PROTRACTILE MOUTHS 



creatures, for all alike feed upon living substances, 

 and the quantity of this food has nothing to do with the 

 activities that secure it; but they exhibit those activities 

 in a manner more sustained. They reveal themselves 

 as predatory creatures, whereas the microphagous 

 animals appear to hide their true nature. Many of 

 the former assert the fact with vigour and assurance 

 and develop new characteristics. 



In another tank now before me are a few cuttle-fish, 

 with oval bodies, heads with great eyes, and a circle 

 of tentacles with suckers. They swim along quietly, 

 undulating the fin which surrounds their sides, looking 

 like creatures on the prowl, their eyes for ever on the 

 look-out. When a possible victim presents itself, 

 even if it is a large one, they seize it with their long 

 tentacles, surround it, immobilize it, then cut it up 

 with their powerful horned beak and swallow it in 

 fragments. Near them in the same tank, lurking curled 

 up in a corner, are octopuses or devil-fish, belonging 

 to the same group in the class of cephalopod molluscs. 

 They spread out round them, moving hither and 

 thither, their flexible snake-like tentacles, waiting for 

 some victim to seize upon. If some rash crab comes 

 within reach, he is snapped up, enwrapped, held by 

 the suckers, and, in spite of the hardness of his shell, 

 cut up into little pieces by the chisel-like beak. In 

 order to get their food, these devourers of large prey 

 have special tentacles designed to facilitate that end. 

 And the crabs themselves, with other crustaceans, have 

 similar powers, for they use their claws to hold the 

 creatures upon which they feed. 



But this is not true of the fishes, whose fins are 

 incapable, except very rarely, of performing any action 

 but beating the water for swimming. As these fins 

 cannot grip, they cannot help directly in the process 

 of securing food. All they can do is to ensure a 

 rapidity of movement which enables the creature to 

 pounce upon its prey. The actual seizing is done by 



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