PERILS AND ENEMIES OF MUSSELS 61 



period, the glochidia are subjected to another danger. 

 When fishermen take large numbers of infected fish from 

 the water they destroy many millions of glochidia. At 

 the end of the parasitic period, the tiny mussels fall to 

 the bottom of the river ; those which fall in mud are said 

 to perish, while those which fall on sand or gravel have 

 a chance to live. The small mussels, however, are con- 

 stantly exposed to many hazards and dangerous enemies. 

 When they reach maturity they are in less danger as 

 they are strongly protected by their heavy shells. Their 

 powerful adductor can hold the shells firmly closed and 

 they are thus enabled to resist the attacks of many ani- 

 mals which are strong enough to open the shells of small 

 young mussels. 



Probably the chief natural enemy of mussels is the 

 muskrat. These animals kill large numbers of them. 

 They usually carry them to the bank, where they open 

 the shells and eat the meats. Muskrats select the lady- 

 finger, pimple-back, monkey-face, or pig-toe varieties 

 usually and always take the younger ones, as they can 

 open them more easily. Sometimes the bank of a stream 

 is a solid network of muskrat tracks where large quanti- 

 ties of shells are gathered by them and left empty on the 

 shore. 



When the water is low, hogs do very much damage to 

 the mussel beds. They not only eat the ones that are 

 loose, but also root up any that may be partially buried. 

 A few hogs can destroy beds covering many acres in a 

 short time. They eat mussels of all sizes, as they are 

 able to break the strongest shells. 



