HABITS OF MARINE ANIMALS. 11 



We have also to take care to close the shutter securely above 

 the tank, for twice we have found, after a short absence, one of 

 the Octopus crawling excitedly about the floor like some monstrous 

 spider. 



Usually they are fed upon the common green Shore Crab 

 (Carcinus), three or four daily — but they are far from being 

 fastidious. If a few limpets be thrown in, they dart from their 

 lairs and pounce upon them in a way which seems very like the 

 turning of a somersault. Cockles, mussels, whelks — all are welcome 

 and quickly devoured. As a rule the detritus of shells is thrown 

 away within a couple of hours or less. In the case of Crabs, 

 the carapace and endophragmal system are picked beautifully clean 

 and are quite unbroken — the limbs too are separated and usually 

 broken at the principal joints. 



Limpets are the most badly cleaned, as there is generally a 

 ragged ring of torn membrane left half-way up the inner surface of 

 the shell. 



Apparently any moving, object — barring fish — is seized and 

 tested for food. Several times I have thrown white pebbles in and 

 in all cases, when hungry, the animals have darted out and drawn 

 them to the mouth. It may be that this habit is not a natural 

 one but is induced by the method of feeding by throwing the food 

 into the tank — but whether or not this be so, I have little doubt 

 that it is by sight and not by scent that the Octopus hunts. 



The Octopus usually, but not invariably, darts out upon the 

 prey. Often enough, if the object — say a crab — run within reach, 

 the Octopus leisurely casts out one of its long arms — as a rod- 

 fisher does his line — and lets the delicate tip touch lightly the 

 carapace of the prey. Lightly it touches, but none the less securely 

 is the crab caught. Some of the suckers have come into play. 

 Often a second arm is then thrown out and some of the terminal 

 sucking discs of this attached. Then the animal is slowly drawn 

 to the mouth to be devoured at leisure, and strangely enough, the 

 Crab almost invariably makes not the slightest resistance. It is as 

 though stupefied and rendered helpless by terror — or is it that it 

 feels powerless to resist ? Once one of the Crabs thrown in, did elect 

 to resist. It snapped viciously at the delicate arms, and surprised, 

 the Octopus cowered down, letting go its hold. Instantly the Crab 

 scurried away to climb up the tank side as far as possible out of 

 reach of the foe. Several times in the course of succeeding days 

 one or other of the Octopus tried to snare it, but with similar result 

 as the Crab always made a stout resistance. At last one day it 

 was mastered and we have never since seen a similar instance of 

 fight on the part of Crabs. 



