SHIP WORM ON ATLANTIC COAST 95 



SESSIONAL PAPER No. 38a 



piles had been creosoted (ten pounds to the square foot) before they were driven in, 

 but not to much purpose."^ 



The palmento of the southern states and some of the Australian woods are said 

 to be immune from the attacks of Teredo. The papers by Putnam^ and Cunningham^ 

 contain much information on the habits of Teredo. 



An Icelandic naturalist^ has made some interesting observations and experi- 

 ments on the habits and biological characteristics of Teredo norwegica, the species 

 found on the southern and western coasts of Iceland. Mr. Frits Johansen has kindly 

 furnished the following translation and summary of these from the Danish : " The 

 propagating (spawning) season continues through the whole summer (April- August). 

 No larvse are found in the mantle-cavity or in the sea ; but numerous very small ones 

 (burrows 1mm. long 0-5mm. wide) are found in driftwood from Faxebugt (W. coast) 

 at the end of July. 



" The growing period is mostly limited to two years as shown by experiment : I 

 kept some pieces of wood with Teredo taken from the false keel of a fishing boat and 

 kept it in a shaded cool place ; the animals remained alive ten days ; but inside of two 

 weeks all were dead. Kept in a temperature of 6° C. for two days they all froze stiff, 

 but were alive when thawed out again. In fresh water they only lived two to three 

 hours ; three hours in half sea and half fresh water or in putrid sea water. 



" It is mostly only on two places that ships are attacked ; at the waterline and in 

 the false keel (or if this is missing the lower part of the keel itself). That this keel 

 part is attacked is because it is buried in the sand, when the ship is beached, and thus 

 gets no paint or tar. The " waterline " part of the ship gets easily its protection of 

 paint or tar scraped off when loading, anchoring, etc. Plank edges are first and most 

 attacked. 



" The Teredo avoids leaving the wood in which it bores. Hence from the false 

 keel only a few had penetrated to the true keel, and the burrows avoided the outer 

 surface of the false keel. Where two parts of the false keel joined, the burrows never 

 went through the contact but stopped short of a couple of inches. But how does the 

 Teredo know when to stop burrowing? Maybe by sound-sense? In piers at Eeykjavik, 

 where Limnoria lignorum Ratk. burrows together with Teredo, one frequently sees that 

 Limnoria eats away the woodparts surrounding the Teredo burrows and the calcareous 

 lining of the Teredo burrows are exposed. Teredo therefore protects itself by thicken- 

 ing its calcerous lining 3 to 4 times the usual thickness by internal secretions. 

 " Boats on the water at the south and southwest coast are attacked by it. 

 " In later years it has been very numerous and destructive in sea-going ships 

 belonging to the southwest coast ; in many cases Teredo has been imported with ships 

 bought in England, but some ships built in Iceland or lumber put into ships in Iceland 

 have been attacked. Ships belonging to the north and northwest coasts (beached 

 during the winter) seem to be free of Teredo. Maybe the many English ships bought 

 and the unusually mild winter, and the fact that the ships are on the sea all winter 

 are the causes of its frequency at the southwest coast for the last five or six years. 



"The largest Teredo I have seen measured 27-5 cm. (to the base of the siphons) 

 siphons ca. 2-5 cm.; average size of Teredo 16-18 cm., built in 1892." 



iIMd, p. 135. 



2 Putnam, J. W. — The Preservation of Timber. Scientific American Supplement, Vol. X, No. 

 236, July 10, 1S80, 3762-3763. 



3 Cunningham, J. T. — Teredo. Encyclopaedia Britannica, 9th Ed., Vol. XXIII, 188S, pp. 

 184-186. 



4 Saemundson, B. Zoolog. Meddel. fra Island (Zool. Notes from Iceland, p. 43, pp. 57-60). 

 Vidmskab. Meddel. fra Naturhist. Poren. Kbhn. for Aared 1903 (Scientific papers from Natural 

 History Society in Copenhagen for year 1903). 



