Enemies of the American Oyster 151 



individual. Its locomotion is accomplished by thrusting 

 out a number of the sucker feet in a definite direction 

 and attaching them by their ends. The feet may be ex- 

 tended an inch or more. After attachment these con- 

 tract, other feet that have been tenaciously holding to 

 the bottom at the same time detaching, and the body is 

 slowly pulled along. Thus, many feet, acting independ- 

 ently, reach out in the direction of locomotion, attach, 

 and then exert a pull by contracting, while all the time 

 other feet that have already contracted loose their hold 

 and then reach out again. Slow as these movements 

 are, they result in migrations of considerable extent, 

 that often surprise and trouble the oyster culturist. 



One other anatomical feature is of interest in this con- 

 nection. Nearly the entire interior of the central disk 

 of the body is occupied by the stomach, while the arms, 

 or rays, are nearly filled by great glands that secrete a 

 large quantity of digestive fluid. The starfish feeds 

 principally on barnacles and bivalve mollusks. The 

 mouth, merely an opening unprovided with teeth, and 

 capable of expanding to a diameter of little more than 

 half an inch, even in large specimens, is not intended 

 to receive the bodies of animals preyed on. Sometimes 

 however, very small mollusks are taken into the stomach, 

 shell and all, but probably not often. Without teeth or 

 other organs for breaking the shell, and with a small 

 mouth — merely an opening through a muscular mem- 

 brane — how is it possible for a starfish to devour an 

 oyster as large as itself? 



Various opinions have been expressed on the matter. 

 It has been supposed that the starfish reaches the soft 

 parts of the oyster by inserting some part of its hard 

 body between the valves so as to keep them wedged open. 



