Fig. U. Mussels (Mollusks) . 



MOIXUSKS (Shellfish or Bivalves) 



This group includes the familiar edible clams, 

 oysters, and mussels (fig. 4) . All of the forms 

 important in fouling are characterized by having 

 paired or "tvo-valved" shells. They are general- 

 ly attached to the hull at the region of the 

 hinge of this double shell. Very many shapes are 

 found, but all are characterized by this paired 

 hinged shell, a structure not found in any other 

 group of fouling organisms. Mollusks may grow to 

 a large size, and since they may become attached 

 to other Mollusks which in turn are attached to 

 the hull, they frequently build up a large bulky 

 mass of fouling. 



14 



