shipworm

Shipworm
Teredo sp.
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia (or Pelecypoda)
Order:	Myoida
Family:	Teredinidae Rafinesque, 1815
Genera
See text.

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.^[1]

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.^[2]

Genera within the family Teridinidae

• Bactronophorus
• Bankia Gray, 1842
• Dicyathifer
• Kuphus
• Lyrodus Binney, 1870
• Nausitoria Wright, 1884
• Neoteredo
• Nototeredo Bartsch, 1923
• Psiloteredo
• Spathoteredo Moll, 1928
• Teredo Linnaeus, 1758
• Teredora Bartsch, 1921
• Teredothyra Bartsch, 1921
• Uperotus

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.^[3]

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 foods, from milk to oysters. ^[4]

See also

• Gribble

References

• Teredinidae (TSN 81832). Integrated Taxonomic Information System.
• Powell A. W. B., New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 ISBN 0-00-216906-1

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