The New International Encyclopædia/Ship-worm

SHIP-WORM, or Teredo. An aberrant or much modified lamellibranch mollusk of the family Teredinidæ, so called from being worm-like in general shape, and from boring into the hulls below the water line of vessels. The animal is several inches to three feet in length. The shell itself is much reduced, equivalve, widely gaping, and only covers a part of the animal. The mantle of the animal secretes a calcareous lining to the burrow. Teredo navalis is said to be cosmopolitan, and is the most abundant species on our coast. Several species habit the eastern coast of the United States. The ship-worm besides honeycombing the logs of wharves, piles, and injuring fish-pounds and traps, as well as lobster-pots, has been a serious pest of wooden ships; for this reason ships have had to be sheathed with copper. Its mode of boring has not been satisfactorily explained; it usually tunnels in the direction of the grain of the wood.

Ship-worms are found in a fossil state first in Jurassic rocks, where their shells are found in burrows made by the animals in wood that is now petrified. They are found in similar situations in the Cretaceous and Tertiary of North America, Europe, and Asia, but show little difference from modern forms. Consult Gould, Invertebrates of Massachusetts (Boston, 1870); Verrill, Invertebrate Animals of Vineyard Sound (Washington, 1874).

A SHIPWORM (Teredo navalis).

Timber bored by the mollusk; t, tube; sh, shell; v, valves of shell; f, foot; c, collar; p, pallets; s, siphons.