When they reach maturity stalked barnacles 

 of this type attach themselves to ships 

 and floating timber. The more common acorn 

 barnacles are stalkless and are found in the 

 millions coating the rocks between tide 

 lines. All barnacles are crustaceans. 



Like the mussel and oyster, the octopus is 

 a mollusc (meaning soft bodied). But its 

 class (Cephalopoda) is higher on the 

 evolutionary scale. Like other cephalopoda, 

 the octopus has an eye as highly developed 

 as that of many land vertebrates. 



In 1236 a shipwrecked sailor started this 

 form of mussel culture in Brittany. The 

 young mussels are placed on the bottom rack 

 where they are bathed by tidal water. As they 

 grow older, and are able to stay out of water 

 longer, they are moved to successively higher 

 levels. After a year or so on the higher levels 

 the mature mussels are ready for marketing. 



Like certain other molluscs, the oyster and 

 mussel (pelecypods) produce pearls when a 

 grain of sand or some other foreign body is 

 embedded in their soft body. To protect 

 itself from the irritation the animal secretes 

 layer upon layer of nacre, "mother-of-pearl." 



90 



