SOME NOTES ON AMERICAN SHIFWORMS, 



BY CHARLES P. SIGERFOOS, B. S., PH. D., 



Assistant Professor of Animal Biology, University of Minnesota. 



In a Congress like this, where men meet to discuss the means of protecting and 

 increasing the supply of the toothsome products of our waters, a paper on shipworms 

 may seem in strange company. While we wish to preserve and protect most of the 

 products of our waters, these creatures we would gladly obliterate from the realm of 

 living things. We have been studying and combating them for a century and more, 

 but have found no adequate means of counteracting their depredations. 



During the summer of 1893, while engaged in observations on the oyster at Beau- 

 fort, N. C., for the U. S. Fish Commission, the writer became interested in the various 

 shipworms found so abundantly in the waters of that region, and having made some 

 observations on their natural history he returned for periods during the two succeed- 

 ing seasons to continue them. The results have been incorporated in a paper on the 

 " Natural History, Organization, and late Development of the Teredinidce," which is 

 almost ready for publication. 



Shipworms were favorite objects of study during the eighteenth century, on 

 account of their great damage to the dikes of Holland in 1733 and subsequent years. 

 The contemporaneous observers seem to have been unaware of the observations of 

 Pliny and others in ancient times, and supposed the shipworms were natives of India, 

 whence they had been brought by shipping in modern times. During these times 

 they were considered true worms, and it was not till the time of Cuvier that their 

 molluscan characters were recognized. 



Even if shipworms were not recognized to be bivalve- moll asks from their adult 

 organization, it would be easy to determine this fact from a study of the development. 

 They start as eggs which none but a specialist could distinguish from the eggs of 

 most bivalves. In the American forms that seem most abundant, at least in our 

 southern waters, the eggs are cast freely into the water and soon fertilized by the male 

 element. They soon begin to develop, and in our warm southern climate become little 

 free-swimming creatures in three to four hours. As yet these little creatures have 

 none of the distinctive features of the shipworms or even of bivalve-mollusks, but within 

 a day the bivalve shell is acquired. For a few days one can rear the larvte in aquaria, 

 but after a time the conditions become unfavorable, and they disappear. For perhaps 

 three weeks more, in a state of nature, they lead a free-swimming life, and are grad- 

 ually transformed into little free-swimming bivalves, almost exactly like the little clam 

 or oyster. But how and where, in nature, this transitional period is passed has not 

 been observed. 



The next stage which the writer found were the little bivalves about T o i Q ch in 

 diameter, crawling over the surface of the wood, in quest of their future homes. Once 



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