Symmetry

- Bilateral Symmetry: having a distinct left and right side

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Body Plan

Segmentation

         - Annelids were the first segmented animals.
                        
                        * Segmentation underlies the body organization of all coelomate 
                        animals except mollusks.
                       
                        * Each segment contains digestive, excretory, circulatory, and 
                        locomotor (movement) organs.

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Characteristics

            
            - Coelem: fluid filled cavity olcated in the mesoderm.

            - Organ Systems: includes a closed circulatory system,
           and excretory structures called nephiridia.           

            - Cerebral ganglion: the primitive brain of an annelid 
            located in an anterior (head) segment. 

            - Setea: external bristles of most annelids which provide 
            traction during movement.

            - Parapodia: fleshy appendages on the worms that don't 
            have setea (ie. fireworms).

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