Teredo
Aiton's Encyclopedia (1910)
ter-e'do, or Shipworm, a marine shellfish noted for boring and living in submerged wood and rocks. The common teredo has a long, gelatinous, transparent, cylindrical, worm-like body, with a pair of minute shell-like valves worn on the head. This animated auger follows the grain of the wood. It makes a passage the full length of the timber, turning aside only when it encounters a knot or the body of another teredo. The teredo enters the wood by a hole no larger than a pinhead. As it grows it excavates farther and farther, simply for a home. The sawdust made is expelled by the small entrance through which a stream of sea water is entering and departing. This water passes through the teredo by a U-shaped tube and supplies a diet of microscopic animals and plants. A timber honeycombed by these parallel borings from the size of a knitting needle to half an inch in diameter is a curious sight. Wooden wharves are rendered unsafe and wooden ships are made worthless, it is said, in a single season. Piling may seem sound and yet be unsafe. Copper sheathing is often used to protect woodwork. Painting with creosote is some protection. See Barnacle Terence (185-159 B. C.), a Roman comedian. Terence was the slave of a rich senator, who, seeing talent in the boy, set him free. The Mother-in-Law, The Self-Tormentor, and The Eunuch, are the translated names of his more prominent plays. He has been compared to the English Congreve, noted rather for wit and sprightliness than for purity of morals. SAYINGS. Hence these tears. I am a man. Fortune favors the brave. Many men, many minds. I did not care one straw. What a difference there is between a wise person and a fool.
What Has Changed in the Last Century
Aiton's 1910 account says the teredo tunnels "simply for a home" and feeds on microscopic plankton drawn in with the seawater. That is only half right: shipworms also digest the wood itself, and in the 1980s researchers found the key — colonies of symbiotic bacteria living in the animal's gill, which supply the cellulose-splitting enzymes and fix nitrogen for their host, a partnership found nowhere else among animals. The practical side of the entry has aged more than the biology: copper sheathing and creosoted piles have given way to concrete and steel piling, and wooden ships no longer rot away "in a single season" because there are almost none left. The pest itself is undiminished, still chewing through harbour works, and warming, less brackish seas have carried it into waters such as the Baltic where it was once scarce.
Written for this edition, 2026.