22 REPORT OF COMMISSIOXERS OF IXLAXI) FISHERIES. 



found to be water tight. If such a shell, recentlj^ opened by the 

 star, be filled with water, and the valves held between the thumb 

 and the finger, the water will not leak out even though the shell 

 be violent!}^ shaken. 



In mussels which have been opened by the star-fish there is 

 no trace of any chipping at all. The reason is plain : the valves 

 of the shell come together firmly at the very edge ; there is no 

 delicate fringe at the margin. The same is, of course, true of the 

 quahaug. Nevertheless the quahaug and mussel are readilj^ 

 opened b}^ the star-fish. It follows, therefore, that if the star-fish 

 gained entrance to the soft oyster by chipping off the edge of the 

 shell, a different process must be adopted in entering a mussel or 

 quahaug, to say nothing of the snails which it also devours. 



The credit of solving the i)roblem— How do the star-fish open 

 oysters? — is due to Dr. Paulus Schiemenz, of Hanover, Germany, 

 who carried on his investigations at the famous Zoological Station 

 at Naples. The problem was suggested to him bj^ Collins' report 

 of the enormous injury done to the oyster beds by the star-fish in 

 Long Island Sound. The i)rocess is briefly as follows : — The star- 

 fish so covers his victim that the suckers on the under side of the 

 arms are distributed i^art to one valve, part to the other, and the 

 remainder frequently to some surrounding object. (In the case of 

 the snails the suckers are attached to the operculum and to the 

 shell). The suckers are very numerous and stick fast, and a 

 tendency to straighten the arms results in a constant pull upon 

 the shells in opposite directions, which, if strong enough, would 

 open the shells. It is true that a star-fish is not strong enough to 

 open an 03'ster or quahaug immediately in this manner, but he 

 can and does fatigue his prey. The constant, steadj^ pull in oppo- 

 site directions soon fatigues the muscle which holds the shell to- 

 gether, and the oyster or clam presently gapes open. The oyster 

 can overcome the strong pull for a short time but not a weaker 

 pull for a long time. The same principle is well illustrated in the 

 case of the i)eri winkle or conch. If a string be tied around the 

 "foot" so as to give a good hold on the animal, a strong man can- 



