Home > Flashcards > Print Preview

The flashcards below were created by user crimsonblaze on FreezingBlue Flashcards. What would you like to do?

  1. Platyhelminthes: Symmetry
  2. Platyhelminthes: # Germ Layers
    • 3 (acoelomate, true organs, no body cavity)
    • have ecto, meso, endoderm
    • evolution of mesoderm important because it produces muscle tissue
    • trues organs with solid mass of mesodermal parenchyma cells surround organs
  3. Platyhelminthes: Metamerism
    some internal
  4. Platyhelminthes: Coelom
  5. Platyhelminthes: Skeletal System
    • none but have...
    • hydraulic skeleton - gastrovascular fluid
    • longitudinal and circular muscles
  6. Platyhelminthes: Cephalization
    • Some (eyespots, brain)
    • cephalization: nervous system concentrated towards one end of organism => becomes head region
  7. Platyhelminthes: Nervous System
    • nerve ladder, eyespots
    • organized like a ladder w/ two lateral cords connected by transverse cords
    • some cephalization w/ sensory association
    • motor neurons
    • pigmented eyespots sensitivity to light but no imaging
  8. Platyhelminthes: Digestive System
    • pharynx leading to 3-branched GV cavity
    • cestodes: none (absorb from host)
    • GVC consists of mouth, pharynx, and 3 branched intestines
    • extends through mouth during feeding and secretes digestive enzymes
    • muscular contractions of pharynx pulls food into mouth
  9. Platyhelminthes: Excretory System
    • protonephridia w/ flame cells: regulate ion balance (osmoregulation)
    • cilia line the blind ended tubes (protonephridia) that open to outside -> create negative pressure to pull fluid into tube -> expelled
    • undigested food expelled out mouth
    • nitrogenous waste diffuses into surrounding environmenta
  10. Platyhelminthes: Reproductive cycle
    • monoecious
    • asexual, via regeneration when cut => budding in some
    • sexual - most hermaphroditic with cross-fertilization
  11. Platyhelminthes: Locomotion
    • swimming via cillated ventral surface
    • outer circular and inner longitudinal muscle contraction beneath epidermis
  12. Platyhelminthes: Classes
    • Turbellaria: free living (eg. Dugesia)
    • Tremetoda: flukes (parasitic)
    • Cestoda: tape worms (parasitic)
  13. Platyhelminthes: Notes
    • acoelomate and lack true body cavity (coelom)
    • 80% parasitic
    • 550 mya
  14. Platyhelminthes: Body Layers
    • Epidermis -> Circular muscle -> Longitudinal muscle -> Parenchyma -> (dorsalventral muscles) -> (testes and oviduct) -> (excretory canal/ protonephridia) -> 2x(gastrodermis->GVC) on each side
    • Epithelium -> Pharyngeal sheath -> Pharyngeal cavity -> Epithelium -> Circular muscles -> Longitudinal muscle -> Gastrodermis -> Pharyngeal lumen

Card Set Information

2011-07-28 15:10:48

Show Answers:

What would you like to do?

Home > Flashcards > Print Preview