Shipworms are not worms at all, but rather a group of unusual saltwater clams with very reduced shells, notorious for boring into (and eventually destroying) wooden structures that are immersed in sea water, such as piers, docks and wooden ships. Sometimes called "termites of the sea", they are marine
bivalve molluscs (
Eulamellibranchiata) in the family
Teredinidae, also often known as
Teredo Worms.
When shipworms bore into submerged wood, bacteria (
Teredinibacter turnerae strain ATCC 39867 / T7901) in a special organ called the gland of
Deshayes allow them to digest
cellulose. The excavated burrow is usually lined with a
calcareous tube. Shipworms have slender worm-like forms, but nonetheless possess the characteristic structures of
bivalves. The valves of the
shell of shipworms are small separate parts located at the anterior end of the worm, used for excavating the burrow.
The shipworms belong to several
genera, of which
Teredo is the most commonly mentioned. The best known species is
Teredo navalis. Historically,
Teredo concentrations in the
Caribbean Sea have been substantially higher than in most other salt water bodies.
Shipworms greatly damage wooden hulls and marine
piling, and have been the subject of much study to find methods to avoid their attacks. Copper sheathing was used on wooden ships during the
Age of Exploration, as a method of preventing damage by "teredo worms".
Christopher Columbus's ships were among the earliest known to employ this defence.
In the
Netherlands the shipworm caused a crisis in the 18th century by attacking the timber that faced the
sea dykes. After that the dykes had to be faced with stones. A genus of shipworm,
Teredo have recently caused several minor collapses along the
Hudson River waterfront in
Hoboken, New Jersey due to damage of underwater pilings.
Genera within the family Teridinidae
Engineering inspiration
Teredolites borings in a modern wharf piling; the work of bivalves known as "shipworms".
In the early 1800s, the behaviour and anatomy of the shipworm inspired the British
engineer Marc Brunel. Based on his observations of how the shipworm's valves simultaneously enable it to tunnel through wood and protect it from being crushed by the swelling timber, Brunel designed an ingenious modular iron tunnelling framework - a
tunnelling shield - which enabled workers to successfully tunnel through the highly unstable river bed beneath the Thames. The
Thames Tunnel was the first successful large tunnel ever built under a navigable river.
Culinary Delicacy
In
Palawan in the
Philippines, the shipworm is called
Tamilok and is eaten as a delicacy there. It is prepared as
kinilaw - that is, raw (cleaned) with vinegar or lime juice, chopped chili peppers and onions, very similar to
Ceviche. The taste of the flesh has been compared to a wide variety of things, from
milk to
oysters.
See also
