THE SEA BOTTOM 69 



Pecten maximus, up to five inches across, to species with not 

 more than a tenth of this diameter. 



The octopus is an inhabitant of this region (and of 

 shallower water in the more southern waters, being found on 

 the shore in the Channel Islands). It prefers rocks, hiding 

 in cracks and holes, for it can flatten its body so that it 

 enters narrow slits in the rock, and darts out on fish and 

 crustaceans as they swim by unsuspectingly. The common 

 British species, found in numbers along the south coast, is 

 the Lesser Octopus (Eledone) (Plate 27), which differs 

 from the larger species (Octopus vulgaris) in its smaller size 

 and the possession of a single, instead of a double, row of 

 suckers on each of its eight arms. The latter is not common 

 on British shores though it occasionally comes into the 

 English Channel from further south during hot summers, 

 doing great damage to the crab and lobster fisheries. 

 In spite of its ungainly appearance, the octopus is capable 

 of rapid and graceful swimming and possesses a larger 

 brain and more highly-developed eyes than any of the 

 other Invertebrate animals ; indeed, in the complexity 

 of the latter organs it is the equal of ourselves. 



Amongst the animals we have not yet mentioned are 

 various lesser known but interesting creatures. In some 

 parts the sea bottom is covered with luxurious growths of 

 the sea mats, the most conspicuous being the Ross (Lepralia), 

 which forms a massive skeleton consisting of many delicate 

 limy sheets, while two others, Cellaria and Flustra, are 

 frequently taken in great quantities in the dredge. Sea 

 squirts of various kinds are found but are not so abundant 

 as on the shore or in the Littoral zone. 



Deep-Sea Zone 



The fauna of the Continental Slope — the Continental 

 Deep-sea zone — is most easily studied in the Norwegian 



