Shipworms could defeat a navy before a single cannon was fired. (RB)

Shipworms could defeat a navy before a single cannon was fired. (RB)

A piece of wood eaten by shipworms is displayed at the Waterfront Museum in New York City. (AP)

A piece of wood eaten by shipworms is displayed at the Waterfront Museum in New York City. (AP)

Shipworms in History

Posted: July 1, 2019

Divers put on their suits and masks. Down they go! But they’ve come too late. Shipworms got to the shipwreck first!

Shipworms—also called teredos—are wood-eaters. They’re a kind of saltwater clam. Their important work makes shipwreck researchers’ work harder. And in history, their ship-chomping has put lives in danger. Just ask the people who rode on old, clam-bitten ships!

We can read about shipworms in writings as old as ancient Greece. The clams hitched rides on boats way back then, eating up wood as they traveled. And the creatures have continued making trouble since then. Life at sea hundreds of years ago was hard enough without having to worry about shipworms. (Think months-long voyages, seasickness, rough waters, and lack of fresh food.) But we know that shipworms were a real problem. They attacked and sank at least two of Christopher Columbus’s ships in 1503.

In 1588, 130 ships—the Spanish Armada—sailed from Spain to invade England. But the shipworms must have been on the British side of that fight! While the Armada was busy sailing, the shipworms were busy eating! The Armada weakened. The clams did their job so well the ships couldn’t stand up to English cannonballs. It also became easier for storms to sink them. Some say shipworms have sunk more ships than pirates have!

It’s no wonder people first called teredos worms. The creatures have long bodies. They wear little shells almost like hats on their heads. Poky parts stick out of their heads like teeth. These “teeth” make them able to drill into wood.

Hundreds of years ago, people looked hard for a good way to fight the toothy clams. Companies in Canada set off dynamite in the water to kill shipworms. Other people poured dangerous chemicals into the water to get rid of them. Sailors looked all over the world for wood that could resist them. None of these ideas worked. They mostly caused more trouble!

In 1761, shipbuilders started covering wooden ship hulls with copper to keep shipworms out. God created shipworms for good reasons. The ocean needs them! They can eat waste most other creatures can’t. But people had to use creativity—and materials like metal and concrete—to learn to live with them.