Teredo The Terrible Shipworm That Eats Wood

Not even the most cleverly crafted horrors of science fiction comes close to a lowly mollusk in terms of the dread that it once inspired in man. It is present in practically all seas near the shore. It is a long worm-like animal with two small shells at the head which serve it for boring implements.

The larvae are free swimmers, which, coming in contact with wood of any sort, attached themselves to it and tunnel, not to eat the wood, but to fashion a home for their soft bodies.

The teredo quickly became an enemy of navigation and the marine arts of man back when ships were made solely of wood. Even worse, for uncounted years, it tunneled and broke up trees and driftwood brought down the rivers, which threatened to dam the waterways, flood the surrounding land, and convert land into marshes.

Man in due course took the sea with his ships of wood, built himself little wooden piers, fenced out the sea with the trunks of trees and hewn timbers. His works and his vessels appeared where the teredo had long been accustomed to see a home in any timber brought into contact with the sea. It took his possessions with rest. It bored the hulls of his ships and became the terror of the mariner. It attacked the timber work of harbors, causing slow but enormous damage.

Less than three centuries ago, these so-called shipworms endangered the existence of Holland. It was discovered that the teredo had eaten far and near into the timber defenses of the land. The terror seized the little nation which had never feared human armies on land nor enemy navies at sea prior to that time.

The quick thinking Dutch soon learned to face their sea dykes with stones. History was to repeat itself though in the 19th century when waterfronts along the New England coast started to collapse for the same reason.

If you think that teredo are a terror of the past -- forget it. They are still wrecking havoc today. They are still taking piers today and it's now known that they will also eat through cement.

In the long record of world exploration, the teredo, it is supposed, accounted for many a little ship which sailed to the tropics on the other side of the world and vanished forever from knowledge.

It's rumored that even Christopher Columbus was stranded briefly during one of his voyages in Jamaica in 1503, when shipworms ate through and damaged his ships.

If you are wondering how that could happen, remember that shipworms don't like to bore into other shipworm's tunnels. So they twist and turn their tunnels away from other teredos until an invested piece of timber becomes a mass of tunnels and holes that eventually collapse. By the time this happens, it's usually too late for the timber to be saved.

When at last it was recognized that no chemical treatment of timber could keep the teredo at bay, copper sheathing for the hulls of ships was applied, but copper sheathing was apt to be torn away, and wherever that happened, in went the deadly teredo, to work secret damage, till perhaps the good ship went down with all on board. Pretty impressive for such a small bivalve mollusk!

How these little devil mollusks work their evil is an interesting short story in a sentence. When the teredo bore into submerged and wet wood with their little valves, a certain bacteria inside their bodies allow them to digest the wood cellulose.

Describing them as "little" probably isn't correct either, as they are known to grow up to two feet in length.

Their bodies have often been compared to being cigar-shaped capped with two razor sharp shells at the head. In the middle of the the two shells is a muscular food that allows the creature to stabilize itself while the shells are working, chomping through the wood.

The teredo essentially eat the wood, digesting the majority of it with the bacteria in their stomachs. However, this diet is not enough to sustain them so they also periodically feed on plankton and other tiny passing animals.

Reproductively, the females cover and protect their eggs waiting for the male sperm to be cast from the males. The eggs grow still protected by their mothers until they become larvae that move on to find their own wood. An entry point for these terrors of wooden ships only need be a tiny crack or indent in the wood grain.

Think of the old Pac-man video game, and you've got a very illustrative picture of how they do their evil deeds.

Since they still are the scourge of wooden boat owners, they are the primary reason why boats frequently and regularly need to be painted. Marine paint contains copper that somewhat wards off the teredos. As the paint wears off, the protection it affords also wears off.

Most people would be shocked to know how many inventions of man were really spin-offs of serious observations of nature. This was true in the case of the teredo.

The behavior and life-cycle of the lowly shipworm was inspiration for much of what would evolve as engineering technics in the development of a tunneling shield. Tunneling shields allows engineering crews to tunnel through unstable land under water. In fact, it was this discovery that allowed the Thames Tunnel to be built under the Thames River.

Seems like basically if it is alive, mankind will find a way to turn anything into food. This is true of the teredo, although in the Philippines the creature is called the Tamilok.

Once cleaned with vinegar or lime juice, it is added to chopped chili peppers and onions. It's considered a delicacy and quite popular dish.