CHAPTER XIII 



THE SINISTER CEPHALOPODS 



UNTIL squids can be observed more closely in 

 their natural surroundings, man's knowledge of 

 them will necessarily remain limited, but enough 

 is known to justify behef that they are among the most 

 extraordinary of all sea creatures. 



They are the most numerous of all cephalopods, which 

 are the most highly organized of all molluscs. Cephalo- 

 pods are therefore relatives of the oyster, the snail, the 

 winkle and the whelk. All molluscs are invertebrates — 

 backboneless animals to which the majority of all living 

 species belong: backboned creatures like man himself 

 forming only five per cent of the whole. 



All molluscs have soft spineless bodies, partly covered 

 with mantles of skin. Nearly all of them are shelled 

 animals, and the gastropods have toothed ribbons which 

 vary considerably in structure but are similar to the 

 whelk's rasp strip with its replaceable teeth. 



The cephalopods we know today are found in abund- 

 ance in all the world's seas, yet their numbers have 

 diminished considerably since primeval times, when 

 there were far more in the oceans. It is probable that 

 only a small minority of them became fossilized, so that 

 the fossil records, preserving vestiges of more than 10,000 

 species, give us only a partial and fragmentary concep- 

 tion of the enormous number of species which swarmed 

 in the oceans before man. 



There are now only about 650 species of cephalopods 

 known to us. Considering their ancient lineage they are 



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