THE SINISTER GEPHALOPODS 



discovered that a sucker with a diameter of one-tenth of 

 an inch — sHghdy larger than a pin's head — needed a 

 pull of two ounces to detach it, while one with a diameter 

 of a quarter of an inch required six ounces. A large 

 octopus has about 240 suckers on each of its eight arms, 

 making a total of 1,920. This means that a force of 

 720 lb. (more than a quarter of a ton) would need to be 

 applied to break the hold of a common octopus with a 

 span of five feet, and even greater force to detach one of 

 the bigger creatures, the arms of which would probably 

 tear away first, leaving the suckers still attached. 



Aquarium officials have sometimes under-rated the 

 power in an octopus's arms. On one occasion at the 

 Brighton Aquarium, before precautions were taken, an 

 octopus pulled up the waste-valve of a tank during one 

 night, releasing all the water, so that the tank contained 

 only a mess of dead octopuses in the morning. 



The octopus uses its suckers to explore surfaces, or the 

 body of its victim, a fact which shows that they are not 

 merely gripping devices but sensitive organs. Having 

 gripped its prey, the animal can kill it in either of two 

 ways, by means of its rounded beak or by administering 

 poison. The former method indicates that the creature 

 has an uncanny knowledge of just the right place to use 

 its powerful sharp instrument as it holds any particular 

 animal. 



When not in use the beak is retracted and hidden, but 

 as the octopus pinions a crab (for instance) in its deadly 

 stranglehold, it turns the crab so that its abdominal plates 

 are towards its mouth and dispatches the crustacean 

 quickly with a sharp crunching action. 



With many octopuses poison is used, and when this 

 happens (again taking a crab as an example) the victim 

 is seized and drawn into the parachute-like mem- 

 braneous folds of the octopus's web, where the poison is 

 injected. The venom is mainly secreted from the 

 creature's posterior salivary glands, and kills the victim 



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