Protostomes

• Acoelomates
• Pseudocoelomates
• Mollusks
• Annelids
• Arthropods & kin

Acoelomates

Phylum Platyhelminthes

• Flatworms
  
  
• Bilaterial symmetry, cephalization
  
  
• Triploblastic
  
  
• Well-developed organs
  
  
• Centralized nervous system
  
  
• No anus
  
  

• Class Turbellaria
  
  
  • Mostly freeliving, marine
    
    
  • Photos
    
    
  • [Fig 33.10]
    
    
• Class Trematoda
  
  
  • Flukes
    
    
  • All parasitic
    
    
  • Photos
    
    
  • [Fig 33.11]
    
    
• Class Cestoda
  
  
  • Tapeworms
    
    
  • All parasitic
    
    
  • Specialized body plan
    
    
    • Scolex
      
      
    • Proglottids
      
      
  • [Fig 33.12] [Photo]
    
    

[ Index ]