THE OYSTER. 91 



and the presence of oysters, but the fact that no oysters 

 are found upon the hard, firm sand of the ocean beach 

 shows that this is not the case. As a matter of fact, 

 they thrive best upon a soft bottom. They feed upon 

 the floating organic matter which is brought to them 

 by the water, and this food is most abundant where 

 the water flows in a strong current over a soft organic 

 mud. When the bottom is hard there is little food, 

 and this little is not favorably placed for diffusion by 

 the water, while the water which flows over soft mud 

 is rich in food. 



The young oysters which settle upon or near a soft 

 bottom are therefore most favorably placed for pro- 

 curing food, but the young oyster is very small so 

 small that a layer of mud as deep as the thickness of 

 a sheet of paper would smother and destroy it. 



Hence the young oysters have the habit of fastening 

 themselves to solid bodies, such as shells, rocks or 

 piles, or floating bushes, and they are thus enabled to 

 profit by the soft bottoms without danger. 



Owing to the peculiar shape of an oyster shell, some 

 portions usually project above the mud long after 

 most of it is buried, and its rough surface furnishes an 

 excellent basis for attachment. It forms one of the 

 very best supports for the young, and a little swimming 

 oyster is especially fortunate if it finds a clean shell to 

 adhere to when it is ready to settle down for life. 

 Then too, the decaying and crumbling shells are 

 gradually dissolved in the sea water, and thus furnish 

 the lime which the growing oyster needs to build up its 



