Phylum: Mollusca (Snails, slugs and octopus)

   ●    Bilateral symmetry with significant modification.

• An extraordinarily varied group which has developed some radically divergence from other groups.
  
  
• Phylogenic studies place them closer to annelids than other groups.
  
  
• Body plan has three major features:
  
  
• Foot, a muscular structure used for movement and burrowing.
  
  
• Central visceral mass containing all the organ structures (separate mouth and anus)
  
  
• Mantle a folded membrane structure that can surround other tissues and create a cavity containing a gill.
  
  
• The mantle frequently secretes a calcareous shell.
  
  

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