The Ship Worm 



be expelled by one female. The young are free-swimming for 

 a week or two. When the size of a pinhead they settle on a 

 floating tree or timber, tree roots, a ship's bottom, piles of bridges, 

 or wharfing — any wood surface soaked in sea water is suitable 

 to harbour them, provided it is not especially "medicated" to 

 discourage their colonising it. 



The tiny hole the Teredo makes to enter is never enlarged, 

 though the burrow widens as it lengthens behind it. Only the 

 slender tips of the siphons are extruded, imbibing and excreting 

 organs. These are also sensitive tentacles. Back from their 

 tips they are bound together, and two shelly valves, called pal- 

 lets, or claustra, are hinged to the muscular wall. Pick up a bit 

 of floating wood in New York harbour or elsewhere, and you are 

 likely to cause a sparse fringe of colourless siphons to be suddenly 

 retracted. The surface shows only inconspicuous pinholes. Cut 

 into the wood, and it is honeycombed with tubes. Long, worm- 

 like bodies inhabit shell-lined burrows. The pallets have sprung 

 forward to cover the tips of the retracted siphons, and form a door 

 barring the entrance eifectually. 



The pallets, by compressing and relaxing the walls of the 

 siphons, help to pump water through the long canal. Perhaps 

 they help to excavate the sides of the burrow after the foot had 

 done the first hard digging. Possibly the valves of the shell assist. 

 The problem is unsolved as yet. The shelly lining of the burrow 

 is deposited by the mantle. 



The shipping of the world has been at the mercy of this hardy 

 little devastator, until metal sheathing and creosote oil were 

 applied to submerged surfaces of wood. Uncounted methods 

 were tried before success was reached. Ships' bottoms crumbled 

 before a sign showed the timbers to be infested with the worm. 

 Piles of bridges and wharves snapped below the water line for 

 like reasons. 



The ship worm does not like the taste of creosote, so painting 

 with this, or better, soaking timbers in the oil or forcing it into 

 the fibre by pressure, insures the preservation and defence of the 

 wood against decay and ship worms. It is a double advantage 

 to use it. Unprotected wood is rarely used in wharf and ship- 

 building. Driving copper nails into timbers discourages the Teredo, 

 but it is not a thorough method. There are still unguarded 

 areas where rot and the borer may enter, and work at the heart. 



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