32 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [BuU. 



pull at right angles to the valves that the shell can be opened. 

 Tlius a starfish finds it quite impossible to open a bivalve when 

 held with its arms outstretched beween two glass plates, even 

 when there is plenty of room for it to carry the bivalve about 

 with it. 



After the resistance of the adductor muscle of the mollusk 

 is completely overcome, the stomach of the starfish is turned out 

 between the two valves of the shell, and the soft body of the 

 mollusk is then digested as in the case of a smaller object, leaving 

 nothing behind except the cleaned and empty shell. Sometimes 

 two or more starfish participate in devouring a single large 

 oyster. 



The processes concerned in the digestion of a large mollusk 

 are so complete in the starfish that little if any refuse remains. 

 But in the case of animals sufficiently small to be taken directly 

 into the stomach, through the mouth, the indigestible food re- 

 mains are thrown out of the mouth again. For this reason the 

 opening of the intestine on the aboral surface of the body is very 

 small, and serves merely for the discharge of fluid waste ma- 

 terials secreted by the glands cormected with it. 



When food is abundant the starfish often devours an 

 enormous quantity, and growth is correspondingly rapid. The 

 observations of Mead, on the voraciousness of young starfish, 

 as noted on page 57, show that as many as 56 clams, some 

 of which were as long as an arm of the starfish, could be 

 devoured by a single starfish within a period of six days. 



On the other hand, in case food cannot be secured, the star- 

 fish is able to survive a fast of several months without apparent 

 discomfort. In the latter case, however, no growth whatever 

 occurs until food is again secured. 



NATURAL ENEMIES 



It would seem that an animal so well protected by its spiny 

 skin and abundant pedicellarise, would be largely exempt from 

 the attacks of other carnivorous animals of the sea. And in the 

 adult condition such is actually the case. Occasionally one star- 

 fish when pressed with hunger will devour another of the same 

 species; fishes of various kinds destroy mutilated individuals 

 and probably large numbers of young. Various species of birds 



