetrical animals have
    • upper (dorsal) surface
    • lower (ventral) surface
    • 2 or 3 tissue layers (diploblastic or triploblastic)
    • Symmetrical animals can be either:
    • Radially symmetrical
    • Bilaterally symmetrical

  7. Animal Body Plans
    • Asymmetrical (sponges)
    • Radial (jellyfish)
    • Two tissue layers- ectoderm and endoderm
    • Bilateral (human)
    • “mirror image”
    • cephalization
  8. Body Cavities
    • Bilateral animals have
    • 3 tissue layers
    • Body cavities
    • Cavity is called a coelom (“space”)
    • Functions include
    • Hydrostatic skeleton
    • Protective and cushion the internal organs
    • They can allow organs to move
    • independently of the body wall
  9. Formation of Body Cavity: Gastrulation
    • The embryo divides until it is a hollow ball (blastula)
    • Through gastrulation tissue layers begin to form
    • The resulting gastrula is two cell layers thick
    • These layers are the ectoderm and endoderm

  10. To Coelom or Not to Coelom?
    What’s the big deal?

    • Advantages of having a coelom
    • Fluid cushions organs
    • Provides hydrostatic skeleton (earthworms)
    • Allows organs to move (e.g. heart beats) without deforming
    • Organism can grow larger due to “delivery
    • systems”
    • No coelom means…
    • No circulatory system so oxygen must diffuse
    • across body wall
    • These animals are limited in size

  11. Embryological Development
    • Protostome (“first mouth”)
    • body cavity forms within the space between the
    • body wall and the digestive cavity
    • Nematodes, arthropods, annelids, and molluscs
    • Deuterostome (second mouth”)
    • Body cavity forms as an outgrowth of
    • the digestive cavity
    • Echinoderms and chordates
  12. How are Coeloms formed?
    • Protostome
    • Blastopore becomes mouth
    • Deuterostome
    • Blastopore becomes anus

  13. Protostome Development
    • Two distinct evolutionary lines
    • Clade Ecdysozoa
    • Bodies are covered by an outer layer that is
    • periodically shed
    • Ex: arthropods, roundworms
    • Clade Lophotrochozoa
    • This group has a lophophore for feeding
    • One phyla passes through a trochophore larva developmental stage
    • Ex: molluscs, annelids, flatworms
  14. types of body cavities
    True Coelom- body cavity is completely lined with tissue derived from mesoderm. (annelids, chordates)

    False or Pseudocoelom- body cavity is partially but not completely lined with tissue derived from the mesoderm. (roundworms)

    No Coelom- no cavity between the body wall and digestive tract. (cnidarians, flatworms)
Card Set
Bio Animal Intro
Bio Animal Intro