Adventist Youth Honors Answer Book/Nature/Shipworm

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 which are immersed in sea water, including piers, docks and wooden ships. Sometimes called "termites of the sea", they are marine bivalve molluscs (Eulamellibranchiata) in the family Teredinidae.

They bore into submerged wood, and bacteria in a special organ called the gland of Deshayes enable them to digest cellulose. The excavated burrow is usually lined with a calcareous tube.

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 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. Shipworms greatly damage wooden hulls and marine piling, and have been the subject of much study to find methods to avoid their attacks.

In the early 1800s, the behavior and anatomy of the shipworm inspired the great 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.