162 Our Food Mollusks 



to grow. Figure 43 well illustrates this condition of 

 affairs. At the right, appear the gaping shell edges of 

 an unfortunate that has succumbed to the extreme neigh- 

 borliness of mussels and barnacles. It may easily be 

 imagined after one has by experience measured the force 

 necessary to tear the muscles away from their attach- 

 ment, what a great task of culling is before the oyster 

 culturist whose beds have become infested with these 

 bivalves. 



The boring sponge is another animal that finds lodg- 

 ment on the oyster shell, and injures its host indirectly. 

 Cliona sulphurea is a sponge mass sometimes six inches 

 in diameter at its base, attaching by strands of root-like 

 tissue that excavate channels within the substance of 

 the shell. While this is not done with the purpose of 

 using any part of the oyster's body for food, the honey- 

 combed shell may accidentally be perforated, making it 

 necessary for the oyster to consume all of its energies in 

 secreting new shell substance, or the shell may break, ex- 

 posing the inner body, which leads to death. Cliona oc- 

 curs frequently enough in northern waters, in the Chesa- 

 peake, in the Carolinas, and in the Gulf, to be recognized 

 as a foe to the oysters. 



In a similar manner the shell of the oyster is per- 

 forated and weakened by the boring clam (Martesia 

 cuneiformis) in the Gulf of Mexico. This creature in 

 infancy bores into the shell and excavates a chamber 

 which is used as a dwelling place. A few of these ani- 

 mals infesting a shell make it as fragile as when bored by 

 the sponge Cliona. 



In brackish and salt water alike, there are almost 

 everywhere certain sea-weeds that attach to objects in 

 the water, such as stones or shells, and produce great 



