Molluscs 151 



on their siphon, which is situated just 

 beneath the head and exhale water 

 previously drawn in to supply the gills 

 with oxygen. By exhaling with extra 

 force the animals can drive themselves 

 backwards through the water at a very 

 high velocity, swimming simply by a 

 process of " hurried breathing." The 

 octopus of our shores is not dangerous. 

 Not only is it a comparatively small 

 animal, its body measuring seldom more 

 than eight inches and the span of arms 

 two to three feet, but it is further rarely 

 in an aggressive mood. It lives entirely 

 on shell-fish and is the arch-enemy of all 

 crab, lobster and oyster dealers. A fair- 

 sized British octopus will capture twenty 

 crabs at a sitting, storing them away 

 amongst its ample folds until needed. 

 When hungry it simply disarticulates the 

 crab, having previously injected it with 

 a poisonous secretion, and a heap of crab 

 shells often marks the entrance to its 



