A1.02 Destructive Species of Marine Borera 



1, DeflMtlon. For centuries the terms "shipworm" and 

 "plleworm" liave teen applied to various marine 'boring organisms, 

 especially Teredo, which have heen ohserved "boring Into wood 

 suTmerged in salt water. In this report, the generic term "marine 

 "borer" Is used to designate any of the several hundred species of 

 meirlne Invertebrates which hore Into tlmher, low-grade concrete, soft 

 stone, or other nonmetallic materials in salt water. 



All of the inrportant species of marine "borers "belong to one of 

 two families: the mollusca, a phylum of the animal kingdom which 

 Includes the limpets, snails, oysters, clams, and cuttlefish; and the 

 crustacean family, which includes cra'bs, lo'bsters, and shrimps. Adult 

 "borers considered in this report range in size from the minute to those 

 approximately one inch in diameter and several feet in length. 



f 2. The Molluscan Borers . The two important species of destructive 



mollusca are the Teredinldae , the most widely distri"buted and most 

 destructive, including the well-known Teredo and important genera such 

 as BanMa and Lyrodus ; and the Pholadldae , a family of "bivalve "borers 

 which includes some very destructive clam- like "borers. Mollusca not 'so 

 well-known are the Martesla , Xylophaga , Lithodomus , Zlrphae , and Petricola . 



a. The Teredinldae are generally found "boring into tim"ber, 

 "but have "been o"bserved working into asphalt, "bakelite, neoprene, manila, 

 •^ sisal, and various plastics. In their larval stage. Teredo navalis and 

 kindred marine forms are free- swimming. This stage lasts, in the case of 

 T. navalis , only one or two days, since they are expelled hy the parent 

 as fully developed em"bryos; whereas Bankia , spawned as minute eggs, roll 

 around in the water from two to four weeks "before their larval stage is 

 over. During this period, the animal appears to "be not too different 

 from other "bivalve larvae. At the end of this period, the larvae, now 

 perhaps l/k mm in length, which lodge on sulta"ble surfaxses, develop 

 into a quite different form and "begin to "burrow into the material. The 

 "body elongates into a worm- like shape of which only the head is covered 

 "by the hinged shells; the latter, edged with rows of microscopic denticles, 

 now constitute the "boring tool. 



The "borer's tall is securely attached to the wall of the tunnel 

 it is "boring, close to the entrance. As the tunnel goes deeper into 

 the material, the shells and "body of the "borer "became longer and grpw 

 rapidly in diameter, some species attaining a diameter of l/2 inch or 

 more. Teredo longer than four feet have "been reported; many two-foot 

 specimens have "been repently found. As "boring progresses, the entrance, 

 hole does not increaso much in size, a situation which imprisons the- 

 "borer in its tunnel, as the tunnel "becomes partially lined with a lime 

 deposit. 



