Biology is life

PHYLUM PLATYHELMITHES !!!
 

 

UNIQUE CHARACTERISTIC

 

 

 

 

• In Greek means ‘flatworms’
• Living in marine, freshwater & damp terrestrial habitats.
• Flatworms are ciliated, soft-bodied animals
• Mostly parasitic, live in at least 1 host
• Others are free-living 

      -Germ layers : triploblastic,the mesoderm contributes to the development of muscles and reproductive organs

       -Body cavities : acoelomates (no body cavity)

       -Bilaterally symmetrical

• Their bodies are  flattened between dorsal & ventral surfaces
• Digestive system with single opening (has mouth but no anus)

 

• Body muscle cannot be contracted
• Locomotion : swimming 
• Lack circulatory system
• Gas exchange occurs by diffusion
• Have an excretory and osmoregulatory system 

           -Use flame cells/ protonephridia located on the side branches

• Simple nervous system

           -Eyespot can distinguish light from dark

• Reproduction–sexual or asexual (regeneration)
  -Mostly are hermaphrodites (monoecious)
  
  

  

  Flatworm anatomy

  
  

  
  

  
  

  
  

  
  

  
  
  
  
   3 Classes of Platyhelminthes :
  1. Class Cestoda (tapeworm :Taenia sp.)
  
  
  
  

  
  

  
  

  

  
  

  • parasitic
  • adult worms live in vertebrates; digestive tract (Endoparasite)  
  • the body consists of: 

            i) head @ scolex

               -with hooks or suckers to anchor the worm to the intestinal lining
  
  
  

  
  

  
  

  2. Class Trematoda (flukes, Fasciola sp.) 

   

   

  

   

   

  
  

  • Parasite on sheep, cattle and occasionally humans.
  •  The gland cells secrete materials which protect the parasite against the host’s antitoxin
  • Endoparasitic, living in bile ducts. 
  • Anaerobic respiration
  
  
  
  
  

  3.Class Turbellaria (planaria, Dugesia sp.)

  
  
  
  

  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

   

  
  

  
  

  
  

  
  

  
  

  
  

  • Free living and ciliated with few parasitic forms 
  • They are mainly marines but can also be found in fresh water

  
  

  
  

  
  

  
  

  

  Life cycle of the pork tapeworm, Taenia solium