Exercise 12

• anterior - head end
• posterior - tail end
• dorsal - back side
• ventral - front side
• lateral - right and left
• proximal - near
• distal - far
• Symmetry


  Association of parts with respect to a plane or an axis of reference
• Types of symmetry


  • Radial
  • Bilateral
  • Biradial
  • Asymmetric
• Radial symmetry


  • State of having similar parts regularly arranged about a central axis (oral-aboral axis, basically mouth to anus)
  • Any plane passing through the center will divide animal into symmetrical halves
  • Example: starfish
• Bilateral symmetry


  • Only one plane divides the body into equal halves
  • Majority of animals
  • Example: mosquito
• Axes of reference

  • Antero-posterior / Longitudinal - head to tail
  • Medio-lateral / Transverse - left to right
  • Dorso-ventral / Sagittal - back to belly
• Planes


  • Longitudinal- Longitudinal + transverse
  • Sagittal- Longitudinal + sagittal
  • Transverse- Sagittal + transverse
• Segmentation


  Division of the body into a series of segments, may be external or internal
• Body regions


  • Head
  • Trunk
  • Thorax
  • Abdomen
  • Cephalothorax
  • Tail
  • Neck
• Appendages


  Extended outgrowths with functions in sensation, feeding, locomotion
• Cephalic appendages


  • Antennae
  • Eye stalks
  • Tentacles
  • Mouthparts
• Locomotory appendages


  • Arms
  • Legs
  • Wings
  • Fins
  • Flippers
  • Lobopods
• Locomotion without appendages


  • Pedal wave
  • Peristalsis
  • Undulatory
  • Wave-like
• Locomotion with appendages


  • Pedal
  • Swimming
  • True flight
  • Gliding
• • External Segmentation
  • Present in arthropods (head louse, american cockroach, crab, lobster, shrimp)
• • cephalothorax - present in crustaceans (shrimp, crab)
• • trunk - present in chordates (mammals, birds, amphibians, fishes)
• • neck - present in land animals
• • Cephalic appendages- only in invertebrates
• 1. paratoid gland
  2. nostrils
  3. eyes
  4. tympanum
  5. upper arm
  6. manus
  7. transverse plane
  8. sagittal plane
  9. thigh
  10. cloacal opening
  11. shank
  12. longitudinal plane
  13. pes
  14. forearm

  
• Bird

  • Symmetry - Bilateral
  • Segmentation - Internal
  • Body Regions - head, neck, trunk, tail
  • Appendages - wings, legs
  • Locomotion - true flight, gliding
• Earthworm

  • Symmetry - Bilateral
  • Segmentation - Internal, External
  • Body Regions - none
  • Appendages - none
  • Locomotion - peristalsis
• Beetle

  • Symmetry - Bilateral
  • Segmentation - Internal, External
  • Body Regions - head, thorax, abdomen
  • Appendages - wings, antennae, limbs, arms, mouthparts
  • Locomotion - true flight, pedal
• Snail

  • Symmetry - Asymmetrical
  • Segmentation - none
  • Body Regions - none
  • Appendages - tentacle, eyestalk
  • Locomotion - pedal wave
• Snake

  • Symmetry - Bilateral
  • Segmentation - Internal
  • Body Regions - head, tail, trunk
  • Appendages - none
  • Locomotion - undulatory
• Shrimp

  • Symmetry - Bilateral
  • Segmentation - Internal, external
  • Body Regions - cephalothorax, abdomen
  • Appendages - uropod, antennae
  • Locomotion - swimming
• Toad

  • Symmetry - Bilateral
  • Segmentation - Internal
  • Body Regions - head, neck, trunk, thorax
  • Appendages - limbs, arms, legs
  • Locomotion - pedal, swimming
• Starfish

  • Symmetry - Radial
  • Segmentation - none
  • Body Regions - central disk
  • Appendages - arms, tube feet
  • Locomotion - pedal
• Sponge

  • Symmetry - asymmetric
  • Segmentation - none
  • Body Regions - none
  • Appendages - none
  • Locomotion - none
• Turtle

  • Symmetry - Bilateral
  • Segmentation - Internal, external
  • Body Regions - head, neck, trunk, tail
  • Appendages - fins
  • Locomotion - swimming, pedal
• Human

  • Symmetry - Bilateral
  • Segmentation - Internal
  • Body Regions - head, neck, trunk, tail
  • Appendages - limbs
  • Locomotion - pedal, swimming