The sea-side book; being an introduction to the natural history of the British coasts / By W.H. Harvey.

  • William H. Harvey
Date:
1849
Catalogue details

Licence: Public Domain Mark

Credit: The sea-side book; being an introduction to the natural history of the British coasts / By W.H. Harvey. Source: Wellcome Collection.

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    TEREDO, OR SHIP-WORM. But the acute observer (]Mr. J. V. Thompson) who first discovered it, had the satisfaction of watching its change from this active life to the sedentary state of a Balanus. The animal fixes itself, the shell is gra- dually formed, ciliated arms or cirrhi take the place of feet, and the eyes are cast away, as being no longer needed. Here we have another instance of what looks like a retrograde developement; but this apparent anomaly is to conduct us to a division of the animal kingdom in which the external organs are less perfect than in the groups below them, but the internal or- ganization, and especially the nervous system, is more complete. Barnacles attach themselves to the surface of ships’ timbers, and their pendant bodies, if suffered to remain, will materially obstruct the ship’s motion or way. But they do no further damage. There are, however, other Mollusca, the Teredines, or Ship-worms, whose attacks are far more fatal. These are not contented with a su- perficial station, but seek a secure resting-place within the log; and, when once they take up their residence, soon riddle the substance through and through, reducing the wood to a mere shell. Any wood-work constantly submerged is subject to their attacks, and it is asto- nishing with what rapidity the work of destruction goes on. Piles of solid pine-timber, of large size, have been proved to be perfectly destroyed within five years. The Teredo enters at any part of the surface, but soon bends its course in the direction of the grain, and forms a burrow some feet in length, and varying from a quarter to half an inch in diameter. This he lines, as