They are normally found attacking submerged wooden structures in harbors, or 

 burrowing into rocks, coral, and mud on the ocean floor. Because of their ability 

 to attack varied materials from soft wood to hard rocks, it is anticipated that under- 

 sea construction materials which serve as a source of food and shelter to these animals 

 will be susceptible to attack and destruction. 



One of the early engineering materials exposed in the deep-sea environment 

 was the submarine cable. Numerous reports and articles have been published per- 

 taining to damages inflicted upon these cables at various depths, and an extensive 

 bibliography has been compiled by Clapp and Kenk. " Most of the attacks upon 

 submarine cables were confined to the coverings of jute and hemp, although a few 

 observers report attacks on the gutta-percha insulation of the cables by the mollusks 

 belonging to the family Teredinidoe . These attacks have occurred from depths of 

 a few feet of water to a depth of 7,200 feet. Roch' in his paper on Mediterranean 

 Teredos refers to Teredo utriculus obtained from a depth as great as 10, 000 feet. A 

 species of Xylophaga was found ranging from a few feet of water to 6, 000 feet or 

 more; some have been found burrowing into the insulation of submarine cables, 

 causing physical damage and short circuits. 



In a recent report, ° mention is made of a species of Martesia boring through 

 the outer solid-lead sheath and subadjacent insulation of an electrical conduit cable 

 (off the coast of Florida), producing a blowout which seriously interrupted urban 

 electrical service. 



Martesia striata has been responsible for attacks and penetration of solid-lead 

 sheathing of a submarine power cable (in Boca Ciega Bay, Florida) resulting in an 

 electrical short. The exposed lead sheathing was riddled with holes. Some holes 

 were about 6 mm in diameter and 2 mm in depth. In another instance, a 4-mm-thick 

 solid-lead sheath covered with two layers of asphalt-impregnated jute which served 

 as a bedding for a single layer of galvanized-steel armor wire was penetrated by 

 Martesia striata and Barnea truncata 300 feet from shore in 3.5 feet of water where 

 the bottom was muddy. 



Even concrete has not been immune to attack by marine animals. Inspection 

 of concrete-jacketed wooden piles in Los Angeles Harbor revealed the presence of 

 7 to 8 burrowing animals per square foot of concrete. Of 18 piles, 16 jackets were 

 found to be attacked by rock-boring animals such as Pholadidae penita , Platyodon 

 cancel lata , Lithophaga plumula , and Botulg talcata . Burrows in the concrete 

 averaged 1-3/4 inches in diameter. The concrete jackets, which had an average 

 thickness of 2-1/3 inches, consisted of cement mortar with no coarse aggregate. 



