C\Cc 



The European Pileworm 



A Dangerous Marine Borer in Barnegat Bay, New Jersey 



by 

 Thurlow C. Nelson, Ph.D. 



March 1, 1922 



Most of us think of clams, oysters, and other bivalve molluscs as 

 animals excellent to eat, and hence as of great value to man. So 

 indeed they are, but just as among some other groups of animals 

 which are mainly beneficial, so among the bivalve molluscs there are a 

 few dangerous pests. The so-called "shipworms,'* marine boring 

 molluscs, have been known for centuries. These curious animals are 

 not worms, as many people believe, but bivalve molluscs closely related 

 to the common clams. The necessity for protecting the bottoms of 

 sea-going vessels from their attacks has long been recognized. 



Destruction by the Pileworm 



Until recently the attacks by marine borers upon wooden structures 

 in this state have been confined to those of the relatively slow-growing 

 native species, Bankia fimbriata (Xylotrya fimbriata, Jeffries), which 

 has done comparatively slight damage. During the past summer, 

 however, there appeared in Barnegat Bay, N. J., the European pile- 

 worm, Teredo navalis, 1 a pest which for centuries has literally ravaged 

 the coasts of Holland, England, and Scandinavia, destroying dikes 

 and other marine structures with great rapidity. A short time ago 

 this mollusc was in some manner introduced into San Francisco 

 Bay, California, where in the last two years it has extensively de- 

 stroyed piling and other marine structures entailing a loss of millions 

 of dollars. To show something of the rapidity with which Teredo 

 navalis multiplies, and the swiftness with which great marine struc- 

 tures are literally wiped out by its activities, a brief history of its work 

 in San Francisco Bay will be instructive. 



From the Report on the San Francisco Bay Marine Piling Survey 

 for 1921 (3), we learn that the European pileworm was first discov- 

 ered in San Francisco Bay in 1914 by A. L. Barrows. For the next 

 five years it did little damage, but suddenly, in 1920, coincident with 

 a period of unusually low rainfall, the attacks of this mollusc became 



iSome doubt has been expressed as to whether this form, is really Teredo 

 navalis, of European waters, or is some native species of Teredo. Our mate- 

 rial has been sent to Mr. W. F. Clapp, of Harvard University; to Dr. W. T. 

 Caiman, of the British Museum of Natural History, and to Dr. Ed. Lamy, 

 Museum D'Historie Naturelle, Paris. The identification given in each case was 

 Teredo navalis, L. Dr. Caiman writes that our specimens "do not differ more 

 from the specimens labelled T. navalis in our collection than the latter do from 

 one another." The writer wishes to express his thanks to each of these gen- 

 tlemen for making the identifications. 



(3) 



