New York Metropolitan Region and New Jersey
Freshwater Mussel Identification Handbook

Family Dreissenidae
Genus Dreissena

    
Status: Two species of genus Dreissena occur in North America. Both are established invasives.
D. polymorpha, the zebra mussel, is abundant along the eastern seaboard from Quebec to Georgia, 
and its range reaches west through the Great Lakes to Minnesota, and south to Louisiana and 
Oklahoma. It is not recorded from New Jersey. The zebra mussel has proliferated rapidly since its 
introduction in 1986, colonizing habitats occupied by various native species whose populations have 
subsequently been reduced or displaced. The other NA species of Dreissena, D. bugensis, does not 
occur in the metro area. Its range is confined to the eastern Great Lakes and St. Lawrence River.  
For a description of D. bugensis go to: Extralimitals



    
Species Summary

    
Dreissena polymorpha (Pallas, 1771) zebra mussel
Features:
  size: 40mm
  beak: pointed
  color patterns: dark, irregular stripes
  shape: triangular in cross section, ventral surface flat, outer margin curved 
  evenly;  "D"-shaped, angled posterior end  
  shell features: acute shoulder laterally across ventral surface; attaches to
  substrate by fibers (byssus)
  teeth: absent; valves attached by internal hinge ligament

Status:
  abundance: abundant
  status: US, NY, NJ, CT: not legally protected

Distribution:
  N.A. distribution:Quebec (Canada) and the lower St. Lawrence River west 
  to the Great Lakes basin and Minnesota, south to Georgia on the Atlantic
  slope, and in the Mississippi River basin to Louisiana and Oklahoma; 
  current US range includes the states of: AK, AL, CT, IA, IL, IN, KY, LA, MD,
  MI, MN, MO, MS, NY, OH, OK, PA, TN, VT, WI, WV
  present metro distribution: NY: lower Hudson River watershed
  other regional localities: NY: Erie Canal to the Mohawk River (upper Hudson River 
  watershed), Lake Erie,  Lake Ontario,  St. Lawrence River, Susquehanna River watershed,
  upper Hudson River; CT: Twin Lakes (Housatonic River watershed) Map

Life History:
  habitat: large rivers and lakes on any hard substrate; displays some tolerance
  to salinity, limited tolerance to low calcium and acidity  Habitat Photo
  hosts: none required

    
 Key Features Refresher
Anterior and Posterior
   Beak and Beak Sculpture   Color Ray
 Hinge Teeth   Length, Width, Height, Profile, Silhouette
Growth Line  Posterior Ridge and Slope
Shell Shape

Plates
D. polymorpha

    


     
 

    
 left view

    
right view

     
 

     
 

    


    


    
dorsal

    
profile


     
 

     
 

    
 

    
 

    
teeth absent 

    
byssal thread 

     
 

     
 

    
 

    



    
 flattened ventrally; D-shaped posterior end

    
strong dark banding 



    
View other genera
Alasmidonta  Anodonta  Corbicula   Dreissena
   Elliptio  Lampsilis  Lasmigona  Leptodea   Ligumia   
Margaritifera  Pyganodon  Strophitus  Utterbackia