4o6 



THE WORLD OF ANIMAL LIFE 



limestone or chalk, like the piddock, but tunnels into solid timber, 

 such as the submerged portions of wooden piers and the hulls of 

 wooden ships. And in this- way it is often the cause of very- 

 considerable mischief. 



In one year only, at Plymouth, it caused damage to the extent 

 of no less than eight thousand pounds; and many a good vessel 



has been rendered 

 useless by its depre- 

 dations. The ruin of 

 the important dykes 

 of Holland has often 

 been threatened by 

 its operations. 



The ship - worm 

 does not eat the wood 

 which it cuts away, 

 but obtains its entire 

 nourishment from the 

 sea- water which is 

 continually passing 

 through its system. 

 It never seems to 

 cease burrowing, and 

 destroys the timber in 

 which it lives so com- 



Teredo or Ship-worm, and Fragment of Wood 

 bored by others 



pletely, that very often, in a large block of wood, there is scarcely 

 a cubic inch of solid substance. The walls between the burrows 

 are frequently no thicker than paper. 



As the animal drives its tunnel along, it lines it with a thin 

 coat of a shelly substance, just as engineers, when they are making 

 a railway tunnel, line it with a coating of brick. And it is 

 interesting to learn that Sir Isambard Brunei, to whose skill and 

 ingenuity we owe the famous Thames Tunnel, first conceived this 

 method of construction while examining the labours of the ship- 

 worm. 



It is found that wood is protected from the ravages of the 

 teredo by covering its surface with rows of broad -headed iron 



