1.%20Asymmetrical,%20Radial,%20or%20Bilateral

1
Patterns of Organization

• 1. Asymmetrical, Radial, or Bilateral
• 2. unicellular, Diploblastic, or triploblastic
• 3. Acoelomate, Psuedocoelomate, or coelomate

2
The Three Arrangement of Appendages

• Asymmetrical appendages are arranged in no set
  pattern.
• Examples sea sponges
• many protists
• These animals do not have
• complex sensory,
• communication, or
• locomotor functions.

3
Arrangement of Appendages

• Radial appendages are arranged in a circular or
  spherical pattern
• Examples octopus, sea stars, sea urchins, etc.
• Advantages can sense predators or prey coming
  from any direction.
• Disadvantages these animals are usually
  sedentary or have minimal locomotion.

4
Arrangement of Appendages

• Bilateral Animals with a distinct left and
  right side, front and back, and head and foot
  regions.
• Examples us, dogs, whales, squirrels, tigers,
  etc.
• Advantages have excellent locomotion.
• Disadvantages can only see the world primarily
  in one direction.
• The evolution of a distinct head with many
  sensory inputs is called cephalization.

5
Unicellular, Diploblastic, or Triploblastic

• Unicellular the whole animal is just one tiny
  cell. Example protists
• Diploblasts Animals who only have an endoderm
  and ectoderm, no mesoderm. Only have tissue
  level organization, no real organs. Examples
  jellyfish, hydra. Picture
• Triploblasts animals with all three layers of
  tissue and true organ systems. Usually display
  bilateral symmetry. Examples us, horses, cows,
  llamas, etc.
• Triplobalsts are further classified based upon
  whether or not they have an internal body cavity!
• Next slide

6

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7
Advantages of Having an Internal Body Cavity

• Body cavity a fluid-filled space in which the
  internal organs can be suspended and separated
  from the body wall.
• 1. provides more room for organs to grow and
  develop.
• 2. allows for an increase in overall body size.
• 3. provides more surface area for gas, nutrient,
  and waste exchange.
• 4. acts as a hydrostatic skeleton.

8
Acoelomates, Pseudocoelomates, Coelomates

• Acoelomates triploblasts with no body cavity,
  flatworms.
• Pseudocoelomates triploblasts with a body
  cavity that is NOT connected to their mesoderm,
  roundworms. Pseudo means false.
• Coelomates triploblasts with a body cavity that
  IS connected to their mesoderm, most animals.