HARDWOOD RECORD 



21 



BLOCK OF TIMBER SHOWING TEREDO'S MANNER 

 OF ATTACK. 



n — Foot of Teredo, 

 b — Siplion Tiiljes. 



c — Body of Teredo. 



d — Holes Through wliieh Animal Enters. 



TEREDu IM K.STED MAHOGANY. 



This specimen was taken from a mahogany log 30" in diameter and 16' 

 long in the bay at Belize, British Honduras, utterly destroyed by teredo. 



like uu'inber that protruJes from the body 

 apjiarently where the head ought to be, and 

 for this reason they are considered acepha- 

 lous or headless. This foot they alternately 

 attach and loosen from the bottom of the 

 hole and thus adjust and hold the delicate 

 edges of their shell so that by their slight 

 rubbing or rasping movement the cutting or 

 boring is slowly performed. They also have 

 two small flexible tubes or siphons which ex- 

 tend into the water from the small orifice 

 which was made when the animal first entered 

 the log or timber. These siphons are vital 

 organs of the teredo and must at all times 

 be in connection with the water, otherwise 

 death would be immediate. These siphon 

 tubes are sensitive and are extended or drawn 

 in on the slightest disturbance, as are the 

 palps or feelers of a snail. Through one of 

 these tubes the animal takes in food and 

 water and through the other discharges the 

 excrement from his body. At maturity the 

 teredo is cylindrical and worm-like in appear- 

 ance, and whitish in color. The hole he makes 

 gradually increases in size in accordance with 

 the growth of his body, from the pin-hole on 

 the surface to as much as three-fourths of an 

 inch in diameter at tlie hemispherical termi- 

 nation where the boring ends. The animal 

 ranges from two or three inches to three feet 

 in length. Of course this is the extreme, and 

 is never attained except in tropical waters, 

 under the most favorable conditions, the aver- 

 age being probably twelve or fourteen inches. 

 When once inside the wood the teredo 

 grows rapidly, and the size of the cavity in 

 which he dwells is adjusted accordingly so 

 as to fit or conform exactly to the size and 

 shape of the mollusk at all stages of his 

 development. As they proceed they line the 

 walls of their cell with a calcareous or limy 

 secretion, which hardens and protects them 



from contact with the wood. Tlie end of the 

 hole, however, is left bare to facilitate the 

 boring until the animal has gone as far as he 

 wishes, when this too is sealed over, and his 

 mission so far is completed and he rests for 

 a time, as it were, in a hermetically sealed 

 cell. 



There are other changes that now take place 

 in the development of the teredo. The spawn- 

 ing season is at hand, the animal dies and is 

 dissolved and passes out in a fluid state 



SECTION OF PINE DESTROYED BY TEREDO. 



This piece of pine was taken from the keel of a row- 

 boat destroyed by Teredo navalis at Porto Barius. 

 (luatemala. 



LOOKING OVER A MAHOGANY RAFT IN 

 SEARCH OF TEREDO. 



from the small orifice through which he en- 

 tered and impregnates the sea to produce his 

 kind. 



The teredo, although there maj- be myriads 

 of them, attack the same piece of timber 

 simultaneously, as many as 50 or 75 to thi' 

 square inch, so crowded together that only 

 a very thin film of wood remains between 

 their adjacent burrows. When they can pro- 

 ceed no farther without boring into the habi- 

 tation of another, one must stop and cease 

 to exist, and the survivors are enabled by the 

 increase of room to proceed until some of 

 their number are again cut off by their neigh- 

 bors who have overreached them ; and for 

 this reason, the tunnels or tubes become 

 larger but less numerous as they go farther 

 into the wood. They never cross the slightest 

 crack or crevice of any kind and if the hull 

 of a boat is made of two layers of lumber. 



the inner one will not be attacked as long as 

 the outer layer remains in place. There is 

 no opening into the animal's cell, save the 

 little speck or opening where he first entered, 

 and these are the only outer indications of 

 his presence, although the interior when 

 opened up may be honeycombed with his 

 borings. 



There arc many varieties of this destruct- 

 ive pest, and the most heavily infested waters 

 on the globe are the Gulf of Mexico and Car- 

 ibbean sea, but they gradually decrease in 

 proceeding northward to the coast of Green- 

 laud, where they are unknown. As a destroy- 

 er of harbor and dock timber the teredo has 

 no equal. The hardness of the wood in which 

 lie works seems to cut no figure whatever 

 with his borings, as he burrows with equal 

 ease in pine, oak or mahogany, not changing 

 his course much to avoid a knot or hard place 

 in the wood, and frequently he perforates the 

 harder woods such as ebony and Ugnumvitae, 

 and it has been proven that a certain species 

 of these mollusks, the limpet, burrow their 

 way through rock. The grain of the timber 

 does not affect his course in the least as he 

 is liable to cut square across it, going through 

 the annular rings or layers at right angles as 

 he passes from the bark toward the heart of 

 a log floating in the water, or he may direct 

 his course downward or lengthwise of the 

 grain as he usually does in a piling or timber 

 standing upright in the water, as the wood- 

 work of harbors or dock, or he may bore 

 through the medullary rays of the wood at 

 any conceivable angle. 



OAK PILING BADLi: DAMAGED P.Y TEREDO. 



This section was cut from an oak piling removed 

 from the dock at Porto Cortez. Honduras, which 

 was utterly ruined by teredo after standing in the 

 water two years. The specimen contained some 

 holes fully three-fourths of an inch In diameter. 



